Browse Topic: Boost pressure

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An Open-Source Framework to Automate Virtual Optimization of Internal Combustion Engine Calibration Maps through Shape-Based Strategy2026-37-00016/9/2026
The automotive industry is facing increasingly stringent regulatory constraints, driving the need for faster and more efficient powertrain development. This results in higher systems complexity, making internal combustion engine calibration progressively more challenging to meet performance and emissions targets. This, combined with the manual nature of traditional calibration workflows, leads to a time-consuming process that heavily relies on human expertise. Although virtualization can reduce development time and costs, the overall workflow remains largely dependent on manual decision-making and iterative refinement. In this context, this work presents a virtual calibration framework based on a genetic algorithm, aimed at the automated optimization of engine calibration maps to satisfy performance and emissions constraints, while reducing manual effort. Each calibration map is represented through a polynomial parameterization. Specifically, a generic three-dimensional polynomial with map-specific order encodes the shape of each map, ensuring smoothness which directly impact on drivability. Accordingly, the calibration problem is reformulated as the optimization of a compact set of polynomial parameters that uniquely define the full set of calibration maps, rather than individual set-point. Each candidate solution is assessed by generating the corresponding calibration maps and simulating the engine behavior through a neural-network-based digital twin, providing predictions of operating conditions, hardware limits, performance metrics, and emissions. The proposed framework was validated on a passenger-car diesel engine, considering a reduced yet representative set of calibration maps, including main injection start of injection, air mass, boost pressure, and injection rail pressure. The objective of optimization was the minimization of brake mean fuel consumption, subject to an upper bound constraint on nitrogen oxides emissions. The global optimization process explored approximately 106 different calibration candidates within about 36 hours, leveraging parallel computation on a standard laptop. The results indicate that the procedure can deliver multiple near-optimal preliminary calibration solutions, providing an effective starting point for subsequent manual finetuning.
Romano, Gianvito, Aglietti, Filippo, Spedicato, Tonio, Cozza, Ivan Flaminio, Capra, Andrea
1D System Evaluations for Efficiency Trade-Offs for a Heavy-Duty H2ICE Concept2026-01-02744/7/2026
Lean H2 combustion strategies have shown promising gross thermal efficiency and ultra-low engine-out NOx emissions for H2-fuel based internal combustion engines (H2ICE) in heavy-duty (HD) transport. Implementing lean combustion strategies require excessive air flow demand that further increases with the engine load increase. To meet such air flow demands efficiently across a wide engine operating region, a detailed system optimization is warranted including next generation turbocharging systems. In this 1D system analysis campaign, a detailed study of various air-system configurations was conducted for a modified HD, direct-injection (DI), H2ICE concept based-off a Cummins heavy-duty 15L engine. The concept engine configuration had a geometric compression ratio of 10.4 and no external exhaust gas recirculation (EGR) was implemented. First, a calibrated 1D engine model representing the H2ICE concept was developed. Using the 1D model, a detailed system-level analysis was conducted at five operating conditions from the heavy-duty SET cycle: A75, A100, B75, B100, and C100. A wide range of lambda levels, valve phasing, miller strategies were characterized by the gross engine performance improvements. Subsequently, different air-system configurations were evaluated for closed-cycle efficiency vs pumping losses trade-offs, while meeting the air flow targets. For next-generation turbocharging, both single stage (1S) and two-stage (2S) boost systems were simulated. Air versus external EGR dilution strategies were also studied at boost-limited engine operating conditions. From the results, high lambda levels reflected the benefits of lean combustion operation. Implementing millerization and cam phasing further elevated these benefits, at the expense of high boost pressure demands. The 1S boost system, with advantages of low-complexity and post-turbine thermal performance, incurred rapidly deteriorating turbocharger performance from the choke and the surge limits for lambda levels beyond 2.2. A 2S boost system achieved higher lambda levels without risking compressors choke or surge limits. Irrespective of turbocharging, the required intake charge cooling was noted ~2-3x times of the conventional diesel engine levels, depending on the targeted lambda levels. A detailed fuel-energy balance analysis was conducted to highlight system trade-offs between the 1S and the 2S based H2ICE configurations.
Kumar, Praveen, Sari, Rafael, Merritt, Brock, Popuri, Sriram
Key Parameters for Turbocharger Selection & Experimental Validation for off-Highway Applications2026-26-01041/16/2026
Customers in off-highway industry are increasingly seeking high-performance capabilities for their tractors due to increasing penetration of mechanisation and labour scarcity. One effective solution to achieve enhanced performance is turbocharging of engines, while meeting emission and highly dynamic transient response of tractor field applications. The process of selecting and validating a suitable turbocharger for tractor field application suitability is significantly time and resources consuming activity due to extensive testbed and field trials. This study focuses on the selection of turbocharger for tractor engines through analytical calculations to freeze key parameters like lambda, boost pressure ratio & temperature within boundaries of exhaust temperature and turbo efficiency maps to deliver best field transient performance and fuel consumption. The selected parameters are further validated under real-world transient operating conditions, involving tractors and their implements. This approach offers significant advantages by cutting development time and costs for engine while meeting highly dynamic transient performance.
Kumar, Harish Kumar, Rawat, Saurabh, Dogra, DaljitSingh, Singh, Sachleen, Singh, Amarinder
Development of High BMEP Natural Gas Engine with Knock Mitigation2026-26-01211/16/2026
The stringent emission norms over the past few years have driven the need to use low-carbon fuels and after treatment technology. Natural gas is a suitable alternative to diesel heavy-duty engines for power generation and transportation sectors. Stoichiometric combustion offers the advantages of complete combustion and low carbon dioxide emissions. Turbocharging and cooled exhaust gas recirculation (EGR) technology enhances the power density along with reduced exhaust emissions. However, there are several constraints in the operation of natural gas spark ignition engine such as exhaust gas temperature limit of 780 °C, sufficient before turbine pressure for EGR drivability, boost pressure, peak cylinder pressure limit and knocking. These limits coulld restrict the engine BMEP (brake mean effective pressure). In the present study, tests were conducted on a V12, 24 liters, heavy duty natural gas fuelled spark ignition engine (600 HP) with different EGR and turbocharger configurations to achieve 16 bar BMEP without abnormal combustion. Considering the maximum exhaust temperature limit of 780 °C of exhaust system, minimal engine hardware changes were done to ensure less complexity, cost-effective engine development with robust design. The turbine trim was decreased from 89% to 84% to avoid excessive high before turbine backpressure, backflow of residual gases into cylinder and knock possibility. EGR system optimization with mixer enhanced EGR mixing and distribution in all cylinders that improved BSFC by 3%. During knock calibration, the offset to base ignition timing was used for individual cylinders to mitigate knock. Endurance trial of 100 hours was carried out to validate the reliability of engine design and calibration, and no issues were detected. The developed engine is the highest BMEP V12 engine in its segment in India using stoichiometric combustion with cooled EGR and three-way catalyst. The engine is certified with latest Indian CPCB IV+ emissions norms.
Khaladkar, Omkar, Marwaha, Akshey
Optimization of a Positive Displacement Type Supercharger Using Response Surface Modeling (RSM)2026-26-04291/16/2026
Air suction in a naturally aspirated engine is a crucial influencing parameter to dictate the specific fuel consumption and emissions. For a multi-cylinder engine, a turbocharger can well address this issue. However, due to the lack of availability of continuous exhaust energy pulses, in a single or two-cylinder engine, the usage of turbocharger is not recommended. A supercharger solution comes handy in this regard for a single or two-cylinder engine. In this exercise, we explore the possibility of the usage of a positive displacement type supercharger, to enhance the air flow rate of a single cylinder, naturally aspirated, diesel engine for genset application, operating at 1500 rpm. The supercharger parametric 3D CAD model has been prepared in Creo, with three design parameters i.e. (a) Generating radius, (b) depth of blower and (c) clearance between lobes & lobe and casing. The optimum roots blower design is expected to fulfil the target boost pressure, power consumption and hydraulic efficiency requirements. The baseline DoE using Sobol algorithm generates 28 designs, which has been simulated using the Ansys CFX software via modeFRONTIER process automation. A sensitivity analysis of the input variables on the response variables establishes that generating radius is the most dominant parameter influencing the pressure, efficiency and power consumption. A detailed Response Surface analysis using 12 different algorithms showed that, Anisotropic Kriging captures the pressure variable accurately, while Gaussian Process captures the efficiency and power consumption with the best accuracy as per R-squared comparison. A virtual optimization conducted using the favorite RSMs using the MOGA algorithm generated an optimum roots blower design which complies all the constraints for pressure, efficiency and power. RSM optimized design is further validated in the CFX software, and the results for response variables are accurate within 6% error margin.
Satre, Santosh Dadasaheb, Mukherjee, Nalini, Rajput, Surendra, Nene, Devendra
Improving Late Pilot Injection Strategy in Dual-Fuel Diesel/Methane Engines through Supercharging and Hydrogen Enrichment03-18-08-004912/24/2025
In this study, a novel dual-fuel combustion strategy is investigated, employing late pilot injection in diesel–methane engines to improve performance and reduce emissions. The engine was first tested with conventional diesel and methane, exploring a wide range of pilot injection timings, injection pressures, and intake boost pressures. Subsequently, experiments were repeated using a methane/hydrogen blend to assess the influence of hydrogen addition. Results show that, when using only methane, delayed pilot injections have minimal effects on engine performance. In naturally aspirated operation, unburned hydrocarbons and carbon monoxide are reduced, while in supercharged conditions, emissions increase; however, they remain within acceptable limits. Nitrogen oxides and particulate matter reach their lowest levels with delayed injection. Introducing hydrogen reduces engine performance and hydrocarbons and carbon monoxide emissions; notably, it suppresses the typical nitrogen oxides increase associated with hydrogen, while also lowering particulate matter. These findings demonstrate that combining late pilot injections with hydrogen addition and supercharging is a promising strategy for improving dual-fuel engine efficiency and emissions, offering a potential pathway toward cleaner combustion.
Carlucci, Antonio Paolo, Strafella, Luciano, Ficarella, Antonio
Effective Power Management on Diesel Engine Using Electrified Turbocharger2025-28-024211/6/2025
The growing demand for improved fuel efficiency and reduced emissions in diesel engines has led to significant advancements in power management technologies. This paper presents a dual-mode functional strategy that integrates electrified turbochargers to enhance engine performance, provide boost and generate electrical power. This helps in optimizing the overall engine efficiency. The engine performance is enhanced with boosting mode where the electric motor accelerates the turbocharger independent of exhaust flow, effectively reducing turbo lag and provides immediate boost at low engine speeds. This feature also improves high altitude performance of the engine. Conversely, in generating mode, the electric turbocharger recovers or harvest energy from exhaust gases depending on engine operating conditions, converting it into electrical energy for battery recharging purpose. Advanced control systems enable real-time adjustments to boost pressure and airflow in response to dynamic driving conditions, maximizing engine efficiency. Simulation studies and engine testing validate the expected benefits, demonstrating that the electrified turbocharger can significantly facilitate engine downsizing, reduce fuel consumption, and lower emissions through precise power management. These advancements align with global sustainability goals, presenting a viable solution to meet stringent environmental regulations while maintaining robust engine performance. The integration of electrified turbochargers represents a critical step towards the next generation of eco-friendly diesel engines, supporting both environmental sustainability and economic efficiency.
Borle, Shraddha, Prasad, Lakshmi, Couvret, Sebastien, Fournier, Hugo, Chenuet, Laurent
Diagnostics Methodology for Turbocharger System Using Data Driven Models2025-28-040410/30/2025
In a conventional powertrain driven by Internal combustion (IC) engines, turbocharger (TC) is a key component for enhancing performance and efficiency. Predominantly turbochargers are used to serve multiple purposes of downsizing, increased power, better fuel efficiency, reduced emissions, and improved performance at high altitudes. TC is responsible for fulfilling the air mass requirement of the engine at different operating conditions. Failure of TC system leads to abnormal engine operation. If the TC hardware is beyond repair, the associated replacement cost is very high. Ultimately, a predictive diagnostics approach is required to identify the issue with TC so that the failure of TC could be avoided. The proposed methodology uses advanced artificial intelligence technique called recurrent neural network (RNN) and long short-term memory (LSTM) network for predicting faults in a typical TC system. In this study, actual values of TC speed and boost pressure are obtained from physical sensors present on the vehicle whereas estimated values of TC speed and boost pressure are obtained from data driven models. To enable predictive diagnostic of TC, a fault detection unit is incorporated which differentiates between the various fault conditions such as TC hardware fault or sensor fault. For initial validation, this methodology was applied to a healthy TC system to ensure that fault conditions were not getting active. For further validation, a faulty TC system was selected. Using the proposed approach, degradation in the boost pressure and TC speed for faulty TC was successfully identified. Various fault conditions and steps involved in the fault detection are clearly described.
Jagtap, Virendra Shashikant, Ganguly, Gourav, Mitra, Partha, Patidar, Sachin
Experimental Measurement of Dynamometer Homologation Cycles in a Dual-Fuel Medium-Duty Engine2025-24-00369/7/2025
Dual-fuel engines employing alternative combustion concepts have shown promising results in meeting significant emission reductions while maintaining engine performance. In the medium and heavy-duty transport sectors, where electrification remains challenging, developing low-temperature combustion is still a technological solution for reducing carbon impact. However, most of the results in this research field have been presented under stationary conditions, which still positions the transient operation as a challenge. One of the main reasons has been the lack of a dedicated control system to manage the load transitions and the inoperability of stock turbochargers to satisfy the EGR dilution ratios and boost pressure to sustain dual-fuel combustion. This study employs a modified 7.7 L dual-fuel engine for its operation in transient conditions by incorporating a prototype turbocharger system. The study addresses the recalibration of the engine to introduce modifications to the injection and air management strategies, allowing for a smoother transition between fully premixed and diffusive combustion modes while maintaining low emissions and similar performance. The study identified the transition from 50% to 75% as the most challenging transition from moving from a fully premixed zone with pressure gradients near the physical limits to a more diffusive combustion region in the engine map. After refining the calibration to allow smooth transitions between loads, transient cycle performance under the World Harmonized Stationary Cycle (WHSC) is experimentally measured, progressively increasing load from 50% to 100%. The results under transient tests confirmed that the recalibration successfully enables full-load operation while mitigating combustion instability and excessive emissions. This research advances the understanding of dual-fuel combustion strategies and highlights the potential of dual-fuel engines as a technological solution for its implementation under real-world vehicle applications in the freight transport sector.
Garcia, Antonio, Monsalve-Serrano, Javier, Marco-Gimeno, Javier, Iñiguez, Erasmo
Waste Heat Recovery in Hydrogen Fueled Internal Combustion Engines2025-24-01089/7/2025
Waste Heat Recovery is one of the most investigated and promising technologies for energy efficiency in the transportation sector. It consents to maintain the high-level technology of the present propulsion systems, based on Internal Combustion Engines, while increasing the overall engine and vehicle system efficiency. At the same time, the use of alternative fuels, like hydrogen, has the same crucial role to reduce harmful and greenhouse emissions, without overturn the existing mature technology. A hydrogen-fueled Internal Combustion Engine is proposed in this paper, equipped with waste heat recovery consisting in an additional radial turbine downstream the turbocharger of the engine (Turbo-Compound). The aim is to have a reduction of the specific consumption in most of the operating points of the engine, considering the effect of the recovery and the engine equilibrium rearrangement. The use of hydrogen increases recoverable enthalpy at the engine exhaust, which is intended to be recovered through an expansion of the gases inside the additional turbine. When this secondary turbine is installed downstream of the turbocharger, the overall engine backpressure increases. This alters the turbocharger's operating point, which in turn shifts the engine’s operating conditions. Ultimately, this has a counterproductive effect on the engine efficiency: it faces higher backpressure at exhaust valve opening, leading to an increase in specific fuel consumption. This paper examines the modifications to the engine’s exhaust line resulting from the conversion of waste heat into mechanical energy via a Turbo-Compound system. It discusses the conditions under which the system yields a net positive effect, primarily by compensating for the increased back pressure it introduces. Changes in key engine parameters—such as Variable Geometry Turbocharger control, boost pressure, air/fuel mass flow rate, and equivalence ratio—are analyzed, along with their influence on in-cylinder pressure. Furthermore, the paper identifies the operating range in which the Turbo-Compound system provides a net performance benefit.
Di Battista, Davide, Cipollone, Roberto, Corti, Enrico, Brancaleoni, Pier Paolo, Di Prospero, Federico, Ravaglioli, Vittorio
Using Turbogenerators for Energy Recovery in Turbocharged Hybrid Powertrains2025-24-01009/7/2025
The widespread adoption of battery electric vehicles (BEVs) is progressing more slowly than anticipated, making hybridization crucial for improving efficiency through load point shifting, running the engine at its most efficient operating points and kinetic energy recovery. As the world continues to use fossil fuels, enhancing powertrain efficiency is critical to reducing CO2 emissions. Improved efficiency will also increase the share of renewable e-fuels in the energy mix, supporting the transition to low-carbon mobility. A significant portion of energy in ICEs is lost through exhaust heat, which is a high-grate energy source that can be converted into electricity in hybrid systems. Conventional turbochargers, widely used to enhance volumetric efficiency and drivability, typically incorporate a wastegate (WG) to regulate boost pressure. However, this results in the intentional dumping of excess valuable exhaust energy leading to energy loss. This paper investigates the replacement of conventional wastegate-based turbocharging systems with energy recovery technologies—specifically a turbogenerator and an electrically assisted turbocharger (e-turbocharger)—in a light-duty spark-ignition (LD SI) engine. A fully validated 1D GT-Power simulation model of a production 2.0 L turbocharged engine is used to assess system-level trade-offs in energy recovery, exhaust backpressure, and engine performance. The turbogenerator features a downsized variable geometry turbine (VGT) operating in parallel to the main turbocharger, while the e-turbocharger replaces the conventional turbo system entirely. Parametric simulations evaluate the impact of turbine sizing, mass flow variations, and shaft inertia. Results indicate a maximum recoverable power of up to 21 kW, with realistic net recovery after generator losses in the range of ~ 9–11% of crankshaft power. These findings support the technical feasibility of wastegate-free turbocharging architectures to enhance hybrid powertrain efficiency. Simulation results show that by eliminating WG and implementing a turbogenerator or an e-turbocharger, up to 11.3% of the original crankshaft power – previously lost through WG exhaust can be recovered at high engine loads. This recovered energy can be stored in a battery and reused, contribution to lower CO2 emissions. The findings demonstrate the protentional of such systems to replace conventional turbocharging strategies and pave the way for more energy efficient hybrid vehicle architecture.
Kodaboina, Raghu Vamsi, Vorraro, Giovanni, Turner, James W. G.
Experimental Study of the Lubricating Oil Impact on the Unsteady Performance of an Automotive Turbocharger2025-24-00789/7/2025
Turbocharging technique is a key technology for the development of hydrogen engines, allowing high lambda values to reach low NOx emissions. In ultra-lean mixture conditions, the thermal management of the lubricating oil and its cold condition becomes a crucial aspect that cannot be neglected. Accordingly, the impact of different lubricating oils and different lubricant thermal conditions is highlighted referring to the performance of a turbocharging system for automotive application. To this aim, an experimental campaign is conducted at the test bench for components of propulsion systems of the University of Genoa. Tests are performed on a turbocharger equipped with a variable geometry turbine under both steady and unsteady flow conditions, considering different positions of the turbine regulating device. A 4-cylinder engine head was coupled to the turbocharger in order to reproduce the pulsating flow related to the opening and closing of the engine valves. The influence of the lubricants on the assessment of turbine thermo-mechanical efficiency is analyzed under steady flow conditions considering different lubricating oils. The study reports the effects of the oil temperature on instantaneous turbine power and turbocharger efficiency under unsteady flow conditions. This analysis aims to provide a comprehensive understanding of turbocharger performance during the engine warm-up phase. The effects of heat transfer between turbocharger components are taken into account, along with the impact of different oil temperatures on friction losses and their effects on the instantaneous rotational speed of the turbocharger. The aim of this work is to provide valuable information on the actual performance of the turbocharger under unsteady flow condition with reference to the impact of the lubricating oil characteristic on the boost pressure provided to the engine.
Marelli, Silvia, Usai, Vittorio, Cordalonga, Carla
Influence of Gas Pressure Levels on Injection Timing, Combustion Anomalies, and Emissions of a Hydrogen Gas Engine2025-24-00539/7/2025
A former diesel heavy-duty engine was retrofitted to hydrogen operation to simultaneously facilitate the shift from fossil to renewable fuels and maximize the quantity of reusable engine parts. Simply changing the fuel in this case does not make a properly working engine; the burning process needs to be realized in a premixed flame regime, rather than a diffusional flame regime. Therefore, an additional ignition source is necessary. A well-known characteristic of hydrogen is the low need for ignition energy and the wide range of ignitable air/ fuel ratios. Both must be considered to reach a diesel engine equivalent performance. Port fuel injection (PFI) and direct injection (DI) are commonly used in spark-ignited internal combustion engines. Some disadvantages, such as weak volumetric efficiency and combustion abnormal phenomena like backfire, are connected to PFI. To further improve the volumetric efficiency, high boost pressures are needed. To maximize volumetric efficiency with DI, injection timing after intake valve closure is mandatory. With a high-pressure level for hydrogen injection, a new field of application possibilities is generated regarding the degree of freedom in the injection timing. Furthermore, combustion anomalies can be prevented or their effects mitigated. The influence of pressure on the mixture formation mechanisms and time scales regarding engine load and speed variation was investigated. Simultaneously, the exhaust gas was analyzed concerning the common emissions, nitrogen oxide (NOx), and hydrogen slip (H₂ slip). Investigations were carried out on a single-cylinder research engine in two experimental setups. A low-pressure direct injection setup with pressure levels up to 30 bar and a high-pressure direct injection setup with up to 200 bar pressure. While varying the hydrogen injection pressure, two novel injectors were in use. The single-cylinder research engine’s displacement is representative of heavy-duty applications such as trucks, buses, and excavators. In a series application in a four-cylinder diesel engine setup, the following data is representative of the employed engine type: IMEP of 24.5 bar @ 1400 U/min NOx 9.1 g/kWh | ind. Eff 46.5%
Rößlhuemer, Raphael, Fellner, Felix, Fitz, Patrick, Prager, Maximilian, Jaensch, Malte
Experimental Analysis of Enhanced Scavenging Efficiency in Hydrogen-Powered Internal Combustion Engines for Heavy-Duty Applications2025-24-00569/7/2025
The purpose of this work is to highlight the benefits of improved scavenging efficiency for premixed, lean-burn, spark-ignited heavy-duty engines fueled by hydrogen. Scavenging efficiency measures the effectiveness of replacing exhaust gases with fresh air (or an air-fuel mixture) within the cylinder of an internal combustion engine. Enhanced scavenging efficiency reduces residual gas content and increases the proportion of fresh air, resulting in a cooler local mixture temperature. Additionally, it improves heat dissipation within the combustion chamber, cooling potential hotspots and allowing for earlier injections with fewer restrictions due to combustion anomalies, particularly pre-ignitions. To increase scavenging efficiency in a 4-stroke internal combustion engine, valve timing adjustments were made by introducing a valve lift profile with greater overlap of the exhaust valve closing and the inlet valve opening sequences. Additionally, a high-efficiency turbocharger was used to reduce backpressure and thereby increase the pressure gradient across the engine and promote scavenging. A test campaign was conducted on a 12.9-liter inline 6-cylinder heavy-duty engine to determine the impact of increased scavenging efficiency. The benefits were quantified using indicators such as intake and exhaust manifold pressures and maximum power output. In addition to an engine map and a full-load performance study, start-of-injection trade-offs were made at various engine speeds, loads, and different lambda targets. The test results confirmed the anticipated improvements. The increased valve overlap, and the high-efficiency turbocharger led to enhanced volumetric efficiency and a greater negative pressure differential between the intake and exhaust manifolds. These enhancements were particularly beneficial in the high-load area, where high boost pressure is essential to achieve the desired lambda value. At lower loads, where the engine typically operates in throttled conditions with a positive pressure gradient, no deterioration was observed. In summary, implementing the scavenging concept enabled the engine to operate more stable and achieve on average approximately 15 % higher performance without experiencing pre-ignition. Additionally, the lower local mixture temperature reduced thermal stress on the combustion chamber hardware, which helps mitigate wear and potential engine damage.
Schuette, Christoph, Borg, Jonathan, Giordana, Sergio, Rapetto, Nicola
Characterization of Exhaust Gas Recirculation Effects in a Hydrogen-Fueled 4-Cylinder Engine with Direct Injection2025-24-00529/7/2025
The increasing importance of hydrogen as alternative energy source to reduce CO2 emissions in the transport sector makes its adoption in spark-ignited engines an attractive and cost-efficient alternative to fuel cell-powered vehicles. Lean combustion is the preferred operating strategy for H2-engines in order to achieve performance targets, enhance efficiency and at the same time avoid critical knocking and pre-ignition phenomena. Additionally, an effective approach to lower cylinder temperatures, relevant engine-out NOx emissions and boost pressure requirements at the same time, is an external exhaust gas recirculation (EGR) system. The aim of this work is to analyze and compare the effects of exhaust gas recirculation on the combustion of a lean hydrogen mixture in a turbocharged 4-cylinder H2-ICE with direct injection. For this investigation a load point at 18 bar BMEP and 4000 rpm is selected with and without the utilization of additional external EGR. In this case, a BTE of 38 % is achieved at lambda 1.8 with an 11 % EGR rate. Under these conditions, the NOx emissions are also reduced by 80 % while the efficiency rises by 0.7 %pt., compared to the case without exhaust gas recirculation. Several experiments at the test bench were carried out and used to calibrate a 3D-CFD engine model, in which the complete 4-cylinder engine is virtually reproduced, including high-pressure injection and detailed chemistry for combustion and knock modeling in a single simulation. By investigating the impact of a varying residual gas concentration and air-to-fuel ratio on the mixture formation and the combustion properties, consequences for NOx emissions and abnormal combustion events are derived. A sensitivity study regarding the EGR temperature was additionally performed by means of 3D-CFD simulation to analyze the effects of 80 °C, 160 °C and 240 °C hot external EGR on the combustion process.
Schmelcher, Robin, Kulzer, Andre Casal, Gal, Thomas, Vacca, Antonino, Chiodi, Marco, Grabner, Peter, Gschiel, Kevin
Hydrogen Operation Strategies in a Turbocharged SI Engine: Challenges and Solutions03-18-04-00246/5/2025
Hydrogen is a promising fuel for internal combustion engines, offering the potential for efficient, environmentally friendly, and reliable operation. With a large number of technical challenges, there is currently no mass production of hydrogen-powered engines despite great efforts. One of the key challenges is the complexity of optimizing hydrogen combustion and its control. Despite the variety of proposed operation strategies, questions regarding their comparative efficiency, interrelation, and mutual influence remain open, particularly in turbocharged engines with direct multi-injection. To explore various hydrogen operation strategies, a mathematical simulation of a turbocharged hydrogen-powered engine was performed over its full range of loads and speeds. This study employed a modified mathematical model based on Wiebe functions, which describes the combustion of a premixed mixture in the flame front, diffusion combustion, and relatively slow combustion occurring behind the flame front, in lean mixture zones, and near-wall regions. The results revealed that in hydrogen engines, the use of well-known mixture formation strategies in combination with early direct injection, spark timing, and boost control presents significant challenges. These challenges include an increased risk of abnormal combustion, reduced maximum engine power, higher NOx emissions, and increased mechanical stress on engine components. The study identified the operating conditions under which these issues are most likely to occur. To mitigate these problems and improve engine efficiency, the focus was placed on implementing a late injection strategy in conjunction with dual injection (two injections of hydrogen during a single engine cycle). A methodology for selecting the optimal dual injection and ignition parameters was developed and the engine power cycle under these strategies was simulated. The research results showed that the proposed approach leads to an increase in engine power, a lower probability of abnormal combustion, reduced peak cylinder pressures, and decreased nitrogen oxide emissions.
Osetrov, Oleksandr, Haas, Rainer
Saw-Tooth Ramps for the Suppression of Flow-Acoustic Coupling in a High-Frequency Silencer for Turbocharger Compressors2025-01-00235/5/2025
The ported shroud casing treatment for turbocharger compressors is desirable for mitigating broadband/whoosh noise and enhancing boost pressures at low to mid flow rates. Yet, it is accompanied by elevated narrowband noise at the blade-pass frequency (BPF). Compressor BPF noise occurs at high frequencies where wave propagation is often multi-dimensional, rendering traditional planar wave silencers invalid. An earlier work introduced a novel reflective high-frequency silencer (baseline) targeting BPF noise in the 8-12 kHz range using an “acoustic straightener” that promoted planar wave propagation along arrays of quarter-wave resonators (QWRs). The design, however, faced challenges with high-amplitude tonal noise generation at specific flow conditions due to flow-acoustic coupling at the opening of the QWRs, thereby compromising the noise attenuation. The current study explores two QWR interface geometries that weaken the coupling, including linear and saw-tooth ramps on the upstream edge of each QWR. Computational fluid dynamics is utilized to study the mechanism of flow-acoustic coupling and assess the effectiveness of these modified interface geometries. Prototypes of the improved designs fabricated by additive manufacturing are then experimentally evaluated on a flow bench against the baseline silencer. The saw-tooth ramps prove particularly effective, achieving superior suppression of flow-acoustic coupling with lower flow restriction relative to the linear ramps. Next, the insertion loss of the baseline silencer and that with the saw-tooth ramps are determined on a turbocharger gas stand equipped with a rotating inlet duct. This unique setup is utilized to calculate the transmitted sound power upstream of the configurations with and without the silencer and therefore its insertion loss. The sharp valleys of negative insertion loss indicating tonal noise due to flow-acoustic coupling in the baseline silencer are eliminated by the saw-tooth ramps, therefore enhancing the overall noise attenuation.
Sriganesh, Pranav, Selamet, Ahmet
DoE-Based Numerical Optimization of Intake and Exhaust Port Geometry of a Small Opposed-Piston 2-Stroke (OP2S) Hydrogen Engine2024-32-00544/18/2025
The future potential of an opposed-piston two-stroke (OP2S) engine has attracted the attention of researchers worldwide as it offers a high thermal efficiency and power-to-weight ratio with a simple engine configuration. This engine can be used with low-carbon fuels and hydrogen to reduce greenhouse gas emissions. However, the two-stroke operation has always been limited by its low scavenging efficiency and short-circuit of fresh charge. The current work is focused on optimizing scavenging efficiency and short-circuit in a small 200 cc single-cylinder OP2S SI engine using 3-D computational fluid dynamic (CFD) simulations. The effect of four parameters, namely, area of intake ports, area of exhaust ports, and angular orientations of intake ports (swirl and tilt) on scavenging efficiency and short-circuit, has been assessed and optimized. A Latin-hypercube based Design of Experiments (DoE) methodology is used to sample the design space spanning over a range of four parameters. A response surface is generated using the Kriging method, and the geometry of intake and exhaust ports have been optimized for maximum scavenging efficiency and minimum short-circuit using a genetic algorithm on the response surface. The results show that the scavenging efficiency improves with the increase in exhaust port area, but it also increases the short circuit of fresh air. The Intake port swirl angle significantly impacts scavenging efficiency and short-circuit. The current optimization process achieved a scavenging efficiency of 85% (percentage of the total mass in the cylinder) and a short circuit of 12% (percentage of trapped fresh air). Apart from the geometric parameters, the effect of intake boost pressure and the engine speed on scavenging efficiency and short-circuit has also been evaluated.
Singh, Saurabh, Boggavarapu, Prasad, Himabindu, M., Ravikrishna, R.V.
Research on Boost Control for Powertrain Control System2025-01-85144/1/2025
In the domain of new energy vehicles, the role of the bidirectional DC/DC converter holds great significance. Based on the two-phase interleaved parallel BOOST topology, this paper adopts the approach of combining the double-loop PI controller with the feedforward control algorithm respectively from the aspects of following the target voltage and response speed, and conducts research on the performance of the DC/DC converter in BOOST mode in terms of output voltage overshoot, steady-state error, and system adjustment time. The test results fully validate the feasibility and effectiveness of the design scheme. The test results indicate that the double-loop PI control + feedforward control method accelerates the circuit response speed, reduces the steady-state error, and significantly reduces the input/output current ripple, fully verifying the feasibility and effectiveness of the control method. Furthermore, regarding the overvoltage issue that occurs after a large accelerator pedal in the hybrid vehicle with BOOST, the influence of post-overvoltage processing is analyzed emphatically, and the calibration strategy for the overvoltage problem is introduced. Among them, the fault handling mechanism for the BOOST software output overvoltage is that the BOOST upper and lower bridge software is blocked, and the P1/P2 software performs zero torque processing after receiving the BOOST software output overvoltage signal; after waiting for the BOOST fault to recover and enter the working mode, P1/P2 can operate in accordance with the current available power. Optimization calibration and real vehicle tests have been carried out. The test results demonstrate that the overvoltage problem can be effectively addressed by the adopted calibration method, and the drivability has been significantly enhanced.
Jing, Junchao, Liu, Yiqiang, Zuo, Botao, Huang, Weishan, Dai, Zhengxing
Redundant Brake Boost Control Strategy of Integrated Electro-hydraulic Braking System2024-01-703812/13/2024
The traditional braking system has been unable to meet the redundant safety requirements of the intelligent vehicle for the braking system. At the same time, under the change of electrification and intelligence, the braking system needs to have the functions of braking boost, braking energy recovery, braking redundancy and so on. Therefore, it is necessary to study the redundant braking boost control of the integrated electro-hydraulic braking system. Based on the brake boost failure problem of the integrated electro-hydraulic brake system, this paper proposes a redundant brake boost control strategy based on the Integrated Brake Control system plus the Redundant Brake Unit configuration, which mainly includes fault diagnosis of Integrated Brake Control brake boost failure, recognition of driver braking intention based on pedal force, pressure control strategy of Integrated Brake Control brake boost and pressure control strategy of Redundant Brake Unit brake boost. The designed control strategy of redundant brake boost is tested and verified on the real vehicle platform. The results show that the designed control strategy can effectively judge the brake boost fault of Integrated Brake Control and accurately identify the driver’s braking intention after the Integrated Brake Control is in brake boost failure. After receiving the expected braking pressure of the driver, the braking pressure is built by Redundant Brake Unit, which can accurately respond to the driver’s braking request and improve the redundant safety of the braking system.
Dexing, Lao, Luping, Yan, Qinghai, Sui, Long, Cao, Shang, Gao, Zhigang, Chen, Mingxing, Ren, Zhicheng, Chen
Performance and Emissions of a Hydrogen Dual-Fuel Engine Using Diesel and HVO as Pilot Fuels2024-01-428611/5/2024
A comprehensive experimental study of hydrogen–diesel dual-fuel and hydrogen-hydrotreated vegetable oil (HVO) dual-fuel operations was conducted in a single-cylinder diesel engine (bore 85.0 mm, stroke 96.9 mm, and compression ratio 14.3) equipped with a common rail fuel injection system and a supercharger. The hydrogen flow rate was manipulated by varying the hydrogen excess air ratio from 2.5 to 4.0 in 0.5 increments. Hydrogen was introduced into the intake pipe using a gas injector. Diesel fuel and HVO were injected as pilot fuels at a fixed injection pressure of 80 MPa. The quantity of pilot fuel was set to 3, 6, and 13 mm3/cycle. The intake and exhaust pressures were set in the range of 100–220 kPa in 20 kPa increments. The engine was operated at a constant speed of 1,800 rpm under all conditions. The pilot injection timing was varied such that the ignition timing was constant at the TDC under all conditions. The results demonstrated that smoke was lower when HVO was used as the pilot fuel than when diesel fuel was used, and that knocking occurred at lower excess air ratios of hydrogen when diesel fuel was used as the pilot fuel than when HVO was used. This is owing to the longer ignition delay of diesel fuel compared to that of HVO. The wider distribution of diesel fuel compared to that of HVO accelerates the chemical reactions in the premixed mixture, leading to autoignition. In addition, misfiring occurred when diesel fuel was used under low boost pressure operating conditions. This was attributed to differences in the ignition properties of the pilot fuel. These results demonstrate that HVO can be operated over a wider load range and at a wider hydrogen excess air ratio than diesel fuel operation.
Mukhtar, Ghazian Amin, Tange, Kota, Nakatani, Satoshi, Horibe, Naoto, Kawanabe, Hiroshi, Morita, Gin, Hiraoka, Kenji, Koda, Kazuyuki
Benefits of Supercharger Boosting on H 2 ICE for Heavy Duty Applications2024-01-30067/2/2024
The fast acceleration of GHG (CO2 in particular) emitted by human activities into the atmosphere is accelerating the average temperature increase of our globe causing heavy climate change. This phenomenon has triggered a strong pressure on GHG emission reduction in all the human activities including the transportation sector which contributes for the 29% to the total emissions in EU [1]. A mitigation to this tendency can come from synthetic fuels: when produced by using clean energy, they can be considered CO2 neutral. H2 is the building block of synthetic fuels and can be used in spark ignited engines where releases the energy accumulated during its production. This solution is particularly attractive for HD applications thanks to the high energy density. H2 can be burned in a quite wide range of λ, but staying on 2,2 the amount of engine out NOx will be low enough for the use on a 13L engine with a relatively simple aftertreatment system. This λ value is difficult to maintain in the full speed range for the turbocharger system as the exhaust gases energy may not be enough to spin compressor meeting the boost demand. This is particularly true at low speed and during acceleration. The Eaton Supercharger system driven by the engine crankshaft through a belt can compensate this gap and guarantee required λ also in critical conditions. The benefit of the additional boosting at full load is large enough for measuring in the mid/low speed range an increase in torque matching the Diesel values, and a 3% BTE rise. Going higher with the speed the Supercharger will not provide any more an advantage as turbocharger system is good enough for the λ 2,2. A clutch will disconnect the supercharger in that speed range and will prevent a drop in performance due to the power absorbed by the Supercharger itself. The use of Supercharger will also bring almost 30% improvement in transient response of the engine with no impact on air fuel ratio. With this strategy it is possible to convert a 13L Diesel engine for HD into an H2 maintaining same full load torque and power curves, while maximizing transient performance and efficiency.
Andrisani, Nicola, Bagal, Nilesh
Miller Cycle and Internal EGR in Diesel Engines Using Alternative Fuels2024-01-30207/2/2024
The Single Cylinder Research Engine (SCRE) at the Institute of Internal Combustion Engines and Powertrain Systems is equipped with a variable valve train that allows to switch between regular intake valve lift and early intake valve closing (Miller). On the exhaust side, a secondary exhaust valve lift (SEVL) on each valve is possible with adjustable back pressure and thus the possibility of realizing internal EGR. In combination with alternative fuels, even if they are Drop-In capable as HVO, properties differ and can influence the emission and efficiency behavior. The investigations of this paper are focusing on regenerative Drop-In fuel (HVO), fossil fuel (B7), and an oxygenate (OME), that needs adaptions at the engine control unit, but offers further emission potential. By commissioning a 2-stage boost system, it is possible to fully equalize the air mass in Miller mode compared to the normal valve lift. This enables a comprehensive analysis of the behavior of the fuels under different boundary conditions. In addition to the boost pressure, the exhaust gas pressure and engine speed are varied and analyzed with regards to emissions and efficiency. The SEVL is varied and investigated in terms of emission and efficiency behavior. For the evaluation, a combustion analysis is carried out and analyzed based on cylinder pressure data to work out the causes of the respective effects. One expected effect is a NOx reduction in Miller mode with the same air mass due to reduced effective compression, without significant efficiency losses due to the constant expansion. In the investigations this effect is clearly visible and therefore represents great potential for reducing NOx emissions.
Knost, Friedemar, Beidl, Christian
Evaluation of an Optimal Engine Configuration for a SI Engine Fueled with Ethanol for Stationary Applications2024-37-00246/12/2024
This work aims at investigating the optimal configuration of an internal combustion engine fueled with bio-ethanol for improving its brake power and efficiency as well as for reducing the NOx emissions, in stationary applications. A turbocharged spark ignition engine characterized by a single-point injection was preliminarily considered; subsequently, a direct injection configuration was investigated. For both cases, a 1-D numerical model was developed to compare the injection configurations under stoichiometric conditions and different spark timings. The analysis shows that the direct injection guarantees: a limited improvement of brake power and efficiency when the same spark timing is adopted, while NOx emissions increases by 20%; an increase of 6% in brake power and 2 percentage points in brake thermal efficiency by adopting the knock limited spark advance, but an almost double NOx emissions increase. In order to exploit the advantages of the direct injection, an engine configuration characterized by higher compression ratio, lower boost pressure and different cam phasing was proposed. By adopting a spark timing of 23°CA BTDC and a lean mixture (ϕ = 0.8), the engine provides a brake power of 232 kW, a brake thermal efficiency of 42%, which are 4% and 14 percentage points higher than single point configuration, respectively, and NOx emissions, amounting to 3 g/kWh, 9% lower with respect to single point injection.
Perrone, Diego, Falbo, Luigi, Falbo, Biagio, Castiglione, Teresa
1D Modeling of a High-Performance Engine Fueled with H 2 and Equipped with a Low NO x After-Treatment Device2024-37-00096/12/2024
Hydrogen engines are currently considered as a viable solution to preserve the internal combustion engine (ICE) as a power unit for vehicle propulsion. In particular, lean-burn gasoline Spark-Ignition (SI) engines have been a major subject of investigations, due to their reduced emission levels and high thermodynamic efficiency. Lean charge is suitable for the purpose of passenger car applications, where the demand of mid/low power output does not require an excessive amount of air to be delivered by the turbocharging unit, but can difficulty be tailored in the field of high performance engine, where the air mass delivered would require oversized turbocharging systems or more complex charging solutions. For this reason, the range of feeding conditions near the stochiometric value is explored in the field of high performance engines, leading to the consequent issue of abatement of pollutant emissions. In this work a 1D model is applied to the modeling of a V8 engine fueled with direct injection (DI) of hydrogen. The engine has been derived by a gasoline configuration and adapted to hydrogen in such a way to keep the same performance. The lambda condition has been chosen as a best compromise between performances and emissions, focusing onto a single cylinder configuration. The calibration of the engine has been performed onto this single cylinder configuration, tailoring the same power output and delivering the air mass flow imposing the desired boost pressure to match the desired engine torque. Then, the 1D schematic of a V8 engine has been built, based on the developed single cylinder and the air delivery system configured to satisfy the required air mass flow rate. Three different test cycles have been investigated (one WLTP and two RDEs) with different driving conditions. The after treatment system has been consequently sized to guarantee the abatement of NOx and the pollutant emissions analyzed showing different scenarios that can be adopted for this kind of engines, guaranteeing the reduced level of pollutant emissions and keeping the desired performance and fun of drive.
Montenegro, Gianluca, Marinoni, Andrea, Della Torre, Augusto, D'Errico, Gianluca, Onorati, Angelo, Cerri, Tarcisio
3-Dimentional Numerical Transient Simulation and Research on Flow Distribution Unevenness in Intake Manifold for a Turbocharged Diesel Engine2024-01-24204/9/2024
The design of engine intake system affects the intake uniformity of each cylinder of the engine, which in turn has an important impact on the engine performance, the uniform distribution of EGR exhaust gas and the combustion process of each cylinder. In this paper, the constant-pressure supercharged diesel engine intake pipe is used as the research model to study the intake air flow unevenness of the intake pipe of the supercharged diesel engine. The pressure boundary condition at the outlet of each intake manifold is set as the dynamic pressure change condition. The three-dimensional numerical simulation of the transient flow process in the intake manifold of diesel engine is simulated and analyzed by using numerical method, and the change of the Intake air flow field in the intake manifold under different working conditions during the intake overlapping period is discussed. The dynamic effects of diesel engine intake boost pressure, rotated speed, and intake pipe geometrical characteristic on the air mass flow at the outlet of each intake manifold, intake air distribution quality, and maximum intake unevenness are analyzed. According to numerical calculation result, it was obtained that the main reasons affecting the intake unevenness of each cylinder of diesel engine and the methods to reduce the intake unevenness: The lower the intake boost pressure of diesel engine, the greater the maximum intake unevenness. The greater the intake overlapping angle, the greater the maximum intake unevenness. When the diesel engine was working at low rotated speed, the maximum intake unevenness was higher than that at high rotated speed due to the long intake overlapping time. By increasing the boost pressure of the intake air, the unevenness intake air distribution of the diesel engine during the intake process could be reduced.
Yang, Shuai, Yan, Kai, Liu, Haifeng, Fu, Yahao, Liu, Hairan, Li, Tong
Numerical Study of a Six-Stroke Gasoline Compression Ignition (6S-GCI) Engine Combustion with Oxygenated Fuels2024-01-23734/9/2024
A numerical investigation of a six-stroke direct injection compression ignition engine operation in a low temperature combustion (LTC) regime is presented. The fuel employed is a gasoline-like oxygenated fuel consisting of 90% isobutanol and 10% diethyl ether (DEE) by volume to match the reactivity of conventional gasoline with octane number 87. The computational simulations of the in-cylinder processes were performed using a high-fidelity multidimensional in-house 3D CFD code (MTU-MRNT) with improved spray-sub models and CHEMKIN library. The combustion chemistry was described using a two-component (isobutanol and DEE) fuel model whose oxidation pathways were given by a reaction mechanism with 177 species and 796 reactions. The key advantage of six-stroke engine operation is the ability to switch the combustion mode among kinetical controlled mode (KCM), kinetically-driven mixing control mode (K-MCM) and mixing controlled mode (MCM) in the second power stroke (PS2) providing a wider range of combustion control. The K-MCM mode operation has shown to reduce both soot and NOx emissions substantially at low load (around 7bar IMEP) engine operations. The current work focuses on 6S-GCI engine operation using synthetic fuels at high load engine operation with the constraints on pressure rise rate (<10bar/deg), combustion efficiency (>90%), soot and NOx emissions (<1g/kg fuel). With the constraints met, engine operating conditions at 15 bar IMEP and 2000 rpm were identified as a function of fuel split ratio and injection timings. Parametric study was also performed by varying fuel injection pressure, initial gas temperature at IVC, boost pressure and exhaust gas recirculation ratio. Engine performance and emissions characteristics of parametric variation are presented as well.
Purushothaman, Ashwin Karthik, Ra, Youngchul, Ha, Kyoung Pyo, Zhu, Shengrong, Ullal, Ankith
Performance of Spark Current Boost System on a Production Engine under Lean-Burn Conditions2024-01-21064/9/2024
In order to improve the fuel economy for future high-efficiency spark ignition engines, the applications of advanced combustion strategies are considered to be beneficial with an overall lean and/or exhaust gas recirculation diluted cylinder charge. Stronger and more reliable ignition sources become more favorable under extreme lean/EGR conditions. Existing research indicates that the frequency of plasma restrikes increases with increased flow velocity and decreased discharge current level, and a higher discharge current can reduce the gap resistance and maintain the stretched plasma for a longer duration under flow conditions. An in-house developed current boost control system provides flexible control of the discharge current level and discharge duration. The current boost ignition system is based on a multi-coil system with a discharge current level of 180mA. In this study, a comparative study has been conducted to investigate the efficacy of multi-coil and multi-core ignition systems on a spark-ignited inline-four cylinder production engine under lean-burn conditions. Both total ignition energy and discharge duration are kept the same. The ignition performance of both strategies has been investigated under various levels of engine loads, including idling (1.1 bar BMEP at 900rpm) and partial engine load (2.6 bar BMEP at 1500rpm) conditions. Using the multi-coil system, the spark advance window could be extended beyond that of the traditional transistor coil ignition. Furthermore, the application of the multi-core ignition system consistently realized a shorter ignition delay period by 2~4°CA regardless of boundary conditions.
Yu, Xiao, Leblanc, Simon, Wang, Linyan, Zheng, Ming, Tjong, Jimi
Downsizing a Heavy-Duty Natural Gas Engine by Scaling the Air Handling System and Leveraging Phenomenological Combustion Model2024-01-21144/9/2024
A potential route to reduce CO2 emissions from heavy-duty trucks is to combine low-carbon fuels and a hybrid-electric powertrain to maximize overall efficiency. A hybrid electric powertrain can reduce the peak power required from the internal combustion engine, leading to opportunities to reduce the engine size but still meet vehicle performance requirements. Although engine downsizing in the light-duty sector can offer significant fuel economy savings mainly due to increased part-load efficiency, its benefits and downsides in heavy-duty engines are less clear. As there has been limited published research in this area to date, there is a lack of a standardized engine downsizing procedure. This paper uses an experimentally validated one-dimensional phenomenological combustion model in a commercial engine simulation software GT-SUITE™ alongside turbocharger scaling methods to develop downsized engines from a baseline 6cyl (2.1 L/cyl, 26 kW/L) pilot-ignition, direct-injection natural gas engine. Since there is a reduced power demand from the engine in the hybrid powertrain over transient drive cycles, this study compares two methodologies to achieve a 230 kW engine: a reduction in number of cylinders at fixed displacement (4cyl- 2.1 L/cyl) and a reduction in cylinder displacement volume but retaining six cylinders (6cyl-1.4 L/cyl). The power for the downsized engine is reduced compared to the baseline engine since a future hybrid powertrain will not need as much power as a non-hybrid. By retaining similar total displacement and equivalent power rating, the impacts of engine size reduction can be distinguished from the scaling of the turbocharging and air handling system. The engines are evaluated over a series of steady-state and transient cycles based on a reduced load duty cycle for an engine in a hybridized vehicle. The results indicated that, as expected, downsized engines demonstrate increased peak cylinder pressure, exhaust gas temperature, boost pressure, and turbocharger speed compared to the baseline engine when all engines undergo the same reduced load duty cycle. Distinctly, the 6 cyl-1.4 L/cyl variant showed increased heat losses due to the higher surface area to volume ratio in the combustion chamber, while the 4 cyl-2.1 L/cyl variant had higher exhaust enthalpy losses. Both downsized engines showed lower friction losses than the baseline engine. Due to these offsetting effects, neither of the downsized engines showed a significant improvement in brake specific fuel consumption (BSFC). The change in mass due to the smaller engine offers only a minor improvement in payload capacity compared to the reduction in the maximum torque.
Balazadeh, Navid, Munshi, Sandeep, Shahbakhti, Mahdi, McTaggart-Cowan, Gordon
Highway Exhaust Emissions of a Natural Gas-Diesel Dual-Fuel Heavy-Duty Truck2024-01-21204/9/2024
Diesel-fueled heavy-duty vehicles (HDVs) can be retrofitted with conversion kits to operate as dual-fuel vehicles in which partial diesel usage is offset by a gaseous fuel such as compressed natural gas (CNG). The main purpose of installing such a conversion kit is to reduce the operating cost of HDVs. Additionally, replacing diesel partially with a low-carbon fuel such as CNG can potentially lead to lower carbon dioxide (CO2) emissions in the tail-pipe. The main issue of CNG-diesel dual-fuel vehicles is the methane (CH4, the primary component of CNG) slip. CH4 is difficult to oxidize in the exhaust after-treatment (EAT) system and its slip may offset the advantage of lower CO2 emissions of natural gas combustion as CH4 is a strong greenhouse gas (GHG). The objective of this study is to compare the emissions of an HDV with a CNG conversion kit operating in diesel and dual-fuel mode during highway operation. Road tests were conducted on a three-axle Class-8 highway semi-trailer tractor hauling a two-axle loaded box trailer. The gross combined weight of the tractor-trailer was 34,470 kg (~76,000 lbs). The tractor was powered by an inline 6-cylinder, direct injection diesel engine with EAT system, and met EPA 2010 emission regulations. The primary components of the conversion kit were: CNG tank, regulator, and mixing manifold with solenoid CNG injectors. CNG was injected into the intake manifold of the engine downstream of the intercooler. The CNG injection map was based on the throttle position, engine speed, load, and intake boost pressure. Portable emissions measurement systems (PEMS) were used to analyze the exhaust gas before and after the EAT system. The vehicle’s onboard diagnostic (OBD) data was also recorded concurrently. The highway test route was 74 km long and the average road speed was ~102 km/h. Results showed that up to 34% of the diesel consumption could be replaced by CNG. When compared to diesel-only, the CO2 and total hydrocarbon emissions of the dual-fuel case were lower and higher, respectively. Engine-out black carbon emissions were lower for the dual-fuel case in comparison to diesel, while tail-pipe nitrogen oxides (NOx) emissions were higher. Distinct differences in the exhaust temperature profiles were observed as well.
Dev, Shouvik, Qi, Aidu, Anderson, Andrew, Dahlseide, Austin, Smith, Brett, Lussier, Simon-Alexandre, Guo, Hongsheng, Rosenblatt, Deborah
Sea-Level Characterization of Electrically Assisted Turbocharger for Use on Aviation Diesel Engine2024-01-19143/5/2024
Airborne compression-ignition engine operations differ significantly from those in ground vehicles, both in mission requirements and in operating conditions. Unique challenges exist in the aviation space, and electrification technologies originally developed for ground applications may be leveraged to address these considerations. One such technology, electrically assisted turbochargers (EATs), have the potential to address the following: increase the maximum system power output, directly control intake manifold air pressure, and reignite the engine at altitude conditions in the event of an engine flame-out. Sea-level experiments were carried out on a two-liter, four-cylinder compression-ignition engine with a commercial-off-the-shelf EAT that replaced the original turbocharger. The objective of these experiments was to demonstrate the technology, assess the performance, and evaluate control methods at sea level prior to altitude experimentation. This work covers the baseline characterization of the EAT as a turbocharger, on-engine EAT electrical operation for boost control, and a demonstration of system power extension capabilities. The baseline characterization quantified the aerodynamic performance of the EAT through the engine power curve. Then, the motor-generator on the EAT was used to directly control the intake manifold pressure. During this operation, the EAT recovered 2.4% of the exhaust energy as electrical power at the maximum nominal engine power condition. During the power extension demonstration, the manifold pressure and fueling was increased simultaneously to maintain a constant equivalence ratio. This resulted in a 6% increase engine mechanical power output and an increase in total system power output (electrical power plus mechanical power) of approximately 9%. Examples for potential on-aircraft configurations and recommendations for altitude experimentation are also expressed.
Pope, Aaron, Kim, Kenneth, Schroen, Erik, Clerkin, Peter, Musser, Marshall, Mattson, Jonathan, Meininger, Rik, Gibson, Joseph, Kang, Sang-Guk, Kruger, Kurt, Hepp, Kyle, Kweon, Chol-Bum
Simulation Study on High Expansion Ratio Dedicated Hybrid Engine for Hybrid Commercial Vehicle Application2023-01-700510/30/2023
The fuel economy and emission of the hybrid vehicle depend largely on the selected engine. And the dedicated hybrid engine (DHE) can be controlled to operate in the optimal operating range because DHE can be decoupled from the vehicle transmission system. The main purpose of this paper is to improve the thermal efficiency of the diesel engine under common operating conditions combined with high compression ratio (CR) and early or late intake valve closing (IVC) angle. According to the vehicle road spectrum data, the optimal operating range of the engine is determined to be 1200-1400 rpm and 70%-90% load. Then CR and IVC angle are optimized by using the calibrated one-dimensional thermodynamic model of the engine under limited peak combustion pressure (Pmax). The results show that the adjustment of IVC angle and CR can control the thermal state at the end of compression stroke. The combination of CR and IVC angle can achieve the optimal fuel consumption improvement. The minimum brake special fuel consumption (BSFC) is reduced from 189.2 g/kWh to 184 g/kWh. Based on the thermal process analysis of internal combustion engines, the effects of CR, IVC, and boost pressure on engine performance are analyzed. The improvement of thermal efficiency caused by higher CR would be compensated by the decrease of combustion constant degree. What is more, early or late IVC angle can reduce combustion phase loss and gas exchange loss. Further, a more efficient turbocharger can be matched to achieve higher thermal efficiency.
Wang, Xiaosa, Lin, Zhiqiang, Wang, Hu, He, Hua, Wang, Xiaohui, Liang, Depu
Pre-ignition Behavior of Gasoline Blends in a Single- Cylinder Engine with Varying Boost Pressure and Compression Ratio2023-32-01209/29/2023
Pre-ignition in a boosted spark-ignition engine can be triggered by several mechanisms, including oil-fuel droplets, deposits, overheated engine components and gas-phase autoignition of the fuel-air mixture. A high pre-ignition resistance of the fuel used mitigates the risk of engine damage, since pre-ignition can evolve into super-knock. This paper presents the pre-ignition propensities of 11 RON 89-100+ gasoline fuel blends in a single-cylinder research engine. Albeit the addition of two high-octane components (methanol and reformate) to a toluene primary reference fuel improved the pre-ignition resistance, one high-RON fuel experienced runaway pre-ignition at relatively low boost pressure levels. A comparison of RON 96 blends showed that the fuel composition can affect pre-ignition resistance at constant RON.
Rönn, Kristian, Larmi, Martti, Pehlivanlar, Benjamin, Göbel, Christoph, Pischinger, Stefan, Karvo, Anna, Lehto, Kalle, Fryjan, Johannes
Thermodynamics of Lean Hydrogen Combustion by Virtual Investigations on a Single-Cylinder Engine with Port Fuel Injection and Pre-Chamber Ignition2023-24-00638/28/2023
In order to achieve the climate targets, a mix of different powertrain technologies must be pursued to effectively reduce emissions. By producing hydrogen based on renewable energy sources, it becomes a reasonable choice for fueling internal combustion engines. The specific molecular properties of hydrogen thereby open up new possibilities for favorably influencing the combustion process of engines. The present paper deals with the analysis of a single-cylinder engine with passive pre-chamber ignition and a port fuel injection system, which was adapted for lean hydrogen operation. In this way, the test unit was operated in various load and speed ranges with lambda values from 1.5 to 2.5 and achieved up to 23 bar indicated mean effective pressure. The focus of this work is on the numerical investigation of the hydrogen combustion and its effects on the engine system. Special attention is hereby paid to the influence of different lambda operations. Simulations were carried out to evaluate the heat transfer towards the cooling system and to determine energy losses dependent on the gas temperatures. The validated 3D-CFD simulation illustrates the thermodynamic properties, as well as the interaction of injection strategies and mixture formation inside the cylinder and pre-chamber. The analysis points out that lean operation across all loads is advantageous in terms of indicated efficiency and particularly in lower loads up to 6 %-pts can be achieved by applying a de-throttling strategy. By going beyond test bench limitations, the virtual environment shows that the engine is knock-limited with lambda 1.5 and increased combustion temperatures imply high NOx emissions at high loads. In contrast, with lambda 2.5, the pressure gradient and turbulence level decrease sharply, so that a boost pressure of 4.5 bar is required to achieve the maximum load with a peak cylinder pressure of 180 bar.
Gal, Thomas, Vacca, Antonino, Chiodi, Marco, Schmelcher, Robin, Kulzer, Andre, Bucherer, Sebastian, Rothe, Paul, Sobek, Florian, Gottwald, Theo, Kraljevic, Ivica
Experimental and Numerical Investigation of Spark Plug and Passive Pre-Chamber Ignition on a Single-Cylinder Engine with Hydrogen Port Fuel Injection for Lean Operations2023-01-12056/26/2023
The race towards zero carbon emissions is ongoing with the need to reduce the consumption of fossil energy resources. This demands immediate and reliable developments regarding technical environmentally friendly solutions for the power and transportation sectors. An alternative way to achieve a carbon-free powertrain is the use of green hydrogen for internal combustion engines. In this work the self-designed Fraunhofer single-cylinder engine with a displacement volume of 430 mm3 developed for extreme lean combustion and passive pre-chamber ignition was adapted for hydrogen engine operation. With hydrogen combustion, the customized cooling system resulting in low metal temperatures is simulated and optimized to avoid hot spots in the combustion chamber. The investigated single-cylinder engine is characterized by a compression ratio of 12.2, port fuel injection and a conventional spark plug. Based on the results, the engine is operated with a passive pre-chamber to investigate its influence on the ignition of hydrogen mixture. The advantages of pre-chamber combustion for short burning duration and high knock resistance have been demonstrated, especially at full load. This work points out the possibility to reach 23 bar indicated mean effective pressure with optimization of the port fuel injection strategies, operating the engine at lambda 2 and achieving an indicated efficiency above 43 %. The further increase in performance is restricted by the mechanical load limit of 180 bar peak cylinder pressure. Since the engine was still not knock-limited, virtual optimisation showed the possibility to increase the indicated mean effective pressure up to 28 bar at lambda 1.5, with 4 bar boost pressure.
Bucherer, Sebastian, Rothe, Paul, Sobek, Florian, Gottwald, Theo, Kraljevic, Ivica, Vacca, Antonino, Gal, Thomas, Chiodi, Marco, Kulzer, Andre
Investigation of Compressor Deposit in Turbocharger for Gasoline Engines (Part 1: Research on Deposit Formation Mechanism)2023-01-04104/11/2023
Contribution to carbon neutrality is one of the most important challenges for the automotive industry. As CO2 emission has been reduced through electrification such as hybrid electric vehicle (HEV) and plug-in hybrid electric vehicle (PHEV), internal combustion engines (ICEs) equipped in those powertrain systems are still necessary for the foreseeable future, and continuous efforts to improve fuel efficiency are demanded. To improve powertrain thermal efficiency, direct-injection turbocharged gasoline engines have been widely utilized in recent years. Super lean-burn combustion engine has been researched as a next generation of turbocharged gasoline engines. Further utilization of turbochargers is expected. Compared with turbocharged downsized gasoline engines available in the current market, much higher boost pressure must be utilized to realize the super lean-burn engines. As a result, compressor housing temperature will be very high compared with the current market one. Blow-by gas containing engine oil mist is always recirculated into intake air upstream of the turbocharger compressor in the boosting operation. Therefore, the possibility of deposit formation derived from the engine oil mist is increased. It is very important to inhibit the deposit formation for the realization of more efficient turbocharged gasoline engines and the reduction of vehicle CO2 emission. In this research, it is expected that solutions to inhibit the deposit formation will be found by clarification of the condition and the mechanism of this deposit formation in the turbocharged gasoline engines.
Ishizaki, Noriya, Hirano, Satoshi, Kuma, Hiroshi, Ura, Haruto
Investigation of Compressor Deposit in Turbocharger for Gasoline Engines (Part 2: Practical Application to Turbocharger)2023-01-04124/11/2023
Contribution to carbon neutrality is one of the most important challenges for the automotive industry. Though CO2 emission has been reduced through electrification, internal combustion engines equipped in vehicles such as Hybrid Electric Vehicle (HEV) and Plug-in Hybrid Electric Vehicle (PHEV) are still necessary for the foreseeable future, and continuous efforts to improve fuel economy are demanded. To improve powertrain thermal efficiency, direct-injection turbocharged gasoline engines have been widely utilized in recent years. Super lean-burn combustion engine has been being researched as the next generation of turbocharged gasoline engines. It is known that an increase of the boost pressure causes deposit formation, which decrease the turbocharger efficiency, in the turbocharger compressor housing. To avoid the efficiency loss due to deposit, air temperature at compressor outlet has to be limited low. In this paper, the methodology was constructed to predict compressor efficiency loss, based on the mechanism of turbocharger deposit formation in gasoline engines. Test procedure to reproduce compressor deposit in turbocharger unit test equipment was developed. The correlation between the temperature of compressor housing inner surface and the rate of compressor efficiency loss was clarified. In addition, the correlation between the location where deposit was formed and the compressor efficiency loss was also investigated. As opposed to steady-state operation such as engine dyno tests, vehicle operations in actual markets are transient, and the boost pressure of turbocharger and its outlet air temperature can vary widely. Due to the thermal capacity of compressor housing, the temperature of housing changes after the outlet air temperature changes with certain time delay. The temperature model considering this delay has been developed and enabled to estimate the deposit formation, turbocharger efficiency loss and engine performance deterioration in transient conditions.
Ura, Haruto, Kuma, Hiroshi, Hirano, Satoshi, Ishizaki, Noriya
Development of New V6 3.0 L Turbocharged and 3.5 L Naturally Aspirated Gasoline Direct Injection Engines2023-01-03984/11/2023
With the objective of further enhancing the engine performance of the Acura brand and the environmental performance of the Honda brand in relation to the North American market, where there is a need for powertrains with driving force margin for SUVs and pickup trucks, Honda has developed a 3.0 L turbocharged engine and a 3.5 L naturally aspirated engine. Both engines adopt the same newly developed valvetrain structure and share main engine geometries. These newly developed engines are equipped with a compact new valvetrain structure combining Hydraulic Lash Adjusters and roller rocker arms with a valve-lifter based Variable Cylinder Management system which has an internalized switching mechanism. This newly developed valvetrain made it possible to incorporate dual overhead cam structure without enlarging the cylinder head shape relative to the single overhead cam structure. It further achieves this while permitting application of a Variable Cylinder Management system and of a Variable Timing Control for intake and exhaust valves to this engine. Sharing the main engine geometries and components for each type of engine, primarily the new valvetrain structure, also facilitated changes in reciprocating and other parts, and minor changes such as the mounting of a turbocharger and increases in fuel injection system pressure, enabling the required enhancements in engine and environmental performance to be achieved. Regarding the turbocharged engine, the twin-scroll type turbocharger combined with the V6 engine made it possible to increase power and enhance boost pressure responsivity while preventing enlargement even over the single turbocharger. That turbocharged engine achieves maximum power of 265 kW and maximum torque at 1400 rpm of 480 Nm, raising the figures for the existing engine by 26.7% for power, and 35.2% for torque. Regarding the natural aspiration engine, the high fuel pressure system and the multi-stage injections made it possible to reduce emissions by reducing fuel adhesion in the cylinders and enhancing homogeneity. It further enables enhancement of the thermal efficiency by combining dual Variable Timing Control and high-tumble ports and piston crown shape designed to maintain tumble flow. That natural aspiration engine achieves a maximum power of 213 kW and a maximum torque of 355 Nm. In terms of environmental performance, the thermal efficiency is 37.5%, an increase over the 36.5% of the existing engine. A vehicle equipped with this engine was also able to achieve LEV III and SULEV30 standards as well as particulate matter (PM) of 1 mg/mile.
Taki, Shotaro, Konishi, Yukio, Tomitani, Yuki, Ishii, Kazumasa, Imakita, Akio, Kawawa, Satoshi
Exhaust Gas Recirculation (EGR) Cooler Nomenclature and ApplicationJ2914_202211 (Current)11/22/2022
This document provides an overview on how and why EGR coolers are utilized, defines commonly used nomenclature, discusses design issues and trade-offs, and identifies common failure modes. The reintroduction of selectively cooled exhaust gas into the combustion chamber is just one component of the emission control strategy for internal combustion (IC) engines, both diesel and gasoline, and is useful in reducing exhaust port emission of nitrogen oxides (NOx). Other means of reducing NOx exhaust port emissions are briefly mentioned, but beyond the scope of this document.
Cooling Systems Standards Committee
A Technical Review on Low Speed Pre Ignition in Turbocharged Gasoline Direct Injection Engines2022-28-002310/5/2022
The current market demand and ever tightening global legislation mandate automotive OEMs to improve vehicle fuel consumption and reduce carbon based emissions. One approach to do so is by downsizing of gasoline engines. The reduced engine displacement causes lesser pumping and frictional losses and lower gas to wall heat transfer making engine more efficient. While downsizing an engine can enhance fuel economy it also brings down the power output. The power lost can be compensated by integrating a turbocharger to the engine to increase the boost pressure however, this again may create an abnormal combustion event known as low-speed pre-ignition (LSPI). The increase of pressure and temperature inside the combustion chamber at high loads also leads to a pre-ignition induced super knock and in severe cases, LSPI leads to broken piston rings, damaged pistons and bent connecting rods. Thus LSPI has become a great concern since it operates in a very common driving pattern of rapidly accelerating the vehicle at lower speed range, thereupon limiting further downsizing of gasoline engines. The present review paper comprehends the details the conditions for occurrence of LSPI mainly focusing on cause and effect of the local auto ignition taking place inside the cylinder due to formation of contaminants entering from the top land crevice during blow-down and washed from the cylinder walls during direct injection wall impingement, the parameters effecting it and various methods to mitigate the LSPI issue in turbo charged gasoline direct injection engines.
Deva, Dinesh, Dhyani, Vipin, Kansara, Shekhar, Muralidharan, M.
Parametric Investigation of Various Factors Affecting Engine Performance and Emissions in a Homogeneous Charge with Direct Injection Strategy at High Load: A CFD Approach2022-01-10488/30/2022
Over the years, much progress has been made in automotive vehicle technology to achieve high efficiency and clean combustion. Reactivity controlled compression ignition (RCCI) is one of the most widely studied high-efficiency, clean combustion strategies. However, complex dual-fuel injection systems and associated controls, high unburned hydrocarbon (UHC), and carbon monoxide (CO) emissions limit RCCI use in practical applications. Recently, single fuel RCCI strategies are gaining more attention as the above shortcomings are effectively addressed. Homogeneous charge with direct injection (HCDI) is a single fuel RCCI strategy that results in high thermal efficiency and lower UHC and CO emissions. In HCDI, the port-injected diesel fuel vapour and air are inducted during the intake stroke and ignited with direct-injected diesel fuel near the end of the compression stroke. However, high oxides of nitrogen (NOx) make HCDI less viable for practical applications. Water vapour dilution proved an effective method to suppress NOx emissions without reducing thermal efficiency in HCDI. However, thermal and dilution effects at higher loads resulted in a NOx-soot trade-off and high soot emissions. A parametric study of different parameters and their combined impact on the performance and emissions of a light-duty diesel engine operated in HCDI mode is evaluated in the present study. A commercial CFD code, CONVERGE, validated with experimental data, is used for parametric investigations. Different parameters such as direct-injected fuel timing, fuel injection pressure, boost pressure and dilution are varied. The results show that increasing boost pressure improves air-fuel mixing and reduces soot formation among the investigated parameters. The combined effects of increased dilution, higher injection and boost pressure increased thermal efficiency by ~13%, with a penalty in NOx and 37.8% soot reduction.
Chaurasiya, Rishabh, Krishnasamy, Anand
Investigations on a Novel Supercharging and Impulse Turbo-Compounding of a Single Cylinder Diesel Engine2022-01-11118/30/2022
Single-cylinder engines in mass production are generally not turbocharged due to the pulsated and intermittent exhaust gas flow into the turbocharger and the phase lag between the intake and exhaust stroke. The present work proposes a novel approach of decoupling the turbine and the compressor and coupling them separately to the engine to address these limitations. An impulse turbine is chosen for this application to extract energy during the pulsated exhaust flow. Commercially available AVL BOOST software was used to estimate the overall engine performance improvement of the proposed novel approach compared to the base naturally aspirated (NA) engine. Two different impulse turbine layouts were analyzed, one without an exhaust plenum and the second layout having an exhaust plenum before the power turbine. The merits and limitations of both layouts are compared in the present study. An optimum nozzle area ratio of 50% for the first layout was arrived, which provided better net engine performance with 53.7% higher brake power output and 5.8% higher brake thermal efficiency. The second layout fared better with a nozzle area ratio of 13% and a plenum volume of 1 litre. The second layout delivered 52.8% higher brake power output and 5.5% higher brake thermal efficiency at rated power conditions. Both supercharged configurations produced 1.8 bar (absolute) boost pressure that increased airflow rate by 33% more than the NA configuration. This would improve combustion efficiency and reduce exhaust emission congruent with any charged engine. Thus, the present novel approach with both the layouts benefitted from charging the single-cylinder diesel engine, which was otherwise difficult in conventional turbocharging.
Ramkumar, J, Krishnasamy, Anand, Ramesh, A
Real-Time Prediction of Pre-ignition and Super-Knock in Internal Combustion Engines03-16-03-00217/1/2022
Super-knock is a phenomenon triggered by pre-ignition and has limited the design envelope of internal combustion engines (ICEs) in terms of power density. This poses a huge challenge for the automotive industry where engine sizes have been continuously decreasing due to the demand for weight savings and integration with electrified powertrains. Such downsized engines typically require increased boost pressure, availing conditions conducive to pre-ignition, which in turn may trigger super-knock. Traditionally, this and other forms of knock have been managed by way of a “detection and mitigation” approach in place of “perdition and avoidance” due to an evolving understanding of corresponding combustion dynamics, as well as the incapability of emerging real-time computational methods to perform and actuate over the timescale required. In this study, a data-driven algorithm is used to extract (and adapt) a globally linearized system representation using eigen-time-series, isolating the dynamic modes of the system to capture underlying effects leading to pre-ignition without the need for physics-based modeling. This approach is a unique application of the “Hankel Alternative View of Koopman” (HAVOK) analysis for chaotic systems and can be executed on board an engine control module supplying a buffer of recent to latest time-step data to predict an impending pre-ignition event. The proposed design does not require any change to existing sensors and actuators in the existing knock management system architecture, nor would it require any significant increase in computational capacity in terms of the associated engine control unit. A simulation was conducted with real super-knock data to nominally test the applicability of the algorithm. From this training dataset, the linearized dynamic system was able to predict pre-ignition approximately 2.27 s prior to the event, which is adequate to take mitigating action. Further validation runs covering low, medium, and high engine speeds within the envelope of low-speed pre-ignition (LSPI) generated similar results.
Manzoor, Waqas A., Rawashdeh, Samir, Mohammadi, Alireza
Automotive Turbocharger Rotor Optimization Using Machine Learning Technique2022-01-02163/29/2022
Turbochargers are widely employed in internal combustion engines, in both, diesel and gasoline vehicle, to boost the power without any extra fuel usage. Turbocharger comes in different sizes based upon the boost pressure to increase. Capacity of turbocharger are available in great range in the market which are designed to match the requirement. From structural point of view, key component of an automotive turbocharger is rotor. This rotor consists of compressor wheel, turbine wheel, shaft and bearing (journal/ball) mainly. In industries, design & development of turbocharger rotor for its dynamic characteristics is done using virtual engineering technique (Computer Aided Engineering). Multibody dynamic (MBD) analysis simulation is one of the best approaches which is used to study the rotor in great details. In this current MBD procedure fluid-structure interaction problem is solved by modelling oil film in the journal bearing and solving it using “Reynolds equation”. Shaft displacement is provided to oil film which eventually output the pressure development in the bearing. This pressure then acts upon the shaft and modal transient analysis is performed for the structure analysis. As current approach is a quite complex, time require to complete the simulation is in days. Multiple simulation is required to study the design sensitivity and reach to an optimum design of turbocharger rotor. So, any essential design study takes this huge time to carry out, hence it is one of the challenges in the development cycle. Over the period of last few years, a lot of such simulation has happened for variety of turbocharger. It provides a huge data set which could be utilized to find a pattern or prediction of rotor dynamic characteristics. One of such effort has been made and a deep learning-based rotor dynamics model has been developed. This model further with non-linear Optimization technique is very promising for optimizing the rotor design parameters. This method not only predicts the outcomes with given design parameter but also minimize the outcomes by providing the most optimized set of design parameters within hours.
Shrivastava, Sandeep, Sinha, Ankur, Ray, Sudipto, Du, Isaac, Begin, Louis
Control Oriented Engine Model Development for Model-Based PPC Control2022-01-04803/29/2022
A model-based control approach is proposed to give proper reference for the feed-forward combustion control of Partially Pre-mixed Combustion (PPC) engines. The current study presents a simplified first principal model, which has been developed to provide a base estimation of the ignition properties. This model is used to describe the behavior of a single-cylinder heavy-duty diesel engine fueled with a mix of bio-butanol and n-heptane (80vol% bio-butanol and 20 vol% n-heptane). The model has been validated at 8 bar gross Indicated Mean Effective Pressure (gIMEP) in PPC mode. Inlet temperature and pressure have been varied to test the model capabilities. First the experiments were conducted to generate reference points with BH80 under PPC conditions. And then CFD simulations were conducted to give initial parameter set up, e.g. fuel distribution, zone dividing, for the multi-zone model. The in-cylinder pressure results show that, across the range of input conditions, the physics-based model is able to capture the auto-ignition characteristics and predicts the start of combustion within 3 oCA. CA50 characteristics has also been successfully captured, with root mean square error (RMSE) of 0.62 oCA and 2.2 oCA under the variation of boost pressure and temperature. The pressure rise rate and peak pressure have also been well predicted, with an RMSE of 2.54 bar/ oCA and 3.17 bar for boost pressure variation. As a first step towards model-based control, this model has been successfully validated over the effectiveness for effective, future combustion control.
Pan, Wang, Bekdemir, Cemil, Willems, Frank
Development and Validation of a Multi-zone Predictive Combustion Model for Large-Bore Dual-Fuel Engines03-15-05-003812/22/2021
Numerical simulation represents a fundamental tool to support the development process of new propulsion systems. In the field of large-bore dual-fuel (DF) engines, the engine simulation by means of fast running numerical models is nowadays essential to reduce the huge effort for testing activities and speed up the development of more efficient and low-emissions propulsion systems. However, the simulation of the DF combustion by means of a zero-dimensional/one-dimensional (0D/1D) approach is particularly challenging due to the combustion process evolution from spray autoignition to turbulent flame propagation and the complex interaction between the two fuels. In this regard, in this activity a 0D/1D multi-zone DF combustion model was developed for the simulation of the combustion process in large-bore DF engines. The model combines a multi-packet approach for tracking the evolution and the autoignition of the pilot fuel with an entrainment and burn-up approach for the simulation of the premixed air-gas mixture flame propagation. To properly consider the properties of the fuels involved in the combustion process and to capture the interaction between the two fuels, the DF combustion model was optimized by developing and implementing a refined ignition delay model and specific laminar and turbulent flame speed correlations optimized for high-pressure and lean air-gas mixture. In addition to this, a multi-zone Nitrogen Oxides (NOx) model was developed and integrated into the combustion model. Experimental measurements from a single-cylinder Wärtsilä research engine were used for the model development and validation. The proposed DF combustion model is able to properly capture the effect of the main engine settings (i.e., load, pilot fuel injection strategy, compression ratio (CR), and boost pressure), providing accurate predictions of the ignition timing, combustion duration, and NOx emissions. The developed numerical model can be therefore exploited to virtually assess the potential of different engine technologies and calibration strategies.
Millo, Federico, Accurso, Francesco, Piano, Andrea, Fogla, Navin, Caputo, Gennaro, Cafari, Alberto, Hyvönen, Jari
Power Cylinder Blow-by: Problem SolvingJ2798_202112 (Current)12/21/2021
This document describes methodologies to determine the causes blow-by oil consumption caused by the power cylinder.
Piston and Ring Standards Committee
NOx Tracking Parameter AccuracyJ3349_202110 (Historical)10/19/2021
This SAE Information Report provides SAE’s recommendations for meeting the requirements for REAL NOx accuracy demonstration and for the implementation of REAL NOx binning requirements as defined in OBD regulations 13 CCR 1971.1 and 13 CCR 1968.2.
Vehicle E E System Diagnostic Standards Committee
Developing a NEXT-GEN VGT21TOFHP10_0310/1/2021
Engineers from Mitsubishi Heavy Industries refine the design of a variable geometry turbocharger for commercial vehicles. Variable geometry turbochargers (VGT) have been applied to commercial engines for a long time, owing to their operability at wide operation range. One of the major advantages of using a VGT is its ability to provide high boost pressure at low engine speeds, which ensures optimum supply of air for proper combustion, leading to a significant reduction in emissions. Recent emission standards by U.S. EPA and in Europe (Euro VI) demand a higher efficiency from the turbine at all operating points, which motivated engineers from Mitsubishi Heavy Industries to do an in-depth loss analysis of each component and carry out design modifications to achieve these demands. The multi-vane VGT, which has been found to be the most effective among all the configurations, consists of a plurality of nozzle vanes distributed circumferentially upstream of the radial turbine rotor. These vanes are controlled by an electric actuator working in coherence with the engine control unit (ECU) to control the mass flow rate entering the rotor. There are many different types of link mechanisms to transfer the actuation force to the vanes; the authors selected a mechanism consisting of a plurality of lever arms connected to each vane, driven by a drive ring moved circumferentially using a crank arm connected to the actuator.
Fuel Stratification Effects on Gasoline Compression Ignition with a Regular-Grade Gasoline on a Single-Cylinder Medium-Duty Diesel Engine at Low Load2021-01-11739/21/2021
Prior research studies have investigated a wide variety of gasoline compression ignition (GCI) injection strategies and the resulting fuel stratification levels to maintain control over the combustion phasing, duration, and heat release rate. Previous GCI research at the US Department of Energy’s Oak Ridge National Laboratory has shown that for a combustion mode with a low degree of fuel stratification, called “partial fuel stratification” (PFS), gasoline range fuels with anti-knock index values in the range of regular-grade gasoline (~87 anti-knock index or higher) provides very little controllability over the timing of combustion without significant boost pressures. On the contrary, heavy fuel stratification (HFS) provides control over combustion phasing but has challenges achieving low temperature combustion operation, which has the benefits of low NOX and soot emissions, because of the air handling burdens associated with the required high exhaust gas recirculation rates. This work investigates HFS and PFS combustion, efficiency, and emissions performance on a single-cylinder, medium-duty engine with a regular-grade gasoline (91 research octane number) at 1,200 rpm, 4.3 bar, and 3.0 nominal gross indicated mean effective pressure operating points with boost levels similar to those in a medium-duty diesel application. Authority of combustion phasing with main injection timing sweeps for HFS and second injection timing sweeps and fuel split sweeps for PFS are shown. In addition, this work is discussed in the context of previous findings with a light-duty diesel platform, and next steps and future direction for this work are presented1.
Curran, Scott, Szybist, James, Kaul, Brian, Easter, Jordan, Sluder, Scott
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