Browse Topic: Combustion chambers

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Improving Cold Start and Transient Performance of Medium BMEP CEV Stage V Engines at Low Ambient Temperature and Pressure2026-26-014201/16/2026
Meeting the stringent emissions norms of CEV stage V for medium BMEP engines, CI engines present significant challenges, particularly concerning cold startability. Low ambient temperatures and pressures intensify the cold start difficulties which are characterized by prolonged cranking, incidences of misfiring, compromised transient response and overall engine performance. This paper highlights the strategies and technologies employed to enhance cold start and transient performance of medium BMEP engines under such demanding environmental conditions. Investigations were conducted up to an altitude of 4500m and ambient temperatures as low as-20°C, utilizing only air heater at intake manifold as the sole cold start aid. This cost effective approach is integrated with an optimized combustion chamber design, along with minimal pilot injection timing and quantity to facilitate smooth ignition and stable combustion during cold start. The paper also explore the techniques to improve the
Saxena, Harshit, Lokare, Prasad, Santhosh, Ajith, Gandhi, Naresh, Shinde, Prashant
Optimization of Negative Crankcase Pressure Mechanism to Minimize Oil Pumping into Combustion Chamber and Ensure Particulate Number Compliance in Euro VI Emission for Natural Aspirated Gas Engine2026-26-022301/16/2026
Emissions regulations, such as Euro VI, drives the Automotive industry to innovate continuously in Engine development. One significant challenge is the engine oil pumping from the crankcase into the combustion chamber, where it participates in combustion, which contributes to increased Particulate Numbers and fails to meet Euro VI emission compliance. This issue is most noticeable during engine idling and motoring conditions. During this time, a higher negative pressure difference develops between the intake manifold, which is acting above the combustion chamber and the engine crankcase. This pressure difference drives oil-laden blow-by aerosols past piston rings during the intake stroke and through the valve stem seals, allowing oil into the combustion chamber. The impact of the pressure difference between the intake manifold and crankcase was studied by varying the crankcase pressure through crankcase ventilation system. The results confirm that oil entry into the combustion chamber
R, Mahesh Bharathi, Bondfale, Shubham, Jeyaprakasan, Dharoon Gautham
Development of High BMEP Natural Gas Engine with Knock Mitigation2026-26-012101/16/2026
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
Khaladkar, Omkar, Marwaha, Akshey
Evaluation of Intercooler Effectiveness with No Fan, Single Fan, and Dual Fan: A Simulation and Experimental Study2026-26-057901/16/2026
Turbochargers play a crucial role in modern engines by increasing power output and fuel efficiency through intake air compression, thereby improving volumetric efficiency by allowing more air mass into the combustion chamber. However, this process also raises the intake air temperature, which can reduce charge density, lead to detonation, and create emissions challenges—such as smoke limits in diesel engines and knock in gasoline spark-ignited (GSL) engines. To mitigate this, intercoolers are used to cool the compressed air. Due to packaging constraints, intercoolers are typically long and boxy, limiting their effectiveness, especially at low vehicle speeds where ram air flow is minimal. This study investigates the use of auxiliary fans to enhance intercooler performance. Two methodologies were adopted: 1D simulation using GT-Suite and experimental testing on a vehicle under different fan configurations—no fan, single fan, and dual fans (positioned near the intercooler inlet and outlet
Patra, Somnath, Hibare, Nikhil, Ganesan, Thanigaivel, Gharte, Jignesh Rajendra
Unveiling the Dynamics of Methanol-Diesel Dual Direct Injection Compression Ignition Combustion: A Synergistic Experimental and Numerical Study2026-26-011001/16/2026
The pressing global need for de-fossilization of the transport sector, especially within the heavy-duty segment, has intensified the exploration of alternative clean fuels. In this context, methanol gained traction due to their renewable production pathways, carbon-neutrality, and are being highly promoted by the Indian government to reduce CO2 emissions. Dual direct injection compression ignition (DDICI) is an effective combustion strategy to use methanol in heavy-duty engines, which combines the advantage of high-efficiency compression ignition with the clean-burning potential of methanol. In contrast to spark-ignited premixed methanol engines, this strategy involves a diffusion combustion of the methanol flame, thereby eliminating knocking and enabling running with high compression ratios. This experimental and numerical study presents a comprehensive investigation into the DDICI strategy using methanol as primary fuel and diesel as a pilot for ignition assistance. The work
Singh, Inderpal, Dhongde, Avnish, Raut PhD, Ankit, Güdden, Arne, Emran, Ashraf, Berry, Sushil
Combustion Chamber Geometry Comparison in Natural Gas Engines under Conventional and Dethrottled Operation2025-36-021712/18/2025
Growing interest in cleaner energy has spurred progress in engine technology, focusing on greater efficiency and lower emissions. Methane-based fuels, like compressed natural gas (CNG), have become an alternative for spark-ignition engines, especially in Brazil. Among performance strategies, dethrottled operation stands out by reducing intake restrictions and minimizing pumping losses, a major inefficiency in conventional spark ignition engines. This improves thermal efficiency and reduces both fuel consumption and emissions. This study experimentally examines the performance and combustion of a CNG-powered Hyundai HR 2.5 16V engine, converted from diesel to spark ignition with natural gas, comparing factory (omega) and custom (reentrant) piston geometries under both conventional and dethrottled modes. The research evaluates how piston design affects combustion stability, efficiency, and emissions across different load strategies. Tests were conducted at 7, 8, and 9 bar loads, as well
Silva, Cristian Douglas Rosa da, Garlet, Roberto Antonio, Dapper, Jackson Mayer, Fagundez, Jean Lucca Souza, Lanzanova, Thompson Diórdinis Metzka, Martins, Mario Eduardo Santos
Combustion Chamber Pressure and Temperature Analysis Based on Heat Release Rate Parameters of a Spark Ignition Engine2025-36-008212/18/2025
Internal combustion engines have been developed and widely used since the last century, and they continue to be extensively employed today. Engine development has progressed significantly, and due to the environmental impacts caused by their use, new technologies are being developed to reduce pollutant formation after the combustion process and to increase thermal efficiency. Computational modeling is a tool that has supported this development and can be categorized into three types: zero-dimensional, quasi-dimensional, and three-dimensional models. The 0D and 1D models offer a good balance between computational processing time and result uncertainty when compared to three-dimensional models. The Wiebe function is a simple analytical approach capable of describing the fuel burn rate in combustion engines. Previous studies have shown that applying this function yields results that accurately describe the apparent heat release rate in PFI engines.The present study aims to determine the
Souza Pereira, Felipe Augusto de, Araújo Moreira, Thiago Augusto de, Filho, Fernando Antônio Rodrigues
Methodology for Characterizing the Spray of an Internal Combustion Engine Fuel Injector2025-36-019412/18/2025
This study presents a methodology for characterizing the spray of an internal combustion engine (ICE) fuel injector, focusing on direct injection (DI) systems. It addresses the knowledge gap in academic research regarding injector spray patterns by conducting experimental tests and numerical simulations. Using a Bosch HDEV 1.1 pressure swirl injector and EXXSOL D60 test fluid, spray characteristics were captured with a high-speed camera under varying injection pressures and ambient/counterpressure conditions. These experimental data were used to calibrate a numerical model for simulating spray dynamics within the combustion chamber. The research examines the impact of parameters such as breakup length and breakup size constant on spray behavior, revealing that the breakup size constant significantly affects spray penetration. The study successfully developed and validated a methodology for characterizing and modeling fuel injector sprays, providing a valuable reference for optimizing
Paula Araújo, Gabriel Heleno, Assis, Marcelo Suman Silva, Malaquias, Augusto Cesar Teixeira, Carvalho Torres Filho, Marcos, Baeta, José Guilherme Coelho
The Technological Concept of a Self-Adjusting Segmented Ceramic Sealing System for a Turboshaft Engine with Isochoric Combustion03-18-08-004612/08/2025
The article presents self-adjusting segmented ceramic seals designed for a novel turboshaft engine operating according to the Humphrey thermodynamic cycle. The sealing system is an integral part of the developed engine concept, which features rotating isochoric combustion chambers. The seals utilize centrifugal force as the sealing force, enabling uniform sealing regardless of thermal conditions and associated deformations. The sealing consists of segments with adjustable dimensions in both circumferential and transverse directions. The sealing elements should be made of Si3N4 ceramic, characterized by high thermal resistance (1300°C) and low thermal expansion (3.2•10−6/°C). The article presents three different variants of sealing systems, differing in terms of the technological possibilities of their manufacturing. Special treatments must be applied to ensure high machining accuracy of the sealing elements. The proposed sealing system is a critical point in the design of an engine
Tarnawski, Piotr
Knock Phenomenon Investigation in SI Engine Fuelled with Ammonia-Hydrogen Mixture2025-01-053211/25/2025
Ammonia has emerged as a compelling carbon-free alternative fuel for applications in sectors such as power generation and heavy-duty transportation, where thermal energy conversion plays a dominant role. Its potential lies in its high hydrogen content, carbon-free combustion, and the feasibility of large-scale storage and transport. However, ammonia’s combustion behavior poses significant challenges due to its low reactivity, characterized by a low laminar burning velocity, high autoignition temperature, and narrow flammability range. These properties hinder stable and efficient operation in conventional internal combustion engines. A common strategy to mitigate these limitations involves blending ammonia with hydrogen—often generated via on-board catalytic cracking of ammonia—which improves ignition and flame speed. Despite these benefits, the presence of hydrogen increases the risk of knock, particularly in high-compression-ratio engines designed to improve thermal efficiency. This
Hurault, Florian, Brequigny, Pierre, Foucher, Fabrice, Rousselle, Christine
Ammonia Combustion with Active Pre-Chamber Spark Plug - A CO 2 -Free Combustion Process2025-01-052711/25/2025
As a zero-carbon fuel, ammonia has the potential to completely defossilize combustion engines. Due to the inert nitrogen present in the molecule, ammonia is difficult to ignite or burn. Even if the ammonia can be successfully ignited, combustion will be very slow and there is a risk of flame quenching, i.e. the flame going out before the ammonia-air mixture has been almost completely converted. Both the difficult flammability and the slow combustion result in high ammonia slip, which should be avoided at all costs. The engine efficiency is also greatly reduced. Safe ignition and burn-through can be achieved by drastically increasing the ignition energy and/or using a reaction accelerator such as hydrogen. The planned paper will use detailed 1D and 3D CFD calculations to show how high the potential of ammonia combustion in an internal combustion engine is when an active pre-chamber is used as the ignition system. As a result of the flame jets penetrating into the main combustion chamber
Sens, Marc, von Roemer, Lorenz, Rieß, Michael, Fandakov, Alexander, Casal Kulzer, Andre
Sustainable Engines with Carbon-Neutral Fuels – Fast Adaptation for Efficient Multi-Fuel Operation by Tailored Charge Motion Design2025-01-053411/25/2025
As a fundamental element of measures to reduce the carbon footprint of commercial applications, carbon-neutral fuels are increasingly coming into focus for heavy installations. In addition to diesel substitute fuels, alternative energy carriers like NG, H2, MeOH and NH3 are gaining increasing attention. The energy conversion of these fuels is typically taking place on the principle of premixed combustion, which places different demands on fuel injection and mixture formation, as compared to optimized diesel-like combustion. Accordingly, the demand to layout multi-fuel capable engine designs centers to a high share on the above-mentioned design that can burn these different fuels with high efficiency and support a high degree of commonality with the in-series engine to carry over reliable operation and to maintain attractive cost figures. FEV has developed the Charge Motion Design (CMD) process, which can be applied to design the intake ports and combustion chambers for multi-fuel
Koerfer, Thomas, Dhongde, Avnish, Boberic, Aleksandar, Zimmer, Pascal, Pischinger, Stefan
Investigation of Active Pre-Chamber Ignition on an Optically Accessible Ultra-Lean DI Hydrogen Engine2025-01-052411/25/2025
Hydrogen is a promising alternative to conventional fuels for decarbonizing the commercial vehicle sector due to its carbon-free nature. This study investigates the ignition and flame propagation characteristics of hydrogen in a 2-liter single-cylinder optical research engine representative of the commercial vehicle sector. The main objective was to enable high power density operation while minimizing NOx emissions. For that, ultra-lean combustion was employed to lower in-cylinder temperatures, addressing the challenge of NOx formation. To counteract delayed and unstable combustion under lean conditions, an active pre-chamber ignition system was implemented. It uses a gas-purged pre-chamber with separate hydrogen injection and spark plug ignition. Turbulent hot gas jets from the pre-chamber ignite the fresh mixture in the main combustion chamber, enabling faster and more stable ignition compared to conventional spark plugs. Additionally, the low volumetric energy density of hydrogen
Borken, Philipp, Bill, Daniel, Link, Lukas, Dinkelacker, Friedrich, Hansen, Hauke
Optimization of Injection Parameters for a Free-Piston Engine Equipped with Flat-Head Combustion Chamber2025-01-507511/11/2025
The free-piston engine represents a paradigm shift in internal combustion engine technology, with its unique structure promising efficiency gains. However, injection parameters are one of the core elements of free-piston engine performance. This study employs computational fluid dynamics analysis to optimize the spray cone angle and start of injection timing for a two-stroke dual-piston opposed free-piston engine equipped with a flat-head combustion chamber. A three-dimensional transient model incorporating dynamic adaptive mesh refinement was constructed by using CONVERGE 3.0 software. The results indicate that a spray cone angle of 25° achieves optimal fuel distribution, yielding a peak indicated thermal efficiency of 42.14% and an indicated mean effective pressure of 9.08 bar. Crucially, advancing the ignition timing to 215°CA improves mixture homogeneity but simultaneously increases peak cylinder temperatures and NOx. Conversely, delayed start of injection timings reduces NO
Xu, Zhaoping, Yang, Shenao, Liu, Liang
An Open-Source Solenoid Injector Driver Circuit for Fuel Injection Research03-18-07-004111/10/2025
Common rail, high-pressure electronic fuel injection is one of the primary technologies enabling high-efficiency and low emissions in modern diesel engines. Most fuel injectors utilize an actively controlled solenoid valve to actuate a needle that modulates the fuel supply into the combustion chamber. The electrical drive circuit for the injector requires extensive development costs, and thus, most designs are proprietary in nature, making it difficult to perform academic studies of the fuel injection processes. This research presents an injector driver circuit to control one or more solenoid injectors simultaneously for research-based injector development efforts. The electrical circuit was computationally modeled and optimized iteratively, and then, electronic hardware was developed to demonstrate control of a Bosch CRIN3 solenoid diesel injector as proof of concept. In addition, the injector performance was quantified by the fuel rate of injection (ROI) profiles obtained in a test
Bogdanowicz, Edward, Agrawal, Ajay, Lemmon, Andrew N., Bittle, Joshua
Effect of EGR and Ethanol additive on Performance and Emission Characteristics of Diesel Engine Fuelled with Rubber Seed Biodiesel Blends2025-28-022411/06/2025
Alcohol is being considered as an alternative to traditional fuels for compression ignition engines due to their oxygen content and biomass origin. Although alcohol generally has lower cetane numbers, which makes them more favorable for premixed combustion, they also offer potential for lowering emissions in internal combustion engines, particularly when combined with strategies such as exhaust gas recirculation (EGR). This research focuses on enhancing the performance of a single-cylinder, four- stroke diesel engine by introducing ethanol into the intake port during the intake phase. Diesel and rubber seed biodiesel were used as primary fuels and were directly injected into the combustion chamber. The findings indicated that adding ethanol to rubber seed biodiesel, along with 10% EGR, led to improved brake thermal efficiency and a reduction in NOX emissions. The ethanol injection timing and duration were optimized for effective dual-fuel operation. At full engine load, the highest
Saminathan, Sathiskumar, G, Manikandan, Bungag, Joel Quendangan, T, Karthi
Measurement of the Liquid Fuel Film on the Combustion Chamber Wall of a Gasoline Engine using a Novel Capacitive Sensor2025-32-001811/03/2025
The reduction of exhaust emissions and particulate matter from internal combustion engines remains a critical challenge, particularly under cold start and warm-up conditions, where a significant portion of total emissions is generated. In spark-ignition (SI) gasoline engines, the formation of liquid fuel films on intake ports wall, piston and cylinder wall surface significantly contributes to unburned hydrocarbon and particulate emissions. Also, the fuel film adhering to the wall can be a cause of the lubricating oil dilution. To address these issues, a novel capacitive sensor, fabricated using MEMS technology, was developed and applied to investigate the behavior of liquid fuel films formed inside the combustion chamber of a single-cylinder engine. The sensor detects changes in capacitance caused by fuel film adhesion to the sensor surface. The sensor was installed in a single-cylinder test engine along with a direct fuel injector allowing for the controlled formation of fuel films on
Kuboyama, Tatsuya, Nakajima, Takeru, Moriyoshi, Yasuo, Takayama, Satoshi, Nakabeppu, Osamu
Visualization Study on Combustion Characteristics of Ammonia/Methane/Air Mixtures Ignited by Diesel Pilot in Rapid Compression and Expansion Machine2025-32-005411/03/2025
The application of ammonia fuel in engines can significantly reduce carbon emissions, serving as a crucial method for achieving carbon neutrality. However, its potential is hindered by the challenges of ammonia's difficulty in ignition and slow combustion rate. An effective solution to these drawbacks is to blend methane into ammonia mixtures and use a small amount of diesel for ignition. This study investigates the effects of mixture equivalence ratio and gas composition on the combustion characteristics of diesel-ignited NH3/CH4/Air mixtures. Pressure measurements and visual observations were conducted using a rapid compression expansion machine (RCEM). Experimental results reveal that the combustion process exhibits two distinct stages: initial intense diesel combustion followed by mixture combustion. Higher equivalence ratios prolong ignition delay while accelerate secondary combustion. Pure ammonia mixtures show incomplete lean combustion, while richer mixtures achieve more
Yin, Shuo, Dai, Zhizhuo, Zhou, Qingxing, Cui, Zechuan, Zhang, Xiaolei, Ye, Mingyuan, Ren, Yifang, Wang, Zhanpeng, Nishida, Keiya
Diesel Combustion Parameter Estimation via Machine Learning – A Comparative Study2025-32-004111/03/2025
This paper presents an analysis and comparison of distinct approaches for data-driven combustion parameter estimation for Diesel engines. Thereby, characteristic quantities are modelled by a set of selected regression models and via a convolutional neural network (CNN). While the former use settings from the Engine Control Unit (ECU) as input, the latter works by processing the raw crankshaft vibration signal. The central point of this study is a broad evaluation of data-driven modelling for Diesel combustion. This includes whether using a signal recorded from individual combustion cycles achieves better representation of the target values than using operational parameters from the ECU which cannot reflect unforeseeable, stochastic phenomena within the combustion chamber. This was evaluated by assessing predictions of six combustion characteristics: the crank angle of 10, 50 and 90 percent mass fraction burned, Peak-Firing-Pressure, Combustion Duration, and Ignition Delay. In two
Ofner, Andreas Benjamin, Sjoblom, Jonas, Geiger, Bernhard, Haghir Chehreghani, Morteza
Development of a Combined Injection and Ignition Unit for a Gas Engine with Direct Hydrogen Injection Integrated into the Standard Spark Plug Access Hole2025-32-005911/03/2025
To achieve the desired fuel switch from natural gas to hydrogen in internal combustion engines for combined heat and power units, it is necessary to make some adjustments to the fuel supply system. External gas mixers increase the probability of backfiring when natural gas is replaced by hydrogen. In addition, the low density of hydrogen results in a loss of power. Therefore, direct gas injection is preferred when using hydrogen. A drawback of direct injection is the requirement of higher injection pressures to achieve the desired fuel mass and mixture homogeneity as well as the additional access to the combustion chamber for the direct gas injector in the cylinder head. This paper proposes an alternative approach that does not necessitate the implementation of a high-pressure direct injection system nor additional access to the combustion chamber via the cylinder head. A combined injection and ignition unit, called HydroFit, was developed which uses a sleeve inside the spark plug bore
Rischette, Nic, Holzberger, Sascha, Helms, Sven, Kettner, Maurice
Effect of In-Cylinder Hydrogen Mixture Formation on Hydrogen Combustion2025-32-006511/03/2025
Global efforts to mitigate climate change include ambitious long-term strategies by countries to achieve net-zero greenhouse gas emissions by 2050. The automotive sector is exploring carbon-free powertrains, with hydrogen emerging as a key technology. Its zero-emission potential positions it for widespread adoption in power generation, transportation, and industry. Hydrogen engines, particularly direct injection engines offering high power and efficiency, are gaining traction due to their adaptability using existing engine components. However, in a hydrogen direct injection engine, achieving proper mixing of hydrogen and air in the cylinder is challenging, making in-cylinder mixture formation a crucial factor for ensuring stable combustion. To predict hydrogen mixture formation in the cylinder, we conducted a Schlieren visualization experiment of the hydrogen jet. Based on the results, a detailed hydrogen jet model for the direct injection injector was developed. This model was then
Hisano, Atsushi, Saitou, Masahito, Sakurai, Yota, Ichi, Satoaki
Investigating the Influence of Intake Runner Configuration on Scavenging and Combustion Processes in Elliptical Rotor Engines2025-32-008911/03/2025
Elliptical rotor engines (ERE), also known as X-engines, feature intake and exhaust ports located on the rotating rotor. As the rotor turns, these ports traverse the entire combustion chamber, sequentially completing the scavenging process in three distinct combustion chambers through coordination with the cylinder walls. This intake and exhaust characteristic significantly differs from the characteristic found in traditional Wankel rotor engines. This study established an optical elliptical rotor engine to obtain the in-cylinder flow field by using Particle Image Velocimetry (PIV) and constructed a CFD model based on the experimental results. Then the effects of two different intake runners on the scavenging and combustion process of ERE were investigated. The results indicated that: Due to structural limitations, the prolonged intake port opening duration results in significant gas backflow during the intake process. The curved intake runner exhibits a higher turbulent kinetic energy
Qin, Jing, Wang, Yingbo, Pei, Yiqiang, Yao, Dasuo, Deng, Xiwen
Development of Automatic Calibration System for PFI Engines2025-32-008411/03/2025
This report summarizes the research findings on fuel injection calibration methods, aiming to improve engine performance and reduce environmental impact. In Port Fuel Injection (PFI) engines, the injected fuel adheres to the port walls and mixes with air as it vaporizes, then flows into the combustion chamber. Traditionally, the fuel injection quantity is determined by the base map, which is calibrated for a steady state, and corrections for transient conditions. During steady-state operation, the air-fuel ratio of the mixture is uniquely determined by the amount of fuel injected, allowing for reproducible calibration. However, during transient conditions, the amount of fuel adhering to the walls and the amount vaporized do not balance, necessitating transient compensation to achieve the desired air-fuel ratio. Traditional transient compensation has been adapted for each engine model based on experience to accommodate differences in port shapes and injector placements. This approach
Haraguchi, Kazuki
Experimental and Kinetic Study of Methane Blending on The Laminar Combustion and Emission Characteristics of Ammonia Under Various Oxygen Contents at High Temperature and Pressure2025-32-006011/03/2025
As a carbon-free fuel, ammonia is one of the alternatives to traditional fossil fuels, but its combustion characteristics are poor, and it is usually optimized by blending methane and increasing oxygen content. However, there are few relevant studies under different conditions. In this study, the laminar burning velocities (LBV) and flame instability of NH3/CH4/O2/N2 mixture at high initial temperature (T), high initial pressure (p), various oxygen contents (Ω) and methane energy ratios (α) are analyzed using a constant volume combustion chamber (CVCC). Through numerical simulation, how various oxygen contents and methane energy ratios affect the combustion characteristics of NH3/CH4/O2/N2 mixture and NO emission is analyzed. The results show that LBV is positively correlated with T, α and Ω, and negatively correlated with p. Markstein length (Lb) does not change significantly with T, but increases with α and decreases with p and Ω. Both oxygen enrichment and methane blending
YU, Yuantao, Dai, Zhizhuo, Hou, Chunlei, Ye, Mingyuan, Zhang, Xiaolei, Cui, Zechuan, Yin, Shuo, Nishida, Keiya
Numerical Analysis of Combustion Stability and Efficiency Improvement in Ammonia Engine Utilizing Passive Turbulent Jet Ignition (PTJI)2025-32-004911/03/2025
Ammonia, a carbon-neutral fuel, is a promising candidate for next-generation engine applications. However, its low flame speed (~7cm/s) and prolonged ignition delay (~10ms at stoichiometric conditions) impose significant challenges in achieving stable and efficient combustion across varying operating conditions. At high-speeds, incomplete combustion due to limited residence time reduces efficiency, while at low-speeds, ignition instability and low combustion temperatures hinder reliable operation. To address these challenges, the Passive Turbulent Jet Ignition (PTJI) system has been proposed to enhance turbulence-driven mixing and improve ignition characteristics. This study focuses on optimizing a PTJI system for ammonia-fueled engines using a three-phase methodology. First, the 800cc 2-cylinder gasoline engine was modified for ammonia using numerical analysis, and a baseline analysis of the combustion characteristics was conducted. Next, a turbulent intensity study within the PTJI
Ju, Kangmin, Kang, Hyun-Ung, Kim, Jeong Hyeon
Effect of Plasma-Assisted Ignition on Combustion and Emission Characteristics of Two Stroke Engines with Different Fuels2025-32-003011/03/2025
This study explores the effect of plasma-assisted ignition (PAI) on combustion stability and emissions in two-stroke spark-ignition engines. Two engine platforms were evaluated: a conventional single-cylinder two-stroke engine and a thermodynamically advanced opposed-piston two-stroke (OP2S) engine. The OP2S engine configuration offers reduced heat loss and higher power density due to its uniflow scavenging and favorable geometry, but suffers from high residual gas fraction, which increases ignition difficulty and combustion instability. To address this, nanosecond-pulsed PAI was applied in various spatial arrangements and discharge voltages, using both gasoline and a low-reactivity gasoline/DMC blend fuel. Spark ignition timing was held constant at the minimum advance for best torque across all tests. Combustion stability was assessed via indicated mean effective pressure (IMEP) and its coefficient of variation, while CO and HC emissions were measured as environmental indicators
Liu, Jinru, Yamazaki, Yoshiaki, Otaki, Yusuke, Kato, Hayato, Kobayashi, Daichi, Umegaki, Tetsuo, Asai, Tomohiko, Iijima, Akira
Full-Cycle CFD Modeling of a Wankel Engine for UAV Applications Tommaso Lucchini, Federico Ramognino, Giovanni Gaetano Gianetti2025-32-001311/03/2025
Rotary engines offer a highly attractive solution for uncrewed aerial vehicles (UAVs) and portable power generation, thanks to their compact design, high power-to-weight ratio, fewer moving parts, and ability to operate on multiple fuels. Despite their promising advantages, these engines still require significant improvements to match the efficiency and lifespan of traditional reciprocating internal combustion engines. In particular, fuel consumption is impacted by heat losses due to the high surface-to-volume ratio of the combustion chamber, as well as the unfavorable interaction between the rotor and stator, which slows down flame propagation. To address these challenges, computational fluid dynamics (CFD) has become an important tool for the study and optimization of Wankel engines, providing insight into how fuel efficiency is influenced by the complex interactions between combustion chamber design, flame dynamics, flow characteristics, and turbulence distribution. This work
Lucchini, Tommaso, Gianetti, Giovanni, Ramognino, Federico, Cerri, Tarcisio, Marmorini, Luca, Buttitta, Marco
Advanced Multi-Fidelity Simulation of Piston Oil Jet Cooling in High-Performance Engines2025-32-008111/03/2025
The development of next-generation hydrogen-fueled engines introduces critical challenges related to thermal loads within the combustion chamber, particularly in high-performance applications. To address the extreme temperatures encountered, effective piston cooling strategies, such as oil jet impingement, are essential. Accurately predicting thermal stresses to prevent component failure is therefore crucial. However, numerical simulations often come with significant computational costs. This paper presents a comprehensive multi-fidelity modeling approach to predict the thermal behavior of pistons under these demanding conditions. The model integrates a simplified 3D thermal representation of the piston, a lumped-parameter mechanical model of the piston-liner assembly, and convective boundary conditions obtained at various levels of fidelity, from high-level Computational Fluid Dynamics (CFD) simulations to literature correlations. Additionally, the study examines the influence of
Sassoli, Andrea, Romani, Luca, Ferrara, Giovanni, Paolicelli, Giovanni, Balduzzi, Francesco
CFD Analysis of Knocking in Hydrogen-Fueled Spark-Ignition Engines with Large Eddy Simulation and Conjugate Heat Transfer2025-01-038910/07/2025
In the pursuit of a carbon-neutral society, hydrogen-fueled power generation engines are gaining considerable attention. However, knocking remains a significant problem that hinders efficiency improvements in hydrogen-fueled spark-ignition (SI) engines. In particular, the large displacement engines, such as those used in cogeneration and distributed energy sources, often face issues with knocking. This is because, with a larger bore and lower rotational speed, there is a higher risk of auto-ignition occurring before the flame has spread throughout the combustion chamber. Knocking is a complex phenomenon influenced by several interrelated physical factors:1) Flow: the non-uniform distribution of fuel concentration and flow velocity within the cylinder; 2) Combustion: the non-uniform propagation of flames affected by the mixture's concentration and flow velocity distribution; 3) Heat Transfer: the non-uniform temperature of the unburned mixture resulting from the temperature distribution
Nomura, Kazutoshi, Suzuki, Keita, Imamori, Yusuke, Fuse, Azusa, Oda, Yuji, Nakano, Hiroki, Tsujimura, Taku, Suzuki, Yasumasa
CFD and FE Toolset for Predicting Structural Temperatures in a Hydrogen Internal Combustion Engine2025-01-038310/07/2025
Hydrogen has been identified as a promising decarbonization fuel in internal combustion engine (ICE) applications in many areas including heavy-duty on- and off-road, power-generation, marine, etc. Hydrogen ICEs can achieve high power density and very low tailpipe emissions. However, there are challenges; designing systems for a gaseous fuel with its own specific mixing, burn rate and combustion control needs, which can differ from legacy products. Being able to determine the thermal distribution and temperatures of the power cylinder components has always been critical to the design and development of ICE. SAE-2023-01-1675 [1] presented an analytical FE-based tool, and validation using both FE and CFD methods for a Euro VI HD Diesel engine converted to operate on hydrogen gas using direct injection. In this study, updated methods and investigations are presented for Hydrogen ICE including applicability of the Woschni heat transfer correlation, use of CFD thermal wall functions and a
Bell, David J., Shapiro, Evgeniy, Turquand d Auzay, Charles, Hernandez, Ignacio, Hynous, Jan, Kohutka, Jiri, Osborne, Richard, Penning, Richard, Tomiska, Zbynek
Approaches for Mechanical Development and Validation of Hydrogen Internal Combustion Engines2025-01-039810/07/2025
Hydrogen Internal Combustion Engines (H2 ICEs) are seen as a viable zero-emission technology that can be implemented relatively quickly and cost-effectively by automotive manufacturers. The changed boundary conditions of a hydrogen-fueled engine in terms of mechanical and thermal aspects require a review and potential refinement of the design especially for the 'piston bore interface' (liner honing, ring and piston design) but also for other engine sub-systems, e.g. the crankcase ventilation system. The influence of oil entry into the combustion chamber is even more important in hydrogen engines due to the risk of oil-induced pre-ignition. Therefore, investigations of the interaction between friction, blowby and oil transfer into the combustion chamber were performed and are presented in this paper. During the investigations, experimental tests were carried out on a single-cylinder engine ('floating liner') and on a multi-cylinder engine. The 'floating liner' concept allows the crank
Plettenberg, Mirko, Gell, Johannes, Grabner, Peter, Gschiel, Kevin, Hick, Hannes
Experimental Analysis of Enhanced Scavenging Efficiency in Hydrogen-Powered Internal Combustion Engines for Heavy-Duty Applications2025-24-005609/07/2025
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
Schuette, Christoph, Borg, Jonathan, Giordana, Sergio, Rapetto, Nicola
Methodology for the Study of Hydrogen Combustion in an Optical Spark Ignition Engine2025-24-006209/07/2025
The use of hydrogen as a fuel in internal combustion engines represents a promising alternative for reducing CO2 emissions. To optimize its efficiency and better understand the phenomena associated with its combustion, it is essential to have advanced visualization techniques for a better understanding of the processes involved. This paper presents the methodology used in the development of an optical engine for the study of hydrogen combustion, designed from a 454cc single-cylinder engine. The configuration of the optical system is described, which includes the use of high-speed cameras to capture the spark plug activation as well as the flame propagation in the combustion chamber. The engine has two optical accesses, one through the piston and one at the top of the cylinder that allows side viewing of the combustion chamber. In addition, the experimental procedure that alternates combustion cycles with motoring cycles, the determination of the air-hydrogen ratio with which the engine
Pastor, Jose V., Novella, Ricardo, Tejada, Francisco J., Cáceres-Carías, José
Analysis of Momentum Flux Distribution in Jets Produced by a Hydrogen Direct Injection System2025-24-006509/07/2025
The adoption of hydrogen as carbon-free fuel for internal combustion engines in both transport and off-road applications could offer a significant contribution towards carbon neutrality. In the technical pathway to the conversion of conventional engines operating with liquid fuels to hydrogen, a key role is played by the injection systems. In particular for direct-injected combustion systems, the achievement of an adequate capability to control the gas jets development and the following mixing with air in the combustion chamber is mandatory in order to govern the heat release rate, so to obtain high efficiency levels while limiting the knock tendency and NOx formation. In order to achieve this complex task, injector caps featuring multiple holes (often non uniform in size) can be installed on the injector nozzle so to properly distribute hydrogen obtaining a proper matching with the combustion chamber design and with the air charge flow structure. To this end, the development of both
Postrioti, Lucio, Fontanesi, Stefano, Martino, Manuel, Maka, Cristian, Breda, Sebastiano, Falcinelli, Francesco, Ricci, Andrea
Numerical Analysis of the Combustion Process in a Pre-Chamber Marine Engine Fueled with Ammonia-Hydrogen Mixtures2025-24-002109/07/2025
Ammonia and hydrogen, as carbon-neutral fuels, possess the potential to play a crucial role in the decarbonization of the mobility sector. This research examines the optimization of the combustion process in a marine spark-ignition engine through the use of a passive pre-chamber. The study has been carried out using computational fluid dynamics (CFD) models. Considering a hydrogen content in the fuel blend of 15% by volume, at a fixed equivalence ratio equal to 0.8, two different nozzle diameters have been tested, and the optimal spark timings have been identified. Then, the effect of different hydrogen amounts in the fuel mixture on the engine’s performance and emissions has been assessed. An optimal spark timing of 712 CAD has been found for both 3 mm and 5 mm nozzles at the specified operating point. The 5 mm nozzle provides slightly higher IMEPH and gross efficiency, with minimal impact on emissions. Reducing hydrogen in the fuel blend from 15% to 10% lowers IMEPH from 31 to 12 bar
D'Antuono, Gabriele, Lanni, Davide, Galloni, Enzo, Fontana, Gustavo
Exploring the Emission Spectrum of Pure Hydrogen Combustion in Spark Ignition Engines: A Comprehensive Experimental Study2025-24-005109/07/2025
Hydrogen internal combustion engines (H2ICE) have shown enormous potential for zero-carbon emissions, aligning with the European zero-carbon targets in 2050. Adopting hydrogen as a zero-carbon fuel offers a time- and cost-effective approach to directly replacing carbon-based and fossil fuel-powered ICEs. The study aims to provide comprehensive data on the H2ICE engine during steady-state operations of a single-cylinder spark ignition engine with a direct hydrogen injection system. It focuses on emissions, including carbon monoxide (CO) and unburnt hydrocarbons (HC), utilising ultra-fast analysers positioned close to the exhaust valves to minimise signal delay. Particulate matter (PM) emissions are also measured to evaluate the potential for zero-carbon emissions from the H2ICE. Additionally, NO and NO2 emissions are analysed against air-fuel ratios (AFR) to estimate combustion temperature and NOx mechanisms. Water vapour and oxygen emissions are captured to assess their quantities
Mohamed, Mohamed, Zaman, Zayne, Wang, Xinyan, Zhao, Hua, Hall, Jonathan
Spray Dynamics and Collapsing Process of Methanol in a Lateral-Cylinder-Mounted DI Injector2025-24-006309/07/2025
The morphology and collapsing behavior of fuel sprays play a critical role in determining atomization and vaporization characteristics, directly influencing combustion efficiency and emission formation in direct injection systems. In this study, spray dynamics and collapsing processes of methanol and gasoline fuels were examined using a lateral-cylinder-mounted direct injection (DI) injector in a constant volume combustion chamber (CVCC). A tomographic imaging technique was applied to analyze the spatial and temporal characteristics of fuel sprays. Extinction imaging was performed to capture the distribution of droplets within the spray, and the liquid volume fraction (LVF) was quantified based on the Beer-Lambert law. By acquiring extinction images from multiple viewing angles, 3D tomographic reconstructions of the spray morphology were achieved, providing detailed insights into the structural evolution of the sprays during injection. The high latent heat of vaporization of methanol
Kim, Hyunsoo, Lee, Seungwon, Bae, Sumin, Hwang, Joonsik, Bae, Choongsik
Lignin as Cetane Booster for Methanol and Ethanol2025-24-007509/07/2025
Low carbon, though poorly igniting (i.e., low cetane) fuels, such as methanol, ethanol, and ammonia, are gaining momentum in the maritime fuel market. The most adopted strategy to address the fact that these fuels will not, under typical two-stroke marine engine conditions, auto-ignite, is to co-inject a pilot fuel, such as (very) low sulfur marine fuel oil, which does auto-ignite and furthermore doubles as a spark of sorts for the poorly igniting base fuel. This so-called dual-fuel approach is costly and cumbersome. Cetane boosters are known to improve ignitability of alcohol fuels to the point that a pilot fuel is no longer required. In our earlier research, we found some indication that lignin model compounds could likewise improve the ignitability of alcohols. This paper builds further on this hypothesis, now using commercially available lignin rather than model compounds. Auto-ignition behavior of methanol and ethanol was investigated with up to 10 wt% of therein solubilized
Sementa, Paolo, Tornatore, Cinzia, Catapano, Francesco, Lazzaro, Maurizio, Iannuzzi, Stefano, Kouris, Panos, Boot, Michael
Parametric Analysis of Liquid Ammonia Direct Injection for Optimal Ammonia-Hydrogen Combustion in Spark-Ignition Engines2025-24-007209/07/2025
As the global effort to reduce carbon emissions intensifies, ammonia has emerged as a promising fuel alternative due to its carbon-free molecular composition. This study explores the potential of direct liquid ammonia injection combined with port fuel hydrogen injection technology in a spark ignition engine, leveraging Computational Fluid Dynamics (CFD) simulations informed by experimental data and literature. The methodology involves reproducing and validating an evaporation model sourced from the literature. Once validated, the fraction of injected liquid ammonia actively participating in combustion was quantified, an essential step in refining the engine combustion simulation. The engine model was divided into two key simulations: (i) a Volume of Fluid (VoF) simulation of the injector to characterize ammonia behaviour at the nozzle outlet, and (ii) an engine simulation utilizing a Lagrangian spray configuration, based on the VoF results and the validated evaporation model. The
Silvestrini, Sandro, Kinkhabwala, Brijesh, Kubach, Heiko, Koch, Thomas, Seba, Bouzid
A Study on Sensitive Spots in Hydrogen Engines2025-24-005909/07/2025
Premature self-ignitions in hydrogen internal combustion engines have been associated with the presence of hot spots. However, local increases in charge reactivity may be triggered not only by elevated temperatures but also by composition inhomogeneities. Such non-uniformities, in addition to imperfect mixing (e.g., in the case of direct hydrogen injection), may result from external contamination by more reactive components, such as lubricant oil. The present study aims to shed light on the mechanism through which lubricant oil contamination leads to the formation of sensitive spots, by analysing the behaviour of an isolated droplet suspended in a hydrogen/air environment. The “HyLube” chemical kinetic mechanism was employed to reproduce the chemical behaviour of lubricant oil, as it was specifically developed for this purpose. A one-dimensional numerical model was used to simulate the heating, vaporization, and combustion of the droplet. Zero-dimensional simulations were also
Distaso, Elia, Baloch, Daniyal Altaf, Amirante, Riccardo, Tamburrano, Paolo
Comparison of Ignition Modes to Enable Ammonia Combustion Engines: Dual Fuel, Multi-Spark and Pre-Chamber2025-24-000509/07/2025
This study presents a CFD-based evaluation of ignition strategies for enabling ammonia combustion in a light-duty internal combustion engine. The model was first validated against experimental data for both pure ammonia spark ignition and dual-fuel ammonia-diesel compression ignition cases. Upon validation, three ignition strategies were investigated: dual-fuel compression ignition with sixty percent ammonia energy fraction, and multi-spark and passive pre-chamber ignition under stoichiometric conditions. Simulations were used to assess combustion phasing, efficiency, and emissions characteristics. The dual-fuel mode enabled stable ignition but resulted in incomplete combustion, with three-dimensional contours revealing that central regions of the chamber remained largely unburned, contributing to high ammonia slip and highlighting the need for further optimization of spray targeting and combustion chamber design. The multi-spark strategy achieved the highest efficiency through rapid
Shafiq, Omar, Menaca, Rafael, Liu, Xinlei, Uddeen, Kalim, Tang, Qinglong, Turner, James, Im, Hong G.
Effects of Piston Pre-Heating and Friction Reduction on Cold-Start Charge Preparation for DI Methanol Engine: An In-Cylinder CFD Study2025-24-004009/07/2025
Methanol is gaining interest as a renewable fuel for Internal Combustion Engine (ICE) applications. A key challenge for this fuel is its low evaporation rate at low temperatures, which makes cold-starts problematic, particularly in cold climate conditions. The first combustion cycles are characterized by a low combustion chamber temperature and high engine friction. In previous work by the authors, a practical approach was presented to pre-heat the pistons and pre-condition the bearings, thereby reducing friction. In this article, in-cylinder Computational Fluid Dynamics (CFD) modeling is used to study the charge preparation of a DI-SI methanol ICE up to the end of compression. The model is calibrated in-house using measurements from a warm methanol engine. The piston temperature is varied within the range expected from the pre-heating and pre-lubricating device. Friction reduction is translated into the reduced amount of fuel needed to generate the IMEP required to idle the engine
Bovo, Mirko, Mubarak Ali, Mohammed Jaasim
Investigation of Micro Gas Turbines Topped with Wave Rotors for a Hybrid Vehicle Range Extender Engine2025-24-010609/07/2025
Micro gas turbines are gaining renewed interest as range-extender engines in hybrid vehicles due to their superior power-to-weight ratio, fuel flexibility, and robust steady-state performance. However, their widespread adoption is hindered by modest efficiency and high component costs, particularly from recuperators. This study investigates the thermodynamic performance enhancement of two commercial micro gas turbines, the Capstone C-30 and C-60, through wave rotor integration as a topping device. Using Aspen Plus and Aspen Custom Modeler, three configurations were analyzed: a recuperated engine with a single wave rotor, and unrecuperated engines with a single and two cascaded wave rotors, respectively. Key performance metrics—including brake thermal efficiency, specific fuel consumption, and specific work—were evaluated across a range of wave rotor pressure ratios. Results show that the wave rotor significantly improves power output and pressure ratio while maintaining or improving
Babaji, Badamasi, Kenkoh, Kesty Yong, Turner, James W.G.
CFD Evaluation of the Effects of Surface Area-to-Volume Ratio on the Heat Transfer and Flow Field in Wankel Rotary Engines2025-24-001109/07/2025
Wankel rotary engines generally present an unfavourable surface area-to-volume ratio that prevents them from obtaining the high efficiency needed for the currently challenging applications in the mobility sector. In a previous study, an optimisation of Wankel engine geometry was carried out in order to minimise the surface area-to-volume ratio, with the aim of reducing the overall heat loss during the combustion phase. The study reported a counterintuitive finding that the minimum surface area-to-volume ratio configuration actually produced the worst heat loss due to the unusual flow field inside the combustion chamber affecting the Reynolds and Nusselt numbers. The present study aims to provide insights into the surprising results using a detailed flow and heat transfer analysis by undertaking detailed CFD simulations for the most representative configurations in the previous study. The CFD results confirmed the findings of the previous study, showing that the modified Woschni model
Vorraro, Giovanni, Im, Hong G., Turner, James
Numerical Study of Mixing, Combustion and NOx Emissions in a DI High Performance Hydrogen Engine Operated at Stoichiometry2025-24-001009/07/2025
The roadmap towards carbon neutrality by 2050 makes necessary drastic reduction of road vehicle tailpipe carbon emissions. One viable approach to reach the abatement of carbon monoxide and dioxide is to fuel internal combustion engines (ICEs) with hydrogen. The burning of a hydrogen-air mixture inside the combustion chamber reduces to minimal amount the production of carbon emissions and particulate matter that are only produced by the presence of lubricant oil. However, the high temperatures reached by the end-gases promote the formation of nitrogen oxides. In high-performance ICEs, the pursuit for high-specific power by means of the adoption of stoichiometric mixtures is hindered by the need to reduce NOx - as this pollutant drastically drops when moving towards ultra-lean mixtures. The paper aims to present a CFD-3D framework to simulate the full engine-cycle of a high-performance Spark-Ignited (SI) Direct-Injection (DI) ICE fuelled at stoichiometric conditions. The methodology is
Baudone, Antonio Denny, Marini, Alessandro, Sfriso, Stefano, Falcinelli, Francesco, Mortellaro, Fabio, Tonelli, Roberto, Breda, Sebastiano
Enhancing Ammonia Combustion in Heavy-Duty SI Engines: A 3D-CFD Study on Pre-Chamber Ignition, Methane Addition, and Spark Timing Optimization2025-24-000609/07/2025
Ammonia is a promising fuel for achieving zero-carbon emissions in internal combustion engines. However, its low flame speed and heat of combustion pose significant challenges for efficient combustion. The pre-chamber (PC) spark-ignition (SI) system offers a viable solution by generating multiple ignition points in the main chamber (MC), enhancing combustion efficiency and enabling at the same time lean-burn operation. This study investigates the combustion characteristics and emissions of an active PC spark-ignition heavy-duty engine fueled with ammonia and ammonia-methane mixtures through numerical 3D-CFD simulations performed using the CONVERGE software. These simulations provide an accurate representation of the complex chemical and physical phenomena occurring within the combustion chamber. The study starts from a fully methane-fueled case, validated against experimental data, and subsequently explores different ammonia-methane mixtures. Then, a detailed spark timing (ST) analysis
Palomba, Marco, Salahi, Mohammad Mahdi, Cameretti, Maria Cristina, Mahmoudzadeh Andwari, Amin
A One-Piece Liquid Rocket Thrust Chamber AssemblyTBMG-5371209/01/2025
NASA is developing a lightweight one-piece regeneratively cooled thrust chamber assembly (TCA) for liquid rocket engines. Liquid rocket engines create thrust through the expansion of combusted propellants within the TCA. Standard manufacturing of TCAs involves individually building the injector, main combustion chamber and nozzle, and then bolting or welding the components together at the joints. However, potential seal failures in these complex joints can cause catastrophic explosions, as in the tragedy of the Space Shuttle Challenger.
Variable Valve Actuation and Multiple Injections to Enhance the Gas Exchange of a Passive Pre-Chamber Igniter2025-01-031507/02/2025
Pre-chambers, in general, represent an established technology for combustion acceleration by increasing the available ignition energy. Realizing rapid fuel conversion facilitates mixture dilution extension with satisfying combustion stability. More importantly, knock-induced spark retarding can be circumvented, thus reducing emissions and increasing efficiency at high engine loads. Adapted valve actuation and split injections were investigated for this study to enhance the gas exchange of a passive pre-chamber igniter in a single-cylinder engine. The findings support the development of passive pre-chamber ignition systems operable over the whole engine map for passenger vehicles. There are two configurations of pre-chamber igniters: passive pre-chambers and scavenged pre-chambers. This study focuses on the passive design, incorporating an additional small volume around the spark plug into the cylinder head. Hot jets exit this volume after the ignition onset through several orifices
Fellner, Felix, Härtl, Martin, Jaensch, Malte
Method for Externally Controlled Availability of Lubricating Oil in Internal Combustion Engines2025-01-030207/02/2025
Reduced raw emissions from internal combustion engines (ICE) are a key requirement to reach future green-house-gas and pollutive emissions regulations. In parallel, to satisfy the need for increased engine efficiencies, the friction losses of ICEs gains attention. Measures to reduce parasitic drag inside the piston assembly such as reduced piston-ring pretension or thinner grade engine oils may increase oil ingress into the combustion chamber. The oil ingress is known to imply increased particle emissions directly counteracting the raw emission reduction target of engine development. To resolve this target conflict, the transport mechanisms of oil into the combustion chamber are the topic of current research. Specially developed research engines featuring a vertical optical window come with big potential to visualize the phenomena of the oil behavior inside the piston assembly group. Such ‘glass-liner’ engines play a pivotal role in identification and quantification of local and global
Stark, Michael, Fellner, Felix, Härtl, Martin, Jaensch, Malte
Parametric Analysis of Injector Operational Parameters, Charge Dilution, and Intake Valve Opening on In-Cylinder Motion and Flame Development in an Automotive, Lean-Burn, Gasoline Engine with High-Tumble2025-01-019806/16/2025
The effect of injection pressure, start of injection (SOI) timing, charge dilution, and valve timing on charge motion and early flame development was investigated for a pre-production automotive gasoline engine. Experiments were performed in a single-cycle optical engine designed to represent the high-tumble (Tumble ratio = 1.8), lean-burn engine. Time-resolved particle image velocimetry (PIV) was used to characterize velocity flow fields throughout the swept volume during the intake and compression strokes. Diffuse back illuminated imaging allowed for visualization and quantification of the injected liquid fuel spray and its interactions with the tumble vortex. Hydroxyl (OH*) chemiluminescence imaging was performed to image spark channel elongation and early flame kernel development. It was observed that an optimal injection timing of 320° before top dead center (bTDC) resulted in attenuation of the tumble motion and an associated reduction in compression flows that shifted the tumble
MacDonald, James, Ekoto, Isaac, Han, Donghee, Lee, Jonghyeok
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