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 Engines

2025-01-0302

07/02/2025

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

“A Comparative Assessment of Port Fuel Injection and Direct Injection of Hydrogen in Internal Combustion Engines: Performance, Efficiency, and Emissions”

2025-01-0239

06/16/2025

With the transition toward low-carbon fuel-based transportation systems, hydrogen is becoming increasingly promising as a sustainable internal combustion engine (ICE) fuel. There are two pathways for introducing hydrogen: Port Fuel Injection (PFI) and Direct Injection (DI) in an engine, which greatly affect performance, efficiency, and emissions. In the Port Fuel Injection (PFI), hydrogen is introduced into the intake manifold and mixed with air before reaching the combustion chamber. This approach is preferred due to its affordability, ease of use, and compatibility with current engine configurations. Because of PFI's more uniform air-fuel mixture, combustion is smoother, and NOx emissions are reduced. On the other hand, it raises the possibility of pre-ignition, particularly when engine loads are high, and a decrease in volumetric efficiency due to a reduction in the volume of intake air as hydrogen replaces it. Direct injection gives exact control over the timing and volume of fuel

Ahirwar, Sachin, Kumar, Naveen

Combustion and Emission Characteristics of Marine Ammonia-Diesel Dual Fuel Engine with Micro-Pilot Injector Change

2025-01-0235

06/16/2025

Recently, as regulations on greenhouse gas emissions have become stricter, driven by global warming, there is increasing interest in engines utilizing environmentally friendly fuels. In this context, ammonia is attracting attention as a potential alternative to fossil fuels in the future. However, due to its distinct fuel properties compared to conventional fuels, research is being conducted on utilizing diesel as an ignition source for ammonia. In this study, the effects of diesel injector fuel flow rate, and micro-pilot (MP) diesel injection timing on combustion and exhaust emission characteristics were analyzed in a single cylinder 12L marine ammonia-diesel dual-fuel engine. Two types of diesel micro-pilot injectors were tested. The first one was high flow rate micro-pilot injector (HMPI) and the second one was low flow rate micro-pilot injector (LMPI). HMPI injector had 66% more number of fuel injector nozzle hole and 250% larger fuel flow rate. Therefore, HMPI injector could

Jang, Ilpum, Park, Cheolwoong, Kim, Minki, Park, Chansoo, Kim, Yongrae, Park, Gyeongtae, Lee, Jeongwoo

Development of Combustion System for a Hybrid-Dedicated Homogeneous Lean Burn Engine

2025-01-0216

06/16/2025

This study explores strategies to extend the lean combustion limit, improve thermal efficiency, and reduce engine-out emissions in a hybrid-dedicated homogeneous lean-burn engine. Under lean combustion conditions, slow laminar flame speed hinders flame kernel growth, leading to combustion instability and limiting lean limit of air excess ratio. To address this challenge, the combustion system is developed to generate high-intensity in-cylinder flow promoting plasma channel expansion at the spark plug gap and enabling the formation of larger initial flame kernel. A newly designed intake port and piston bowl geometry were introduced to enhance tumble flow, significantly raising convective flow speed at the spark plug gap. This accelerated the initial combustion process and effectively expanded the lean combustion limit. A high-energy multiple ignition was also implemented to prevent spark channel blow-off or short circuit caused by increased electrical resistance, further improving

Oh, Heechang, Lee, Jonghyeok, Sim, Kiseon, Park, Jongil, Kim, Taekyun, Kang, Hyunjin, Hong, Seungwoo, Han, Donghee, Kim, Dokyun

Analysis of Diesel-Ethanol Blends: Impact on Spray Behavior and Combustion Properties under Various Injection Parameters in CI Settings

2025-01-0208

06/16/2025

With rising fuel consumption across road transportation, there is growing interest in expanding the market share of renewable fuels, such as ethanol. Ethanol can be produced from raw materials from various starch-rich plants. In CI engines, ethanol cannot be utilized on its own, largely due to its low cetane number. In this study, a constant volume combustion chamber (CVCC) is employed to investigate the effects of adding ethanol in diesel with different proportions (10%, 20%, 30% v/v) on the spray and combustion characteristics. Optical techniques, such as shadowgraph and direct photography using high-speed imaging methods, were employed to reveal the spray and flame development process. This study examines the effects of varying fuel injection pressures (50, 80, and 110 MPa) and ambient pressures (1.5 and 3 MPa) on diesel-ethanol (DE) fuel blends. The study emphasizes the impact of DE blending ratios on the spray’s macroscopic features, while the microscopic characteristics are

Putra, I Komang Gede Tryas Agameru, Lim, Ocktaeck

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-Tumble

2025-01-0198

06/16/2025

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

Experimental Investigation of n-C7H16/Ethanol Blended Fuels on Auto-ignition and Flame Propagation in High Temperature/Pressure Constant-Volume Combustion Vessel

2024-32-0050

04/18/2025

This study aims to investigate the effect of ethanol blends on flame propagation and auto-ignition under high pressure and high temperature conditions. Experimental investigations are conducted using n-C7H16 / ethanol blends at various blending ratios (0, 5, 10, 20, 40, 70, and 100 vol%). The blends are premixed with air at stoichiometric ratios and ignited centrally in a cylindrical constant-volume combustion chamber (20-mm inner diameter, 80-mm long) under elevated temperature (500 K) and pressure (1.0 MPa) conditions. The results show that auto-ignition occurs at an ethanol blend ratio of 10% or less and ceases above 20%. Increasing the ethanol blend to 70% results in a slight change in flame propagation speed, with a noticeable delay at 100%. The pressure measurements show a peak of about 5.6 MPa at a blend ratio of 5%, which gradually decreases with increasing ratios. High-pass filtering reveals the maximum pressure fluctuation amplitude at the 5% blend ratio, indicating increased

Tateishi, Tokua, Yamaguchi, Riki, Shimokuri, Daisuke, Terashima, Hiroshi, Hara, Takaya, Honda, Yuya, Kawano, Michiharu

Statistical Analysis of Data Acquired from Propagating Flames in Gasoline Engines Using a Multiple Ion Probe

2024-32-0035

04/18/2025

Multiple-ion-probe method consists of multiple ion probes placed on the combustion chamber wall, where each individual ion probe detects flame contact and records the time of contact. From the recorded data, it is also possible to indirectly visualize the inside of the combustion chamber, for example, as a motion animation of moving flame front. In this study, a thirty-two ion probes were used to record flames propagating in a two-stroke gasoline engine. The experiment recorded the combustion state in the engine for about 3 seconds under full load at about 6500 rpm, and about 300 cycles were recorded in one experiment. Twelve experiments were conducted under the same experimental conditions, and a total of 4,164 cycles of signal data were obtained in the twelve experiments. Two types of analysis were performed on this data: statistical analysis and machine learning analysis using a linear regression model. Statistical analysis calculated the average flame detection time and standard

Yatsufusa, Tomoaki, Okahira, Takehiro, Nagashige, Kohei

Experimental Study on Pre-Chamber Hydrogen Flame Jet Ignition of Ammonia/Air Mixture in Constant Volume Combustion Chamber

2024-32-0117

04/18/2025

To address the issues of difficult ignition and slow combustion when ammonia is used as engine fuel, a method of igniting ammonia/air mixture with hydrogen flame jet generated by a pre-chamber is proposed. The combustion characteristics of mixtures ignited by the hydrogen flame jet were studied in a constant volume combustion chamber with high-speed video camera and pressure acquisition in the main chamber. The characteristics were compared with those ignited by the ammonia flame jet. The introduction of the hydrogen flame jet notably improved mixture combustion and expanded the lean flammability limit. Combustion with hydrogen injection demonstrated reduced pressure rise delay and combustion duration, increased average heat release rate, and sustained combustion stability. This phenomenon was more pronounced under low equivalence ratio conditions in the main combustion chamber. The hydrogen flame jet was shuttle-shaped when touched the lower surface owing to the rapid combustion speed

Yin, Shuo, Tian, Jiangping, Cui, Zechuan, Zhang, Xiaolei, Nishida, Keiya, Dong, Pengbo

Experimental Investigation for the Effect of Cavity Geometry on the Flame Propagation and Auto-Ignition in RCM

2024-32-0060

04/18/2025

In this experiment, we investigated the auto-ignition and flame propagation behavior by using flat piston and cavity pistons which has different geometries, depth, and width of the cavity. In this study, flame behavior inside the cavity is visualized with the ion-probes, which is embedded every 3mm radially from the center of the piston. We also used the pressure sensor in the combustion chamber and high-speed camera through the quartz window near the cylinder wall. Flame appearance obtained with high-speed camera shows that the flame propagation of the cavity piston is faster than that of flat piston. This is considered because of the outward induced flow in the squish area. That is, the flame propagation inside the wide cavity area pushes the unburned gas outwardly and induced the outward flow in the squish area. This induced flow promotes the flame propagation. As a result, unburned gas is consumed rapidly, and thus, it is also found that the intensity of Knocking is reduced by

Yamaguchi, Riki, Esaki, Daigo, Tateishi, Tokua, Osaf, Ali Hassan, Miyoshi, Akira, Shimokuri, Daisuke, Yatsufusa, Tomoaki, Terashima, Hiroshi, Hara, Takaya, Honda, Yuya, Tadokoro, Tadashi, Kawano, Michiharu

CFD Analysis of Pintle-Nozzle Spray for Swirl Chamber Type Small Diesel Engine -Application of Hole-Nozzle Atomization Model to Pintle-Nozzle

2024-32-0109

04/18/2025

Swirl chamber combustion system is commonly used for IDI (In-Direct Injection) diesel engine. It is characterized by swirl combustion chamber arranged in cylinder head, main combustion chamber with shallow piston recess and connecting throat where fuel spray and flame mixture is ejected out from the swirl chamber to the main chamber [1]. Fuel is supplied in the swirl chamber and a pintle type nozzle is often used in this type engine as its simple structure and robustness for operating condition. In this paper, numerical simulation of a pintle nozzle spray was focused on and simulated results were compared with high speed photo data obtained in a constant volume vessel (CVV). Spray angle and tip penetration were mainly evaluated, but simulated angle and penetration could not be matched simultaneously to these characteristics of the pintle nozzle spray when conventional spray models were used for the simulation. To overcome this mismatch, “Multi-hole replacement model” was newly

Okazaki, Tadao, Fujiwara, Tsukasa

Fuel Film Measurement in a SI Gasoline Engine Using a Newly Developed MEMS Sensor

2024-32-0071

04/18/2025

The previously developed capacitance sensor for detecting a liquid fuel film was modified to apply to the in-cylinder measurement. On the developed sensor surface, comb-shaped electrodes were circularly aligned. The capacitance between the electrodes varies with the liquid fuel film adhering. The capacitance variation between the electrodes on the sensor surface was converted to the frequency variation of the oscillation circuit. In the previous study, it was revealed that the frequency of the oscillation circuit varies with the variation of the liquid fuel coverage area on the sensor surface. The developed sensor was installed in the combustion chamber of the rapid compression and expansion machine, and the performance of the developed sensor was examined. Iso-octane was used as a test fuel to explore the sensor that had been developed. As a result, the adherence of the liquid fuel directly injected into the cylinder was successfully detected under the quiescent and motoring

Kuboyama, Tatsuya, Moriyoshi, Yasuo, Takayama, Satoshi, Nakabeppu, Osamu

Effect of Ignition Position on Lean Limit of Main Chamber Combustion in Pre-Chamber Ignition

2024-32-0022

04/18/2025

An engine was built in this study that enabled the conditions in a pre-chamber and in the main combustion chamber to be visualized simultaneously for the purpose of elucidating the mechanism of pre-chamber combustion. An investigation was made of how the state of pre-chamber combustion, including the location of initial flame generation and its subsequent propagation, influenced pre-chamber jet combustion. The state of pre-chamber combustion was intentionally varied by changing the position of pre-chamber ignition. As a result, it was found that changing the position of pre-chamber ignition varied the location where the pre-chamber flame occurred, how the flame propagated and the timing and strength of the flame jet that was ejected into the main chamber. The results revealed that these differences in the state of pre-chamber combustion markedly changed the rate of combustion fluctuation, combustion period, lean-burn limit and other combustion characteristics depending on the ignition

Onuma, Takeru, Yamada, Hiroto, Ugajin, Taisei, Shinozaki, Kaito, Tahara, Ryota, Iijima, Akira

Detailed Approach for Pre-Chamber Heat Release Analysis for the HSASI Pre-Chamber Spark Plug Using a Pressure Sensor Glow Plug

2024-32-0063

04/18/2025

The hot surface-assisted spark ignition (HSASI) pre-chamber spark plug, which was developed at the Karlsruhe University of Applied Sciences, increases the dilution limit with excess air and the tolerance to residual gas in the pre-chamber compared to a conventional passive pre-chamber spark plug. In this study, the conventional glow plug which is integrated in the pre-chamber of the HSASI pre-chamber spark plug was replaced by a pressure sensor glow plug (PSG) from BERU. This allows for a detailed combustion analysis in the pre-chamber. The signal of the PSG was validated with a piezoelectric cylinder pressure sensor and a method to analyse the pre-chamber heat release was introduced. Experimental investigations were carried out on a single-cylinder gasoline engine. A series of operating points diluted with excess air and a variation in load were conducted. The gas flow rate through the orifices of the pre-chamber was calculated from the pressure difference between the pre-chamber and

Holzberger, Sascha, Kettner, Maurice, Kirchberger, Roland

Effects of Jet Caps on Hydrogen Piezoelectric Injectors for DI Applications: Experiments and 3D-CFD Simulations

2025-01-8454

04/01/2025

The adoption of hydrogen as a sustainable replacement for fossil fuels is pushing the development of internal combustion engines (ICEs) to overcome the technical limitations related to its usage. Focusing on the fuel injector in a DI configuration, it must guarantee several targets such as the adequate delivery of hydrogen mass for the given operating condition and the proper mixture formation in the combustion chamber playing a primary role in reaching the target performance in H2-ICEs. Experimental campaigns and computational fluid dynamics simulations can be used as complementary tools to provide a deep understanding of the injector behaviour and to drive design modifications in a quick and effective way. In the present work an outward opening, piezo-actuated injector purposely designed to be fuelled with hydrogen is tested on several operating conditions to evaluate its performance in terms of delivered mass flow and jet morphology using the Schlieren imaging technique. To

Pavan, Nicolò, Cicalese, Giuseppe, Gestri, Luca, Fontanesi, Stefano, Breda, Sebastiano, Mechi, Marco, Vongher, Sara, Postrioti, Lucio, Buitoni, Giacomo, Martino, Manuel

Development of the New 2.0L In-Line 4 NA Gasoline Direct Injection Engine

2025-01-8395

04/01/2025

Honda Motor Corporation has developed a new naturally aspirated in-line 4-cylinder direct injection gasoline engine for C segment sedans that combines high environmental performance and power output. Development time and cost were greatly reduced by utilizing basic structures and components that had previously been developed engine for hybrid vehicles. In addition to the environmental performance at which hybrid engines excel, the driving performance required from a pure gasoline engine for C segment sedans with a low environmental impact was aimed to achieve by optimizing the shape of the combustion chamber to obtain rapid combustion, adjusting intake and exhaust valve timing, employing fuel injection control and adopting a two-piece water jacket that protects the exhaust system component by lowering the exhaust gas temperature at high load. As a result, the newly developed engine achieves a maximum thermal efficiency of 40% with knock suppression effect through rapid combustion

Kondo, Takashi, Ohmori, Takeyuki, Yamamoto, Junpei, Miki, Kentaro

Three-Body Abrasive Wear Surface Characterization of Military Diesel Engine Piston Rings and Cylinder Bores

2025-01-8346

04/01/2025

Two 50-hr engine dynamometer tests were conducted on 12-cylinder diesel military engines with differing piston ring sets. Engine A exhibited more than double the oil consumption over engine B. An investigation was conducted to explain why the oil consumption differed by employing several posttest analytical techniques including cylinder bore geometry measurements, surface metrology, wear characterization, and chemical analysis on the piston rings and cylinder wall coatings. The 3D colormaps of cylinder bore deformation showed uneven volumetric deformation through the piston stroke instead of 2D plane deformation. It was found that the primary reason of high oil consumption was direct loss of sealing between the piston, piston ring and cylinder bore due to predominately abrasive wear, three-body abrasive wear and bore polishing. Furthermore, the compromised sealing of the combustion chamber led to blow-by. Carbon deposits, corrosive byproducts, surface abrasives, loss of desired surface

Thrush, Steven, Chen, Aijie, Foley, Michael, Sebeck, Katherine, Boufakhreddine, Ziad

Nitrogen Oxides Reduction Potential Via Water Direct Injection in a Single-Cylinder Hydrogen-Fueled Direct Injection Spark Ignition Engine

2025-01-8427

04/01/2025

In hydrogen-fueled internal combustion engine (H2ICE), there are some ways to reduce nitrogen oxides (NOx) emissions. Using the wide flammability range of hydrogen, such as conducting lean combustion to reduce nitrogen oxides and employing exhaust gas recirculation (EGR), have been adopted. However, challenges exist in terms of load expansion, and due to the absence of high heat capacity of carbon dioxides in the exhaust, EGR also struggles to exhibit significant effects. In such a scenario, there is growing interest in injecting water into the H2ICE as an alternative to augment the EGR effect. In this study, the spark ignition (SI) single-cylinder engine equipped with two direct injectors was used to evaluate the hydrogen and the water dual direct injection combustion system. This system involved the direct injection of hydrogen using a wall-guided gasoline direct injector and the direct injection of water into the combustion chamber using a diesel injector. This approach utilizes the

Kim, Kiyeon, Lee, Seungil, Kim, Seungjae, Lee, Seunghyun, Min, Kyoungdoug, Oh, Sechul, Son, Jongyoon, Lee, Jeongwoo

Combustion and Emissions Improvement of Engine Idling Via Advanced Ignition Strategies

2025-01-8404

04/01/2025

During engine idling, the low engine speed, typically from 600 rpm to 800 rpm, together with the low throttle opening angle, makes it challenging for a proper fuel air mixing process. The uneven intake charge distribution and high portion of internal EGR because of the inefficient gas exchange process further make the air fuel ratio unstable, which is challenging for a robust ignition and combustion process. In this paper, the challenge of achieving proper combustion phasing while maintaining acceptable combustion stability is investigated, and a specially designed common-coil pack was utilized to improve engine idling performance by supplying prolonged ignition duration and elevated discharge current amplitude. The common-coil pack, which comprises three parallel connected ignition coils, was shared by all 4 cylinders of the engine. The ignition strategy shows the capability to advance the combustion phasing for higher IMEP output, while maintaining the combustion stability, and

Yu, Xiao, Chen, Guangyun, Qian, Jin, Leblanc, Simon, Wang, Linyan, Zheng, Ming

Characterization of Dimethyl Ether (DME) Spray Using ECN Spray D Under Engine-Relevant Conditions

2025-01-8457

04/01/2025

This research experimentally investigates the spray vaporization of high-pressure dimethyl ether (DME) using a single-hole research injector focusing on nominal operating conditions from the Engine Combustion Network (ECN). DME is a synthetic alternative to diesel fuel, offering both high reactivity and potential reductions in particulate emissions. Because DME only features half of the energy density of diesel fuel, a specifically designed fuel system with a high mass flow rate to meet the energy delivery requirements is needed. The unique physical properties of DME, including higher vapor pressure and lower viscosity, introduce challenges like cavitation and unique evaporation characteristics that deviate from typical diesel fuel. These features are likely to lead to differences in fuel mixing and combustion. This study aims to provide detailed experimental data on DME spray characteristics under engine-like conditions, helping the development of predictive CFD models for optimal

Yi, Junghwa, Wan, Kevin, Pickett, Lyle, Manin, Julien

Optical Investigation of DI Hydrogen Jet Development and Jet-Wall Interactions Under Engine-Like Conditions

2025-01-8456

04/01/2025

Direct injection (DI) hydrogen internal combustion engines are gaining attention as a promising technology for a sustainable energy transition, particularly in the transport sector. A key factor in improving the performance of these engines is understanding how hydrogen jets behave within the combustion chamber, especially their interactions with the chamber walls. These jet-wall interactions are critical since they have a major influence on fuel-air mixing which directly affects combustion efficiency and emissions. This study investigates the behavior of high-velocity hydrogen jets formed after exiting the injector. These jets propagate through surrounding air and interact with wall surfaces. When they impinge on wall surfaces, they undergo various processes such as radial spreading outward along the wall surface, mixing, and diffusion. These processes are influenced by factors including pressure ratio (PR) - the ratio between injection pressure and chamber pressure - and the geometry

Gong, Miaoxin, Lundgren, Marcus, Eismark, Jan, Andersson, Mats

Evaluation of the Effect of Image Processing Methodology on Vapor Length and Spray Angle in a Constant Volume Combustion Chamber

2025-01-8465

04/01/2025

In direct injected engines the spray formation is important for both combustion performance and emission formation. Thus, being able to compare how the spray formation is affected by changes in nozzle design, injection pressure or fuel formulation is an important area of research for all engine sizes. This becomes especially important for the introduction of new sustainable fuels, or for fuel injection optimization to increase efficiencies and minimize the formation of emissions such as particles. High-speed imaging of the fuel spray using the schlieren technique is well established for this purpose, and the Engine Combustion Network (ECN) has developed multiple guidelines to ensure that a similar experimental approach is used in different laboratories around the world. For the initial image processing, the ECN provides a procedure based on an image-temporal-derivative approach. Many researchers however rely on intensity-based thresholding, preceded by contrast adjustment, background

Sileghem, Victor, Larsson, Tara, Dejaegere, Quinten, Verhelst, Sebastian

Comprehensive Investigation of Combustion Characteristics, Emissions, and Tribological Properties of Synthetic Kerosene (S8) in a CVCC and CRDI Research Engine

2025-01-8443

04/01/2025

There is a need to reduce both the greenhouse gas emissions of internal combustion engines, and the reliance on traditional fossil fuels like Ultra Low Sulfur Diesel (ULSD). In this research, a synthetic paraffinic kerosene fuel, designated S8 and created from natural gas feedstocks using the Fischer-Tropsch process was investigated to determine its autoignition and combustion characteristics, emissions, and tribological properties. This fuel, S8, was found to have a Derived Cetane Number (DCN) of 62, which reflects a shorter Ignition Delay (ID), and Combustion Delay (CD) compared to ULSD, which has a DCN of 48. However, due to the chemical properties of S8, it lacks sufficient lubrication qualities in comparison to ULSD, so addition of 3% methyl oleate by mass was used to improve lubricity. The shorter ignition delay of S8, initially observed in a Constant Volume Combustion Chamber (CVCC) and confirmed in a fired Common Rail Direct Injection (CRDI) experimental engine. Investigations

Soloiu, Valentin, Willis, James, Norton, Coleman, Davis, Zachary, Graham, Tristan, Nobis, Austin

Virtual Evaluation of Ceramic Glow Plug Design using Multiphysics Simulation Approach

2025-01-8367

04/01/2025

A glow plug is generally used to assist the starting of diesel engines in cold weather condition. Low ambient temperature makes the starting of diesel engine difficult because the engine block acts as a heat sink by absorbing the heat of compression. Hence, the air-fuel mixture at the combustion chamber is not capable of self-ignition based on air compression only. Diesel engines do not need any starting aid in general but in such scenarios, glow plug ensures reliable starting in all weather conditions. Glow plug is actually a heating device with high electrical resistance, which heats up rapidly when electrified. The high surface temperature of glow plug generates a heat flux and helps in igniting the fuel even when the engine is insufficiently hot for normal operation. Durability concerns have been observed in ceramic glow plugs during testing phases because of crack formation. Root cause analysis is performed in this study to understand the probable reasons behind cracking of the

Karmakar, Nilankan, Orban, Hatem

Numerical Investigation of Injector Cap Design on Hydrogen Jet Characteristics

2025-01-8463

04/01/2025

One of the most critical enablers of hydrogen internal combustion engines is achieving rapid injection and mixing of hydrogen into the combustion chamber. Optimal cap is actively being investigated to improve the injector performance without major hardware modifications. In this study, detailed computational fluid dynamics simulations using the Reynolds-averaged Navier-Stokes (RANS) turbulence model were undertaken to investigate the behavior of hydrogen jets with various cap designs mounted on a hollow-cone injector within a constant volume chamber. It was found that the implementation of a cap in general enhances mixture formation, leading to a higher proportion of lean mixture over time. Key parameters, such as the cap's inner volume and throat area ratio, directly influence the amount of hydrogen mass trapped within the cap. A smaller volume or larger throat area ratio results in less trapped hydrogen mass. Excessive enlargement of the cap's throat area can lead to a decrease in

Zaihi, Abdullah, Moreno Cabezas, Kevin, Liu, Xinlei, Ben Houidi, Moez, Wu, Hao, AlRamadan, Abdullah, Cenker, Emre, Mohan, Balaji, Roberts, William, Im, Hong

Flame Extinguishing and Heat Transfer in the Combustion Chamber of a Hydrogen Engine

2025-01-8420

04/01/2025

Conversion to hydrogen of automobile internal combustion engines powered by fuels of petroleum origin is the most important direction for solving environmental, energy and climate problems of modern civilization. A number of researchers, based on experimental studies, note the presence of a phenomenon of a significant increase in heat losses in hydrogen engines compared to gasoline engines. This phenomenon is explained by an increase in temperature and speed of movement of the working fluid. In this paper, it is shown that the main reason for the increase in thermal losses is the ability of the hydrogen flame to penetrate into the narrow gap between the piston and the engine sleeve. This problem has not been discussed in engine theory before. D mathematical modeling of flame penetration and extinguishing processes in the specified gap of a hydrogen engine (D/S=86/86 mm/mm, Ne=60 kW, n=5500 min-1) was carried out. Critical gap sizes for various fuels have been established, heat transfer

Kavtaradze, Revaz, Natriashvili, Tamaz, Gladyshev, Sergey

An Experimental Investigation of the Liquid Jet Breakup Characteristics in a Vaporizer under Equivalent Operating Conditions of a Microturbine Combustion Chamber

2025-01-8458

04/01/2025

This study experimentally investigates the liquid jet breakup process in a vaporizer of a microturbine combustion chamber under equivalent operating conditions, including temperature and air mass flow rate. A high-speed camera experimental system, coupled with an image processing code, was developed to analyze the jet breakup length. The fuel jet is centrally positioned in a vaporizer with an inner diameter of 8mm. Airflow enters the vaporizer at controlled pressures, while thermal conditions are maintained between 298 K and 373 K using a PID-controlled heating system. The liquid is supplied through a jet with a 0.4 mm inner diameter, with a range of Reynolds numbers (Reliq = 2300÷3400), and aerodynamic Weber numbers (Weg = 4÷10), corresponding to the membrane and/or fiber breakup modes of the liquid jet. Based on the results of jet breakup length, a new model has been developed to complement flow regimes by low Weber and Reynolds numbers. The analysis of droplet size distribution

Ha, Nguyen, Quan, Nguyen, Manh, Vu, Pham, Phuong Xuan

Investigation into Abnormal Combustion Events in a PFI and DI Hydrogen Spark-Ignition Engine

2025-01-8399

04/01/2025

The hydrogen internal combustion engine technology, with its potential for almost full carbon emissions reduction and adaptability to a wide range of fossil fuel-based internal combustion engine (ICE) platforms, offers a promising future. However, as with any innovative technology, it also presents challenges, such as abnormal combustion phenomena. These challenges, including intake backfire, which is more common when using port fuel injection (PFI), and pre-ignition in the combustion chamber, which can be experienced with PFI or direct injection (DI), require detailed investigation to understand and optimize the engine’s performance and efficiencies. This study comprehensively investigates the main abnormal combustion events that could happen in a spark ignition (SI) hydrogen engine. It examines both direct and port fuel injection systems and uses high-resolution in-cylinder, intake, and exhaust pressure measurements alongside a suite of fast-response gas analyzers. The study provides

Mohamed, Mohamed, Mirshahi, Milad, Wang, Xinyan, Zhao, Hua, Harrington, Anthony, Hall, Jonathan, Peckham, Mark

Development of a 6.7L Direct Injection, Lean Burn H2 Spark Ignition Engine for Medium- and Heavy-Duty Commercial Vehicles

2025-01-8393

04/01/2025

This work is part of a production-intent program at Cummins to develop a 6.7L direct injection (DI), lean burn H2 spark ignition (SI) engine for medium- and heavy-duty commercial vehicles that are intended to be compliant with global VII criteria pollutants emissions standards. The engine features a low-pressure DI fuel injection system, a tumble-based combustion system with a pent-roof combustion chamber, two-stage boosting system without EGR, and dual overhead cams (DOHC) with cam phasers. The paper focuses primarily on the performance system architecture development encompassing combustion system, air-handling system, and valve strategy. Comprehensive 3D-CFD guided design analysis has been conducted to define the tumble ports, injection spray pattern, and injection strategy to optimize charge homogeneity and turbulence kinetic energy (TKE). In addition, the boosting system architecture and the valve strategy have been thoroughly evaluated through 1-D system-level engine cycle

Liu, Lei, Zhang, Yu, Qin, Xiao, Hui, He, Min, Xu, Leggott, Paul

Development of the Tour Split-Cycle Internal Combustion Engine

2025-01-8394

04/01/2025

The Tour engine is a novel split-cycle internal combustion engine (ICE) that divides the four-stroke Otto cycle of a conventional ICE between two separate cylinders, an intake and compression cylinder and a second expansion and exhaust cylinder, interconnected by an innovative charge transfer mechanism. The engine working fluid, air and fuel, is inducted into the engine and compressed by a dedicated compression cylinder, transferred with minimal pressure loss via an input port to a specifically designed combined spool shuttle transfer mechanism and combustion chamber. It is then ignited and then transferred from the combustion chamber via an exit port to a separate expansion cylinder where it is expanded and exhausted from the engine. The primary advantage of the Tour engine is that it provides the engineering freedom to independently design, control and optimize the compression, combustion, and expansion processes within a slider-crank piston engine. By decoupling the compression

Tour, Oded, Cho, Kukwon, Hofman, Yehoram, Anderson, Bradley, Kemmet, Ryan, Morris, Daniel, Wahl, Michael, Bhanage, Pratik, Sivan, Ehud, Tour, Gilad, Atkinson, Chris, Tour, Hugo

An Integrated Material Science Approach to Evaluate the Viability of Ethoxy Ethane and Rubber Seed (Heavea Brasiliensis) Biodiesel as Sustainable Fuel for Compression Ignition Engines

2025-28-0130

02/07/2025

The primary issues in using pure vegetable oils for internal combustion engines are their high soot output and reduced thermal efficiency. Therefore in the present investigation, a Heavea Brasiliensis biodiesel (HBB) is used as a carbon source of fuel and ethoxy ethane as a combustion accelerator on a compression ignition (CI) engine. In this investigation, an only one cylinder, four-stroke, air-cooled DI diesel engine with a rated output of 4.4 kW at 1500 rpm was utilized. Whereas heavea brasiliensis biodiesel was delivered straightly into the cylinder at almost close to the end of compression stroke and ethoxy ethane was sprayed instantly in the intake manifold in the event of intake stroke. At various loads, the parameter of ethoxy ethane volume rate were optimised. To minimise exhaust emissions, an air plasma spray technology was employed to cover the engine combustion chamber with a thermal barrier coating. Because of its adaptability for high-temperature applications, YSZ (Yttria

Sagaya Raj, Gnana, Natarajan, Manikandan, Pasupuleti, Thejasree

Designing Next-Generation Piston Geometry for LPG Powered Spark Ignition Engines: An Integrated CFD and Experimental Approach

2025-28-0123

02/07/2025

The efficiency of combustion has a major impact on the performance and emission characteristics of a spark-ignited LPG (Liquified Petroleum Gas) engine. The shape of the combustion chamber determines the homogeneous charge intake velocity, which is crucial for the turbulent motion that encourages flame propagation and quickens combustion. It need the right amount of compression ratio, charge squish velocity and turbulent kinetic energy to sustain combustion and propel laminar flames. There are a number of names for the motion of the charge within the cylinder: swirl, squish, tumble and turbulence. All of these terms affect how air and fuel are mixed and burned. Piston shape affects in-cylinder motion, which in turn reduces fuel consumption and improves combustion characteristics. The shape of the piston quench zone has a substantial impact on the charge velocity inside the combustion chamber. The impact on charge motion was analyzed using computer modeling using STAR-CD on pentroof

Sagaya Raj, Gnana, R L, Krupakaran, Pasupuleti, Thejasree, Natarajan, Manikandan

Effects of Injection Parameters On the Evaporation, Mixing, Combustion and Emission Characteristics of a Spark Ignition Methanol Engine

2025-01-7119

01/31/2025

The combustion performance test under different injection parameters was carried out on an inline 6-cylinder spark-ignition (SI) methanol engine, and the influence mechanism of injection parameters on methanol evaporation, mixing, combustion and emission was revealed through simulation. The results indicate that compared to the low-flow nozzle scheme (14*D0.26), when adopting the high-flow nozzle scheme (16*D0.30), the injection duration is shorter. The evaporation rate of methanol in the intake port is increased, the amount of methanol droplets and wall-attached liquid film in the cylinder is reduced, and the temperature in the cylinder is elevated. Moreover, the changes are more significant under high-load operating conditions. The change in the methanol charge rate during the intake process leads to a slightly higher inhomogeneity of the in-cylinder mixture. The relatively high temperature in the cylinder and the appropriate increase in the mixture concentration on the exhaust side

Zhang, Zhi, Liu, Haifeng, Li, Yongzhi, Chang, Weide, Shu, Zanqiao, Ju, Chengyuan, Ratlamwala, Tahir Abdul Hussain, Yao, Mingfa

Flash Boiling Impact on Spray, Flame, Emissions, and Soot of Gasoline-Acetone-Butanol-Ethanol Blend at Simulated Cold-Start GDI Operation Using a CVCC

2025-01-7046

01/31/2025

The use of carbon-neutral fuels instead of conventional fuels in gasoline direct injection (GDI) engines is beneficial to global decarbonization. However, the application of renewable non-petroleum fuels in GDI engines is still unclear due to their different physicochemical properties. Acetone-Butanol-Ethanol (ABE) is a promising low-carbon alternative fuel for GDI engines, but its high viscosity and latent heat cause pool firing during cold start. The existing flash boiling technology can solve this problem. This study explores the effects of flash boiling on spray characteristics, flame propagation, soot, and emissions of gasoline-ABE blend in a constant volume combustion chamber (CVCC) without airflow. Optical windows, high-speed camera recording, in-chamber pressure measurement, Fourier transform infrared spectroscopy (FTIR), and transmission electron microscope (TEM) were used to analyze flame spreading, combustion characteristics, exhaust gases, and soot morphology. Flash boiling

Nour, Mohamed, Zhang, Weixuan, Cui, Mingli, Li, Xuesong, Xu, Min, Qiu, Shuyi

Study of Soot Generation in Hybrid Engines during Cold Start and Low-Load Conditions Using an Optical Engine

2025-01-7047

01/31/2025

As regulations regarding vehicle emissions and fuel consumption become increasingly stringent, the development of hybrid power systems is accelerating, primarily due to their benefits in fuel efficiency and reduction of pollutants. Hybrid engines are specially designed to operate optimally at mid to high speeds and loads. But for low-speed low-load conditions, due to the relatively low in-cylinder tumble intensity and lower injection pressure, the fuel-air mixture tends to deteriorate, resulting in an increase in particle number. To enable the engine to reach optimal RPM and load quickly during frequent start-stop cycles, hybrid engines typically set a higher startup engine speed and establish fuel rail pressure more quickly compared to traditional engines. Yet hybrid engines still encounter challenges of soot generation during cold start conditions. Especially in urban driving conditions where the hybrid engine frequently experiences startups and idling, the soot generation problem

Liu, Changye, Man, Xingjia, Cui, Mingli, Liang, Yuanfei, Wang, Shangning, Li, Xuesong

Jet-Induced Compression Ignition (JICI)—Application of Spark-Assisted Compression Ignition (SACI) in a Combustion System with Active Pre-Chamber

03-18-01-0009

01/17/2025

The application of short burn durations at lean engine operation has the potential to increase the efficiency of spark-ignition engines. To achieve short burn durations, spark-assisted compression ignition (SACI) as well as active pre-chamber (PC) combustion systems are suitable technologies. Since a combination of these two combustion concepts has the potential to achieve shorter burn durations than the application of only one of these concepts, the concept of jet-induced compression ignition (JICI) was investigated in this study. With the JICI, the fuel is ignited in the PC, and the combustion products igniting the charge in the main combustion chamber (MC) triggered the autoignition of the MC charge. A conventional gasoline fuel (RON 95 E10) and a Porsche synthetic fuel (POSYN) were investigated to assess the fuel influence on the JICI. Variations of the relative air/fuel ratio in the exhaust gas (λex) were performed to evaluate both the occurrence of the JICI and the dilution

Burkardt, Patrick, Günther, Marco, Villforth, Jonas, Pischinger, Stefan

Performance and Emissions Analysis Using Ducted Fuel Injection in Compression Ignition Engine with Load Variation

2024-36-0154

12/20/2024

Despite the increasing electrification of current vehicles, Diesel engines will continue to be used for several decades to come. There is still a need to introduce emission control technologies, especially those that show good potential and do not require extensive engine modifications. The increasing focus on reducing pollutant emissions and improving energy efficiency has prompted engine manufacturers to continuously strive for technological progress. The aim is to ensure compliance with environmental regulations and the fulfillment of social expectations. Specifically, new Diesel engine projects face the challenge of minimizing both nitrogen oxides (NOx) and soot emissions, which requires significant investiment in research to develop innovative combustion methods and exhaust gas treatment. One of these innovative methods is Ducted Fuel Injection (DFI), which aims to reduce emissions by improving spray development to obtain a better mixture at flame upstream. This study presents an

Dias, Fábio Jairo, dos Santos, Leila Ribeiro, Rufino, Caio, Garcia, Ezio Castejon, Lomonaco, Raphael, Argachoy, Celso, Lacava, Pedro Teixeira

Items per page:

1 – 50 of 3910