Browse Topic: Engine components

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In-Depth Experimental Investigation into Performance and Emission Characteristics of a Diesel Light-Duty Engine Fuelled with Pure Hydrogen2025-01-0314To be published on 07/02/2025
Transitioning to zero-carbon fuels is pivotal for expediting the reduction of carbon emissions. Hydrogen demonstrates significant adaptability and emerges as a principal zero-carbon alternative fuel for carbon-based internal combustion engine (ICE) platforms. Implementing hydrogen in both spark ignition (SI) and compression ignition (CI) engines has proven to be both economically viable and timely; nevertheless, it presents several technical challenges that must be addressed. The study analyses the performance and emissions of a single-cylinder boat engine converted from diesel to 100% hydrogen. A port fuel injection (PFI) system was adopted to operate the engine with hydrogen by replacing the diesel injector with a spark plug engine without any modification to the cylinder head. The engine features an automated shutdown system to mitigate intake backfire risks associated with hydrogen PFI systems. A comprehensive engine characterization was conducted at a wide range of relative air-to
Mohamed, Mohamed, Zaman, Zayne, Lu, Enshen, Feng, Yizhuo, Wang, Xinyan, Zhao, Hua
Technical Paper
A New Electrified Planetary Gear Set - The Cost- and Fuel-Efficient Alternative to Continuously Variable Transmissions2025-01-0309To be published on 07/02/2025
In order to mitigate the effects of climate change, the global transport sector, one of the largest emitters of CO2, needs to drastically reduce its emissions. Although hybridization and electrification are becoming increasingly popular as a solution for a variety of applications, their use in two- and three-wheelers, as well as in recreational and powersports vehicles, remains limited due to their high costs and complexity compared to conventional drivetrains with continuously variable transmissions (CVTs). Despite their affordability and simplicity, CVTs suffer from low mechanical efficiency, with transmission losses ranging from 20–50 %, highlighting a significant opportunity for improvement. In response to these limitations, this study presents the development and experimental evaluation of an electrified planetary gear set (ePGS) in a lightweight off-road vehicle. It is designed to overcome the efficiency limitations of CVTs while maintaining high driving comfort and low system
Jakoby, Moritz, Engels, Michael, Fahrbach, Timm, Andert, Jakob
Technical Paper
Variable Valve Actuation and Split Injection to Enhance the Gas Exchange of a Passive Pre-chamber Igniter2025-01-0315To be published on 07/02/2025
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
Technical Paper
Method for externally controlled availability of lubricating oil in internal combustion engines.2025-01-0302To be published on 07/02/2025
Reduced emissions in internal combustion engines (ICE) are a key component in reaching green-house-gas and pollutive emissions regulations. With increased effort, clean and efficient burning combustion cycles are being developed. With the need of even more efficient engines the friction of ICE engines plays an increasing role in engine efficiency. Also, ingress of lubricating oil into the combustion chamber is a source of particle emissions. Increased optimization to reduce parasitic drag in the piston assembly such as reduced ring pre-tension ore thinner grade oils further increase oil ingress into the combustion chamber with the result of increased particle emissions. The transport mechanisms of oil ingress into the combustion chamber therefore the topic of current research. Specially developed research engines with a vertical optical window have big potentials to visualize phenomena of the oil behavior inside the piston assembly in internal combustion engines. Therefore, these
Stark, Michael, Fellner, Felix, Härtl, Martin, Jaensch, Malte
Technical Paper
Numerical analysis of direct-injection and combustion inside a H2 engine2025-01-0301To be published on 07/02/2025
The direct injection of hydrogen (H2) inside internal combustion engines (ICEs) is gaining large research interest over the port-fuel injection strategy, because of several advantages as higher volumetric efficiencies, increased power output and reduced risks of abnormal combustion. However, the required high pressure ratios across the injector nozzle produce moderate-to-high under-expanded jets, characterized by complex flow structures. This poses a challenge for the numerical modelling of the mixture preparation by means of 3D computational fluid dynamic (CFD) approaches. In this work, a validated 3D-CFD methodology has been employed to simulate the closed-valve cycle of a direct injection H2 engine equipped with a centrally mounted hollow-cone injector and a non-axisymmetric piston bowl. First, injection and mixture preparation have been studied considering an early injection at the beginning of the compression stroke, and a delayed injection in the second half of the compression
Capecci, Marcolucio, Sforza, Lorenzo, Lucchini, Tommaso, D'Errico, Gianluca, Pezza, Vincenzo, Tosi, Sergio
Technical Paper
Investigation on Thermal Management of Heavy-Duty Commercial FCEV with Focus on Vehicle System Efficiency2025-01-0265To be published on 07/02/2025
The primary approach to meet the objectives of the EU Heavy Duty CO2 Regulation involves decarbonizing the road transport sector by battery electric vehicles (BEV) or hydrogen-fueled vehicles. Even though the well-to-wheel efficiency of hydrogen-fueled powertrains like fuel cell electric vehicles (FCEV) and H2-internal combustion engines (H2-ICE) is much lower in comparison to BEV, they are better suited for on-road heavy-duty trucks, long haul transport missions and regions with scarce charging infrastructure. Hence, this paper focuses on heavy-duty FCEVs and their overall energetic efficiency enhancement by intelligently managing energy transfer across coolant circuit boundaries through waste heat recovery, while ensuring that all relevant components remain within required temperature boundaries under both cold and hot ambient conditions. Results were obtained using a 1D-model that comprises all thermal fluid circuits (refrigerant, coolant, air) created through GT-Suite software
Uhde, Sophia, Langhorst, Thorsten, Wuest, Marcel, Naber, Dirk
Technical Paper
Analysis of Combustion Characteristics of a Small 2-Stroke Opposed Piston Engine Using an Optically Accessible Engine and Numerical Analysis2025-01-0223To be published on 06/16/2025
As global warming becomes more serious, decarbonization of internal combustion engines, which emit a large amount of carbon dioxide, is being promoted. It is predicted that many vehicles will still be equipped with engines in 2035, and a variety of powertrains will be required in the future. Therefore, we focused on the opposed-piston engine as an internal combustion engine specialized for power generation applications. The opposed-piston engine is characterized by its light weight due to the absence of a cylinder head, low S/V ratio due to the ultra-long stroke, reduced cooling loss due to the long stroke, and reduced vibration due to the offsetting of the reciprocating inertial forces of the left and right pistons. We believe that the engine for power generation can achieve the required high efficiency operation and vibration reduction. Therefore, in this study, combustion analysis of a two-stroke opposed-piston engine with features of low vibration, high efficiency, and high output
Yamazaki, Yoshiaki, Watanabe, Sou, Okawara, Ikumi, Otaki, Yusuke, Liu, Jinru, Iijima, Akira
Technical Paper
Numerical Simulation and Parametric Optimization of Engine/Powertrain Mounts: Identifying Key Design Variables to Reduce NVH Noise2025-01-0251To be published on 06/16/2025
Abstract: Introduction: Engine and powertrain mounts are vital for isolating vibrations and reducing the transmission of Noise, Vibration, and Harshness (NVH) from the engine to the vehicle structure. Despite technological advancements, addressing NVH issues related to tribological factors continues to pose significant challenges in automotive engineering. Aim: This study aims to systematically identify and optimize design parameters of engine/powertrain mounts to minimize NVH levels using CAE tools and parametric optimization techniques in Abaqus and Isight, respectively. Purpose: The purpose of this research is to investigate the correlation between various design parameters of powertrain mounts and their impact on NVH characteristics. Specific attention is focused on noises such as clunking, banging, or thumping that emerge from the engine bay under dynamic conditions like acceleration, braking, or turning. These sounds often occur as the engine moves excessively due to worn mounts
Ganesan, Karthikeyan, Seok, Sang Ho
Technical Paper
A Comparative Assessment of Port Fuel Injection and Direct Injection of Hydrogen in Internal Combustion Engines: Performance, Efficiency, and Emissions2025-01-0239To be published on 06/16/2025
With the transition toward low-carbon fuels-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 affects 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
Ahirwar, Sachin, Kumar, Naveen
Technical Paper
Design and optimisation of pre-chamber ignition system for a heavy-duty hydrogen engine at lean conditions2025-01-0229To be published on 06/16/2025
Strict regulations and legislation for carbon emissions and pollution from heavy-duty engines are pushing towards carbon-free fuels such as Hydrogen as a fuel for internal combustion engines. Moving towards this goal, the engine design needs to fully comply with Hydrogen’s unique characteristics to achieve optimum performance and efficiency. One of the aspects that has the potential to improve combustion efficiency and emissions is adopting the pre-chamber ignition strategy in large bore engines at lean conditions. The pre-chamber is a small cavity, usually 3-6% of the total engine volume, installed on the cylinder head, housing the initial combustion event, which would then be injected into the main chamber via nozzles placed at the bottom of the pre-chamber. This ignition strategy would provide multiple flame fronts into the main chamber, accelerating combustion speed and enhancing engine performance. However, the pre-chamber must be designed dedicatedly for Hydrogen combustion to
Keshtkar, Hossein, Feng, Yizhuo, Zhao, Hua, Wang, Xinyan
Technical Paper
A study on improving the methodology for Torque modeling using a virtual engine model2025-01-0204To be published on 06/16/2025
This study aims to develop an engine torque prediction model using virtual engine simulation data. Accurate torque prediction is essential for minimizing shift shock and ensuring consistent driving performance, particularly in hybrid vehicles where smooth transitions between electric motors and internal combustion engines are necessary. The Engine Control Unit (ECU) uses a physics-based torque prediction model, requiring ignition timing swing data for precise calibration. The virtual engine model, based on 1D gas dynamics, was calibrated using real engine data obtained from a small number of main operating points. The simulation data obtained from the virtual engine model showed a good correlation with the experimental data. By combining large-scale simulation data with limited experimental data, we effectively calibrated the torque prediction model in ECU and confirmed that the calibration results met the development goals. This study demonstrates the potential for efficient engine
Hur, Donghan, Paeng, Jeonghwan, Kim, Kyusup, Chang, Jinseok, Park, Jongil
Technical Paper
Effects of Injection and Intake Timing on Atomization and Combustion in a Hybrid Gasoline Direct Injection Optical Engine under the Low-Speed Low-Load Condition2025-01-0203To be published on 06/16/2025
With the growing trend of hybridization in modern engines, hybrid gasoline direct injection (GDI) engines are typically designed for high-load, mid-to-high-speed operation to achieve optimal fuel economy. However, these engines inevitably operate under low-speed, low-load conditions where insufficient intake air often leads to poor air-fuel mixing and weak turbulence, resulting in suboptimal combustion. Adjusting intake and injection timing presents a simple and effective approach to optimizing the combustion process in hybrid GDI engines. In this study, an optical engine with a combustion system geometry identical to that of an advanced hybrid GDI engine is used. The engine features a compression ratio of 15.0:1 and is equipped with a variable timing camshaft for intake timing control and an electronically controlled system for injection timing. High-speed color imaging, using transparent pistons and cylinder liners, captures the in-cylinder spray development and combustion processes
Cui, Mingli, Fu, Jinhong, Man, Xingjia, Nour, Mohamed, Zhang, Weixuan, Li, Xuesong, Xu, Min
Technical Paper
Flame developments of pilot diesel ignited hydrogen jet in an optical dual direct injection engine2025-01-0237To be published on 06/16/2025
This study aims to characterise the flame development for hydrogen-diesel dual direct injection (H2DDI) in an optically accessible heavy-duty engine through high-speed imaging of the natural combustion luminosity. A single hole, side mounted injector was used to inject H2 at 350 bar in addition to a centrally mounted eight-hole diesel injector providing the ignition source for the H2. The diesel pilot flame was examined without H2 to establish the combustion characteristics of the pilot flame. The pilot fuel energy was reduced from 1200J to 120J while examining the distribution of the pilot flame as the H2 energy fraction was increased. The flame distribution transitioned from an initial quasi-steady diesel flame at peak load (1200 J), to a piston bowl wall-centric flame distribution (840 J) and then to an injector centric flame (120 J). The pilot fuel quantity of 120 J was selected to investigate the ignition process of hydrogen main fuel mixtures supplying 90% energy (only 10% energy
Heaton, Alastar, Chan, Qing Nian, Kook, Sanghoon
Technical Paper
Effect of Ignition Condition and Fuel Octane Number on Knock Intensity in a Small 2-Stroke Engine2025-01-0211To be published on 06/16/2025
The internal combustion engines are widely used on automotive transportation for its high energy storage system efficiency and economic benefits. The 4-stroke engine has dominated all other forms to date, because the Otto cycle is simpler to comprehend. However, the significant benefits such as, less pumping work and friction, lighter construction of 2-stroke engine, helped with applications which appreciate the simplicity and power density as well as meet the emission regulations. The disadvantages of the 2-stroke engine mainly caused by the lack of sufficient scavenging process, which limited its trapping efficiency. Also, the overlap of the intake and exhaust phases results in charge short-circuiting, more fuel consumption and high unburned hydrocarbon emissions. For the reason above, it is difficult for 2-stroke engines to realize stoichiometric combustion and unable to use three-way catalyst to control emissions. The residual exhaust gas in the cylinder makes the spark ignition
Liu, Jinru, Yamazaki, Yoshiaki, Otaki, Yusuke, Kato, Hayato, Yokota, Takumi, Iijima, Akira
Technical Paper
Three-Dimensional CFD Analysis of a Flat Engine Lubrication System2025-01-0215To be published on 06/16/2025
This study presents a comprehensive, transient, 3D Computational Fluid Dynamics (CFD) model of a multi-cylinder flat engine's lubrication system, simulated using Simerics-MP+. Engine lubrication system is crucial for reducing friction, cooling, and cleaning engine components. Understanding its performance is essential for optimal engine operation. The model was applied to the lubrication system of a 4-cylinder, reciprocating internal combustion engine. The computational domain includes the positive displacement gear pump, pressure regulation valve, bearings, piston pins, piston cooling jets, oil cooler, oil filter, and other relevant components. Bearing deformation and orbiting due to force imbalance were prescribed in the simulations. A series of simulations were conducted under both fixed and time-dependent gear pump rotation speeds. For fixed speeds, the simulated flow pressure distributions closely matched experimental data. For time-dependent speeds, the predicted pressure buildup
Shiyi, Pan, Nan, Zhang, Jing, Liu, Mingliang, Liu, Wei, Wang
Technical Paper
CFD Study of Lubrication Pump Starvation Due to Oil Pan Sloshing2025-01-0213To be published on 06/16/2025
Dynamic vehicle operation, such as acceleration, deceleration, and tilting, can cause severe oil sloshing in the engine oil pan. This can lead to oil starvation at the pickup tube, compromising lubrication pump performance, and potentially damaging engine components. This study presents a Computational Fluid Dynamics (CFD) multiphase model of an engine oil pan and lubrication pump, simulated using Simerics-MP+. A series of numerical simulations were conducted at various pump speeds and extreme oil pan tilt angles. Time-dependent oil distributions were visualized, and real-time oil flow rates were monitored at the pickup tube to assess the impact of pump speed and pan position on oil starvation. This CFD model provides valuable insights into oil pan and pump behavior under extreme vehicle operation conditions, aiding in the design and optimization of lubrication systems to mitigate the risk of oil starvation and improve overall engine safety and performance.
Nan, Zhang, Shiyi, Pan, Jing, Liu, Mingliang, Liu, Wei, Wang
Technical Paper
Comparison of spark and turbulent jet ignition in a fully ammonia-fueled engine2025-01-0201To be published on 06/16/2025
Ammonia (NH₃) is an emerging carbon-free fuel with the potential to decarbonize the energy sector. However, its widespread adoption is hindered by challenges like low flame speed, high ignition energy, and elevated emissions of nitrogen oxides (NOx) and unburnt NH₃. These limitations necessitate innovative combustion strategies for efficient and stable engine operation. This study investigates the potential of turbulent jet ignition (TJI) to overcome these challenges through the implementation of a pre-chamber, a small auxiliary chamber equipped with a spark plug to create hot, reactive jets that propagate into the main chamber, promoting rapid combustion from distributed ignition sites. In this work, TJI operation is compared to conventional spark ignition (SI) in a Cummins ISB6.7 engine retrofitted for 100% ammonia operation. Experiments were conducted at 1200 and 1800 RPM across varying loads (25%, 50%, 75%, and 100%) with equivalence ratio and spark timing sweeps. Combustion
Dhotre, Akash, Voris, Alex, Okey, Nathan, Kane, Seamus, Northrop, William
Technical Paper
Research on Combustion Characteristics of Flash-Boiling Spray in Cylinders Based on Machine Learning Methods2025-01-0205To be published on 06/16/2025
With the increasing number of vehicles in operation, exhaust emissions from engines have exerted negative impacts on ecological environments, prompting researchers to actively pursue cleaner and more efficient in-cylinder combustion strategies. Flash-boiling spray technology, capable of generating superior fuel atomization under relatively low injection pressures, has emerged as a promising approach for achieving performance breakthroughs in gasoline direct injection (GDI) engines. While current research primarily focuses on morphological characterization and mechanistic analysis of flashboiling spray, there remains insufficient understanding of flame development characteristics under flash boiling spray conditions within engine cylinders. This study systematically investigates the combustion characteristics of TPRF and PRF fuels under both subcooled and flash-boiling spray conditions through the integration of image processing and machine learning methodologies. Experimental
Zhang, Weixuan, Shahbaz, Muhammad, Cui, Mingli, Li, Xuesong, Xu, Min
Technical Paper
Analysis of Diesel-Ethanol Blends: Impact on Spray Behavior and Combustion Properties under Various Injection Parameters in Compression Ignition Settings2025-01-0208To be published on 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 compression ignition 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 (0%, 10%, 20%, 30% in volume) on the spray, combustion, and flame characteristics. Optical techniques, such as shadowgraph and flame self-illumination direct photography using high-speed imaging methods, were employed to reveal the spray and flame development process. This thesis 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
Putra, I Komang Gede Tryas Agameru, Lim, Ocktaeck
Technical Paper
Development of Combustion System for a Hybrid-dedicated Homogeneous Lean Burn Engine2025-01-0216To be published on 06/16/2025
This study explores methods to extend the lean combustion limit, improve efficiency, and reduce engine-out emissions in a hybrid-dedicated homogeneous lean combustion engine. Under lean combustion conditions, slow laminar flame speed restricts flame kernel growth, leading to instability and limiting the lean combustion threshold. To address this challenge, a combustion system was developed that leverages the engine’s internal flow to enlarge the spark channel at the spark gap and promote the formation of a larger-scale flame kernel. The combustion chamber was optimized by redesigning the intake port geometry and piston bowl to generate a high tumble flow. This new design significantly increased airflow around the spark plug gap, accelerating the initial combustion process and effectively expanding the lean combustion limit. Additionally, multiple ignition was implemented to prevent spark channel shortening caused by increased electrical resistance, further enhancing combustion
Oh, Heechang, Lee, Jonghyeok, Sim, Kiseon, Park, Jongil, Kim, Taekyun, Kang, Hyunjin, Hong, Seungwoo, Han, Donghee, Kim, Dokyun
Technical Paper
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-Tumble2025-01-0198To be published on 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
Technical Paper
The Accelerated Roughness Noise Optimization of One PHEV Vehicle2025-01-008705/05/2025
To optimize the noise that heard like ‘kalakala’ produced by the plug hybrid electric vehicle when accelerating with a small accelerated pedal opening while in the charging state of series modal. The LMS test device was used to acquire the noise of the driver's outer ear. Through filtering and playback analysis, it was confirmed that the noise is mainly contains the frequency bands of 250-400Hz and450-700Hz. The frequency bands of the noise were used as carriers for Hilbert transform, and their envelopes were obtained for Fourier transform analysis. It was found that the modulation order of the noise is 0.5 times of the engine ignition order, and the modulation frequency is 20-30Hz, which let the customer hears like roughness. Regarding the spectral characteristics of this noise, firstly, at the excitation source, selected a reasonable moment of inertia and frequency of the Crank torsional damper, to decrease the torsional excitation of the engine. Secondly, investigated the structural
Shouhui, Huang, Zhongxun, Hu, Zhao, Yun, Shanyin, Ren, Ruifeng, Dong, Teng, Charlie, Changshui, Zhou, Xu, Ling
Technical Paper
Hybrid RLDA Methodology for Passenger Car Engine Mount Applications2025-01-009505/05/2025
In the development of engine mounting systems for passenger cars, accurately capturing dynamic loads during real-world driving conditions is crucial for optimizing performance, durability, and NVH (Noise, Vibration, and Harshness) characteristics. This paper introduces an innovative approach that integrates load cell and strain gauge technologies for Road Load Data (RLD) acquisition, specifically designed for engine mounting applications. By combining load cells and strain gauges, this method offers a comprehensive solution for measuring both direct forces and the resulting strains on engine mounts, providing a more detailed understanding of the load profiles. Load cells capture the overall forces exerted on the engine mounts, while strategically placed strain gauges measure local deformations and stress distributions within the mounts. This dual-method approach enables precise correlation of force and strain data, enhancing the accuracy of load calculations under various driving
Hazra, Sandip, Khan, Arkadip Amitava, Mohare, Gourishkumar
Technical Paper
Noise Analysis and Optimization of Thermal Management Integrated Module2025-01-008105/05/2025
Thermal Management Integration Module (TMIM), which comprises components such as water pumps, runner boards, brackets, sensors, etc., is a multifunctional integrated component for electric vehicles. However, the water pump generates an excitation over a wide range of frequencies due to a wide range of speed variations. This excitation causes the TMIM to vibrate and generate noise. In this study, a TMIM that generates noise is studied and analyzed. Using the TMIM of an electric vehicle as a case study, a full-vehicle experimental test was conducted, revealing that the noise originates from the integration module. The finite element method is used to analyze the cause of noise generation. Given the characteristics of the TMIM, which comprise many components, high integration, and a complex structure, this paper simplifies the bracket, heat exchanger, sensor, and other components using the centralized mass point method. The modal state of the TMIM is obtained by impact hammer testing the
Xu, Shenao
Technical Paper
Evaluation of Invariant Structural and Acoustic Loads Estimation Methods to be Used in Vehicle Platform Development Independent to the Boundary Conditions of Load Generation2025-01-005305/05/2025
Platform based vehicle development is standardized at John Deere. The challenges of frontloading the integration of individual components within different platforms using predictive methods is key to shortening the development cycle. Components are individually characterized on test benches and results cannot directly be used to evaluate system performance. Invariant characterization is needed instead, which is possible through techniques such as blocked loads estimation. To evaluate the applicability of such methods, the component-based loads and vehicle in-situ operational loads need to be compared. The confident use of these methods for obtaining structural and acoustic loads enables the use of hybrid system models, enhancing early NVH response predictions. The objective of this work was to enable the confident use of test stand measurements in predictive models across various vehicle platforms. This study compares a powertrain characterization in a vehicle against a test stand to
Vesikar, Prasad Balkrishna, Edgington, Jason, Drabison II, John
Technical Paper
Designing Rubber Flaps for Resonance Management: High-Frequency Tuning in Electric Vehicles Using AI/ML Approaches2025-01-012505/05/2025
High-frequency whine noise in electric vehicles (EVs) is a significant issue that impacts customer perception and alters their overall view of the vehicle. This undesirable acoustic environment arises from the interaction between motor polar resonance and the resonance of the engine mount rubber. To address this challenge, the proposal introduces an innovative approach to predicting and tuning the frequency response by precisely adjusting the shape of rubber flaps, specifically their length and width. The approach includes the cumulation of two solutions: a precise adjustment of rubber flap dimensions and the integration of ML. The ML model is trained on historical data, derived from a mixture of physical testing conducted over the years and CAE simulations, to predict the effects of different flap dimensions on frequency response, providing a data-driven basis for optimization. This predictive capability is further enhanced by a Python program that automates the optimization of flap
Hazra, Sandip, Khan, Arkadip
Technical Paper
Optimization of HEV Vehicle’s Engine Modulated Noise2025-01-008405/05/2025
One 1.5L Miller-cycle turbocharged four cylinder gasoline hybrid engine is installed on a certain hybrid vehicle. When accelerating at low to medium speeds with a small throttle, there is a "da da" knocking noise inside the car, which seriously affects the overall sound quality of the vehicle. By analyzing the vibration and noise data of the engine, it was found that the frequency of the abnormal knocking sound is 200-2000Hz, which presents a half order characteristic in the time domain, that is, one knocking occurs when the engine crankshaft rotates twice. Through Hilbert demodulation analysis of the vibration data in the problem frequency range, it was found that the knocking noise was modulated in the frequency domain, with a modulation frequency of half of the crankshaft rotation frequency. By building a fully flexible multi-body dynamic model of a hybrid powertrain and inputting the engine's cylinder pressure excitation, the combustion excitation is coupled with mechanical
Dan, Kong
Technical Paper
Crash Performance Improvement: The Impact of Engine Mount Crash Plates on Achieving a 5-Star Safety Rating2025-01-008505/05/2025
Electric vehicles (EVs) differ from internal combustion engine (ICE) vehicles in that they lack a conventional engine and feature an electric drive unit, leading to distinct dynamic behaviours in the powertrain. Additionally, the arrangement of auxiliary components in EVs often differs from that in traditional ICE vehicles, which can sometimes significantly impact safety ratings. This paper examines a case study of a critical failure during a crash test, where displacement of an engine mount arm caused substantial structural intrusion and reduced the vehicle’s safety rating. To address this issue and enhance crashworthiness, a “crash plate” was designed and integrated into the mount system. This solution effectively constrained the mount arm’s movement during impact, preventing the intrusion observed in previous tests. The paper provides a detailed analysis of the crash plate’s dimensions and its relationship to the engine mount, demonstrating its potential for broader application in
Hazra, Sandip, Khan, Arkadip, Mohare, Gourishkumar
Technical Paper
Simulation of Pass-by Fan Noise Emissions and Advancing Test Regulations for Heavy-Duty Electric Vehicles2025-01-008605/05/2025
The rapid adoption of electric vehicles (EVs) necessitates updates to the automotive testing standards, particularly for noise emission. This paper examines the vehicle-level noise emission testing of a Nikola Class 8 hydrogen fuel cell electric semi-truck and the component-level noise emission testing needed to create a predictive simulation model using Wave6 software. The physical, component-level noise emission testing focused on individual cooling fans in a semi-anechoic chamber to assess their isolated noise contributions. With this data, an initial model was developed using spatial gradient statistical energy analysis, which successfully predicted pass-by noise levels based on varying fan locations and speeds. Real-world pass-by testing confirmed the model's accuracy across different cooling fan speeds. By leveraging advanced simulation techniques, engineers aim to enhance the accuracy and reliability of pass-by noise predictions through cost-effective studies of architectural
Passador, Stephen, Woo, Sangbeom, Liu, Ting-Wei, De La Vega Alonso, Gerardo, Kim, James
Technical Paper
Evaluating Powertrain Mount Decoupling: Insights from Simulation, Experimental Results, and Analytical Calculations2025-01-002205/05/2025
Powertrain mounts are vital for isolating vibrations and enhancing vehicle ride comfort and performance, making their dynamic behavior critical for effective design. This study provides a comprehensive analysis of powertrain mount decoupling by integrating virtual simulations, physical testing, and analytical calculations. In our approach, we first derived stiffness data through analytical calculations, which were validated through multi-body dynamics (MBD) simulations that modeled interactions within the powertrain mounts. By adjusting bush stiffness parameters within the MBD framework, we predicted decoupling frequencies and analyzed kinetic energy distribution. The iterated stiffness values from simulations were then confirmed through physical testing, ensuring consistency in decoupling frequencies and energy distribution. This alignment between virtual and experimental data enhances the reliability of our findings and helps identify overlapping frequencies across vehicle systems
Shende, Kalyani, Shingavi, Shreyas, Rane, Vishesh, Hingade, Nikhil
Technical Paper
Indirect Blocked Force Measurement of a Hydraulic Power Pack for Structural Vibration Transmission into an Airframe2025-01-005205/05/2025
Centralization of electrically driven hydraulic power packs into the body of aircraft has increased attention on the noise and vibration characteristics of the system. A hydraulic power pack consists of a pump coupled to an electrical motor, accumulator, reservoir, and associated filter manifolds. In previous studies, the characteristics of radiated acoustic noise and fluid borne noise were studied. In this paper, we focus on the structure-borne forces generated by the hydraulic pump characterized through blocked force measurements. The blocked force of the pump was determined experimentally using an indirect measurement method. The indirect method required operation with part under test fixed to an instrumented receiver structure. Measured operational accelerations on the receiver plate were used in conjunction with transfer function measurements to predict the blocked forces. Blocked forces were validated by comparing directly measured accelerations to predicted accelerations at
Smither, Matthew, Tuyls, Zachary, Patel, Pratik, Yan, Xin, Herrin, David
Technical Paper
Glossary of Terms Related to Fluid Filters and Filter TestingJ1124_202505 (Current)05/03/2025
Over the years during which fluid filtration systems have been developing, many terms have come into use for descriptions of characteristics of filter media, filter assemblies, test methods, and test materials. Inevitably, some terms have been applied loosely so that the same term may have different meaning to different people, or in different frames of reference. Recognizing the need for clearly defined terms, which can have only one meaning for all persons in all circumstances, so that documents dealing with standard methods of evaluation of filters will have only one interpretation, the Filter Test Methods Subcommittee of the SAE Engine Committee has compiled this Glossary of related terms. No attempt has been made to produce an all-inclusive document, containing definitions of all terms related to all types of fluid filters. Instead, the Glossary is confined to the terms likely to be encountered in relation to filters for lubricating oil and fuels. At the same time, we have
Filter Test Methods Standards Committee
Recommended Practice
General Requirement for Preformed Hoses for Air Induction on Heavy-Duty EnginesJ2140_202505 (Current)05/03/2025
This SAE Standard outlines the requirements for a preformed thermosetting hose intended for use in heavy-duty vehicle engines, such as air cleaner inlet, crank case vent, or air cleaner to turbo or to engine inlet.
Non-Hydraulic Hose Committee
Technical Standard
Drilling Methods for Controlling Exit Burr Height in CRES Material Stacks2025-01-016905/02/2025
The Electroimpact Automatic Fan Cowl Riveter uses two novel drill processes to control exit burr height and achieve the required hole quality in CRES (Corrosion-Resistant Steel, also called stainless steel) material stacks. Both processes use piloted cutters on the OML side, and two different tools are used in a backside spindle on the IML side of the component. The first process uses a shallow-angle shave tool in the IML spindle to directly control the exit burr height after it is produced by the OML spindle and is called the “burr shave” technique. The second process uses a countersink tool in the IML spindle and produces an “intermediate countersink” after the pilot hole is drilled by the OML spindle, but before the final hole diameter is drilled. These drill processes were able to achieve the required hole quality in a challenging CRES material stack, which allows the machine to be qualified for one-up assembly of the component.
Schultz, Rich, Peterman, Randy, Luker, Zachary, Murakonda, Sai Krishna
Technical Paper
Eddy Current Inspection of Circular Holes in Nonferrous Metallic Aircraft Engine HardwareAS4787A (Current)05/02/2025
This SAE Aerospace Standard (AS) establishes minimum requirements for eddy current inspection of circular holes in nonferrous, metallic, low conductivity (less than 5% IACS) aircraft engine hardware with fasteners removed. The inspection is intended to be performed at maintenance and overhaul facilities on engine run hardware.
AMS K Non Destructive Methods and Processes Committee
Technical Standard
Influence of Coolant Properties on Battery Thermal Management in Electric Buses during Cold Starts02-18-03-001304/25/2025
Improving electric vehicles’ overall thermal management strategy can directly or indirectly improve battery efficiency and vehicle range [1]. In this study, the effect of the coolant type used in BTMS (battery thermal management system) units used for heating batteries in cold weather conditions was investigated in electric buses. In this investigation, tests were performed with two types of antifreeze, which have different characteristics. The study evaluated the impact of coolant flow, BTMS circulation pump performance, and battery heating using these two types of antifreeze in the BTMS coolant line. In addition to carrying out tests, 1D computational fluid dynamics models’ simulations were carried out for both types of antifreeze, and the results were validated with experimental findings. In this study, a 12-m EV Citivolt vehicle of Anadolu Isuzu was used for tests. As a result, it was observed that differences in the properties of the antifreeze that is used in BTMS coolant line
Çetir, Özgür, Birgül, Çağrı Emre
Journal Article
Aerated Oil in the Rotating Channel03-18-03-001804/24/2025
In this article we examine the behavior of oil in the lubrication channel between the main bearing and the connecting rod bearing in the crankshaft of an internal combustion engine. The requirement for high service life and proper operation of these bearings, while minimizing input power of the lubrication system, lead to the need to understand the function of these structural parts in detail. To simulate and visualize this process, an experimental device was created. The device allows the experimenters to change individual parameters such as rotation speed, oil pressure, oil temperature, and aeration, while simultaneously visualizing the process with the help of a special rotating camera. These parameters are then obtained by image processing. In this way, the following influences are investigated here: at oil temperatures of 30, 50, and 80°C, relative oil pressures of 1, 2, 3, and 4 bar, at undissolved air in the oil of 5 and 10 vol% and crankshaft station speeds from 0 to 6000 1/min
Rychtar, Vaclav
Journal Article
Experimental Study on Pre-Chamber Hydrogen Flame Jet Ignition of Ammonia/Air Mixture in Constant Volume Combustion Chamber2024-32-011704/18/2025
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
Technical Paper
Dynamic Analysis of Intake and Exhaust Valve Motion in a High-Performance four Stroke Engine. Part 2 - Development of a Numerical Model for the Simulation of the Valvetrain2024-32-008404/18/2025
The intake and exhaust valve motion have, as known, a pivotal role in determining engine operation and performances. When dealing with high specific power engines, especially at high rpm, the dynamic behavior of the valve can differ from the kinematic one defined during the design phase. This is related to the high acceleration and forces to which the valve and the other components of the valvetrain system are subjected. In particular, the valve can detach from the cam profile at the end of the opening stroke, and it can show a bouncing behavior during the closing stroke. In addition, all the elements of the valvetrain system are not infinitely rigid and aspects such as the timing chain elongation, the camshaft torsion and the valve stem compression can determine a change in phase with respect to the kinematic one. Since the high complexity level of valvetrains, advanced numerical simulations are mandatory to deeply analyze the behavior of the whole mechanism and each subsystem. The
Tarchiani, Marco, Romani, Luca, Raspanti, Sandro, Bosi, Lorenzo, Ferrara, Giovanni, Trassi, Paolo, Fiaschi, Jacopo
Technical Paper
Optimization of Combustion Efficiency and Conversion Efficiency of Catalytic Converter in Spark-Ignited Engine using Taguchi Methods Robust Optimization Technique for Flex Fuel Application2024-32-012304/18/2025
Flex fuel vehicles (FFV) can operate effectively from E5 (Gasoline 95%, ethanol 5%) fuel to E100 (Gasoline 0%, ethanol 100%) fuel. It is necessary to meet the performance, drivability, emission targets and regulatory requirements irrespective of fuel mixture combination. This research work focuses on optimizing the combustion efficiency and conversion efficiency of catalytic converter of a spark-ignited less than 200 cc engine for FFV using Taguchi methods robust optimization technique. The study employs an eight-step robust optimization approach to simultaneously minimize engine out emissions and maximize catalytic converter efficiency. Six control factors including type of fuel, catalyst heating rpm, lambda (excess-air ratio), injection end angle, lambda controller delay, and ignition timing are optimized. Four noise factors like compression ratio, clearance volume, catalyst noble metal loading, and catalyst aging are also considered. Through approximately 100 physical experiments on
Vaidyanathan, Balaji, Arunkumar, Praveenkumar, Shunmugasundaram, Palani, Murugesan, Manickam, Jayajothijohnson, Vedhanayagam
Technical Paper
Development of Cylinder Deactivation Control during Idle for Conventional Engines2024-32-001904/18/2025
This report examines the advancement and utilization of cylinder deactivation technology that enhances fuel efficiency in conventional engines without hardware modifications. It operates by halting fuel supply to some of the cylinders in multi-cylinder engines and increasing the output power of the remaining active cylinders to maintain an idle state. By implementing this technology in the mass-produced 90° V-twin engine, the U502, and deactivating one of its two cylinders, fuel consumption during idling is reduced by over 30%. The focus of this study is on the technology developed to minimize engine speed fluctuations during the transition to cylinder deactivation and reactivation for the engine. By making various modifications to the fuel injection control sequence and optimizing the throttle opening of each cylinder in idle and driving conditions, engine speed fluctuations were minimized. This allows users to reduce fuel consumption while maintaining the engine’s original
YANAGIDA, Shoji
Technical Paper
CFD Analysis of Pintle-Nozzle Spray for Swirl Chamber Type Small Diesel Engine -Application of Hole-Nozzle Atomization Model to Pintle-Nozzle2024-32-010904/18/2025
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
Technical Paper
Development of Pistons Suitable for Compact Air-Cooled Engines2024-32-003004/18/2025
For the realization of carbon neutrality, we are working on research to improve the thermal efficiency of engines for motorcycles. Friction losses in the cylinder bore account for about 40% of the total friction losses of the engine (Figure 1), which is directly related to thermal efficiency improvement [1]. Air-cooled engines are suitable for motorcycles due to their simplicity and light weight, but it is difficult to achieve both efficiency and reliability. Friction in the cylinder is generated by piston scuffing. The oil film distribution of the piston-skirt(=skirt) is thin at the center of the skirt and thick at the edge. To reduce piston friction, it is effective to make the thin oil film at the center of the skirt thicker. On the other hand, to reduce oil consumption, the oil film must be thinned. However, air-cooled engines, which are difficult to keep the cylinder temperature constant, cannot make the clearance between the cylinder bore and the piston small. An increase in
Suda, Naoyuki, Hihara, Taiki, Ninomiya, Yoshinari
Technical Paper
Experimental Study of Port Water Injection System on Single Cylinder Diesel Engine Performance and Exhaust Emission2024-32-002504/18/2025
Vehicle emission standards have become more and more stringent and have driven the development of advanced engine design with low-cost emission control technologies. For small diesel engine which is used in three-wheel (3W) passenger and load carrying vehicles, it was major task to improve lower engine rpm torque and performance to comply with stringent exhaust emissions standard as well, especially for Oxides of Nitrogen (NOx) and Particulate Matter (PM) emissions. Bharat Stage (BS) VI emission standards for three-wheel vehicles was implemented from April 2020 onwards in India. Water injection technology has proven advantageous for low-cost solution with Mechanical fuel injection system on small diesel engines, Intake port water injection is the easiest method to introduce water to engine cylinder, which calls for minimal modification of existing engine structure. In the present study 435cc naturally aspirated DI Diesel engine used for three-wheel vehicle was explored by adding water
Syed, Kaleemuddin, Chaudhari, Sandip, Khairnar, Girish, Katariya, Rahul, Jagtap, Pranjal, Bhoite, Vikram
Technical Paper
Effect of Ignition Position on Lean Limit of Main Chamber Combustion in Pre-Chamber Ignition2024-32-002204/18/2025
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
Technical Paper
Reducing the Waste of Plating Solution for Magnetostrictive Torque Sensors2024-32-000604/18/2025
The power assist system of an electric bicycle uses a magnetostrictive torque sensor to detect the pedal force based on the magnetic properties of the crankshaft, which change according to stress. Fe–Ni alloy plating is used to coat the surface of the crankshaft with a magnetic film to enhance the magnetostrictive effect. However, the sensor performance decreases as the plating solution degrades, which necessitates replacement of the plating solution. In this study, experiments were performed to investigate how to prevent or mitigate degradation of the plating solution to reduce waste. The amounts of carbon and sulfur in the magnetic film were found to increase with degradation of the plating solution. The carbon derived from organic reducing agents and their decomposition products, and the sulfur derived from stress relievers and their decomposition products. A method was developed for reducing the amounts of carbon and sulfur in the magnetic film, which would help maintain the sensor
Ohnishi, Hiromichi
Technical Paper
Fuel Film Measurement in a SI Gasoline Engine Using a Newly Developed MEMS Sensor2024-32-007104/18/2025
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
Technical Paper
A Concept for Functional Modelling of an E-Bike Powertrain2024-32-001704/18/2025
The increasing popularity of e-bikes, especially pedelecs, has led to a growing interest in consideration of e-bike cycling. To achieve a deeper understanding on the process of e-bike cycling and in particular the effects on the rider it can be instrumental to use simulation methods. In this context, the e-bike drive system and its function are of central importance for e-bikes. Therefore, this work proposes a functional modeling of the powertrain of an e-bike with a mid-drive motor, considering legal constraints and support functionalities. The model incorporates the mechanical transmission between pedals, motor, and crank shaft, allowing for a detailed analysis of the e-bike’s performance. Additionally, the support mechanism is depicted, where an electric motor amplifies the rider’s pedaling torque. The electrical behavior of the motor, energy consumption, and battery state of charge are also integrated into the model. This comprehensive approach aims to provide a generic
Rauch, Yannick, Kettner, Maurice, Kriesten, Reiner
Technical Paper
A Study on Optimal Combinations of Winding and Cooling Methods for Downsizing Power Units in Motorcycles2024-32-000704/18/2025
In commercially available electric motorcycles, there is a notable shift in the cooling method, moving from air cooling to water cooling, and in the winding method, moving from concentrated winding to distributed winding, as the output increases. This shift occurs around 8 to 10 kW. However, there is a paucity of empirical investigations examining these combinations to ascertain their optimality. In order to verify this trend, a verification model has been constructed which allows for the comparison of the capacity and weight of the motor and cooling system according to the vehicle’s required output and thermal performance. A comparison and verification of the combinations of winding methods (concentrated winding or segment conductor distribution winding) and cooling systems (water-cooled or air-cooled) was conducted using the model that had been constructed. In the motor designed for this study, when the maximum output of the vehicle was 35 kW or less (European A2 license), the total
Otaki, Ryota, Tsuchiya, Teruyuki, Sakai, Yu, Yamauchi, Takuya, Shimizu, Tsukasa
Technical Paper
Prediction of Pre-Ignition Borderline on Supercharged SI Engine by Livengood-Wu Integral2024-32-000804/18/2025
The LSPI (Low Speed Pre-Ignition) is one of the consecutive abnormal combustion cycles of supercharged SI engine with direct injection fuel supply system [1]. The LSPI occurs when the engine is running at low speed and high load condition. It is important for the SI engine to control essentially with alternative fuel, e-fuel and hydrogen in the future. It is considered that the LSPI would be caused by the autoignition of the deposit, the lubricating oil from ring crevice, the lubricating oil from piston crown and so on [2, 3, 4, 5]. Among of these causes, this research focuses on the scattering lubricating oil from piston crown. The previous our research has reported on the two points. One is about the frequency and quantity of the lubricating oil scattering from piston crown [6]. Another is about the frequency of abnormal combustion by the engine test [7]. As the result, it has been cleared that the frequency of abnormal combustion is 1/10 of scattering frequency of the lubricating
Omori, Takaya, Tanaka, Junya
Technical Paper
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