SAE International Journal of Engines最新文献

{"title":"Advanced, Guided Procedure for the Calibration and Generalization of\u0000 Neural Network-Based Models of Combustion and Knock Indexes","authors":"A. Brusa, Fenil Panalal Shethia, Jacopo Mecagni, N. Cavina","doi":"10.4271/03-17-02-0009","DOIUrl":"https://doi.org/10.4271/03-17-02-0009","url":null,"abstract":"In the last few years, the artificial neural networks have been widely used in\u0000 the field of engine modeling. Some of the main reasons for this are, their\u0000 compatibility with the real-time systems, higher accuracy, and flexibility if\u0000 compared to other data-driven approaches. One of the main difficulties of using\u0000 this approach is the calibration of the network itself. It is very difficult to\u0000 find in the literature procedures that guide the user to completely define a\u0000 network. Typically, the very last steps (like the choice of the number of\u0000 neurons) must be selected by the user on the base of his sensitivity to the\u0000 problem.\u0000\u0000 \u0000This work proposes an automatic calibration procedure for the artificial neural\u0000 networks, considering all the main hyper-parameters of the network such as the\u0000 training algorithms, the activation functions, the number of the neurons, the\u0000 number of epochs, and the number of hidden layers, for modeling various\u0000 combustion indexes in a modern internal combustion engine. However, the proposed\u0000 procedure can be applied to the training of any neural network-based model.\u0000\u0000 \u0000The automatic calibration procedure outputs a configuration of the network,\u0000 giving the optimal combination in terms of hyper-parameters. The decision of the\u0000 optimal configuration of the neural network is based on a self-developed\u0000 formula, which gives a rank of all the possible hyper-parameter combinations\u0000 using some statistical parameters obtained comparing the simulated and the\u0000 experimental values. In the end, the lowest rank is selected as the optimal one\u0000 as it represents the combination having the lowest error. Following the\u0000 definition of this rank, high accuracy on the results has been achieved in terms\u0000 of the root mean square error index, for example, on the combustion phase model,\u0000 the error is 0.139°CA under steady-state conditions. On the maximum in-cylinder\u0000 pressure model, the error is 1.682 bar, while the knock model has an error of\u0000 0.457 bar for the same test that covers the whole engine operating field.","PeriodicalId":47948,"journal":{"name":"SAE International Journal of Engines","volume":"74 1","pages":""},"PeriodicalIF":1.2,"publicationDate":"2023-08-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"86156188","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Gas-Dynamic Interactions between Pre-Chamber and Main Chamber in\u0000 Passive Pre-Chamber Ignition Gasoline Engines","authors":"Tianxiao Yu, Dong Eun Lee, Jay P. Gore, Li Qiao","doi":"10.4271/03-17-01-0008","DOIUrl":"https://doi.org/10.4271/03-17-01-0008","url":null,"abstract":"Pre-chamber turbulent jet ignition (TJI) is a method of generating distributed\u0000 ignition sites through multiple high-speed turbulent jets in order to achieve an\u0000 enhanced burn rate in the engine cylinder when compared to conventional spark\u0000 plug ignition. To study the gas-dynamic interactions between the two chambers in\u0000 a gasoline engine, a three-dimensional numerical model was developed using the\u0000 commercial CFD code CONVERGE. The geometry and parameters of the engine used\u0000 were based on a modified turbocharged GM four-cylinder 2.0 L GDI gasoline\u0000 engine. Pre-chambers with nozzle diameters of 0.75 mm and 1.5 mm were used to\u0000 investigate the effect of pre-chamber geometry on pre-chamber charging,\u0000 combustion, and jet formation. The local developments of gas temperature and\u0000 velocity were captured by adaptive mesh refinement, while the turbulence was\u0000 resolved with the k-epsilon model of the Reynolds averaged Navier–Stokes (RANS)\u0000 equations. The combustion process was modeled with the extended coherent\u0000 flamelet model (ECFM). Data from engine experiments were compared with the\u0000 computed main chamber pressures and heat release rates, and the results show\u0000 good consistency with the model calculations. The scavenging and air–fuel\u0000 equivalence ratio (λ) distribution of the pre-chambers improved with the larger\u0000 nozzle, while the smaller nozzle generated jets with higher velocity, greater\u0000 turbulence kinetic energy, and longer penetration length. Moreover, after the\u0000 primary jet formation, secondary pre-chamber charging, combustion, and secondary\u0000 jet formation were observed.","PeriodicalId":47948,"journal":{"name":"SAE International Journal of Engines","volume":"73 1","pages":""},"PeriodicalIF":1.2,"publicationDate":"2023-08-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"72989774","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Model-Based Combustion Control to Reduce the Brake Specific Fuel\u0000 Consumption and Pollutant Emissions under Real Driving Maneuvers","authors":"A. Brusa, Jacopo Mecagni, Fenil Panalal Shethia, E. Corti","doi":"10.4271/03-17-01-0007","DOIUrl":"https://doi.org/10.4271/03-17-01-0007","url":null,"abstract":"A previously developed piston damage and exhaust gas temperature models are\u0000 coupled to manage the combustion process and thereby increasing the overall\u0000 energy conversion efficiency. The proposed model-based control algorithm is\u0000 developed and validated in a software-in-the-loop simulation environment, and\u0000 then the controller is deployed in a rapid control prototyping device and tested\u0000 online at the test bench. In the first part of the article, the exhaust gas\u0000 temperature model is reversed and converted into a control function, which is\u0000 then implemented in a piston damage-based spark advance controller. In this way,\u0000 more aggressive calibrations are actuated to target a certain piston damage\u0000 speed and exhaust gas temperature at the turbine inlet. A more anticipated spark\u0000 advance results in a lower exhaust gas temperature, and such decrease is\u0000 converted into lowering the fuel enrichment with respect to the production\u0000 calibrations. Moreover, the pollutant emissions associated with production\u0000 calibrations and the implementation of the developed controller are compared\u0000 through a GT-Power combustion model.\u0000\u0000 \u0000Finally, the complete controller is validated for both the transient and\u0000 steady-state conditions, reproducing a real vehicle maneuver at the engine test\u0000 bench. The results demonstrate that the combination of an accurate estimation of\u0000 the damage induced by knock and the value of the exhaust gas temperature allows\u0000 to reduce the brake specific fuel consumption by up to 20%. Moreover, the\u0000 stoichiometric area of the engine operating field is extended by 20%, and the\u0000 GT-Power simulations show a maximum CO reduction of about 50%.","PeriodicalId":47948,"journal":{"name":"SAE International Journal of Engines","volume":"95 1","pages":""},"PeriodicalIF":1.2,"publicationDate":"2023-08-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"89901370","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"A Novel Experiment Approach for Measurement Breakup Length, Cone\u0000 Angle, Sheet Velocity, and Film Thickness in Swirl Air-Blast\u0000 Atomizers","authors":"D. Phung, Thin V. Pham, Phuong X. Pham","doi":"10.4271/03-17-01-0006","DOIUrl":"https://doi.org/10.4271/03-17-01-0006","url":null,"abstract":"Measuring the dynamic parameters of liquid fragments generated in the near-field\u0000 of atomizing sprays poses a significant challenge due to the random nature of\u0000 the fragments, the instability of the spray, and the limitations of current\u0000 measuring technology. Precise determination of these parameters can aid in\u0000 improving the control of the atomization process, which is necessary for\u0000 providing suitable spray structures with appropriate flow rates and droplet size\u0000 distributions for various applications such as those used in heat engines. In\u0000 piston and gas turbine engines, controlling spray characteristics such as\u0000 penetration, cone angle, particle size, and droplet size distribution is crucial\u0000 to improve combustion efficiency and decrease exhaust emissions. This can be\u0000 accomplished by adjusting the structural and/or operating parameters of the fuel\u0000 supply system. This article aims to measure the breakup length, spray cone\u0000 angle, axial velocity, breakup time, and liquid sheet film thickness for a swirl\u0000 air-blast atomizer used in a gas-steam engine. The measurement was conducted\u0000 using a shadowgraph imaging system developed specifically for this study,\u0000 consisting of a high-speed camera, a lens, and a light source. While lasers are\u0000 commonly used as light sources in the literature, this study utilized a special\u0000 LED high-speed pulse light generator, which is cheaper, easier to handle, and\u0000 provides a more uniform background. Images were processed using a MATLAB code\u0000 developed for this study. Although the breakup zone is naturally random and the\u0000 breakup location significantly varies with time, the novel method developed in\u0000 this study helps quantify critical parameters under different operating\u0000 conditions.","PeriodicalId":47948,"journal":{"name":"SAE International Journal of Engines","volume":"20 1","pages":""},"PeriodicalIF":1.2,"publicationDate":"2023-07-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"72879189","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Transient Response of Turbocharged Compression Ignition Engine under\u0000 Different Load Conditions","authors":"S. Saad, Asiya Rummana","doi":"10.4271/03-17-01-0005","DOIUrl":"https://doi.org/10.4271/03-17-01-0005","url":null,"abstract":"In urban roads the engine speed and the load vary suddenly and frequently,\u0000 resulting in increased exhaust emissions. In such operations, the effect of air\u0000 injection technique to access the transient response of the engine is of great\u0000 interest. The effectiveness of air injection technique in improving the\u0000 transient response under speed transient is investigated in detail [1]; however, it is not evaluated for the\u0000 load transients. Load step demand of the engine is another important event that\u0000 limits the transient response of the turbocharger. In the present study,\u0000 response of a heavy-duty turbocharged diesel engine is investigated for\u0000 different load conditions. Three cases of load transients are considered:\u0000 constant load, load magnitude variation, and load scheduling. Air injection\u0000 technique is simulated and after optimization of injection pressure based on\u0000 orifice diameter, its effect on the transient response is presented. The results\u0000 reveal that air injection into the intake manifold is an effective technique to\u0000 improve the turbo lag of a heavy-duty turbocharged diesel engine under the\u0000 transient conditions of load.","PeriodicalId":47948,"journal":{"name":"SAE International Journal of Engines","volume":"19 1","pages":""},"PeriodicalIF":1.2,"publicationDate":"2023-07-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"89805364","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Misfire Detection Technology with Deep Neural Network Based on\u0000 Ignition Coil Signals","authors":"Naoki Yoneya, K. Amaya, Kengo Kumano, Y. Sukegawa, Yoshifumi Uchise, Hideo Jitsu, Yukio Fujiyama","doi":"10.4271/03-17-01-0004","DOIUrl":"https://doi.org/10.4271/03-17-01-0004","url":null,"abstract":"For achieving high efficiency and low exhaust emissions, engines need to be\u0000 operated near the limits of stable combustion, such as lean or exhaust gas\u0000 recirculation (EGR) conditions. Sensing technologies of the combustion state by\u0000 existing engine components are of high interest. And the utilization of voltage\u0000 and current signals from ignition coils is discussed in this article. The\u0000 discharge channel of an ignition spark is strongly affected by flow variation\u0000 and spark plug surface conditions, and the behavior of discharge channel\u0000 stretching and restrike event can vary greatly from cycle to cycle. As a result,\u0000 the effects of flow velocity, temperature, pressure, and electrode surface\u0000 resistance are compounded in the voltage-current response, making it difficult\u0000 to accurately detect the combustion state for each cycle by a threshold judgment\u0000 process using a single feature value.\u0000\u0000 \u0000In this article, a method for inductively detecting misfires from voltage and\u0000 current signals of ignition coils by applying deep learning image recognition is\u0000 introduced. First, post-ignition for misfire detection is performed on the\u0000 engine bench during the expansion stroke in an engine cycle, when the cylinder\u0000 pressure is expected to differ between the combustion cycle and the ignition\u0000 cycle, and the ignition coil voltage and current are measured. Next, a\u0000 two-dimensional frequency distribution of voltage and current (discharge\u0000 histogram) is created as an input image for deep learning, and the AlexNet\u0000 model, which has been trained with more than one million images, is trained with\u0000 images of the ignition and combustion cycles as a supervised learning. The\u0000 accuracy of classification is then verified using a validation dataset. In\u0000 addition, to making the deep learning model more explainable, the activation\u0000 score distribution on the discharge histogram was visualized when the trained\u0000 model judges the images, and the discharge characteristics that provided the\u0000 basis for deep learning classifications were analyzed.","PeriodicalId":47948,"journal":{"name":"SAE International Journal of Engines","volume":"42 1","pages":""},"PeriodicalIF":1.2,"publicationDate":"2023-07-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"74704854","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"A Mid-Infrared Laser Absorption Sensor for Gas Temperature and Carbon\u0000 Monoxide Mole Fraction Measurements at 15 kHz in Engine-Out Gasoline Vehicle\u0000 Exhaust","authors":"Joshua W. Stiborek, Ryan J. Tancin, Nathan J. Kempema, J. Szente, Michael J. Loos, C. Goldenstein","doi":"10.4271/03-17-01-0002","DOIUrl":"https://doi.org/10.4271/03-17-01-0002","url":null,"abstract":"Quantifying exhaust gas composition and temperature in vehicles with internal combustion engines (ICEs) is crucial to understanding and reducing emissions during transient engine operation. This is particularly important before the catalytic converter system lights off (i.e., during cold start). Most commercially available gas analyzers and temperature sensors are far too slow to measure these quantities on the timescale of individual cylinder-firing events, thus faster sensors are needed. A two-color mid-infrared (MIR) laser absorption spectroscopy (LAS) sensor for gas temperature and carbon monoxide (CO) mole fraction was developed and applied to address this technology gap. Two quantum cascade lasers (QCLs) were fiber coupled into one single-mode fiber to facilitate optical access in the test vehicle exhaust. The QCLs were time-multiplexed in order to scan across two CO absorption transitions near 2013 and 2060 cm–1 at 15 kHz. This enabled in situ measurements of temperature and CO mole fraction to be acquired at 15 kHz in the engine-out exhaust of a research vehicle (modified production vehicle) with an 8-cylinder gasoline ICE. Three different vehicle tests were characterized with the LAS sensor as follows: (1) cold start with engine idle, (2) warm start with a drive cycle on a chassis dynamometer, and (3) hot start with a drive cycle on a chassis dynamometer. The measurements obtained from the LAS sensor had a time resolution that was three orders of magnitude faster than that of thermocouple and gas analyzer data acquired at the Ford vehicle emissions research laboratory (VERL) in Dearborn, Michigan. This enabled the LAS sensor to resolve high-speed engine dynamics and exhaust gas transients, which the conventional instrumentation could not, thereby providing valuable insight into the evolution of ICE emissions during transient engine operation.","PeriodicalId":47948,"journal":{"name":"SAE International Journal of Engines","volume":"43 1","pages":""},"PeriodicalIF":1.2,"publicationDate":"2023-07-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"75945286","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Shot-to-Shot Deviation of a Common Rail Injection System Operating\u0000 with Cooking-Oil-Residue Biodiesel","authors":"Dat X. Nguyen, Cavicchi Andrea, K. Nguyen, Vu H. Nguyen, L. Postrioti, P. Pham","doi":"10.4271/03-16-08-0062","DOIUrl":"https://doi.org/10.4271/03-16-08-0062","url":null,"abstract":"The shot-to-shot variations in common rail injection systems are primarily caused\u0000 by pressure wave oscillations in the rail, pipes, and injector body. These\u0000 oscillations are influenced by fuel physical properties, injector needle\u0000 movement, and pressure and suction control valve activations. The pressure waves\u0000 are generated by pump actuation and injector needle movement, and their\u0000 frequency and amplitude are determined by fluid properties and flow path\u0000 geometry. These variations can result in cycle-to-cycle engine fluctuations. In\u0000 multi-injection and split-injection strategies, the pressure oscillation from\u0000 the first shot can impact the hydraulic characteristics of subsequent shots,\u0000 resulting in variations in injection rate and amount. This is particularly\u0000 significant when using alternative fuels such as biodiesel, which aim to reduce\u0000 emissions while maintaining fuel atomization quality. This study examines the\u0000 shot-to-shot variations in a second-generation common rail system using\u0000 cooking-oil-residue biodiesel. The results demonstrate that biodiesel properties\u0000 impact pressure wave oscillation, shot-to-shot variation, and total injection\u0000 rate. The study also finds that dwell time has a significant effect on the\u0000 hydraulic characteristics of the second shot, with minimal influence up to a\u0000 certain value. However, beyond a certain dwell time value (e.g., 0.8 ms in this\u0000 study), the impact of dwell time on the pressure fluctuation generated by the\u0000 second shot is limited. Conducting further research could help deepen our\u0000 understanding of the influence of shot-to-shot deviations. This could involve\u0000 exploring biodiesel spray characteristics using techniques such as shadowgraph\u0000 imaging and studying the effect of these deviations on flame propagation and\u0000 emission formation. Examining engine performance could also provide valuable\u0000 insights into the effectiveness of the split-injection strategy and biodiesel\u0000 blends. Additionally, characterizing biodiesel spray using the double-shot\u0000 technique to examine spray penetration, cone angle, and/or spray impingement and\u0000 combustion characteristics could be useful in linking it with the shot-to-shot\u0000 variation investigated in this study. Such research can contribute to advancing\u0000 the state-of-the-art knowledge on this topic.","PeriodicalId":47948,"journal":{"name":"SAE International Journal of Engines","volume":"27 1","pages":""},"PeriodicalIF":1.2,"publicationDate":"2023-06-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"88091575","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Numerical Simulation and Experimental Investigation of Different\u0000 Cooling Structures on Cooling Performance and Fuel Consumption of a Two-Cylinder\u0000 Motorcycle Engine","authors":"Libin Tan, Yuejin Yuan, Can Huang","doi":"10.4271/03-16-08-0063","DOIUrl":"https://doi.org/10.4271/03-16-08-0063","url":null,"abstract":"The reasonable engine cooling system design can give a better cooling of engine,\u0000 the coolant flow direction and different cooling structure designs have great\u0000 impact on the cooling performance and fuel consumption of engine. Therefore, to\u0000 gain a deeper understanding of the impact of different cooling system designs on\u0000 engine cooling performance, three different split cooling structures and two\u0000 oil–water heat exchanger (OWHE) layouts are designed for a two-cylinder\u0000 motorcycle engine. Three-dimensional CFD analysis method is used for analyzing\u0000 the coolant velocity distributions and one-dimensional systematic analysis\u0000 method is used for analyzing the system flow rate at those cooling structure\u0000 designs and OWHE designs. Meanwhile, experimental investigation of different\u0000 cooling structures and OWHE layouts on fuel consumption is conducted by the\u0000 bench test of worldwide motorcycle test cycle. Results indicated that the\u0000 difference of coolant flow velocity distribution for four cooling structures are\u0000 small and the flow resistance of Case D is lowest at fully opened thermostat\u0000 condition. The fuel consumption of Case D is 4.78 L/100 km, 1.4% lower than that\u0000 of Case A with the fuel consumption 4.85 L/100 km. The combined split cooling\u0000 structure Case D and OWHE layout one is proven as the optimal cooling design\u0000 with 4% fuel consumption reduction compared with that of original cooling\u0000 structure Case A. The research results can provide theoretical reference for\u0000 engine cooling performance evaluation and give valuable data to motorcycle\u0000 designers for quick evaluation of design and quick solutions of improved\u0000 design.","PeriodicalId":47948,"journal":{"name":"SAE International Journal of Engines","volume":"145 1","pages":""},"PeriodicalIF":1.2,"publicationDate":"2023-06-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"80774465","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Optical Study on Spark Plug Gap in Extending Methane Lean Combustion\u0000 Limits under High Ignition Energy Conditions","authors":"Xiao Zhang, Ren Zhang, Lin Chen","doi":"10.4271/03-16-08-0059","DOIUrl":"https://doi.org/10.4271/03-16-08-0059","url":null,"abstract":"Lean combustion has the potential to achieve high thermal efficiency for internal\u0000 combustion engines. However, natural gas (NG) engines often suffer from slow\u0000 burning rates and large cyclic variations when adopting lean combustion. In this\u0000 study, the effects of spark plug gaps (SPGs) on methane lean combustion are\u0000 optically investigated under high ignition energy conditions. Synchronization\u0000 measurements of in-cylinder pressure and high-speed photography are performed\u0000 for combustion analysis. The results show that large SPGs with high ignition\u0000 energy exhibit great improvement in engine combustion stability and power\u0000 capability. Under ultra-lean conditions, a large SPG with a high ignition energy\u0000 of 150–200 mJ can extend the lean limit to 1.55. Combustion images indicate that\u0000 this is contributed by the enlarged initial flame kernel, which promotes early\u0000 flame propagation. Besides, an empirical criterion is adopted to quantify the\u0000 underlying mechanism, and the results confirm that a more stable early flame\u0000 development with a faster burning rate can be obtained by a larger SPG and\u0000 higher ignition energy under lean conditions. Therefore, a large SPG is an\u0000 effective way to improve combustion stability and thermal efficiency for NG\u0000 engines.","PeriodicalId":47948,"journal":{"name":"SAE International Journal of Engines","volume":"86 1","pages":""},"PeriodicalIF":1.2,"publicationDate":"2023-06-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"76216011","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}