Pub Date : 2024-02-21DOI: 10.1177/14680874241232007
Edward F Bogdanowicz, Allen Loper, Joshua Bittle, Ajay K Agrawal
In conventional diesel combustion (CDC), a centrally located multi-hole injector supplies fuel radially outwards. This study introduces and explores the concept of peripheral fuel injection (PeFI) to supply fuel from multiple locations on top of the combustion chamber using several single-hole injectors. The PeFI concept is designed to eliminate flame-wall and jet-wall interactions, and, ideally, to produce independent flames without any interference. PeFI is also intended to increase air entrainment in the near field and thus, reduce equivalence ratio at the lift-off length and subsequent soot formation. PeFI reduces wall heat transfer compared to CDC although this feature is not considered in the present study. The two methods of fuel injection are compared in a non-reacting optical chamber via high-speed imaging of the jets. N-heptane fuel at 1500 bar supply pressures is injected into a test chamber filled with nitrogen at engine relevant ambient densities of 23.0 and 18.5 kg/m3. Four configurations are trialed including a six-hole central injector and six, single-hole PeFI injectors with holes oriented at a layout angle, defined as the angle between the center of the fuel jet and chamber radius, of 0°, 15°, and 30°. Flow visualizations show jet-to-jet interactions at small layout angles for PeFI, but little to no jet-to-jet (or jet-wall) interference as the layout angle increases to 30°. Image analysis reveals that PeFI provides faster rate of injection, longer jet penetration length, greater width near the jet tip, and larger jet volume compared to those for the central injector. Overall, results demonstrate the potential of PeFI to simultaneously improve fuel efficiency and reduce emissions in diesel engines.
{"title":"Experimental study of peripheral fuel injection for higher performance in diesel engines","authors":"Edward F Bogdanowicz, Allen Loper, Joshua Bittle, Ajay K Agrawal","doi":"10.1177/14680874241232007","DOIUrl":"https://doi.org/10.1177/14680874241232007","url":null,"abstract":"In conventional diesel combustion (CDC), a centrally located multi-hole injector supplies fuel radially outwards. This study introduces and explores the concept of peripheral fuel injection (PeFI) to supply fuel from multiple locations on top of the combustion chamber using several single-hole injectors. The PeFI concept is designed to eliminate flame-wall and jet-wall interactions, and, ideally, to produce independent flames without any interference. PeFI is also intended to increase air entrainment in the near field and thus, reduce equivalence ratio at the lift-off length and subsequent soot formation. PeFI reduces wall heat transfer compared to CDC although this feature is not considered in the present study. The two methods of fuel injection are compared in a non-reacting optical chamber via high-speed imaging of the jets. N-heptane fuel at 1500 bar supply pressures is injected into a test chamber filled with nitrogen at engine relevant ambient densities of 23.0 and 18.5 kg/m<jats:sup>3</jats:sup>. Four configurations are trialed including a six-hole central injector and six, single-hole PeFI injectors with holes oriented at a layout angle, defined as the angle between the center of the fuel jet and chamber radius, of 0°, 15°, and 30°. Flow visualizations show jet-to-jet interactions at small layout angles for PeFI, but little to no jet-to-jet (or jet-wall) interference as the layout angle increases to 30°. Image analysis reveals that PeFI provides faster rate of injection, longer jet penetration length, greater width near the jet tip, and larger jet volume compared to those for the central injector. Overall, results demonstrate the potential of PeFI to simultaneously improve fuel efficiency and reduce emissions in diesel engines.","PeriodicalId":14034,"journal":{"name":"International Journal of Engine Research","volume":"2014 1","pages":""},"PeriodicalIF":2.5,"publicationDate":"2024-02-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139947044","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-01-31DOI: 10.1177/14680874241227536
Yuanyuan Zhao, Chao Xu, Yan Zhang, Zongyu Yue, Chenchen Wang, Zhenyang Ming, Yuqing Cai, Zunqing Zheng, Hu Wang, Mingfa Yao
This work investigates the ignition and flame development processes of low reactivity fuel combustion under compression ignition conditions based on the large eddy simulation approach. The chemical explosive mode analysis (CEMA) is employed to characterize the local combustion features, including gas-liquid fuel zone, auto-ignition, diffusion-assisted, extinction, cool flame and post-ignition zone, among which auto-ignition and post-ignition are found to play a key role in the overall heat release process. The local flame propagation modes in gasoline compression ignition (GCI) are determined by quantifying the relative magnitude of diffusion/chemistry at a representative progress variable in the pre-ignition zone. The results show that autoignition fronts and deflagration waves exist simultaneously in the ignition and intense high temperature heat release (HTHR) stages, but autoignition fronts dominate. In addition, the chemical kinetic processes of four heat release periods are analyzed. The heat release during the ignition period is found to be dominated by the reactions CH3+ H (+M) <=> CH4 (+M) and CH3CHO + H <=> CH2CHO + H2. The reaction CH2OH + OH <=> CH2O + H2O always plays an important role in the heat releases during the other three combustion stages including intense HTHR, moderate HTHR and post-combustion.
{"title":"A numerical study of ignition and flame development characteristics in GCI combustion using large eddy simulations and chemical explosive mode analysis","authors":"Yuanyuan Zhao, Chao Xu, Yan Zhang, Zongyu Yue, Chenchen Wang, Zhenyang Ming, Yuqing Cai, Zunqing Zheng, Hu Wang, Mingfa Yao","doi":"10.1177/14680874241227536","DOIUrl":"https://doi.org/10.1177/14680874241227536","url":null,"abstract":"This work investigates the ignition and flame development processes of low reactivity fuel combustion under compression ignition conditions based on the large eddy simulation approach. The chemical explosive mode analysis (CEMA) is employed to characterize the local combustion features, including gas-liquid fuel zone, auto-ignition, diffusion-assisted, extinction, cool flame and post-ignition zone, among which auto-ignition and post-ignition are found to play a key role in the overall heat release process. The local flame propagation modes in gasoline compression ignition (GCI) are determined by quantifying the relative magnitude of diffusion/chemistry at a representative progress variable in the pre-ignition zone. The results show that autoignition fronts and deflagration waves exist simultaneously in the ignition and intense high temperature heat release (HTHR) stages, but autoignition fronts dominate. In addition, the chemical kinetic processes of four heat release periods are analyzed. The heat release during the ignition period is found to be dominated by the reactions CH<jats:sub>3</jats:sub>+ H (+M) <=> CH<jats:sub>4</jats:sub> (+M) and CH<jats:sub>3</jats:sub>CHO + H <=> CH<jats:sub>2</jats:sub>CHO + H<jats:sub>2</jats:sub>. The reaction CH<jats:sub>2</jats:sub>OH + OH <=> CH<jats:sub>2</jats:sub>O + H<jats:sub>2</jats:sub>O always plays an important role in the heat releases during the other three combustion stages including intense HTHR, moderate HTHR and post-combustion.","PeriodicalId":14034,"journal":{"name":"International Journal of Engine Research","volume":"174 1","pages":""},"PeriodicalIF":2.5,"publicationDate":"2024-01-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139947145","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-01-31DOI: 10.1177/14680874241226580
Bryan P Maldonado, Brian C Kaul, Catherine D Schuman, Steven R Young
To reduce the modeling burden for control of spark-ignition engines, reinforcement learning (RL) has been applied to solve the dilute combustion limit problem. Q-learning was used to identify an optimal control policy to adjust the fuel injection quantity in each combustion cycle. A physics-based model was used to determine the relevant states of the system used for training the control policy in a data-efficient manner. The cost function was chosen such that high cycle-to-cycle variability (CCV) at the dilute limit was minimized while maintaining stoichiometric combustion as much as possible. Experimental results demonstrated a reduction of CCV after the training period with slightly lean combustion, contributing to a net increase in fuel conversion efficiency of 1.33%. To ensure stoichiometric combustion for three-way catalyst compatibility, a second feedback loop based on an exhaust oxygen sensor was incorporated into the fuel quantity controller using a slow proportional-integral (PI) controller. The closed-loop experiments showed that both feedback loops can cooperate effectively, maintaining stoichiometric combustion while reducing combustion CCV and increasing fuel conversion efficiency by 1.09%. Finally, a modified cost function was proposed to ensure stoichiometric combustion with a single controller. In addition, the learning period was shortened by half to evaluate the RL algorithm performance on limited training time. Experimental results showed that the modified cost function could achieve the desired CCV targets, however, the learning time was reduced by half and the fuel conversion efficiency increased only by 0.30%.
{"title":"Reinforcement learning applied to dilute combustion control for increased fuel efficiency","authors":"Bryan P Maldonado, Brian C Kaul, Catherine D Schuman, Steven R Young","doi":"10.1177/14680874241226580","DOIUrl":"https://doi.org/10.1177/14680874241226580","url":null,"abstract":"To reduce the modeling burden for control of spark-ignition engines, reinforcement learning (RL) has been applied to solve the dilute combustion limit problem. Q-learning was used to identify an optimal control policy to adjust the fuel injection quantity in each combustion cycle. A physics-based model was used to determine the relevant states of the system used for training the control policy in a data-efficient manner. The cost function was chosen such that high cycle-to-cycle variability (CCV) at the dilute limit was minimized while maintaining stoichiometric combustion as much as possible. Experimental results demonstrated a reduction of CCV after the training period with slightly lean combustion, contributing to a net increase in fuel conversion efficiency of 1.33%. To ensure stoichiometric combustion for three-way catalyst compatibility, a second feedback loop based on an exhaust oxygen sensor was incorporated into the fuel quantity controller using a slow proportional-integral (PI) controller. The closed-loop experiments showed that both feedback loops can cooperate effectively, maintaining stoichiometric combustion while reducing combustion CCV and increasing fuel conversion efficiency by 1.09%. Finally, a modified cost function was proposed to ensure stoichiometric combustion with a single controller. In addition, the learning period was shortened by half to evaluate the RL algorithm performance on limited training time. Experimental results showed that the modified cost function could achieve the desired CCV targets, however, the learning time was reduced by half and the fuel conversion efficiency increased only by 0.30%.","PeriodicalId":14034,"journal":{"name":"International Journal of Engine Research","volume":"9 1","pages":""},"PeriodicalIF":2.5,"publicationDate":"2024-01-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139947149","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-01-31DOI: 10.1177/14680874241227256
Kazuhito Dejima, Osamu Nakabeppu
Heat transfer between combustion gases and walls is one of the most important phenomena for internal combustion engines; however, its mechanisms have not yet been elucidated. This study proposed a new model based on one-dimensional heat conduction to characterize and predict engine heat transfer. This model assumes a conduction thickness of a thermal boundary layer determined by heat conduction and strain. Through comparison with numerical simulation, it was found that the heat flux from the conduction-strain model was comparable to that in laminar heat transfer. The heat flux calculated with the conduction-strain model is considered to be the minimum heat flux under each operating condition and engine specification. Therefore, the ratio of the measured heat flux to modeled heat flux indicates the intensity of convection and radiation, particularly turbulent mixing. It was also found that the conduction-strain model reproduced the measured heat flux well with a single coefficient, exhibiting a small error of 10.2%; meanwhile, the errors of Woschni and Annand models were greater than 20%, suggesting that the proposed model has good potential in predicting the instantaneous heat flux more accurately than conventional models.
{"title":"Conduction-strain model for heat transfer characterization in internal combustion engines","authors":"Kazuhito Dejima, Osamu Nakabeppu","doi":"10.1177/14680874241227256","DOIUrl":"https://doi.org/10.1177/14680874241227256","url":null,"abstract":"Heat transfer between combustion gases and walls is one of the most important phenomena for internal combustion engines; however, its mechanisms have not yet been elucidated. This study proposed a new model based on one-dimensional heat conduction to characterize and predict engine heat transfer. This model assumes a conduction thickness of a thermal boundary layer determined by heat conduction and strain. Through comparison with numerical simulation, it was found that the heat flux from the conduction-strain model was comparable to that in laminar heat transfer. The heat flux calculated with the conduction-strain model is considered to be the minimum heat flux under each operating condition and engine specification. Therefore, the ratio of the measured heat flux to modeled heat flux indicates the intensity of convection and radiation, particularly turbulent mixing. It was also found that the conduction-strain model reproduced the measured heat flux well with a single coefficient, exhibiting a small error of 10.2%; meanwhile, the errors of Woschni and Annand models were greater than 20%, suggesting that the proposed model has good potential in predicting the instantaneous heat flux more accurately than conventional models.","PeriodicalId":14034,"journal":{"name":"International Journal of Engine Research","volume":"3 1","pages":""},"PeriodicalIF":2.5,"publicationDate":"2024-01-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139947033","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
An experimental investigation on the spatial distribution of knock events in a turbocharged spark-ignition engine for hybrid vehicle applications was conducted by using a multichannel fiber optic method. The knock positions were detected under different conditions to investigate the influence of crucial engine design and operating parameters on the knock characteristics including the spatial distribution in the combustion chamber and its relationship to knock intensity. The measured data reveal that the spatial distribution in the engine with a port fuel injection (PFI) system is mainly located on the exhaust side with insignificant influence of engine speed and load, which is attributed to the elevated thermal load around the exhaust valves. However, the knock events under gasoline direct-injection (DI) conditions were found to occur in more scattered locations with more occurring on the engine front-end and rear-end sides. These results indicate that the in-cylinder fuel-air mixing process may have a significant impact on the knock occurrence spots under DI conditions. The knock positions of the engine with different excessive air ratios, injection timings, and intake-valve timings were also detected, indicating that engine operating parameters have complex influences on the knock-region distribution in a DI engine. In addition, experiments were also carried out in two different cylinders to verify the cylinder-to-cylinder variations in knock regions which may be caused by the engine cooling design. Furthermore, no apparent correlations were observed between the knock position and the knock intensity by analysis of the experimental data.
采用多通道光纤方法，对混合动力汽车应用的涡轮增压火花点火发动机中爆震事件的空间分布进行了实验研究。在不同条件下检测了爆震位置，以研究发动机的关键设计和运行参数对爆震特性的影响，包括燃烧室的空间分布及其与爆震强度的关系。测量数据显示，采用端口燃油喷射（PFI）系统的发动机的空间分布主要位于排气侧，发动机转速和负荷对其影响不大，这归因于排气门周围的热负荷升高。然而，在汽油直喷（DI）条件下，爆震事件发生的位置较为分散，更多发生在发动机前端和后端。这些结果表明，缸内燃料与空气的混合过程可能会对 DI 条件下的爆震发生点产生重大影响。此外，还检测了不同过量空气比、喷油正时和进气门正时下发动机的爆震位置，表明发动机运行参数对 DI 发动机爆震区域分布有着复杂的影响。此外，还在两个不同的气缸中进行了实验，以验证可能由发动机冷却设计引起的气缸间爆震区域的变化。此外，通过对实验数据的分析，没有发现爆震位置与爆震强度之间存在明显的相关性。
{"title":"Experimental study of spatial distribution of knock events in a turbocharged spark-ignition engine","authors":"Shuo Meng, Zhiyu Han, Benzheng Fan, Zhenkuo Wu, Qiang Shao, Laihui Tong","doi":"10.1177/14680874241227552","DOIUrl":"https://doi.org/10.1177/14680874241227552","url":null,"abstract":"An experimental investigation on the spatial distribution of knock events in a turbocharged spark-ignition engine for hybrid vehicle applications was conducted by using a multichannel fiber optic method. The knock positions were detected under different conditions to investigate the influence of crucial engine design and operating parameters on the knock characteristics including the spatial distribution in the combustion chamber and its relationship to knock intensity. The measured data reveal that the spatial distribution in the engine with a port fuel injection (PFI) system is mainly located on the exhaust side with insignificant influence of engine speed and load, which is attributed to the elevated thermal load around the exhaust valves. However, the knock events under gasoline direct-injection (DI) conditions were found to occur in more scattered locations with more occurring on the engine front-end and rear-end sides. These results indicate that the in-cylinder fuel-air mixing process may have a significant impact on the knock occurrence spots under DI conditions. The knock positions of the engine with different excessive air ratios, injection timings, and intake-valve timings were also detected, indicating that engine operating parameters have complex influences on the knock-region distribution in a DI engine. In addition, experiments were also carried out in two different cylinders to verify the cylinder-to-cylinder variations in knock regions which may be caused by the engine cooling design. Furthermore, no apparent correlations were observed between the knock position and the knock intensity by analysis of the experimental data.","PeriodicalId":14034,"journal":{"name":"International Journal of Engine Research","volume":"27 1","pages":""},"PeriodicalIF":2.5,"publicationDate":"2024-01-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139947119","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-01-06DOI: 10.1177/14680874231216664
Saurabh K Gupta, Anand Krishnasamy
Low temperature combustion (LTC) strategies have the potential for simultaneous reduction in oxides of nitrogen (NOx) and soot emissions while achieving higher thermal efficiency. Commercial widespread implementation of LTC strategies demands addressing several challenges, including narrow operating load range, lack of ignition timing control, and reducing high unburned hydrocarbon (HC) and carbon monoxide (CO) emissions. These challenges could be because the conventional engine design and fuels cannot adapt well to LTC modes. Thus, replacing conventional diesel fuel with suitable alternative fuels for LTC strategies is essential. In the present work, three LTC strategies, Homogenous Charge Compression Ignition (HCCI), Premixed Charge Compression Ignition (PCCI), and Reactivity Controlled Compression Ignition (RCCI), are compared with conventional diesel combustion in a production, light-duty diesel engine from an alternative fuel perspective to come up with a befitting strategy and fuel to achieve wider operating range and lower emissions. The fuel selection strategy based on the fundamental fuel property requirements of the three LTC strategies has been discussed in detail. The baseline reference data is fixed by comparing three LTC strategies with conventional diesel combustion using diesel and gasoline as reference fuel at 40% load, the maximum common achievable load among the three LTC strategies. This is followed by an investigation of the effect of alternative fuels across three LTC strategies to address the shortcomings of the LTC strategies. The results show that the engine operating load range could be extended, and HC and CO emissions are reduced significantly with alternative fuels in the three LTC strategies.
{"title":"A relative comparison of HCCI, PCCI, and RCCI combustion strategies: an alternative fuels perspective","authors":"Saurabh K Gupta, Anand Krishnasamy","doi":"10.1177/14680874231216664","DOIUrl":"https://doi.org/10.1177/14680874231216664","url":null,"abstract":"Low temperature combustion (LTC) strategies have the potential for simultaneous reduction in oxides of nitrogen (NOx) and soot emissions while achieving higher thermal efficiency. Commercial widespread implementation of LTC strategies demands addressing several challenges, including narrow operating load range, lack of ignition timing control, and reducing high unburned hydrocarbon (HC) and carbon monoxide (CO) emissions. These challenges could be because the conventional engine design and fuels cannot adapt well to LTC modes. Thus, replacing conventional diesel fuel with suitable alternative fuels for LTC strategies is essential. In the present work, three LTC strategies, Homogenous Charge Compression Ignition (HCCI), Premixed Charge Compression Ignition (PCCI), and Reactivity Controlled Compression Ignition (RCCI), are compared with conventional diesel combustion in a production, light-duty diesel engine from an alternative fuel perspective to come up with a befitting strategy and fuel to achieve wider operating range and lower emissions. The fuel selection strategy based on the fundamental fuel property requirements of the three LTC strategies has been discussed in detail. The baseline reference data is fixed by comparing three LTC strategies with conventional diesel combustion using diesel and gasoline as reference fuel at 40% load, the maximum common achievable load among the three LTC strategies. This is followed by an investigation of the effect of alternative fuels across three LTC strategies to address the shortcomings of the LTC strategies. The results show that the engine operating load range could be extended, and HC and CO emissions are reduced significantly with alternative fuels in the three LTC strategies.","PeriodicalId":14034,"journal":{"name":"International Journal of Engine Research","volume":"8 13","pages":""},"PeriodicalIF":2.5,"publicationDate":"2024-01-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139380381","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-12-26DOI: 10.1177/14680874231217342
Vasileios Karystinos, G. Papalambrou
Virtual Sensors based on deep-learning models for predicting the NOx emissions of a Diesel Engine under transient conditions were developed and verified. Raw data from laboratory experimental measurements, under marine transient loading cycles, were used for training and evaluation of the developed models. NOx prediction under transient conditions is often inaccurate by implementing conventional methods since they fail to capture the dynamic behavior of internal combustion engines. The proposed model is based on Long Short-Term Memory (LSTM) Networks. A Deep Feed-forward Neural Network (DFNN) was also developed to validate the LSTM. The LSTM input is a time sequence of past measurements of the inputs while the DFNN only uses the most recent measurements. The Bayesian Hyberband Optimization (BOHB) algorithm determined the structure and parameters of each network. Each model uses the same inputs and is directly derived from the engine ECU. The LSTM validation showed that the model can generalize and accurately predict the NOx emissions under transient loading compared to the DFNN.
{"title":"Deep long short-term memory neural networks as virtual sensors for marine diesel engine NOx prediction at transient conditions","authors":"Vasileios Karystinos, G. Papalambrou","doi":"10.1177/14680874231217342","DOIUrl":"https://doi.org/10.1177/14680874231217342","url":null,"abstract":"Virtual Sensors based on deep-learning models for predicting the NOx emissions of a Diesel Engine under transient conditions were developed and verified. Raw data from laboratory experimental measurements, under marine transient loading cycles, were used for training and evaluation of the developed models. NOx prediction under transient conditions is often inaccurate by implementing conventional methods since they fail to capture the dynamic behavior of internal combustion engines. The proposed model is based on Long Short-Term Memory (LSTM) Networks. A Deep Feed-forward Neural Network (DFNN) was also developed to validate the LSTM. The LSTM input is a time sequence of past measurements of the inputs while the DFNN only uses the most recent measurements. The Bayesian Hyberband Optimization (BOHB) algorithm determined the structure and parameters of each network. Each model uses the same inputs and is directly derived from the engine ECU. The LSTM validation showed that the model can generalize and accurately predict the NOx emissions under transient loading compared to the DFNN.","PeriodicalId":14034,"journal":{"name":"International Journal of Engine Research","volume":"20 6","pages":""},"PeriodicalIF":2.5,"publicationDate":"2023-12-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139157427","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-12-25DOI: 10.1177/14680874231210929
Sayop Kim, Lorenzo Nocivelli, Anqi Zhang, Alexander Voice, Yuanjiang Pei
Fuel spray modeling plays a critical role during modern gasoline direct injection (GDI) engine development due to fuel injection’s dominant impact on engine performance and emissions as well as the complex physical processes involved. In engineering three-dimensional (3D) computational fluid dynamics (CFD) simulations, the liquid-phase fuel atomization, evaporation, and mixing are usually modeled with the discrete droplet model (DDM) adopting a Lagrangian approach for multiphase CFD simulations. To this end, general practices heavily depend on the reduced order characterization of the injector nozzle flow. However, such simplified injector modeling may lead to insufficient representations of the complex spray dynamics. To tackle this problem, this study proposes a novel workflow to numerically evaluate GDI sub-cooled and flash-boiling sprays under engine-relevant conditions using a side-mounted GDI injector together with real gasoline fuel properties. The workflow introduces a one-way coupling (OWC) method leveraging high-fidelity nozzle flow simulations to provide realistic boundary conditions to the Lagrangian injector model. The proposed workflow was first verified in a constant volume chamber (CVC) environment and then implemented in a practical GDI engine setup to study spray morphology, fuel-air mixing, and wall-wetting propensity. In addition, detailed comparison was performed between the OWC method and the conventional rate of injection (ROI) routine. Quantitative analysis of spray characteristics was conducted to highlight possible source of discrepancies of the conventional ROI method.
{"title":"Realistic fuel spray modeling for gasoline direct injection engine applications","authors":"Sayop Kim, Lorenzo Nocivelli, Anqi Zhang, Alexander Voice, Yuanjiang Pei","doi":"10.1177/14680874231210929","DOIUrl":"https://doi.org/10.1177/14680874231210929","url":null,"abstract":"Fuel spray modeling plays a critical role during modern gasoline direct injection (GDI) engine development due to fuel injection’s dominant impact on engine performance and emissions as well as the complex physical processes involved. In engineering three-dimensional (3D) computational fluid dynamics (CFD) simulations, the liquid-phase fuel atomization, evaporation, and mixing are usually modeled with the discrete droplet model (DDM) adopting a Lagrangian approach for multiphase CFD simulations. To this end, general practices heavily depend on the reduced order characterization of the injector nozzle flow. However, such simplified injector modeling may lead to insufficient representations of the complex spray dynamics. To tackle this problem, this study proposes a novel workflow to numerically evaluate GDI sub-cooled and flash-boiling sprays under engine-relevant conditions using a side-mounted GDI injector together with real gasoline fuel properties. The workflow introduces a one-way coupling (OWC) method leveraging high-fidelity nozzle flow simulations to provide realistic boundary conditions to the Lagrangian injector model. The proposed workflow was first verified in a constant volume chamber (CVC) environment and then implemented in a practical GDI engine setup to study spray morphology, fuel-air mixing, and wall-wetting propensity. In addition, detailed comparison was performed between the OWC method and the conventional rate of injection (ROI) routine. Quantitative analysis of spray characteristics was conducted to highlight possible source of discrepancies of the conventional ROI method.","PeriodicalId":14034,"journal":{"name":"International Journal of Engine Research","volume":"7 1","pages":""},"PeriodicalIF":2.5,"publicationDate":"2023-12-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139158429","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-12-22DOI: 10.1177/14680874231216327
Jun-Mo Kang, Hanho Yun
To achieve robust low-load LTC (Low Temperature combustion), precise metering of fuel is required since the combustion is very sensitive to the variation of the injected fuel quantity, which could range from 1 to 3 mg per injection pulse. Open-loop calibration of individual injectors is simply not a practical option and therefore a fuel control strategy has been developed to ensure robust low-load LTC combustion and validated through experiments on a 2.2 L 4-cylinder LTC engine at two different coolant temperatures. The results show that the fuel control strategy significantly improves low-load LTC combustion stability by reducing cylinder-to-cylinder variation in delivered fuel masses due to different injector characteristics even when engine operating conditions are changed.
{"title":"Fuel control strategy for robust low-load gasoline low temperature combustion","authors":"Jun-Mo Kang, Hanho Yun","doi":"10.1177/14680874231216327","DOIUrl":"https://doi.org/10.1177/14680874231216327","url":null,"abstract":"To achieve robust low-load LTC (Low Temperature combustion), precise metering of fuel is required since the combustion is very sensitive to the variation of the injected fuel quantity, which could range from 1 to 3 mg per injection pulse. Open-loop calibration of individual injectors is simply not a practical option and therefore a fuel control strategy has been developed to ensure robust low-load LTC combustion and validated through experiments on a 2.2 L 4-cylinder LTC engine at two different coolant temperatures. The results show that the fuel control strategy significantly improves low-load LTC combustion stability by reducing cylinder-to-cylinder variation in delivered fuel masses due to different injector characteristics even when engine operating conditions are changed.","PeriodicalId":14034,"journal":{"name":"International Journal of Engine Research","volume":"85 6","pages":""},"PeriodicalIF":2.5,"publicationDate":"2023-12-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139164093","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-12-16DOI: 10.1177/14680874231214300
Ziyang Dai, Jie Li, Hengsheng Liang, Xiaoyang Yu, Binyang Wu
Heavy-duty diesel engines, the heat engines with the highest thermal efficiency, usually operate under transient conditions. Thus, it is important to study the transient performance of heavy-duty diesel engines. This paper aims to solve the problems of combustion deterioration, poor response, and emission deterioration caused by the mismatch between the air intake response and the fuel system under the strong transient condition of sudden loading of 1 s under constant speed. In this paper, an experimental study on the transient performance at different speeds under the coordinated regulation of a variable geometry turbocharger (VGT) and variable valve timing (VVT) is conducted. The study found that the transient torque response is affected by combustion in the cylinder and pump work. During the low-speed transient process, due to reduced airflow and pumping losses, the VVT is switched off while the VGT delay is increased to improve air response. Consequently, the mixture in the cylinder is fully burned, and improved transient performance is obtained. In the high-speed transient process, the engine air intake flow is improved. Through the VVT is ON at the appropriate time and the VGT hysteresis control, the pumping loss can be effectively reduced, and excellent transient performance can be achieved to ensure the fast response of the in-cylinder charge. Given sudden loading from 10% to 100% within 1 s under a high speed of 1600 r/min, the VVT switches on with a 0.15 s delay, and the VGT is controlled with a 0.4 s delay. A torque response of 0.82 s can be achieved, and the soot peak value is reduced by 66.26%, and the accumulated value of soot is reduced by 46.91%. At a low speed of 1000 r/min, given sudden loading from 10% to 100% within 1 s, the 0.6 s VGT delay can reduce the accumulated value of soot by 78.57% and 56.22% compared with delays of 0.2 and 0.4 s.
{"title":"Experimental study on the transient-state performance of diesel engines at different speeds using the synergistic regulation of VGT and VVT","authors":"Ziyang Dai, Jie Li, Hengsheng Liang, Xiaoyang Yu, Binyang Wu","doi":"10.1177/14680874231214300","DOIUrl":"https://doi.org/10.1177/14680874231214300","url":null,"abstract":"Heavy-duty diesel engines, the heat engines with the highest thermal efficiency, usually operate under transient conditions. Thus, it is important to study the transient performance of heavy-duty diesel engines. This paper aims to solve the problems of combustion deterioration, poor response, and emission deterioration caused by the mismatch between the air intake response and the fuel system under the strong transient condition of sudden loading of 1 s under constant speed. In this paper, an experimental study on the transient performance at different speeds under the coordinated regulation of a variable geometry turbocharger (VGT) and variable valve timing (VVT) is conducted. The study found that the transient torque response is affected by combustion in the cylinder and pump work. During the low-speed transient process, due to reduced airflow and pumping losses, the VVT is switched off while the VGT delay is increased to improve air response. Consequently, the mixture in the cylinder is fully burned, and improved transient performance is obtained. In the high-speed transient process, the engine air intake flow is improved. Through the VVT is ON at the appropriate time and the VGT hysteresis control, the pumping loss can be effectively reduced, and excellent transient performance can be achieved to ensure the fast response of the in-cylinder charge. Given sudden loading from 10% to 100% within 1 s under a high speed of 1600 r/min, the VVT switches on with a 0.15 s delay, and the VGT is controlled with a 0.4 s delay. A torque response of 0.82 s can be achieved, and the soot peak value is reduced by 66.26%, and the accumulated value of soot is reduced by 46.91%. At a low speed of 1000 r/min, given sudden loading from 10% to 100% within 1 s, the 0.6 s VGT delay can reduce the accumulated value of soot by 78.57% and 56.22% compared with delays of 0.2 and 0.4 s.","PeriodicalId":14034,"journal":{"name":"International Journal of Engine Research","volume":"74 11","pages":""},"PeriodicalIF":2.5,"publicationDate":"2023-12-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138967497","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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