Based on schlieren imaging method the shock wave generated by diesel injector has been investigated,and the influences of ambient gas property, the progress of the spray, ambient gas density and ambient gas temperatur...Based on schlieren imaging method the shock wave generated by diesel injector has been investigated,and the influences of ambient gas property, the progress of the spray, ambient gas density and ambient gas temperature on shock wave have been analyzed. The results show that:the images of spray shock wave are cleaner using sulfur hexafluoride(SF6) as ambient gas than using the nitrogen(N2); at the beginning of injection, shock wave phenomenon does not generate immediately as the fuel leave the nozzle because of the needle movement, and the hesitation is decided by the injection condition and characteristics of injector. The generation of shock wave in the spray tip and the detachment of shock wave from the spray tip show little effect on the spray macroscopic characteristics. The ambient gas density and temperature have a significant effect on the maximum of spray tip velocity, types of shock wave and the detachment timing of shock wave from the spray tip.展开更多
基于某高速柴油机试验平台,研究了辅喷油器喷油正时、主喷油器喷油正时、双喷油器油量分配比例对发动机燃烧及排放的影响规律。研究结果表明:辅喷正时对发动机放热率形态影响较大,曲轴转角压缩上止点后(after top dead center,ATDC)-100...基于某高速柴油机试验平台,研究了辅喷油器喷油正时、主喷油器喷油正时、双喷油器油量分配比例对发动机燃烧及排放的影响规律。研究结果表明:辅喷正时对发动机放热率形态影响较大,曲轴转角压缩上止点后(after top dead center,ATDC)-100°(记为-100°ATDC,依此类推)到-20°ATDC范围内,放热率由双峰先变为三峰再变为双峰。辅喷正时为-60°ATDC时,缸内呈先缓后急的三峰放热,发动机热效率最高。主喷正时对50%累积放热率对应曲轴转角(CA50)影响较大,但对10%累积放热率对应曲轴转角(CA10)影响较小;随着主喷正时的提前,CA50前移,NO_(x)排放升高,颗粒数量排放降低,但不同工况下,发动机最佳主喷正时略有差异。三阶段放热形态下,随着辅喷油器喷射比例的升高,第一、二阶段放热率峰值增加,但第三阶段放热率峰值降低,辅喷比例每增加10%,CA10提前约6°,发动机缸内最高燃烧压力基本相当。与辅喷正时类似,双喷油器协同喷射模式下,辅喷油器喷射比例的选择主要与上止点前的绝对放热量相关。展开更多
In diesel engines the fuel injection system produces the spray, which directly affects the combustion of the fuel, which in turn determines the production of pollutants. In spite of this, the details of this causal re...In diesel engines the fuel injection system produces the spray, which directly affects the combustion of the fuel, which in turn determines the production of pollutants. In spite of this, the details of this causal relationship remain unclear. There is, however, a lack of quantitative experimental data for determining and visualizing the cavitation inside real size diesel injector nozzle. The present work is devoted to analyze analytically the flow pattern inside the nozzle of a diesel engine working with hydrocarbon fuel (Diesel fuel) and to predict the relationship between the various flow parameters and occurrence of fuel cavitation in such nozzles. Basic physical parameters affecting this phenomenon are identified and quantified while the effect of nozzle geometry, fuel injection pressure, and engine cylinder temperature upon the flow pattern and occurrence of cavitation in such nozzles are assessed. In this study, a commercial computational fluid dynamics (CFD) package (FLUENT-T grid) is used while a computational grid is generated for the real geometry of diesel injector nozzle using (ANSYS). The suitability of the generated computational grid to give reliable results is examined using the suitable procedures and techniques. The results indicated that, cavitation modeling has reached a stage of maturity and it can usefully identify many of the cavitation structures present in internal nozzle flows and their dependence on nozzle design and flow conditions. The qualitative distributions and comparison of cavitation inception and distribution as well as flow parameters at the nozzle exit are also studied.展开更多
External mixture formation (PFI) of a diesel fuel aerosol has employed to investigate the diesel HCCI engine combustion and emissions characteristics. The key to the external mixture formation with diesel fuel is the ...External mixture formation (PFI) of a diesel fuel aerosol has employed to investigate the diesel HCCI engine combustion and emissions characteristics. The key to the external mixture formation with diesel fuel is the proper fuel/air mixture preparation. A proposed intake diesel fuel aerosol system mainly consists of a small chamber, in which the diesel fuel is fully vaporized by means of fuel cavitation inside the diesel injector nozzle. Nozzle cavitation is mainly affected by the injection pressure and the fuel system temperature. Results obtained reveal that the proposed method determines the possibility of producing a complete homogeneous fuel/air mixture, which can be applied to the diesel HCCI engine. With this method, the combustion and emission behavior were entirely optimized and the engine is capable of running in HCCI combustion mode with nearly ideal mixture preparation. In the present investigation, a methodology for the HCCI combustion mode of the diesel aerosol/air mixtures based on the fuel cavitation inside the injector nozzle parameters (such as the injection pressure and the fuel system temperature where fuel premixed ratio, NOx, CO, CO2, and HC emissions) have analyzed. Based on the engine performance and emissions characteristics the fuel injection pressure and the fuel system temperature have optimized to produce a suitable fuel premixed ratio and the perfect fuel/air mixture homogeneity at different engine operating conditions. The optimal injection pressure ranges between 150 - 200 bars, while the fuel system temperature lies within 175℃ - 200℃. Loops of exhaust gas recirculation (EGR) are used to extend the engine load by controlling the combustion phasing.展开更多
The physical model of -20 diesel oil and force model of injector controlvalve of common rail system is built. The changes of the fluid thickness are investigated on thebase of the results of CFD and experiments for co...The physical model of -20 diesel oil and force model of injector controlvalve of common rail system is built. The changes of the fluid thickness are investigated on thebase of the results of CFD and experiments for control valve of injector. The results indicate thata fluid thickness of 0.02-0.03 mm between the poppet and valve guide is sufficient to dampen anyexcessive control valve poppet bouncing.展开更多
The injector is the most critical and vulnerable part of a diesel engine, and injector remanufacturing seems to be a solution to change the adverse market conditions. For remanufactured injector, there are some differ...The injector is the most critical and vulnerable part of a diesel engine, and injector remanufacturing seems to be a solution to change the adverse market conditions. For remanufactured injector, there are some differences between China and developed countries. These differences make a different remanufacturability. New remanufacturing process should be evaluated to determine the feasibility. Fuqiang Power Company's experiment and the survey from Bosch Diesel Centers(BDCs) show the status of the used injectors that nearly one-third of the used injector can be remanufactured with low cost. It is feasible to produce quality remanufactured injector under given process. Promoting clean diesel engine is more likely to be accepted by the consumer.展开更多
The type PT-821 PT Pump test stand and type PT-881 injector test stand are a set of special test stands for calibration of PT Pumps and injectors of Cummins engines. Both test stands may be used in conjunction with an...The type PT-821 PT Pump test stand and type PT-881 injector test stand are a set of special test stands for calibration of PT Pumps and injectors of Cummins engines. Both test stands may be used in conjunction with any model of Bosch injection pump test benches for PT Pumps and injector calibration. During PT Pump calibration, the type PT-821 test stand should be used in conjunction with a Bosch injection pump lest bench. The PT Pump to be tested is installed on the Bosch injection pump test bench through a mounting bracket and is driven by the bench shaft. When calibrating PT injectors, both the PT-881 injector test stand and the PT-821 PT Pump test stand should be used in conjunction with a Bosch injection pump test bench, with the PT-881 injector test stand installed on Bosch test bench. The injector to be tested is driven by the Bosch injection pump test bench through a coupling. This paper describes the structure and function of the PT-821 PT Pump test stand and PT-881 injector test stand. Some technical problems arc described in detail.展开更多
基金supported by the National Natural Science Foundation of China (51076118, 51006075)the Fundamental Research Funds for the Central Universities (1700219089)+1 种基金China Postdoctoral Science Foundation (2013M531209)Shanghai Rising-Star Program (11QH1402500)
文摘Based on schlieren imaging method the shock wave generated by diesel injector has been investigated,and the influences of ambient gas property, the progress of the spray, ambient gas density and ambient gas temperature on shock wave have been analyzed. The results show that:the images of spray shock wave are cleaner using sulfur hexafluoride(SF6) as ambient gas than using the nitrogen(N2); at the beginning of injection, shock wave phenomenon does not generate immediately as the fuel leave the nozzle because of the needle movement, and the hesitation is decided by the injection condition and characteristics of injector. The generation of shock wave in the spray tip and the detachment of shock wave from the spray tip show little effect on the spray macroscopic characteristics. The ambient gas density and temperature have a significant effect on the maximum of spray tip velocity, types of shock wave and the detachment timing of shock wave from the spray tip.
文摘基于某高速柴油机试验平台,研究了辅喷油器喷油正时、主喷油器喷油正时、双喷油器油量分配比例对发动机燃烧及排放的影响规律。研究结果表明:辅喷正时对发动机放热率形态影响较大,曲轴转角压缩上止点后(after top dead center,ATDC)-100°(记为-100°ATDC,依此类推)到-20°ATDC范围内,放热率由双峰先变为三峰再变为双峰。辅喷正时为-60°ATDC时,缸内呈先缓后急的三峰放热,发动机热效率最高。主喷正时对50%累积放热率对应曲轴转角(CA50)影响较大,但对10%累积放热率对应曲轴转角(CA10)影响较小;随着主喷正时的提前,CA50前移,NO_(x)排放升高,颗粒数量排放降低,但不同工况下,发动机最佳主喷正时略有差异。三阶段放热形态下,随着辅喷油器喷射比例的升高,第一、二阶段放热率峰值增加,但第三阶段放热率峰值降低,辅喷比例每增加10%,CA10提前约6°,发动机缸内最高燃烧压力基本相当。与辅喷正时类似,双喷油器协同喷射模式下,辅喷油器喷射比例的选择主要与上止点前的绝对放热量相关。
文摘In diesel engines the fuel injection system produces the spray, which directly affects the combustion of the fuel, which in turn determines the production of pollutants. In spite of this, the details of this causal relationship remain unclear. There is, however, a lack of quantitative experimental data for determining and visualizing the cavitation inside real size diesel injector nozzle. The present work is devoted to analyze analytically the flow pattern inside the nozzle of a diesel engine working with hydrocarbon fuel (Diesel fuel) and to predict the relationship between the various flow parameters and occurrence of fuel cavitation in such nozzles. Basic physical parameters affecting this phenomenon are identified and quantified while the effect of nozzle geometry, fuel injection pressure, and engine cylinder temperature upon the flow pattern and occurrence of cavitation in such nozzles are assessed. In this study, a commercial computational fluid dynamics (CFD) package (FLUENT-T grid) is used while a computational grid is generated for the real geometry of diesel injector nozzle using (ANSYS). The suitability of the generated computational grid to give reliable results is examined using the suitable procedures and techniques. The results indicated that, cavitation modeling has reached a stage of maturity and it can usefully identify many of the cavitation structures present in internal nozzle flows and their dependence on nozzle design and flow conditions. The qualitative distributions and comparison of cavitation inception and distribution as well as flow parameters at the nozzle exit are also studied.
文摘External mixture formation (PFI) of a diesel fuel aerosol has employed to investigate the diesel HCCI engine combustion and emissions characteristics. The key to the external mixture formation with diesel fuel is the proper fuel/air mixture preparation. A proposed intake diesel fuel aerosol system mainly consists of a small chamber, in which the diesel fuel is fully vaporized by means of fuel cavitation inside the diesel injector nozzle. Nozzle cavitation is mainly affected by the injection pressure and the fuel system temperature. Results obtained reveal that the proposed method determines the possibility of producing a complete homogeneous fuel/air mixture, which can be applied to the diesel HCCI engine. With this method, the combustion and emission behavior were entirely optimized and the engine is capable of running in HCCI combustion mode with nearly ideal mixture preparation. In the present investigation, a methodology for the HCCI combustion mode of the diesel aerosol/air mixtures based on the fuel cavitation inside the injector nozzle parameters (such as the injection pressure and the fuel system temperature where fuel premixed ratio, NOx, CO, CO2, and HC emissions) have analyzed. Based on the engine performance and emissions characteristics the fuel injection pressure and the fuel system temperature have optimized to produce a suitable fuel premixed ratio and the perfect fuel/air mixture homogeneity at different engine operating conditions. The optimal injection pressure ranges between 150 - 200 bars, while the fuel system temperature lies within 175℃ - 200℃. Loops of exhaust gas recirculation (EGR) are used to extend the engine load by controlling the combustion phasing.
文摘The physical model of -20 diesel oil and force model of injector controlvalve of common rail system is built. The changes of the fluid thickness are investigated on thebase of the results of CFD and experiments for control valve of injector. The results indicate thata fluid thickness of 0.02-0.03 mm between the poppet and valve guide is sufficient to dampen anyexcessive control valve poppet bouncing.
基金the National Natural Science Foundation of China(No.51675343)
文摘The injector is the most critical and vulnerable part of a diesel engine, and injector remanufacturing seems to be a solution to change the adverse market conditions. For remanufactured injector, there are some differences between China and developed countries. These differences make a different remanufacturability. New remanufacturing process should be evaluated to determine the feasibility. Fuqiang Power Company's experiment and the survey from Bosch Diesel Centers(BDCs) show the status of the used injectors that nearly one-third of the used injector can be remanufactured with low cost. It is feasible to produce quality remanufactured injector under given process. Promoting clean diesel engine is more likely to be accepted by the consumer.
文摘The type PT-821 PT Pump test stand and type PT-881 injector test stand are a set of special test stands for calibration of PT Pumps and injectors of Cummins engines. Both test stands may be used in conjunction with any model of Bosch injection pump test benches for PT Pumps and injector calibration. During PT Pump calibration, the type PT-821 test stand should be used in conjunction with a Bosch injection pump lest bench. The PT Pump to be tested is installed on the Bosch injection pump test bench through a mounting bracket and is driven by the bench shaft. When calibrating PT injectors, both the PT-881 injector test stand and the PT-821 PT Pump test stand should be used in conjunction with a Bosch injection pump test bench, with the PT-881 injector test stand installed on Bosch test bench. The injector to be tested is driven by the Bosch injection pump test bench through a coupling. This paper describes the structure and function of the PT-821 PT Pump test stand and PT-881 injector test stand. Some technical problems arc described in detail.
