It is well known that injection strategies including the injection timing and pressure play the most important role in determining engine performance,especially in pollutant emissions.However,the injection timing and ...It is well known that injection strategies including the injection timing and pressure play the most important role in determining engine performance,especially in pollutant emissions.However,the injection timing and pressure quantitatively affect the performance of diesel engine with a turbo charger are not well understood.In this paper,the fire computational fluid dynamics(CFD)code with an improved spray model has been used to simulate the spray and combustion processes of diesel with early and late injection timings and six different injection pressure(from 275 bar to 1000 bar).It has been concluded that the use of early injection provides lower soot and higher NOx emissions than the late injection.In this study,it has been tried using the change of fuel injection time at these two next steps:before top dead center(BTDC)and after top dead center(ATDC)in order to achieving optimum emission and power in a specific point.展开更多
随着织机转速提高,共轭凸轮与四连杆组合的平行式打纬机构中的连杆构件会在惯性载荷的作用下变形加大,从而导致钢筘前死心位置与理想位置产生偏差,影响打纬精度。针对该问题采用虚拟仿真与实验结合的方法对机构进行研究,建立了平行打纬...随着织机转速提高,共轭凸轮与四连杆组合的平行式打纬机构中的连杆构件会在惯性载荷的作用下变形加大,从而导致钢筘前死心位置与理想位置产生偏差,影响打纬精度。针对该问题采用虚拟仿真与实验结合的方法对机构进行研究,建立了平行打纬机构柔性连杆下的动力学模型,并运用ADAMS软件进行仿真,探究不同凸轮转速和连杆不同材料对钢筘前死心位置的影响,同时搭建实验平台对仿真结论进行验证。结果表明:凸轮转速对钢筘前死心位置的影响是非线性的,凸轮转速在180 r min以内钢筘的前死心位置稳定且偏差值较小。弹性连杆构件选用比刚度更大的材料有助于减小钢筘前死心位置偏差。研究结果可为高速共轭凸轮平行打纬机构的设计和优化提供参考。展开更多
文摘It is well known that injection strategies including the injection timing and pressure play the most important role in determining engine performance,especially in pollutant emissions.However,the injection timing and pressure quantitatively affect the performance of diesel engine with a turbo charger are not well understood.In this paper,the fire computational fluid dynamics(CFD)code with an improved spray model has been used to simulate the spray and combustion processes of diesel with early and late injection timings and six different injection pressure(from 275 bar to 1000 bar).It has been concluded that the use of early injection provides lower soot and higher NOx emissions than the late injection.In this study,it has been tried using the change of fuel injection time at these two next steps:before top dead center(BTDC)and after top dead center(ATDC)in order to achieving optimum emission and power in a specific point.
文摘随着织机转速提高,共轭凸轮与四连杆组合的平行式打纬机构中的连杆构件会在惯性载荷的作用下变形加大,从而导致钢筘前死心位置与理想位置产生偏差,影响打纬精度。针对该问题采用虚拟仿真与实验结合的方法对机构进行研究,建立了平行打纬机构柔性连杆下的动力学模型,并运用ADAMS软件进行仿真,探究不同凸轮转速和连杆不同材料对钢筘前死心位置的影响,同时搭建实验平台对仿真结论进行验证。结果表明:凸轮转速对钢筘前死心位置的影响是非线性的,凸轮转速在180 r min以内钢筘的前死心位置稳定且偏差值较小。弹性连杆构件选用比刚度更大的材料有助于减小钢筘前死心位置偏差。研究结果可为高速共轭凸轮平行打纬机构的设计和优化提供参考。
