The influence of fuel pressure fluctuation on multi-injection fuel mass deviation has been studied a lot,but the fuel pressure fluctuation at injector inlet is still not eliminated efficiently.In this paper,a new type...The influence of fuel pressure fluctuation on multi-injection fuel mass deviation has been studied a lot,but the fuel pressure fluctuation at injector inlet is still not eliminated efficiently.In this paper,a new type of hydraulic filter consisting of a damping hole and a chamber is developed for elimination of fuel pressure fluctuation and multi-injection fuel mass deviation.Linear model of the improved high pressure common-rail system（HPCRS）including injector,the pipe connecting common-rail with injector and the hydraulic filter is built.Fuel pressure fluctuation at injector inlet,on which frequency domain analysis is conducted through fast Fourier transformation,is acquired at different target pressure and different damping hole diameter experimentally.The linear model is validated and can predict the natural frequencies of the system.Influence of damping hole diameter on fuel pressure fluctuation is analyzed qualitatively based on the linear model,and it can be inferred that an optimal diameter of the damping hole for elimination of fuel pressure fluctuation exists.Fuel pressure fluctuation and fuel mass deviation under different damping hole diameters are measured experimentally,and it is testified that the amplitude of both fuel pressure fluctuation and fuel mass deviation decreases first and then increases with the increasing of damping hole diameter.The amplitude of main injection fuel mass deviation can be reduced by 73%at most under pilot-main injection mode,and the amplitude of post injection fuel mass deviation can be reduced by 92%at most under main-post injection mode.Fuel mass of a single injection increases with the increasing of the damping hole diameter.The hydraulic filter proposed by this research can be potentially used to eliminate fuel pressure fluctuation at injector inlet and improve the stability of HPCRS fuel injection.展开更多
Effect of biodiesel blends on the particle size distribution (PSD) of exhaust aerosol and the mechanism of nanoparticle formation were investigated with a modern common rail light-duty diesel engine. The results showe...Effect of biodiesel blends on the particle size distribution (PSD) of exhaust aerosol and the mechanism of nanoparticle formation were investigated with a modern common rail light-duty diesel engine. The results showed that PSD of diesel included two modes:nucleation mode (NM) and accumulation mode (CM). The criterion diameter of the two modes is 50 nm. Only CM was observed for all fuels under the condition of 50 N.m,2000 r/min. When the engine torque was higher than 150 N.m,log-modal PSD of diesel shifted to bimodal. At higher loads,if the biodiesel blend ratio was below 60%,the PSD of biodiesel blends still included the two modes. However,no NM particles were found for pure biodiesel. At lower loads,only CM was found in PSD of all fuels. Significant reduction of CM particles was found for biodiesel blends compared with diesel. Discussion on the mechanism of nanoparticle formation indicated that for the light-duty diesel engine with oxidation catalysts,fuel consumption and exhaust temperature increased with increasing the engine loads,and SO2 was converted to SO3 by catalyst which,in its hydrated form,could act as the precursor for biodiesel NM formation. Therefore,sulfur level of biodiesel blends dominates the nanoparticle formation in light-duty diesel engine with oxidation catalysts.展开更多
基金Supported by National Natural Science Foundation of China(Grant No.51076014)Research Fund for the Doctoral Program of Higher Education of China(Grant No.20101101110011)
文摘The influence of fuel pressure fluctuation on multi-injection fuel mass deviation has been studied a lot,but the fuel pressure fluctuation at injector inlet is still not eliminated efficiently.In this paper,a new type of hydraulic filter consisting of a damping hole and a chamber is developed for elimination of fuel pressure fluctuation and multi-injection fuel mass deviation.Linear model of the improved high pressure common-rail system（HPCRS）including injector,the pipe connecting common-rail with injector and the hydraulic filter is built.Fuel pressure fluctuation at injector inlet,on which frequency domain analysis is conducted through fast Fourier transformation,is acquired at different target pressure and different damping hole diameter experimentally.The linear model is validated and can predict the natural frequencies of the system.Influence of damping hole diameter on fuel pressure fluctuation is analyzed qualitatively based on the linear model,and it can be inferred that an optimal diameter of the damping hole for elimination of fuel pressure fluctuation exists.Fuel pressure fluctuation and fuel mass deviation under different damping hole diameters are measured experimentally,and it is testified that the amplitude of both fuel pressure fluctuation and fuel mass deviation decreases first and then increases with the increasing of damping hole diameter.The amplitude of main injection fuel mass deviation can be reduced by 73%at most under pilot-main injection mode,and the amplitude of post injection fuel mass deviation can be reduced by 92%at most under main-post injection mode.Fuel mass of a single injection increases with the increasing of the damping hole diameter.The hydraulic filter proposed by this research can be potentially used to eliminate fuel pressure fluctuation at injector inlet and improve the stability of HPCRS fuel injection.
基金Supported by the National Hi-Tech Research and Development Program of China ("863" Project) (Grant No. 2006AA11A1A2)the Program of Shanghai Chief Subjects (Grant No. B303)
文摘Effect of biodiesel blends on the particle size distribution (PSD) of exhaust aerosol and the mechanism of nanoparticle formation were investigated with a modern common rail light-duty diesel engine. The results showed that PSD of diesel included two modes:nucleation mode (NM) and accumulation mode (CM). The criterion diameter of the two modes is 50 nm. Only CM was observed for all fuels under the condition of 50 N.m,2000 r/min. When the engine torque was higher than 150 N.m,log-modal PSD of diesel shifted to bimodal. At higher loads,if the biodiesel blend ratio was below 60%,the PSD of biodiesel blends still included the two modes. However,no NM particles were found for pure biodiesel. At lower loads,only CM was found in PSD of all fuels. Significant reduction of CM particles was found for biodiesel blends compared with diesel. Discussion on the mechanism of nanoparticle formation indicated that for the light-duty diesel engine with oxidation catalysts,fuel consumption and exhaust temperature increased with increasing the engine loads,and SO2 was converted to SO3 by catalyst which,in its hydrated form,could act as the precursor for biodiesel NM formation. Therefore,sulfur level of biodiesel blends dominates the nanoparticle formation in light-duty diesel engine with oxidation catalysts.
