柴油机喷油系统压力波时频特性研究

在柴油机喷油系统压力波的研究中,采用Wigner-Ville分布算法,对液-汽两相流条件下的柴油机喷油系统压力波的时频特性进行了分析,并与采用小波函数分析得到的结果进行了对比.研究结果表明,采用Wigner-Ville分布算法进行分析时,可以更好地显示出液-汽两相流条件下的柴油机喷油系统中压力波在时间和频率范围内的能量密度,能更清晰地反映出这种非稳态信号频率随时间变化的关系.当喷油系统存在长时间存活汽泡时,压力波的能量密度主要集中在主波上,除了低频率的能量外,还包着相当一部分较高频率的能量.而压力波次波则没有高频能量的出现.当喷油系统存在短时间存活汽泡时,其压力主波对应的频率较低,但能量密度比较大,而其压力次波具有一定量的高频率能量. 

Time-frequency characteristics research for pressure waves of fuel injection system of diesel engine

In research of pressure wave of fuel injection system of diesel engine,with Wigner-Ville distribution,the time-frequency characteristics of pressure wave in fuel injection system of a diesel engine under condition of liquid-gas tow-phase flow was analyzed.The comparison of its results with the results of wavelet function analysis was made.The results show that using Wigner-Ville distribution the energy density of pressure wave of fuel injection system in time and frequency field can be better described and the change of frequency of this unstable signal with time can be better reflect.When long living time cavitation existed in fuel injection system,the energy density of pressure wave,which included some high frequency energy besides low frequency energy in this energy,concentrates mostly on the first pressure wave and there is not any high frequency energy in the second pressure wave.When short living time cavitation existed in fuel injection system,frequency of first pressure wave is low and the energy density is high.And there is some high frequency energy in the second pressure wave.