MPI燃料供给方式的LPG喷流特性的研究

Characteristics of LPG jet in MPI System

使用修正的Witze计算模型解析了由多点电喷气体发动机的喷射阀喷出的超音速非稳定LPG喷流的发展过程,调查了LPG喷流的贯穿距离、喷流前端的球形涡区半径Rv等随喷射时间的变化关系,并且与CNG喷流特性进行了比较。结果表明:LPG和CNG喷射阀的喷孔半径以及贯穿距离等没有明显的差别。若仅将MPI方式的汽油机喷油器用LPG喷射阀代替而不改变喷射阀在进气管的安装位置和喷射条件(喷压=0 3MPa,喷孔数=2,喷射时间=5ms)时,LPG喷流在喷射2ms后与进气门相碰,为了减少LPG喷流的贯穿距离等参数,采用降低喷射压力与多喷孔的喷射阀是必要的。

With the modified Witze model,this paper analysed the process of the supersonic unsteady LPG jet for MPI (Multi-Point Injection) gas engine,the penetration of LPG jet and the radius variation of sphere shape vortex in the jet tip was investigated. The research results showed that there was less difference between LPG and CNC in terms of the jet hole radius and the penetration. The study also demonstrated that when LPG injector was used in MPI gasoline engine without changing injector's installation position in intake manifold and other conditions (driving pressure=0.3 MPa,number of injector hole=2,duration of injection=5 ms),the LPG jet would touch on the intake valve after being injected for about 2 ms. Therefore it is necessary to reduce the driving pressure and to increase the number of injector hole to reduce LPG jet's penetration.