二甲醚发动机燃油喷射过程的数值模拟及其试验研究

针对采用普通油泵—油管—油嘴燃油系统的二甲醚发动机,建立了燃油喷射过程的数学模型,通过对不同工况下燃用DME和柴油的燃油喷射过程的数值模拟与计算结果的试验验证,揭示了二甲醚发动机燃油喷射过程的物理本质及其特性参数的变化规律。研究表明,由于DME具有较高的可压缩性,致使其泵端与嘴端压力上升及下降都较柴油缓慢,压力上升始点延迟,实际喷油始点滞后,嘴端油管压力峰值较低,高压油管中的残余压力较高,较易出现二次喷射现象。

Numerical Simulation and Experimental Study on the Fuel Injection Process of DME Engine

In view of the DME engine with conventional pump-pipe-injector fuel system,the mathematical model of fuel injection process is built up.Numerical simulation and tests under varied working conditions were carried out to study the fuel injection process with the two different fuels—DME and diesel.The results revealed the physical essence of DME engine's fuel injection process and the variation rule of its natural parameters.It can be observed that as a result of DME's high compressibility,the up-and-down of pump-end pressure and nozzle-end pressure changes slowly,and that the initial point of pressure-lifting delays,actual fuel injection beginning retards,peak pressure value around the nozzle end gets lower,residual pressure in high-pressure oil pipe gets higher,and secondary injection phenomena may easily occur.