二甲醚发动机燃油喷射过程的实验与数值模拟

The experiment and modeling of dimethyl ether fuel injection process in compression ignition engine

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二甲醚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,由于二甲醚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.

Tested and computed were the hydraulic phenomena and the dynamics of conventional pumppipe-injector fuel supply system in a direct injection diesel engine fuelled with diethyl ether （DME）. The characteristics and variations of the parameters of DME fuel injection system, during the fuel injection process, were also described. On the basis of the computer simulation and validation experiments, it was shown that in comparison with the diesel fuel, higher residual pressure, retarded start of fuel injection and secondary injection phenomena for DME were observed as a result of its higher compressibility and higher vapor pressure. The computed parameters such as line pressure waves and needle lift of the injector operated on DME and diesel fuel were compared with the experimental results, showing good agreements between them.