喷油正时对二冲程航空发动机混合气形成的影响

Effect of Injection Timing on Mixture Formation in Two-stroke Aeroengine

针对航空煤油难以雾化、导致油耗偏高、经济性差等问题,本文通过建立某型二冲程航空发动机三维仿真模型,调整喷油正时匹配回流扫气过程,分析不同喷油正时下混合气形成及分布情况,对气缸内燃油分布特性进行仿真研究。结果发现:将喷油正时设置在强制扫气过程后期阶段,可有效减少燃油短路损失,提高燃油捕获率;但喷油过晚会使得燃油与空气混合不充分,在火花塞附近不能形成合适的当量比,导致发动机性能降低。所研究发动机喷油正时为-130°CA时具有较高的指示功率和较低指示燃油消耗率,分别为14kW和342.9g/kWh。

Aiming at the problems that aviation kerosene is difficult to atomize,resulting in high fuel consumption and poor economy,In this paper,a three-dimensional simulation model of a two-stroke aero-engine is established,the injection timing is adjusted to match the loop scavenging process,analyzes the formation and distribution of mixture at different injection timings,and simulates the fuel distribution characteristics in the cylinder.The results show that setting the injection timing at the later stage of scavenging process can effectively reduce the fuel short-circuit loss and improve the fuel capture rate.However,if the fuel injection is too late,the mixture of fuel and air is not sufficient,and an appropriate equivalence ratio can’t be formed near the spark plug.When the injection timing of the engine is-130 degree CA,it has higher indicated power and lower indicated fuel consumption rate,which are 14 kW and 342.9 g/kWh,respectively.