Effect of injection strategy on an air-assisted direct injection aviation kerosene two-stroke engine

Abstract

In small aviation piston engines, the atomization and combustion of aviation kerosene have attracted much attention. Due to the low volatility and high viscosity of aviation kerosene, high-pressure injection or air-assisted injection is used to improve the fuel atomization quality. Considering the weight, cost and power consumption, air-assisted injection is more appropriate for compact, small aviation piston engines. In the paper, computational fluid dynamics (CFD) software was used to simulate the air-assisted spray and spark ignition combustion of aviation kerosene in a heavy-fuel direct injection spark ignition (DISI) two-stroke engine based on air-assisted direct injection (AADI) technology. The effects of injection pressure, single and double injection on formation and combustion characteristics of the aviation kerosene/air mixture were analyzed. The results show that increasing the air-assisted injection pressure can promote air flow in the cylinder and accelerate fuel evaporation, but also increase the film mass on the combustion chamber wall. When single injection is employed, high combustion pressure and temperature are generated, and the tendency to knocking combustion is greater. The use of double injection can effectively achieve fuel stratification and reduce knock tendency. With the delay of the second mixture injection timing, the peak combustion pressure is reduced, the heat release rate is slowed down, and the knock tendency is reduced correspondingly.