Orthogonal experimental study on the cold-start control strategies of a SI aviation piston engine fueled with kerosene

Abstract

• Fully orthogonal experiments were conducted for the three key control parameters of air-assisted direct injection. • The sensitivities of cold-start time and IMEP to control parameters is analyzed. • The cold-start control boundaries at −10 ∼ 10 °C temperature is drawn. • The cold start strategy of an air-assisted direct injection SI kerosene engine was designed and verified. The fuel used in aviation piston engines for unmanned aerial vehicles is gradually transformed from gasoline to heavy fuel in consideration of safety and the requirement of unified fuel. However, the spark ignition (SI) heavy fuel piston engine has the problem of cold-start due to the poor atomization and poor evaporation of heavy fuel. This study aims to develop a cold-start control strategy and solve the cold-start problem for the two-stroke SI kerosene engine. We install an air-assisted direct injection system on a 4-cylinders two-stroke SI kerosene piston engine and conduct a completely orthogonal experiment on the three key control parameters of injection advance angle, ignition advance angle, and fuel injection volume. Firstly, the effects of key control parameters on the cold-start time and cylinder pressure in the cold-start process are studied at the ambient temperature of 5 °C. The results show that the engine can start quickly and smoothly with less cycle fluctuation of cylinder pressure when the injection advance angle is in the range of 60 ∼ 65°CA BTDC, the ignition advance angle is 40°CA BTDC, and the excess air coefficient is in the range of 0.6–0.8. Secondly, the sensitivities of cold-start time and IMEP to key control parameters are analyzed, and it is found that cold-start time and IMEP are most sensitive to injection advance angle. Thirdly, maps of cold-start control parameters at low temperatures (−10 °C, 0 °C, and 10 °C) are drawn and the control strategies are designed. The cold-start control strategies realize the successful start of the engine at the ambient temperature of −10 °C.