Partial load tests on a two-stroke spark ignition direct injection heavy fuel engine

The partial load tests at the engine speed of 3000r/min and 10%, 20% throttle open positions were carried out on a two-stroke spark ignition diesel-fuelled engine with air-assisted direct injection, and the effects of ignition and injection parameters on the engine performance were investigated. The tests results indicated that, at the small throttle open position, applying the strategies of the ignition timing at 30°-40° crank angle before top dead center, the saturated ignition energy, the partial lean mixture (excess-air-ratio above 1.1) and the suitable injection timing can fully improve the engine power output and fuel economy. With the increase of engine load, the effects of the ignition energy reduced. Applying the strategies of the moderate delayed ignition timing, the partial rich mixture (excess-air-ratio below 1.0) and advancing the end of injection timing to increase the fuel evaporation time resulted in a remarkable engine power output. Furthermore, the fuel economy and HC/CO emissions of the engine improved greatly by the use of the saturated ignition energy and the partial lean mixture (excess-air-ratio above 1.15).