SPRAY AND COMBUSTION VISUALIZATION OF BIODIESEL IN A DIRECT INJECTION DIESEL ENGINE

By using the self-developed dynamic visualization photographic set-up, this article investigated some major factors affecting the spray and combustion process of diesel engine fueled by biodiesel. The experimental results show: With the increase of biodiesel percentage, fuel injection advances slightly, the ignition delay becomes shorter and the duration of combustion lengthens. Engine speed has little effect on the spray. However, the combustion rate is increased and the burning time becomes shorter with the increase of engine speed, although the duration of combustion in terms of crank angle increases. With the increase of needle opening pressure, both the spray cone angle and the spray penetration of biodiesel increases, the atomization of spray improves, the ignition delay and the duration of combustion becomes shorter, the peak pressure increases.