Simulation Of Cavitation Flow In Nozzle And Fuel Atomization Of EMD Locomotive Diesel

Diesel has long been its excellent dynamic performance with an absolute dominant position in the high-power devices like large and medium-sized trucks, generators, diesel locomotives and vessels etc. As the core of the diesel engine-fuel injection system’ terminal, the fuel injector plays a vital role in fuel atomization, cylinder combustion process and post emissions. Theory and experiments show that the cavitation phenomenon appears in injector has particularly prominent influence on working performance.A lot of research about the cavitation in nozzle holes and cylinder combustion process has been done at home and abroad. But the cavitation in nozzle holes will directly affect the quality of fuel atomization, and thus indirectly related to the subsequent combustion process, so it’s obviously not perfect to study a separate part of which, so on the basis of previous studies and with3D CFD software FIRE as a platform, a numerical simulation about the cavitation flow in nozzle holes and cylinder combustion process of16V265H diesel engine which EMD locomotive used is proceeded in this paper, analyzed the effects as the inlet rounded radius of injector hole, the angle between nozzle holes, the length of the nozzle hole and the injector hole diameter of the four geometry parameters to the cavitation flow in nozzle holes and cylinder combustion process, and ultimately get the following conclusions:(1) In the standard conditions the cavitation phenomenon in nozzle holes of16V265H diesel engine is very significant, especially the super-cavitation phenomenon duration up to90%throughout the injection process, the strength of premixed combustion strength is weak in the diesel engine, almost the entire combustion process can be considered belong diffusion combustion, it’s mainly because of its fuel injection law is a typical "ascending arrest" type, and this situation is ideal exothermic law pursued;(2) Increasing the inlet rounded radius of injector hole and the injector hole diameter is increased will make the cavitation phenomenon in nozzle holes that play an important role in the initial fuel crushing are subject to different degrees of inhibition, thus reducing the quality of the gas mixture that formed by the fuel and air and ultimately adversely affect the combustion process;(3) Although the cavitation phenomenon in nozzle holes will be strengthened with the angle between nozzle holes increased and will improve the initial fuel crushing effect, but this parameter has a huge impact on the focus of gas mixture distributions in combustion, thereby seriously affect the utilization of the air in cylinder and eventually produce a strong influence on the combustion process;(4) The cavitation phenomenon at the outlet of the nozzle holes will be weaken with the length of the nozzle hole increased, but the situation of cavitation flow near the inlet of the injection hole hardly has any change, and the effect on the subsequent combustion process also can be ignored.