引擎速度对到拖内燃机缸内滚流的影响-粒子成像测速实验研究
Now-a-days, the stratified and direct injection spark ignition engines are becoming very popular because of their lowfuel consumption and exhaust emissions. But, the challenges to them are the formation and control of the chargewhich is mainly dependent on the in-cylinder fluid flows. Today, an optical tool like particle image velocimetry (PIV)is extensively used for the in-cylinder fluid flow measurements. This paper deals with the experimental investigationsof the in-cylinder fluid tumble flows in a motored internal combustion engine with a flat piston at different enginespeeds during intake and compression strokes using PIV. The two-dimensional in-cylinder flow measurements andanalysis of tumble flows have been carried out in the combustion space on a vertical plane at the cylinder axis. Toanalyze the fluid flows, ensemble average velocity vectors have been used. To characterize the tumble flow, tumbleratio has been estimated. From the results, it is found that the tumble ratio mainly varies with crank angle positions. Atthe end of compression stroke, maximum turbulent kinetic energy is more at higher engine speeds. Present study willbe very useful in understanding the effect of engine speeds on the in-cylinder fluid tumble flows under real engineconditions.