It has known that the in-cylinder flow field has a significant effect on the engine combustion. Especially, the turbulence scale at the ignition toning plays an important role in enhancing propagation speed of initial flame. Thus, in this study, various flow fields such as tumble and swirl flows were generated by intake flow control valves. The effects of tumble and swirl flows on the turbulence scale were experimentally investigated in a 4-valve S.I. engine.
For the investigation of the flow field, the single frame PTV and the two color PIV techniques were developed to clarify in-cylinder flow pattern during intake stroke and turbulence intensity near the spark plug during compression stroke, respectively. The flame propagation was visualized by an ICCD camera and its images were analyzed to compare the flow field.