レーザホモダイン法によるエンジンシリンダ内の乱れ計測

抄録

A laser homodyne principle was applied to the measurement of turbulence within an engine cylinder. This method features direct detection of relative fluid motion in a turbulent flow without relying upon time-sequential data. Because of this advantage, cyclic variation biases that may be encountered in ordinary methods are eliminated. The intensity fluctuation of laser light scattered from tracer particles was measured by a high-speed digital correlator using a photoelectron correlation technique. Tests were conducted on a motored engine at several engine speeds and swirl ratios. The results support the feasibility of the proposed method in measuring turbulence intensity and length scale. It has been shown that swirl increases not only the turbulence intensity but also the length scale at the compression end. finally, a discussion is given of the in-cylinder measurement of the swirl velocity by the present laser homodyne method.