EFFECT OF PARTICLE RESIDENCE TIME ON PARTICLE DISPERSION IN A PLANE MIXING LAYER

A particle dispersion has been experimentally investigated in a two-di mensional mixing layer with a large relative velocity between particle and gas-phase in order to clarify the effect of particle residence ti me on particle dispersion. Spherical glass particles 42, 72, and 135 m um in diameter were loaded directly into the origin of the shear layer . Particle number density and the velocities of both particle and gas phase were measured by a laser Doppler velocimeter with modified signa l processing for two-phase flow. The results confirmed that the charac teristic time scale of the coherent eddy apparently became equivalent to a shorter characteristic time scale due to a less residence time. T he particle dispersion coefficients were well correlated to the extend ed Stokes number defined as the ratio of the particle relaxation time to the substantial eddy characteristic time scale which was evaluated by taking account of the particle residence time.