Abstract: Optical measurements of solid particle velocities and collision process were made in cascade flow by the use of high-speed photogragh. The resin spheres with mean diameter of 600μm were injected into a cascade tunnel to produce the desired gas-particle flow. The film analysis provided the data for the particle velocities, paths and collision process. The results of this study are helpful for understanding the features of solid-particle's motion and collision process.

Key words: caseade, gas-solid two-phase flow, high speed photograph