Measurements of two-phase turbulent flow by LDA with particle size discrimination

A laser Doppler anemometry has been modified for measurements of two-phase turbulent flow, and permitted simultaneous measurements of particle size and velocity of continuous and dispersed phases. An appropriate signal processing system was designed for particle size discrimination which consisted of peak detection circuit of pulse signals of scattering light intensity from particles passing the measuring volume. The two-component velocities in recirculating flow fields behind a step were measured by two beam LDA. This technique was also extended to a three beam LDA system for the simultaneous measurements of two-component velocities. A four beam LDA system which had two coaxial measuring volumes was adopted to apply for two-phase flow involving coarse particles ranging up to about 300 microns. The correlation between particle size and velocities was obtained for a provisional test in the system of free falling glass particles.