MEASUREMENTS OF TWO-PHASE MIST FLOW BY TWO COLOUR FOUR BEAM LDA SYSTEM.

A laser Doppler anemometer has been developed to measure the gas velocity and particle size and velocity in two-phase suspension flow. A two colour four beam LDA system was modified to provide a two co-axial measuring volumes with different size. The larger measuring volume of green beam has a top-hat intensity distribution to reduce a fluctuation in scattering intensity due to the variation of particle path in the measuring volume. The location of the particle path in the measuring volume was discriminated by the presence of a Doppler burst signal from the smaller measuring volume of blue beams. Experimental results using a atomizing spray nozzle indicated flow fields in gas and particle phases.