Optical measurements of local gas and particle velocity in an upward flowing dilute gas-solids suspension.

Local gas and particle velocities in a dilute gas-solids suspension of a fully developed pipe flow are measured with a modified laser Doppler anemometer, whose signal processing consists of an electronic circuit selecting signals of gas and particle velocity by filtering their Doppler frequencies and by comparing the light scattering intensity of an individual particle. Experiments are performed using three kinds of spherical solid particles for mass loading ratios up to 0.54 and pipe Reynolds numbers ranging from 1 x 10SUB4 to 2 x 10SUB4. The results indicate that an addition of small amounts of particles to air flow causes the profiles of velocity and turbulence intensity to flatten at the central core of pipe, and that the flattening of air velocity profiles is correlated to a nondimensional number derived from momentum balance estimated by a drag force of particles in suspension flow. (A)