Measurement of fluctuations in motion of particles in a dense gas-solid suspension in vertical pipe flow

Fluctuating motion of particles in vertical pipe flow of a dense suspension was studied by simultaneous measurements of local density by a fiber optic probe and local mass flow by an electrostatic ball probe. Complete three-dimensional traverse through the vertical pipe section was accomplished by a test section which can be turned about its axis. With the availability of a high frequency data system, the instantaneous particle velocity was determined by dividing the local instantaneous local density into local instantaneous mass flow. Statistical correlation gives local average velocity, intensity of particle motion, frequency of fluctuation, and particle diffusivity. Glass particles of 100 μm suspended in air were tested. Results show large density and velocity fluctuations and large diffusivity at high particle densities.