2-PHASE VELOCITY-MEASUREMENTS IN DENSE PARTICLE-LADEN JETS

Mean velocities and velocity fluctuations are reported for both phases in two downward flowing, low-Reynolds-number, particle-laden jets. The Reynolds number based on the initial bulk air flow is 780. Initial solid-air volume flux ratios of 0.0027 and 0.0225 are studied for spherical particles having a number-average diameter of 163 μm. Both cases may be considerd as gravity driven flows, and in most regions of these jets there is a measurable slip velocity between phases. Gas-phase velocities are obtained using a combination of amplitude discrimination and velocity filtering. The velocity filtering is done on the computer as a postprocessing step. Comparison of the two jets shows that high particle loading decreases the slip velocity, decreases the velocity fluctuations of both phases, and decreases the spreading rate of the particles. © 1990 Springer-Verlag.