Asymmetric oscillation of pressurized dense gas-solid jet in a two-dimensional nozzle

Abstract

The instability of pressurized dense gas-solid jets in a two-dimensional nozzle is experimentally studied using a high-speed camera, and the effects of the hopper pressure and the particle diameter on instability are considered. As particle velocity rises with hopper pressure, dense gas-solid jets become unstable and display an asymmetric oscillation, which is quasi-periodic and its frequency and evolution are further characterized. For particle diameters of d = 185 μm and 410 μm, the time-average frequencies increase linearly with the exit particle velocities. The asymmetric structures grow along the nozzle, and even undergo deformation and merging. The macroshot of the flow transition region between hopper and nozzle indicates that gas-solid separation generates fluctuations which will propagate both upstream and downstream. In the nozzle, fluctuations are amplified by the enhanced gas-solid interaction, evolving to the asymmetric structures.