Experimental on the stability of dense gas-solid jet in two-dimensional nozzle

The stability of dense gas-solid jet in two-dimensional nozzle was studied by using a high-speed camera. Effects of particle diameter, hopper pressure and nozzle convergence angle on the jet flow pattern and stability were investigated. Results showed that for the gas-solid jet with a particle diameter of 78μm, the velocity of gas-solid jet increases with the hopper pressure, and the solid fraction of gas-solid jet decreases. An unsteady bubble-type flow pattern appeared when the hopper pressure was equal or greater than 0.03MPa, the velocity of gas-solid jet was equal or greater than 4.82m/s, and the solid fraction of gas-solid jet was equal or less than 0.168. With the increase of particle diameter, solid fraction of gas-solid jet decreases, and dense gas-solid jet transforms from bubble-type to particle cluster unsteady flow pattern. There is little effect on the jet flow of unsteady pattern when the nozzle convergence angles change. Micro pressure sensors were used to measure the pressure at different positions in the nozzle, and results revealed that the pressure pulsation is mainly caused by the formation and evolution of bubbles and particle clusters. Current study shows that with the increase of the hopper pressure, the fraction of gas permeating into the gas-solid jet increases during the downward movement of the particles in the nozzle, which will lead to the enhancement of the gas-solid interaction in the nozzle, and then cause the instability of the gas-solid jet. © 2020, Chemical Industry Press. All right reserved.