Experimental and numerical study of a horizontal-vertical gas-solid two-phase system with self-excited oscillatory flow

Abstract

To better explore the energy-saving mechanism and flow characteristics of the self-excited oscillatory flow, the experiment is performed by a new self-excited oscillatory flow generator that the 45° oblique sheet is mounted through the pipe axis in a horizontal-vertical closed pneumatic conveying system. The experimental study focuses on the optimum air-velocity and power consumption, and results shows the maximum reduction of the optimum air-velocity and the coefficient of power consumption are approximately 8.2% and 16.4%, respectively. In addition, the CFD-DEM coupled approach is first developed to investigate the interaction of gas-solid flow in terms of the gas turbulent kinetic energy and spatial particle flow characteristics. Compared with the conventional pneumatic conveying, it is found that the optimum air-velocity and power consumption are reduced by the new self-excited oscillatory flow at lower air-velocities. The numerical results show that the approximately symmetric distribution of axial velocity and the intensive tangential velocity is emerged in the self-excited oscillatory flow at upstream. Particles is efficiently dispersed and suspended by the self-exited oscillatory flow reflecting in the smaller particle variation coefficient and the lager particle suspension coefficient. And since the airflow kinetic energy is utilized more fully to promote particles flowing, the spatial particle axial velocity is accelerated and reached early steady state. As a result, the developed numerical model is further explained the mechanism of energy saving with the self-excited oscillatory flow.