关键词: 凹壁面切向射流, 周向多入口, 数值模拟, 非平衡壁面函数, 叠加特性

Abstract: The material inlet was designed to be tangent to the cylinder wall and a concave-wall jet was formed in swirling-flow equipment. This work explored the influence of the concave-wall jets with circumferential multi-inlets in three-dimensional flow field. Realizable k-ε model was used and the turbulent flow near wall was dealt with by the non-equilibrium wall function, the superposition characteristics of circumferential multi-inlets flow field were numerically simulated. The study of the flow field showed that the superposition of flow parameter between front inlet and rear inlet increased firstly and then decreased with the increase of the inlet number. The area superposition of concave-wall jet was the strongest at the circumferential angle of 30°~40° behind the inlet cross-section, and the effect of the jet outside near the inlet was the greatest. The flow field in the vertical cylinder was more uniform because of the superposition of multiple jets, and the vortex structure was more stable near the axis. The superposition effects of circumferential multi-inlets concave-wall jet on the maximum values of tangential velocity, turbulent kinetic energy, and static pressure were greater than that of single inlet. The flow field of three inlets was closer to that of single inlet, and the superposition effect was the smallest. The research on the swirling-flow in multi-inlets structure with the same total flow rate showed that the centrifugal separation factor, turbulent kinetic energy, and static pressure had great correlation with the velocity of inlet cross-section, and the enhancement effect of superposition characteristics on the swirling-flow was not obvious. Therefore, the centrifugal separation factor and material handling capacity could be improved by increasing the multi-inlets jet velocity. Multiple-inlets effectively increased the fluid velocity in the swirling-flow device and the higher kinetic energy was produced near the inner wall. Increasing the number of inlets was an effective way to improve the swirling-flow effect. The research provided theoretical analysis and optimally designed references for the enhanced swirling-flow of related equipment.

Key words: Concave-wall jet, Circumferential multi-inlets, Numerical Simulation, Non-equilibrium wall function, Superposition characteristics