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

摘要： 为了探究三维凹壁面切向射流周向入口数量对流场的影响，选取Realizable k-ε模型，并使用非平衡壁面函数处理近壁面湍流流动，数值模拟了周向多入口流场的流动特性。流场研究表明，随着入口数量增加，前入口对后入口流动参数的叠加先增强后降低，在入口后周向角度30°~40°，射流区域叠加最强，射流外侧靠近入口处的影响最大。多股射流流场叠加使立式圆筒体内部的流动更加均匀，涡旋结构稳定在轴线附近。周向多入口凹壁面射流相较于单入口在切向速度、湍流动能、静压力最大值等参数上均产生叠加作用，其中三入口与单入口更接近，叠加作用最小。对总流量相同的不同入口结构设备内旋流流动研究表明，离心分离因数、湍流动能和静压力与入口速度相关性较大，叠加特性对旋流流动的增强作用不明显。可通过提高多入口射流速度提高离心分离因数及物料的处理量。

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