基于大涡模拟的悬板径向坡度对排沙漏斗流场特性影响数值模拟

Numerical simulation of the effect of the radial gradient of the suspension plate on the characteristics of the sediment discharge funnel flow field based on large eddy simulation

为了解悬板径向坡度改变对排沙漏斗流场的影响,文章采用了大涡模拟和VOF相结合的方法对悬板径向坡度i=0、0. 083、0. 173、0. 259时的排沙漏斗水气两相三维流场进行了数值模拟,并采用离散相颗粒轨道模型(DPM)模拟了悬板径向坡度不同时排沙漏斗对粒径0. 001～0. 1 mm颗粒的截除率。模拟结果表明:随着径向坡度增加,切向流速先增大后减小或趋于恒定,说明室内涡流强度并不是随着悬板径向坡度的增大而单调增加,存在一临界的坡度使室内涡流强度达到最大值;坡度i=0. 173时悬板上方区域(除溢流表层外)径向和垂向的合速度方向平行于悬板径向底坡且指向漏斗中心,使该区内的泥沙被再次输运至漏斗室而不易随溢出水流流出,减少了泥沙进入下游和沉降落淤于悬板的机率。颗粒截除率模拟结果也表明i=0. 173时的漏斗对各级粒径颗粒截除率最大,也表明悬板径向坡度存在一临界值使漏斗截除率达到最大值。

To understand the effect of changing the radial gradient of the suspension plate on the flow field in the sediment discharge funnel,the vortex funnel water with the slope of i = 0,0. 083,0. 173,and 0. 259 was calculated by combining the large eddy simulation and VOF methods. The three-dimensional flow field of gas two-phase flow was numerically simulated,and the discrete phase particle trajectory model( DPM) was used to simulate the cut-off rate of particle size of 0. 001 mm ~ 0. 1 mm particle size by the sand funnel at different radial slopes. The simulation results showed that the tangential flow velocity increased first,then decreased or tends to be constant as the radial gradient increases,indicating that the indoor vortex intensity does not increase monotonically with the radial gradient of the suspension plate,and there is a critical gradient. The eddy current intensity in the room was maximized;when slope i = 0. 173,the radial and vertical combined velocity in the upper region of the suspension plate( except for the overflow surface) is parallel to the radial slope of the suspension plate and points to the center of the funnel. The sediment was transported to the hopper chamber again and it was not easy to flow out with the overflow stream,reducing the probability that the sediment will enter the downstream and the sediment will fall on the suspension. The simulation results of the particle rejection rate also showed that the funnel has the largest cut-off rate for the particle size at each stage when i = 0. 173,and it also indicated that there is a critical value for the radial slope of the suspending plate,so that the funnel cut-off rate reaches a maximum value.