基于DPM模型的旋流式沉沙池悬沙数值模拟

Numerical Simulation of Suspended Sediment in Vortex-type Sedimentation Basin Based on DPM Model

为了研究旋流式沉沙池泥沙颗粒的运动及沉沙机理和旋桨转速N与沉沙率之间的关系,借助商业软件Fluent,采用湍流模型和DPM模型相结合的数值模拟方法对泥沙颗粒进行颗粒追踪,通过设置7种不同的湍流模型模拟旋流式沉沙池悬沙在7种转速下的运动,与已有的试验结果进行对比,验证了模型的可行性,并选出在不同转速下最合适的湍流模型,进而运用选出的湍流模型分别模拟7不同转速下旋流式沉沙池流场分布,分析了旋流式沉沙池的流场和颗粒轨迹。结果表明,在沉沙池转桨所在的平面上,速度从池壁到池中心逐渐增加,相应位置上的压力逐渐减小;在沉沙池立面上,存在二次流现象,在转桨附近存在较大的漩涡;相同转速下粒径较大的颗粒比较小的颗粒更易沉降;随着桨叶转速的增加,颗粒总去除率逐渐减小。

For the research of the movement of sediment particles,sediment settling mechanism and the relationship between rotational speed N and rate of desilting in the vortex-type sedimentation basin,the commercial software Fluent was used to track sediment particles by using the numerical simulation method which combined the turbulence model and the DPM model.Firstly,seven different turbulence models were set up to simulate the movement of suspended sand in the vortex-type sedimentation basin at seven kinds of rotational speeds.The results were compared with the existing experimental results,and the feasibility of the model was verified.The most appropriate turbulence model was selected at different rotational speeds.Secondly,the selected turbulence model was used to simulate the flow field distribution of the vortex-type sedimentation basin at seven different rotational speeds,and the flow field and particle trajectory of the vortex-type sedimentation basin were analyzed.The results show that the velocity increases gradually from the wall to the center of the sedimentation basin,and the pressure decreases gradually.On the surface of the sedimentation basin,there is secondary flow and a large vortex near the rotor.By studying the particle trajectory,it can be concluded that larger particles are more likely to settle than smaller particles at the same rotating speed.With the increase of blade speed,the total removal rate of particles decreased gradually.