旋流排螺装置内水流特性数值模拟

Numerical Simulation on Flow Characteristics in Vortex Basin for Oncemelania

旋流排螺装置借鉴旋流排沙的原理,通过装置内产生的螺旋流使水和钉螺分离。为了探明装置内水螺分离机理,必须研究其流场全面图景。采用雷诺应力模型(RSM),结合流体体积函数(VOF)方法对旋流排螺装置的水气两相流进行三维数值模拟研究,并分析研究二次流分布特性。计算的自由水面和三维流速分布均与试验结果吻合较好。计算结果表明:切向流速分布呈现强迫涡特征,流速随半径的减小而减小;隔板能够抑制边壁处向上运动的水流、减弱携钉螺溢出的二次环流,对钉螺的有效排除有着关键作用。研究成果可为控制涵闸渠道钉螺扩散,改进旋流排螺装置提供技术技撑。

Similar to the principle of desilting funnel,vortex basin for oncemelania separates oncemelania from water by spiral flow. A full understanding of the flow field in the vortex basin is essential to investigating into the separation mechanism. In this paper,the Reynolds Stress Model and VOF method are applied to simulate water-air twophase flow in vortex basin. The calculated results of free surface and three-dimensional velocity are in good agreement with experimental data. The simulation results show that tangential velocity reduces with the decrease of distance from the center of the basin,resembling the velocity distribution of forced vortex. Analysis on the distribution of secondary flow indicates that deflector plays a key role in the efficient removal of oncemelania by suppressing the upwelling current on the sidewall and weakening the secondary flow carrying oncemelania. The research result offers technical support for controlling oncemelania and improving vortex basins.