新型旋流沉砂池砂粒去除效果的数值模拟

采用MRF模型和DPM模型对新型旋流沉砂池的小试模型进行数值模拟，分析沉砂池内部流场和砂粒运行轨迹、搅拌桨旋转方向以及搅拌桨运动和进水流速关系对砂粒去除效果的影响。结果表明：当搅拌桨旋转运动方向不同时，形成的轴向环流流场有较大差异，其中顺时针旋转有助于砂粒的沉降与去除。当搅拌桨静止时，进水流速对砂粒的沉降有一定影响，其中进水流速较小时池体内会累积较多的砂粒；流速较大时砂粒的逃逸率也随之增大。在进水流速一定时，搅拌桨转速的变化对砂粒的去除有一定的影响，其中转速较小时，形成的涡旋强度不足以将砂粒移向池心；而当转速逐渐增大时，形成的径向流和较强的轴向流将不利于砂粒的沉降与去除。

Numerical Simulation on the Influence of the Relationship of the Impeller Movement and Influent Speed on the Sand Removal Efficiency of the New Rotational Flow Grit Chamber

For the new-type rotational flow grit chamber, the MRF model and the Discrete Phase Model were used to analyze the influence on sand removal efficiency of the internal flow field of the grit chamber, the trajectory of sand, the direction of impeller rotation and the relationship of the impeller movement and the water flow rate. The results showed that when the rotation direction of the impeller movement was different, the formation of axial circulation flow field was quite different, and the clockwise rotation was helpful to sand deposition and removal. When the paddle was stationary, the water flow rate had a certain impact on the sand settlement. When the water flow rate was small, more sand was accumulated in the grit chamber, and when the flow rate was larger, the escape rate of the sand also increased. When the water flow rate was constant, the variation of the paddle speed had some impact on the removal of sand. When the paddle speed was small, the formation of the forced vortex was not sufficient to move sand toward the center of the grit chamber. When the speed gradually increased, the formation of radial flow and strong axial flow was not conducive to the settlement and removal of sand.