螺旋轴流式多相流泵内流场可视化测试

Visualization Test on Internal Flow Field of Helical Axial Multiphase Flow Pump

螺旋轴流式多相流泵适用于输送气液两相流介质,由于两相介质的密度不同,运动轨迹也不相同,气体以气泡的形式流动,在流动过程中大小和形态的转变可直观反映泵内流体参数的变化,通过设计试验系统观测以及数值模拟的两种方式结合对气泡轨迹进行研究。结果表明:在转速低于1200 r/min时,气泡在叶轮叶片骨线1/2处体积达到最大,与压力面接触破碎向吸力面运动,在导叶内气泡自身能量不足开始逆压力梯度回流,两相流通流情况差;转速高于1450 r/min时,叶轮内气泡数量增多、尺寸减小,开始出现叶顶间隙回流且强度不断增加,跨流道运动强度也逐渐增加,在叶顶间隙有明显的气泡冲撞并有叶顶间隙涡的形成,导叶内气泡的气泡跨流道运动导致在其出口尾缘出现气体涡旋,随转速的增加所占流道面积增大,阻碍两相流通流。

Spiral axial flow multiphase flow pump is suitable for conveying gas-liquid two-phase flow medium.Due to the different densities of the two-phase medium and the different motion trajectories,the gas flows in the form of bubbles,and the change in size and shape during the flow process can be intuitive.Reflecting the change of the fluid parameters in the pump,the bubble trajectory is studied by combining the three methods of designing the experimental system observation,the basic theory of multiphase fluid mechanics and numerical simulation.The results show that when the rotation speed is lower than 1200 r/min,the volume of the bubbles reaches the maximum at 1/2 of the impeller blade bone line,and the bubbles contact the pressure surface and move toward the suction surface.The two-phase flow situation is poor;when the speed is higher than 1450 r/min,the number of bubbles in the impeller increases and the size decreases,and the tip clearance begins to flow back and the intensity increases,and the movement intensity across the flow channel also gradually increases.Obvious bubble collision and the formation of tip gap vortex,the bubble movement of bubbles in the guide vane across the flow channel causes gas vortex to appear at the trailing edge of its outlet,and the area of the flow channel increases with the increase of rotation speed,hindering the two-phase flow flow.