Fluctuating Hydraulic Force Around a Centrifugal Impeller Due to Inlet Flow Distortin and Whirling Motion

研究了泵吸壳与离心叶轮侧叶冠之间空间的非定常流动特性，了解了进口气流畸变和旋转运动引起的水力波动。主要进行了以下研究结果：(1)进口旋流的非定常心使叶轮进行旋转运动。(2)进口畸变对叶轮出口流量影响较大。当旋流方向与叶轮旋转方向相反时，其影响极大，且叶片数所给出的周期性流动波动在出口截面处变得较大。(3)其波动传导到吸力机匣与叶轮侧围之间的空间，不仅引起非定常轴向推力，而且引起旋流运动。(4)随着泵送流量的增加，空间内的脉动压力值在周边方向上发生变化。这种现象使叶轮旋转产生颤振运动。(5)上述波动是由叶轮旋转运动引起的另一波动。后者在靠近叶轮环处波动剧烈。(6)利用气缸内稳定转盘模型可以粗略地预测径向平均压力分布。

Unsteady flow behavior in the space between the pump suction casing and the centrifugal impeller side shroud was investigated, to know the fluctuating hydraulic force due to inlet flow distortion and whirling motion. The following results were mainly carried out.(1)The unsteady core of the inlet swirling flow makes the impeller whirling motion.(2)The inlet distortion affects strongly the impeller outlet flow. Its effect is extreamly when the swirling direction is negative to the impeller rotation, and the periodical flow fluctuation given by the blade number becomes heavy at the outlet section.(3)Its fluctuation is conducted to the space between the suction casing and the impeller side shoroud, and causes not only the unsteady axial thrust but also the swirling motion.(4)The fluctuating pressure value in the space becomes to change in the peripheral direction with increasing the pumping discharge. This penomenon makes the impeller rotation flutter motion.(5)Above fluctuation lies on another fluctuation induced from the whirling motion of the impeller. The latter fluctuation is sharp in close to the impeller ring.(6)The avaraged pressure distribution in the radial direction can be predicted roughly with the steady rotating disk model in the cylinder.