基于流固耦合的离心泵蜗壳振动特性优化

Optimization of Vibration Characteristics for Centrifugal Pump Volute Based on Fluid-structure Interaction

摘要:

针对具有超厚叶片的离心泵叶轮与蜗壳匹配问题，采用双向耦合方法对3种蜗壳结构产生的振动位移和振动速度进行了数值模拟。计算结果表明，由于叶轮与隔舌之间的流场动静干涉作用，蜗壳受到交替的激振力作用，在不同时刻振动位移和振动速度分布呈周期性变化；蜗壳基圆直径与叶轮直径的比值D3/D2对蜗壳振动有明显的影响，当D3/D2≤1.013时，超厚叶片出口压力诱导蜗壳振动强烈；当D3/D2逐渐增大时，蜗壳振动明显减弱。在设计工况下，方案A（D3/D2=1.013）振动位移最大值为4.288×10-6m，振动速度最大值为8.547×10-4m/s；方案C（D3/D2=1.19）振动位移最大值为2.923×10-6m，振动速度最大值为5.253×10-4m/s；优选方案B（D3/D2=1.13）的振动最小，其位移和速度最大值分别为2.56×10-6m和4.823×10-4m/s，仅约为方案A的60%。该结果也验证了径向力的作用规律与蜗壳振动特性的直接关联性。

Abstract:

In order to optimize the matching of impeller with extra-thick blades and volute in centrifugal pump, the structure displacement and velocity of different volutes were simulated by two-way coupling fluid-structure interaction method. The numerical results showed that volute was influenced by alternately exciting force due to the flow field interaction between the impeller and the tongue, and vibration displacement and vibration velocity distribution changed cyclically at different time steps. The ratio of volute base circle diameter and impeller diameter D3/D2 had a significant impact on volute vibration. When D3/D2 was less than 1.013, the un-uniform velocity distribution induced by jet-wake in blade outlet leaded to the strong pressure pulsation and vibration of volute. However, the peak-to-peak value of the pressure pulsation was reduced and the vibration of the volute was weakened when the ratio D3/D2 gradually increased. In the design conditions, maximum vibration displacement in case A (D3/D2=1.013) was 4.288×10-6m, and the maximum vibration speed was 8.547×10-4m/s. In case C (D3/D2=1.19) was 2.923×10-6m and 5.253×10-4m/s respectively. The optimized case B (D3/D2=1.13) had the minimal vibration with the maximum displacement of 2.56×10-6m and the maximum vibration speed value of 4.823×10-4m/s. The results also demonstrated the direct relevance between the radial force law and volute vibration characteristics in centrifugal pump.