蜗壳隔舌安放角对离心泵特性及流动稳定性的影响

The influence of volute tongue angle on the characteristic and flow stability of centrifugal pump

采用数值模拟方法对蜗壳隔舌安放角角度的大小进行研究,分析其对离心泵内部流动状态的影响。根据比转速与蜗壳隔舌安放角的关系,设计4种蜗壳隔舌安放角方案;采用Navier-Stokes方程与SST(剪切应力传输)k-ω湍流模型来研究高比转速离心泵的瞬态内部流动。结果表明:在外特性方面,蜗壳隔舌安放角为35°时,离心泵的扬程和效率最高,并且大流量工况时,蜗壳隔舌安放角为29°和32°的离心泵扬程和效率都急剧下降;在能量方面,蜗壳隔舌安放角从29°增大到38°的过程中,离心泵的能量损耗和熵产率都先减小后增大,在蜗壳隔舌安放角为35°时取得最小值;在内部流动稳定性方面,适当地增大蜗壳隔舌安放角,可以明显地降低蜗壳内部的压力脉动,减少蜗壳隔舌处的回流,使蜗壳和叶轮的内部流动更加稳定。因此,适当地增大蜗壳隔舌安放角对离心泵内部流动的稳定起促进作用,同时也能够抑制能量的耗散。

Numerical simulation is used to study the volute tongue angle and analyze its influence on the internal flow state of the centrifugal pump. According to the relationship between the specific speed and volute tongue angle, 4 volute tongue angle schemes are designed. The Navier-Stokes equation and SST(shear stress transport) k-ω turbulence model are used to explore the transient internal flow of centrifugal pump at high specific speed. The results indicate that in terms of external characteristics, the lift and efficiency of centrifugal pump are the highest when the volute tongue angle is 35° and the lift and efficiency of centrifugal pump decrease sharply when the volute tongue angles are 29° and 32° under high flow conditions;in terms of energy, the energy loss and entropy generation rate of centrifugal pump decrease first and then increase when the volute tongue angle grows from 29° to 38° and the minimum value is obtained when the volute tongue angle is 35°;in terms of internal flow stability, the pressure fluctuation inside the volute and the back-flow at the volute tongue decrease dramatically when the volute tongue angle increases as appropriate, which makes the internal flow of the volute and impeller more stable. To sum up, increasing the volute tongue angle as appropriate can not only promote the stability of the internal flow of centrifugal pump, but also inhibit energy dissipation.