多级离心泵扬程预测及内部流场数值模拟

Multi-stage centrifugal pump head prediction and numerical simulation of internal flow field

为了研究多级离心泵的性能及其内部流场分布,采用SST k-ε湍流模型对原型泵的首级、第二级及第三级叶轮进行定常和非定常数值模拟计算,分析其外特性、内部流场和压力脉动。研究表明,通过前三级叶轮的扬程能较准确地预测原型泵的扬程。不同流量工况下隔舌处均易出现低压区域,大流量工况蜗壳出口近隔舌处也易出现局部低压区和高压区,隔舌处压力梯度较大。小流量下首级叶轮近隔舌区域的压力脉动不稳定,周期性较差,频域幅值主要集中在低频率区域;对于设计流量和大流量工况,首级叶轮近隔舌区域和远离隔舌区域的压力脉动较为稳定,呈现出较明显的周期性,主频在1倍和2倍叶片通过频率处,频域幅值主要集中在叶片通过频率及其高次谐波频率处。

In order to study the performance of the multistage centrifugal pump and its internal flow field distribution,the SST k-εturbulence model was used to simulate the steady and unsteady flow in the first,second and third stage impellers of the prototype pump.The external characteristics,internal flow field and pressure pulsation of the centrifugal pump were analyzed.The results show that the head of the prototype pump can be accurately predicted by the head of the first three stage impellers.Under different flow rates,the low pressure area tends to appear at the tongue.Under large flow rate,the local low and high pressure area also tend to appears near the tongue at the volute outlet.The pressure gradient in the area near the tongue is large.At small flow rate,the pressure pulsation near the tongue in the first-stage impeller is extremely unstable,and the cycle is poor.The frequencydomain amplitude is mainly concentrated in the low-frequency region.For design flow rate and large flow rate,the pressure pulsations in the first-stage impeller near the tongue region and away from the tongue region are relatively stable,showing a more obvious periodicity.The main frequency is at 1 and 2 times of blade passing frequency.The frequency domain amplitude is mainly concentrated at the blade passing frequency and its higher harmonic frequency.