低扬程大流量泵装置马鞍区的流动特性

Flow characteristics of low-lift and large flow rate pump installation in saddle zone

运用数值模拟与模型试验相结合的方法,采用计算流体动力学软件Fluent,在双参考坐标系下,利用有限体积法对雷诺时均Navier-Stokes方程进行数值离散,选用标准k-ε湍流模型,SIMPLEC方法求解,对轴流泵模型装置20%～130%额定流量工况点的外特性进行了数值模拟,并将计算结果与模型试验结果进行对比.通过对设计工况和小流量马鞍区工况下CFD流态图样的对比分析,对马鞍区的流动特性进行了研究.结果表明:在50%～65%设计流量区域存在轴流泵的运行不稳定马鞍区;小流量工况下泵室内转轮进出口均存在大范围的回流和旋涡,激烈的能量交换是轴流泵出现不稳定区、装置无法稳定运行的主要原因;数值模拟与模型试验结果吻合较好,整体误差不超过5%,由此证明了数值模拟的有效性和准确性.

Numerical and experimental methods were applied to investigate the axial pump flow characteristics in the saddle zone.The standard k-ε turbulence model and SIMPLEC algorithm were chosen in computation fluid dynamics software Fluent,the Reynolds-averaged Navier-Stokes equation was dispersed by the finite volume method,and external characteristics of axial pump model were numerical simulated in a test facility from 20% to 130% of designed flow rate.The results between numerical calculation and model experiment were compared.Flow characteristics in saddle zone were studied by comparing flow patterns between designed condition and small flow rate condition.The results show that unsteady operation saddle zone exists between 50% of designed flow rate and 65% of designed flow rate.Large range recirculation and vortex exist at the inlet and outlet of the impeller under small flow rate condition.Intensive power-exchange is the main cause of the pump unstable operation.The results of three dimensions CFD simulation and test results agree well near the best efficiency point,and deviations are up to 5% at part load condition,which indicates the effectiveness and accuracy of numerical simulation.