竖井贯流泵装置水力特性的数模分析

Numerical Analysis of Hydraulic Characteristics of Shaft Tubular Pump Set

为了探讨水泵与进出水流道水力耦合所诱发的水泵装置水力特性畸变,选择了典型竖井贯流泵装置作为研究对象,采用雷诺时均的纳维-斯托克斯方程(RANS)和标准k-ε湍流模型,首先数值模拟整体水泵装置的能量特性,并与模型试验结果进行比较。计算结果表明,在水泵装置运行净扬程0~1.22 m范围内,相同净扬程下的流量相对偏差小于3.53%,验证了三维建模、网格剖分和数值模拟方法的合理性。在此基础上,数模研究了不同工况下水泵与进出流道水力耦合与非耦合时的竖井贯流泵装置水力特性。研究结果表明:(1)耦合与非耦合时的进、出水流道水力损失变化规律差异显著;(2)小流量工况,水泵进口存在较大的速度环量诱导进水流道水流旋转,导致进水流道水力损失曲线畸变,水泵进口入流条件变差,并与水泵马鞍区显著关联,但大流量工况时耦合与非耦合特性差异较小;(3)水泵出口存在速度环量,导致出水流道水力损失曲线畸变,出水流道内存在螺旋流动,但随流量增大而减弱,水泵出口断面涡角随流量增大而增大。

In order to investigate the hydraulic characteristic distortion of the pump set induced by coupling between the pump and the inlet and outlet conduit,taking a typical Shaft tubular pump set as a research object,using the Reynolds-averaged Navier-Stokes equations（ RANS） and the standard k-ε turbulence model,the energy characteristics of the whole pump set are numerically simulated and compared with the model test. The calculation results reveal that the relative deviation of flux is less than 3.53% under the same net water head,which is valid in the range of 0 ~ 1.22 m net water head. That verifies the rationality of 3 D modeling,meshing and numerical simulation. On this basis,the hydraulic characteristics of the Shaft tubular pump set under different working conditions are studied. Research indicates：（1） There is a significant difference in the variation of hydraulic losses between the inlet and outlet conduit whether coupling or uncoupling;（2） In low flow condition,velocity circulation is much large in the pump suction inlet inducing water flow to rotate,and resulting in distortion of the water loss curve. The flow pattern are worsened and significantly correlated with pump instability zone. However,in high flow conditions the hydraulic characteristics is little difference between the coupled and uncoupled;（3） much more velocity circulation exists in the pump outlet,which leads to distortion of hydraulic loss curve of the outlet conduit. Spiral flow also exists in the outlet conduit,but its intension decreasing with flow rate increasing. Accordingly,the eddy angle on the outlet section increases.