混流泵导叶对其性能的影响

Effects of diffuser vane on mixed-flow pumps performance

采用两类相对流面迭代计算轴面流网,给定不同的导叶进口安放角、安放角沿流线分布规律及进出口边位置,通过逐点积分绘制空间骨面,在保角变换平面内完成加厚与修圆,设计了一系列混流泵导叶.应用SIMPLE算法,求解雷诺时均N-S方程与标准k-ε方程,模拟了同一叶轮匹配不同导叶时混流泵内部的全流道三维湍流流场,并预测其水力效率,得到导叶包角与水力效率随不同设计参数变化的曲线,结合导叶前后截面内相对速度、静压和总压分布,分析不同设计参数对于混流泵性能的影响.结果表明:导叶进口安放角对于混流泵性能的影响最为显著,选取适当可以减小进口冲击损失;安放角沿流线变化规律的选取需要考虑控制包角大小,以减小导叶区的水力摩擦损失;进出口边位置选取过程需要考虑导叶的能量转换能力与水力摩擦损失的影响.

A series of vaned-diffusers, which are with various vane inlet angles, vane angle distributions along streamline, leading and trailing edge positions, were designed for a mixed-flow pump impeller by using the point-by-point integration method that was applied to generate the three-dimensional camber of vane on the streamlines determined by employing an iterative calculation between two kinds of relative stream surfaces. The vane thickening and leading and trailing edges smoothing were conduc- ted on a plane of conformal mapping. 3D turbulent flow fields inside the mixed-flow pump with the same impeller but different diffusers were simulated by solving the Reynolds time-averaged N - S equa- tions and the standard k -e turbulence equations based on SIMPLE algorithm, and the pump hydraulic efficiencies were predicted, consequendy, the correlations of both the vane wrap angle and hydraulic efficiency to different design parameters were obtained. In addition, effects of various design parame- ters on the mixed-flow pump performance were analyzed by means of relative velocity, static pressure and total pressure distributions in the inlet and outlet to the diffusers. The results showed that the diffuser vane inlet angle has the strongest influence on the performance and a reasonably selected inlet angle can reduce the shock loss. The vane angle distributions along streamlines should be selected by considering the control of wrap angle to reduce the hydraulic friction loss in diffuser. The leading edge and trailing edge positions should be selected with the consideration of static pressure recovery ability and hydraulic friction loss across diffuser.