不同压出室下叶轮切割对离心泵性能影响

为研究2种不同压出室下叶轮切割对离心泵性能的影响,以及单级单个叶轮切割与多级下单个叶轮切割的差异,基于N-S方程、标准k-ε湍流模型和SIMPLE算法对MD-280-43×6型多级离心清水泵进行三维数值模拟.计算结果表明:以单级单个叶轮为切割目标时,随着切割量增大,螺旋形压出室的水力效率变化趋势比径向导叶式压出室的变化趋势更为明显,压水室水力损失每叶轮2%切割量,损失平均增长分别为0.360,0.193 m,2种压出室内部动压分布及对叶轮所产生径向力的变化趋势有明显差异;以多级下单个叶轮切割与单级单个叶轮切割的对比为目标时,对于径向导叶式压出室离心泵和螺旋形压出室离心泵,其水力效率、扬程、内部湍动能分布与各种单级单个模型平均偏差分别为1.644%,0.279%,2.090 m,1.573 m,1.302 J/kg,1.548 J/kg;不同压出室下叶轮切割特性的研究,应考虑压出室所带来的差异;多级泵叶轮切割特性研究时,应尽量回归多级环境进行研究.

Influence of trimmed impeller on performance of a multistage centrifuge pump with radial diffuser and volute

In order to analyse influence of impeller trim on performance of a multistage centrifuge pump with radial diffuser and volute and identify differences in the performance resulted from impeller trim in single-stage and two-stage cases, 3D turbulence flows through the second and third stages of MD-280-43×6 multistage centrifugal pump are simulated numerically by solving the Navier-Strokes equations and standard k-ε turbulence model based on SIMPLE algorithm. The results show that in the single-stage case the hydraulic efficiency of the pump model decreases more obviously when the impeller is trimmed in the volute than that when the impeller is trimmed in the radial diffuser. In particular, the hydraulic loss is increased by 0.360 m, 0.193 m in the volute and diffuser in average, respectively, for each 2% impeller trim. The fluid dynamic pressure distribution and the change in radial thrust caused from impeller trim are quite different from the diffuser to the volute. In the two-stage case, the hydraulic efficiency, head, turbulent kinetic energy are changed by 1.644%, 2.090 m and 1.302 J/kg in average due to impeller trim, compared with 0.279%, 1.573 m and 1.548 J/kg in the single-stage case. Therefore, the difference in performance caused from diffuser and volute should be taken into account when an impeller is trimmed in a multistage centrifugal pump. Also, the performance prediction for trimmed impellers should be based on two or more stage model rather than single-stage one.