基于CFD的轴流泵针对性设计与试验

凌城抽水站各运行工况下的扬程范围变化比较大,在对该泵站轴流泵选型分析时发现,南水北调同台测试中的水力模型能够满足其运行的基本要求,但均有其不合理性:高效区扬程满足设计扬程时,最高扬程缺少安全余量;最高扬程满足时,高效区扬程偏离设计扬程,效率偏低。基于CFD计算对凌城站水力模型进行针对性设计,通过改变叶栅稠密度和翼型安放角,采用多工况优化设计的方法,使得最终设计方案能够满足凌城站的运行要求。然后对水力模型的最终设计方案进行泵段数值模拟研究,数值模拟结果表明该针对性设计的水力模型效率较高,同时兼顾到凌城站最高扬程的要求。最后对针对性设计的水力模型进行泵段试验,试验结果表明基于CFD的轴流泵水力模型的针对性设计是准确的、可靠的,针对凌城站设计的水力模型确实能够更好地满足该泵站的特殊水位要求。同时也说明,对于大型泵站的更新改造,水泵水力模型的针对性设计研究是必要的。

Specific Design and Experiment of Axial-flow Pump Based on CFD

The change of head range of the running condition is relatively large in Lingcheng Pump Station. It can be found that the hydraulic model test of South-to-North Water Diversion Project on the same test-bed can meet the basic requirements of running condition when making axial-flow pump selection analysis for the pump station. But it has its irrationality: when the design head is according to high efficiency, the maximum head lacks safety margin; when the maximum head is satisfied, the design head is not within the high efficiency area. Thus, a specific design for Lingcheng hydraulic model based on CFD calculation was done. By changing the cascade dense degree and the airfoil placed angle, the method of multi-operation optimization was adopted to make the final design scheme, which can meet the running requirements of Lingcheng Pump Station. Then numerical simulation study of the final specific-designed hydraulic model was conducted. At its design condition, the head was 5.48 m and the efficiency achieved 86.3% of maximum value. Head increased with the decrease of flow rate, in the calculation of minimum flow rate as 240 L/s, it did not reach the saddle area condition, when head reached 8.46 m, and the efficiency was still in the acceptable range. In a word, the simulation results showed that the specific-designed hydraulic model had higher efficiency and satisfied the highest head requirement of Lingcheng Pump Station. Finally, the experiment results showed that the specific design of axial-flow pump based on CFD was accurate and reliable, and it can meet the special water level requirements of Lingcheng Pump Station. At the same time, specific design research is necessary for the large pump station renewal and reconstruction.