基于不同最大拱度位置翼型的高比转数混流泵叶轮优化

Optimization of High Specific Speed Mixed Flow Pump Impeller Based on Hydrofoils with Different Maximum Camber Positions

摘要:

为了拓宽高比转数混流泵高效区范围，采用NACA四位数翼型拱度线叠加NACA66厚度分布设计了最大拱度相对位置分别为0.4、0.5和0.6的3种翼型方案，并基于这3种翼型方案对一比转数为720的混流泵叶轮进行多工况优化设计。研究结果表明：优化后混流泵叶轮加权效率提升约05个百分点，拓宽了混流泵的高效区范围。采用最大拱度位置不同的翼型设计得到的混流泵叶轮最大效率相差不大，翼型最大拱度位置主要影响高效区分布范围，随着最大拱度位置的后移，高效区范围向大流量、低扬程附近移动。设计流量工况下，随着最大拱度位置的后移，空化性能得到有效改善。最大拱度位置在0.4倍和0.6倍弦长附近时，对于小流量工况下和大流量工况下进口边附近的流动分离现象分别具有较好的抑制作用，在混流泵设计时叶尖处拱度靠后、叶根处拱度靠前更有利于扩大混流泵高效区范围。研究结果可为不同运行要求下的流体机械优化设计提供参考。

Abstract:

In order to increase the range of high-efficiency zones in high specific speed mixed pumps, three types of hydrofoil schemes with maximum camber positions of 0.4, 0.5 and 0.6 were designed by using NACA four-digit airfoil camber lines superimposed with NACA66 thickness distribution. Based on the three hydrofoil schemes, the hydraulic performance of the mixed flow pump impeller with specific speed of 720 under multiple operating conditions was optimized. The research results indicated that after optimization, the weighted efficiency of the mixed flow pump impeller was increased by about 0.5 percentage points, expanding the operating range of the high efficiency zone of the mixed flow pump. The maximum efficiency of mixed pump impellers designed with different maximum camber positions of hydrofoils was not significantly different, the position of the maximum camber of the hydrofoil mainly affected the distribution range of the high-efficiency zone. As the position of the maximum camber moved backward, the high-efficiency zone range moved towards the vicinity of high flow and low head. Under the design flow condition, as the maximum camber position moved backward, the cavitation performance showed an improvement trend. When the maximum camber position was around 0.4 times and 0.6 times the chord length, it had a good inhibitory effect on the flow separation phenomenon near the inlet edge under low flow conditions and high flow conditions, respectively. When designing a mixed flow pump, the camber at the blade tip should be placed back and the blade root should be placed forward, which was beneficial for expanding the efficient range of the mixed flow pump. The research results can provide reference for the optimization design of fluid machinery under different operating requirements.