载荷分布对导叶式混流泵水力性能影响

Hydraulic performance of guide vane mixed-flow pump based on loading distribution

基于三维反问题原理,分别针对导叶式混流泵叶片及导叶特征载荷分布,结合CFD数值模拟,以水力效率为目标参数,找出相对最优载荷匹配形式,将定常湍流计算结果作为非定常湍流计算的初始流场进行非定常数值计算.结果表明,当特征载荷位于叶道中间略偏向进口处时,水力效率最高,优化后的模型整体水力效率较原始模型提高了3. 56%,导叶内部流动均匀性有所提高,叶轮出口处的射流-尾迹现象得到改善.非定常结果表明,叶轮进口处压力脉动幅值最大,对机组整体运行稳定性影响最大,通过反问题设计的模型在叶轮进口压力脉动幅值及导叶出口等处压力脉动幅值均有一定改善,有助于提高机组运行稳定性.

Based on the three dimensional inverse design method,a new option to achieve a higher hydraulic efficiency was made by optimizing the blade loading and the guide vane loading combined with the CFD method.In the traditional design method,the blade surface pressure distribution can be got only after the completion of a design,post-processing to get through the CFD method,while the pressure distribution has a very important effect on the efficiency.However,through the control of blade loading distribution with the inverse design method,the goal of controlling blade shape directly could be achieved.The CFD results show that the hydraulic efficiency is higher when the top loading is in the middle and a bit closer to the inlet of the impeller.By comparing the optimized model with the conventional model,the hydraulic efficiency is increased by 3.56%,which improves the flow uniformity and the jet-wake phenomenon at the same time.Unsteady calculation results show that the pressure fluctuation has a high value at the inlet of the impeller by both the conventional model and the optimize model,which has a great influence on the steady of the stability of operation.However,the pressure pulsation amplitudes at the impeller inlet and the outlet of the guide vane get better by the 3-D inverse design method for reasons of better blade loading distribution.The vortex in the outlet of the guide vane disappears in the inverse-method design model because of the improvement of the jet-wake in the impeller,which leads to a better flow character in the guide vane flow zon,thus helping to get good hydraulic efficiency.