多级能量回收水力透平导叶的优化设计

Optimization design of guide vane in multistage energy-recovery hydraulic turbine

为了提高多级能量回收水力透平的效率,对已有的(DCSGT250-175X9)多级能量回收水力透平模型的流道式导叶进行优化设计.通过对设计的流道式正导叶的压力和速度分布的分析,获悉影响正导叶压力和速度分布的关键因素是其翼型工作面出口段的圆弧半径,由此设计了圆弧半径分别为138、135、134mm的3种方案.通过对这3种正导叶方案的多级能量回收水力透平进行全流道三维湍流的定常数值模拟,分别得到其正导叶的压力和速度分布.经分析、比较可见,正导叶工作面出口段圆弧半径为134mm时的设计方案更符合该多级能量回收水力透平流态和流场分布的要求.据此,再按该透平设计流量要求,优化流道式导叶的外径,并依据数值模拟与性能预测的结果,设计出符合要求且性能较优的多级能量回收水力透平的导叶.导叶优化后的多级能量回收水力透平模型的最高计算效率提高了1.1%,平均效率提高了3.4%.

In order to improve the efficiency of multistage energy-recovery hydraulic turbine, the model of such hydraulic turbine （DCSGT250-175xg） available was used for optimization design of its channel guide vane. It was known by analyzing the pressure and velocity distribution in flow passage of channel guide vane, that the arc radius of the outlet segment on pressure side of the stage guide vane would be a key fac- tor, which affected the distribution of pressure and velocity. Therefore, three options of arc radius of 138, 135, 134 mm were selected to design the positive guide vane and, then, carry out the numeric simulation of three-dimensional stationary turbulent flow in entire flow passage, so that the pressure and velocity dis- tribution of positive guide vane were obtained. It was found by analysis and comparison that the option of arc radius of 134 mm would be more appropriate one to meet the requirement of flow pattern and flow field distribution in such hydraulic turbine. Therefore, the outer radius of the channel guide vane was optimized in terms of the requirement of design flow rate of this turbine, and the guide vane meeting the requirement and with more optimal performance was designed for such hydraulic on the basis of numeric simulation and performance prediction. After the optimization of the guide vane, the maximum design efficiency of the model of turbine increased by 1. 1% and its average efficiency increased by 3. 4%.