Abstract In this work, we theoretically analyzed the main factors affecting performance of multistage energy recovery hydraulic turbine (MERHT), and found that the arc radius (r) of the edge at the outlet section of the runner guide vane is the determining factor of the hydraulic efficiency of hydraulic turbines. To further improve the performance of the MERHT, a numerical model is then proposed to optimize the arc radius. The MERHT-type DCSGT250-175 × 9 was taken in the simulation. The hydraulic efficiency η h and the corresponding distributions of pressure and velocity were numerically studied with four different values of r ranging from 133.5 to 138 mm. It is found that the flow state and the flow field distribution were the best when r equals to 134 mm. With the optimum r, the external diameter of the runner guide vane (D) was further adjusted, which can lead to 3.9% increase of average efficiency according to the simulation results.

中文翻译：

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导叶类型对多级能量回收水轮机（MERHT）性能的影响

摘要 本文从理论上分析了影响多级能量回收水轮机（MERHT）性能的主要因素，发现转轮导叶出口段边缘的圆弧半径（r）是影响多级能量回收水轮机（MERHT）性能的决定因素。水轮机的水力效率。为了进一步提高 MERHT 的性能，然后提出了一个数值模型来优化圆弧半径。模拟中采用 MERHT 型 DCSGT250-175 × 9。对水力效率 η h 和相应的压力和速度分布进行了数值研究，r 的四个不同值的范围从 133.5 到 138 毫米。发现当r=134 mm时，流动状态和流场分布最好。以最佳 r，进一步调整转轮导叶 (D) 的外径，