转轮时序对多级水轮机模式液力透平性能影响

Influence of Runner Clocking on the Performance of Multistage Hydraulic Turbine

为研究时序效应对多级水轮机模式液力透平性能的影响,以首级转轮与二级转轮的夹角0°为基准,通过将二级转轮沿旋转方向旋转,每3°为一个时序,组成五种时序方案。通过Fluent对五种方案进行数值计算,并分析不同时序对透平水力特性及压力脉动特性的影响。结果表明,当两级转轮时序位置在C4位置时,能提升二级透平的水力效率,三种工况下,C4位置效率最高,小流量工况下,C4位置效率提升最明显,比效率最低的C3位置提升了10%。时序位置的不同,蜗壳、级间导叶和出水室的脉动变化较小,两级转轮受时序位置影响,压力脉动幅值有所降低,C4位置时,一级转轮内压力脉动降低7%,二级转轮时域图相位随时序位置不同而改变,C0位置的波谷对应C4位置的波峰,在C4位置时,二级转轮内的压力脉动幅值降低了7.7%。轴向力、径向力频域幅值在C4位置分别降低了20.3%、31.3%。因此,当二级转轮时序在C4时,所研究的液力透平的整机性能较好。

In order to study the impact of timing effect on the performance of multi-stage turbine, the 0 °angle between the first stage runner and the second stage runner was taken as benchmark. By rotating the secondary runner in the direction of rotation, every 3 ° was a time sequence, and five time sequence schemes were formed. The Fluent was used to simulate for each scheme, and the impact of different timing effect on hydraulic performance and pressure pulsation of water turbine was analyzed. The results show that when the timing position of the two-stage runner is C4, the hydraulic efficiency of the two-stage turbine can be improved. Under the three operating conditions, the efficiency of C4 is the highest, and the efficiency of C4 is the most obvious under the small flow condition. It’s 10% higher than C3, which has the lowest efficiency. The fluctuation of volute, guide vane and outlet chamber is small at different time sequence positions. The amplitude of pressure fluctuation of two-stage runner decreases with time sequence position. At C4 position, the pressure fluctuation in the first stage runner decreases by 7%. The phase of time domain diagram of the second stage runner changes with different time sequence positions. The trough of C0 position corresponds to the peak of C4 position. The amplitude of pressure fluctuation in the second stage runner is reduced by 7.7%. The frequency domain amplitudes of axial force and radial force decrease by 20.3% and 31.3% at C4, respectively. Therefore, when the second stage runner timing is C4, the overall performance of the turbine is better.