带分流叶片水泵水轮机小开度下非定常分析

为了研究带分流叶片水泵水轮机在小开度运行下各工况的内流特点及受力特点,以国内某带分流叶片水泵水轮机抽水蓄能电站的水力模型为分析对象,运用CFD数值模拟方法,采用SST k-ω计算模型,对其7.5°开度下的水轮机工况、制动工况和反水泵工况的内流特性进行了非定常数值模拟计算,分析了各工况下机组内部典型监测点的压力脉动特性及轴向力分布规律.结果表明:CFD数值计算能较好地模拟分析带分流叶片水泵水轮机的内流特性;在制动工况和反水泵工况下,转轮流道内出现明显的不稳定流动,二次流和涡结构充满整个转轮,进而引起水流拥堵,分流叶片可以使转轮的出水速度更加均匀;机组甩负荷运行进入制动工况后,转轮所受轴向力明显变大,并伴有负值出现,波动幅度也较大;分流叶片的存在可以预防转轮区出现负压,有助于降低涡结构的强度.

Analysis of unsteady characteristics of pump turbine with splitter blades at small guide vane opening degree

In order to study the internal flow characteristics and stress characteristics of pump turbines with diverging blades in different operating conditions under the small opening, with the hydraulic model of a pumped-storage power station with shunt blade pump turbine was taken as the analysis object. CFD numerical simulation method was used, the SST k-ω calculation model was adopted. The internal flow characteristics of the turbine, brake and reverse pump at 7.5° opening were numerically simulated, The pressure pulsation characteristics and axial force distribution of typical monitoring points inside the unit under different working conditions were analyzed. The results indicate that the internal flow characteristics of a pump turbine with shunt blades can be well simulated and analyzed by CFD numerical calculation. Under braking and reverse pump conditions, there is obvious unstable flow in the runner flow passage. Secondary flow and eddy structure fill the runner and cause flow congestion. The distributor blade can make the runner′s outlet speed more uniform; after the unit′s load rejection operation enters the braking condition, the axial force on the runner obviously increases, accompanied by negative value, and the fluctuation range is larger; the existence of the distributor blade can prevent the negative pressure in the runner area and help to reduce the strength of the vortex structure.