抽水蓄能电站甩负荷球阀动水关闭过程流固耦合研究

抽水蓄能电站甩负荷过渡过程中,内部流场与外部结构双向作用,对球阀安全运行造成不良影响。为探讨抽水蓄能电站甩负荷工况球阀动态关闭过程中流场演变对球阀关键部件的影响,基于流固耦合理论,建立球阀系统离散角度有限元仿真模型,以多角度结构分析近似模拟球阀在动水关闭过程中的结构瞬态过程,反映球阀流道的分布特点及薄弱环节的数据特征。为此,先对某抽水蓄能电站进行数值模拟,提取甩负荷过渡过程关键参数,根据仿真结果确定球阀流场边界条件;然后计算球阀流道内流场压力与速度分布;最后基于流场仿真结果建立球阀结构流固耦合模型,求解球阀瞬态过程结构强度相关参数分布。结果表明,甩负荷过渡过程中,在水流三维瞬变流动的影响下,球阀结构的应力分布具有明显规律性,工作密封与检修密封的过流面积突变,导致应力极大值出现在基座与枢轴部位。流场作用于球阀壁面的变形量叠加,球阀总变形量呈现由上游至下游逐渐递增的趋势。

Fluid structure Interaction of Ball Valve in Dynamic Water Closing Process of Pumped storage Power Station under Load Rejection

In the process of load rejection transient of pumped storage power station, the internal flow field and the external structure work in both directions, which affects the safe operation of the ball valve adversely. This paper aims to study the influence of flow field evolution of ball valve dynamic water closing on the key components of ball valve during the load rejection condition in pumped storage power station. Based on fluid structure interaction theory, the discrete angle finite element simulation model of ball valve system is established to simulate the transient structural process of ball valve in the process of dynamic water closing approximately by multi angle structural analysis, which reflects the distribution characteristics of ball valve passage and the data characteristics of weak links. Firstly, the numerical simulation of a pumped storage power station is carried out. The key parameters under load rejection are extracted, and the boundary conditions of the ball valve flow field are determined according to the simulation results. Then, the pressure and velocity distribution of the flow field in the ball valve runner are calculated. Finally, the fluid structure interaction model of ball valve structure is established based on the simulation results of the flow field, and the structural strength distribution of the transient process of the ball valve is solved. The results show that the influence of the three dimensional transient flow process on the maximum stress of the ball valve is obvious in the process of load rejection transient. The maximum stress value appears in the base and pivot position of the ball valve. The effect of the three dimensional transient flow process on the stress maximum of the ball valve is obvious, which is caused by the sudden change of overflow area of work seal and overhaul seal. The total deformation of the ball valve presents an increasing tendency from the upstream to the downstream, which is caused by the superposition of the deformation of the flow field acting on the wall of the ball valve.