水轮机筒阀倾覆稳定性数值模拟研究

Numerical analysis of capsizing stability of ring gate during emergency shutdown of hydro-turbines

为了研究水轮机筒阀动水关闭过程中的倾覆稳定性,本文采用连续方程和Reynolds平均的N-S方程,同时使用RNG k-ε双方程湍流模型进行封闭,对水轮机全流道流场进行了三维非定常湍流数值模拟。运用计算流体动力学软件FLUENT数值计算了筒阀动水关闭过程中在周边水流作用下受到的倾覆力矩。在此基础上,建立了筒阀倾覆稳定性的力学模型。最后,结合具体的筒阀参数,评价了其倾覆稳定性。研究结果表明:筒阀动水关闭过程中,在不平衡侧向水动力的作用下存在一定程度的倾覆,当筒阀关闭到95%行程时,其倾覆力矩达到了最大值。筒阀在整个动水关闭过程中其横向位移均在筒阀与固定导叶所允许的间隙范围内,未发生卡死现象,运行相对较稳定。因此,当水轮机组发生飞逸时,筒阀可以在动水关闭过程中实现安全平稳地关闭,确保水轮机组及其附件的安全。

Unsteady Reynolds-averaged Navier-Stokes equations of viscous uncompressible fluid have been solved for simulations of three-dimensional unsteady turbulent flows to study the capsizing stability of a ring gate of hydro-turbines during emergency shutdown. The fluid dynamics software FLUENT was used to calculate the capsizing moments acting on the ring gate during emergency shutdown. A mathematical model of the capsizing stability was developed on the basis of an analysis on gravitational effects and capsizing moments, and the capsizing stability was evaluated using the model parameters of a specific ring gate. The results show that this ring gate had certain capsizing risk under an unbalanced lateral force in the whole emergency shutdown process and its resultant capsizing moment reached the maximum at a closing stroke of 95%. During its entire dynamic closing from the start to complete closure, its lateral displacements were always within certain limits inside the allowed gap between it and stay vanes. Therefore, the ring gate will not get stuck on the stay vanes, maintaining a well running stability during emergency shutdown.