筒阀动水关闭过程中下边缘形状对流场的影响

为研究筒阀下边缘形状对动水关闭过程周边流场的影响,选用RNG k-ε湍流模型,运用动网格和滑移网格技术,利用Fluent仿真软件对2种不同下边缘形状筒阀的动水关闭过程进行三维非定常流动数值模拟.通过对不同关闭行程的筒阀周边压力场和速度场,以及筒阀内外表面和下端面压力分布的对比分析可知,小倾斜度下边缘形状的筒阀不易产生汽蚀,倾覆力矩较小,下端面所受下拉力较小,且节流处速度分布均匀、过渡平滑,水力损失小.与小倾斜度下边缘形状的筒阀相比,弧形下边缘形状筒阀的倾覆力和下拉力具有较小的波动性,在筒阀下端面入流处压力扰动小,筒阀关闭行程中其下端面压力变化幅度小,能有效防止发卡现象发生.该研究对于筒阀下边缘形状的设计和优化以及提高水轮机筒阀运行稳定性具有一定的参考价值.

Influence of different lower edge shapes on surrounding flow field in shut-down process of ring gate

To study the influence of lower edge shapes on the surrounding flow field of the ring gate in the shut-down process, the ring gate of Nansha Hydropower Station has been discussed for an example. There were two common lower edge shape models of the ring gate. Numerical simulation of three dimensional unsteady flow was conducted by using the fluent software with the RNG k -ε turbulence model. The simulation exerted the dynamic mesh and moving mesh focusing on studying the velocity field and the pressure field around the ring gate as well as the bottom pressure distribution under different ring gate. By the eontrastive analysis, the consequence that the ring gate with a small inclination lower edge has a better performance than with arc-shaped lower edge was got, in the aspects of cavitation corrosion, upsetting moment and hydraulic loss et al. However, the ring gate with arc-shaped lower edge has a smaller fluctuation for overturning force and pull force. During the closing process, the bottom pressure distribution has a smaller variation which can prevent hairpin phenomenon effectively. The study will provide theoretical reference for designing and optimizing the shape of the ring gate edge and can be conducive to the stability of the ring gate operation.