In order to compensate for the stochastic nature of the power grid due to the tremendous development and the integration of renewable energy resources and meet its other requirements, the hydraulic turbines are forced to operate more frequently under partial load conditions with singular and misaligned flows inevitably excited by the inter-blade vortex. This paper presents numerical investigations of the unsteady characteristics of the inter-blade vortex for a low-head model Francis turbine. The SST k - ω turbulent model is used to close the unsteady Reynolds-averaged Navier-Stokes (RANS) equation. The flow structure of the inter blade vortex predicted by the numerical simulation is confirmed by experimental visualizations. It is shown that the total vortex volume in the runner sees a quasi-periodical oscillation, with significant flow separations created on the suction side of the runner blade. A counter measure by using the air admission into the water from the head cover is implemented to alleviate the undesirable effect of the inter-blade vortex. The analyses show that the development of the inter-blade vortex is significantly mitigated by the injecting air that controls and changes the spatial distribution of streamlines. Furthermore, the flow aeration with a suitable air flow rate can reduce the energy dissipation caused by the inter-blade vortex and plays a critical role in preventing the excessive amplitudes of the pressure fluctuation on the suction side of the runner blade. This investigation provides an insight into the flow mechanism underlying the inter-blade vortex and offers a reference to alleviate and mitigate the adverse consequences of the inter-blade vortex for the Francis turbine.

为了补偿由于巨大发展和可再生能源的整合而造成的电网随机性并满足其其他要求，水力涡轮机被迫在部分负载条件下更频繁地运行，不可避免地激发了奇异和错位的流动通过叶片间涡旋。本文介绍了低头型混流式水轮机叶片间涡旋非定常特性的数值研究。SST k - ω湍流模型用于关闭非稳态雷诺平均Navier-Stokes（RANS）方程。通过数值模拟预测的叶片间涡流的流动结构通过实验可视化得到确认。结果表明，转轮中的总涡流呈准周期振荡，在转轮叶片的吸入侧产生明显的流动分离。通过使用从头罩进入水中的空气来采取对策，以减轻叶片间涡旋的不良影响。分析表明，通过控制和改变流线的空间分布的注入空气，叶片间漩涡的发展得到了显着缓解。此外，适当的空气流量通气可减少叶片间涡流引起的能量耗散，并在防止流道叶片吸力侧压力波动幅度过大方面发挥关键作用。这项研究深入了解了叶片间涡流的流动机理，并为减轻和减轻叶片间涡流对弗朗西斯涡轮机的不利影响提供了参考。