基于沉浸边界法的轴流泵内鱼体运动数值模拟

为精细分析鱼类在水力机械流道中的运动特性，本文以轴流泵为例，采用沉浸边界（immersed boundary，IB）与流固耦合（fluid-structure interaction，FSI）及大涡模拟（large eddy simulation，LES）相结合的方法，对泵内流场及鱼体通过泵流道的运动过程进行了数值模拟。结果表明，在相同雷诺数下计算得到的设计工况扬程系数与实验值误差仅为2.7%，验证了IB-FSI-LES方法适合于模拟轴流泵内部流动。与将鱼体视为流体示踪粒子的常规计算相比，采用IB-FSI-LES方法可以得到鱼体在泵内的复杂运动轨迹，捕捉鱼体与叶片发生碰撞时的运动突变以及叶轮内鱼体周围流场中涡结构的形成和脱落。研究结果可为水利水电工程中鱼类过机损伤精确评估及鱼类友好型水力机械优化设计提供科学依据。

Numerical simulations of fish movement in axial pump using immersed boundary method

This research adopts a method of combining immersed boundary (IB) with fluid-structure interaction (FSI) method and the large eddy simulation (LES), to simulate the internal flow of an axial pump and the fish movement in the pump passage for a refined analysis on the characteristics of fish motions in hydraulic machinery. The results show that the calculated head coefficient has a deviation of only 2.7% against the experimental data under the design condition at the same Reynolds number, verifying the feasibility of this new method for the pump flow simulations. Compared with the traditional methods where fishes are simplified into flow tracers, the method adopted in this study is capable in capturing the complexity of fish trajectories, sudden changes in fish orientation after hitting the blade, and the vortex formation, shedding and structure in the fish wake, thereby helping to obtain accurate assessment of fish injury and design optimization of fish friendly hydraulic machinery.