Abstract The performance prediction of two counter-rotating vertical axis hydrokinetic turbines is presented in this paper. The flow field is governed by the 3D time-dependent incompressible Navier–Stokes equations. The system of equations is discretized using the Arbitrary Lagrangian-Eulerian Variational Multi-scale formulation for turbulence modeling on moving domains. Sliding interfaces are used to handle the rotor-stator interactions. Weak enforcement of essential boundary conditions is used to relax the requirement of boundary layers resolution. A grid convergence study based on the evaluation of the grid convergence index for the computed torque and the time-averaged axial wake velocity is performed. The grid convergence study shows good convergence with grid refinement in our formulation. Experimental validation of the averaged torque is performed for two different flow conditions and different turbine rotational velocities with good agreement. The finest mesh resolution from the grid convergence study is used for the multiple turbines simulation. The simulation shows almost 25% deficiency in the averaged torque of the downstream turbine. A multi-domain method is introduced to predict the performance of the turbine array at a lower computational cost than the full array simulation. The results from the multi-domain method show good matching on the averaged torque with the full array simulation. The initial study on the effect of struts on the torque generation is presented. The results assure the robustness of the ALE-VMS formulation and how it can be used to simulate multiple turbines at full-scale and full geometric complexity.

中文翻译：

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使用变分多尺度方法分析两个垂直轴流体动力涡轮机的性能

摘要 本文介绍了两台反向旋转垂直轴水力涡轮机的性能预测。流场由 3D 时间相关不可压缩 Navier-Stokes 方程控制。方程组是使用任意拉格朗日-欧拉变分多尺度公式离散化的，用于运动域的湍流建模。滑动接口用于处理转子-定子相互作用。基本边界条件的弱强制用于放宽边界层分辨率的要求。执行基于计算扭矩和时间平均轴向尾流速度的网格收敛指数评估的网格收敛研究。网格收敛研究表明在我们的公式中网格细化具有良好的收敛性。平均扭矩的实验验证是针对两种不同的流动条件和不同的涡轮机转速进行的，具有良好的一致性。来自网格收敛研究的最精细网格分辨率用于多涡轮机模拟。模拟显示下游涡轮机的平均扭矩有近 25% 的不足。引入了一种多域方法，以比全阵列仿真更低的计算成本来预测涡轮阵列的性能。多域方法的结果表明，平均扭矩与全阵列模拟具有良好的匹配性。介绍了支柱对扭矩产生的影响的初步研究。结果确保了 ALE-VMS 公​​式的稳健性以及如何使用它来模拟全尺寸和全几何复杂性的多个涡轮机。