基于转捩SST模型的钝尾缘水翼绕流数值计算与分析

摘要

Boundary layer transition is one of the primary factors that affect the hydrodynamic characteristics of flow over hydrofoils.This paper presents numerical calculations of flow around the NACA0009 blunt trailing edge hydrofoil at angle of attack 0° by coupling the γ-Reθt transition model and the SST k-ω model,aims to explore the applicability of the γ-Reθt transition model in predicting of boundary layer transition and wake vortex shedding with low free-stream turbulence intensity.The sensitivity of the calculation model to the grid resolution is examined.The boundary layer,features of the wake,and the vortex shedding characteristics of flows at different free-stream velocities are predicted.The calculation results are compared with experimental data and the prediction by the SSTk-ω model.It is shown that the transition location of the hydrofoil boundary layer moves upstream with increasing y+ of the first grid near the wall.The predicted transition location converges to a fixed point when the maximum y+ less than 1.Compared with the SSTk-ω model,the transition SST model shows better prediction of eddy viscosity in the boundary layer and the wake region.The boundary layer thickness and wake flow parameters obtained by the transition SST model agree well with the experimental data.The results shown that the transition SST model can give promising prediction of the frequency of the vortex shedding,with a maximum relative error of 6.2 ％ for flows at different Reynolds number.%边界层转捩是影响水翼绕流水动力学特性的关键因素之一.为了探究y-Reθt转捩模型在低湍流度来流下水翼边界层转捩及尾涡脱落预测中的适用性,本文基于耦合γ-Reθt转捩模型和SST k-ω模型的转换SST模型,对0°攻角的NACA0009钝尾缘水翼绕流进行了数值计算.分析了转捩SST模型对网格尺度的敏感性,预测了边界层和尾迹区流场及不同雷诺数下水翼尾涡脱落特征,并与实验数据和SSTk-ω模型计算结果进行了对比.结果表明:随近壁面第一层网格尺度y+的增大,水翼边界层转捩位置沿流向后移,最大y+值小于1时,预测的转捩位置趋于一致;与SSTk-ω模型相比,转捩SST模型可以求解层流边界层,避免了在边界层和尾迹区对涡黏系数的过高预测,得到的边界层厚度和水翼尾迹区流动参数与实验结果更为接近;转捩SST模型可以较准确预测水翼尾涡脱落频率随雷诺数增大而增加的变化趋势,水翼尾涡脱落频率预测值与实验结果的最大相对误差为6.2％.