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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γ-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SST k-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SST k-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%。
Boundary layer transition is one of the key factors affecting hydrodynamic performance around the hydrofoil. In order to explore the applicability of the γ-Reθt model in predicting the transition of the hydrofoil boundary layer and the wake vortex shedding at low turbulence, based on the SST model of coupled γ-Reθt transition model and SST k-ω model, Numerical simulation of flow around NACA0009 blunt fin at 0 ° angle of attack was carried out. The sensitivity of the SST model to the grid scale was analyzed. The wake vortex shedding characteristics at the flow field and the Reynolds number in the boundary layer and wake region were predicted. The calculated results were compared with the experimental data and the SST k-ω model. The results show that with the increase of the first grid scale y + of the near wall, the position of the hydrofoil boundary layer turns backwards along the flow direction, and the predicted transition position tends to be consistent when the maximum y + value is less than 1; Compared with the model, the transition SST model can solve the laminar boundary layer and avoid over predicting the eddy viscosity in the boundary layer and the wake area. The obtained boundary layer thickness and the wake parameters of the wake are closer to the experimental ones . The SST model can predict more accurately the change tendency of shedding vortex shedding frequency with increasing Reynolds number. The maximum relative error between prediction value of winglet shedding and experimental results is 6.2%.