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为了提高原始剪切应力输运(SST)湍流模型对于分离流动的求解精度,将大涡模拟(LES)中的滤波因子和SST方程相结合构造出一种滤波SST方法,利用湍流尺度对流场求解区域进行划分,近壁面附近的稳态流动由湍流模型控制,远壁面采用LES方法进行模拟。与传统混合RANS/LES方法相比,该方法的特点是:滤波因子的选取不再依赖于网格尺度,可以有效地降低网格诱导分离现象发生的概率。采用该方法对NACA0021翼型深失速特性进行了仿真研究,对比了非定常雷诺平均Navier-Stokes(URANS)方法和SST-DES方法,从仿真结果可以看出滤波SST方法有效地激活了分离区域的脉动,充分展现了分离的三维特性;同时算例求解结果证明该方法的精度高于URANS方法,与试验结果吻合较好,显示其具有一定的工程应用价值。
In order to improve the precision of the SST turbulence model for the separation flow, a filtering SST method is constructed by combining the filtering factor in LES and the SST equation. The turbulence scale is applied to the flow field The solution area is divided. The steady-state flow around the near wall is controlled by turbulence model. The far wall is simulated by LES method. Compared with the traditional hybrid RANS / LES method, this method has the following characteristics: the selection of the filter factor is no longer dependent on the grid scale, and the probability of grid induced separation can be effectively reduced. This method is used to simulate the deep stall characteristics of NACA0021 airfoil. Comparing unsteady Reynolds-average Navier-Stokes (URANS) method and SST-DES method, it can be seen from the simulation results that the filtered SST method effectively activates the separation region The results show that the accuracy of this method is higher than that of URANS method, which is in good agreement with the experimental results, indicating that it has some engineering application value.