基于三种亚格子模型的空腔振荡流动计算

Calculation of Oscillation Flow in Open Cavity Using Three Sub-grid Scale Models

使用三种亚格子应力模型,对长深比(L/D)为5的三维矩形开式空腔的可压缩流体进行大涡模拟计算。研究得到的空腔自激振荡频率与Rossiter公式计算结果和实验结果吻合良好,结果显示振荡能量主要集中在较低频率区域,压力幅值主要出现在前三阶模态。Dynamic Smagorinsky-Lilly(DSM)模型在空腔前后壁面附近区域的脉动强度分布比Smagorinsky-Lily(SM)模型更为接近实验值,Wall Adapting Local Eddy Viscosity(WALE)模型的脉动强度分布与实验值最为接近。由空腔底部监测点声压级分布及声压频谱图可以看出:WALE模型性能最佳,DSM模型结果也与实验结果相符合,SM模型的预测性能略差。

Three sub-grid scale models are employed to calculate the compressible fluid in a three dimensional rectangular open cavity,which has a length-to-depth ratio of 5. The frequencies of sustained- oscillation in the cavity are in agreement with experimental results and the Rossiter formula. The oscillating energy mainly concentrates on the low frequency areas. The first three modes are the basic frequencies of the flow induced oscillation. The main discrepancies of sound pressure level（SPL）occur in the areas near the fore and aft walls. The results of dynamic Smagorinsky-Lilly（DSM） model are more closer to experimental data than that of Smagorinsky-Lily（SM） model. The results of Wall Adapting Local Eddy Viscosity（WALE） model are the closest to the experimental data. The results of sound pressure level and sound pressure spectrum at the bottom of the cavity demonstrate that WALE model is the best one to predict the self-sustained oscillation of the cavity, while DSM model is fairly good, SM model is slightly inaccurate.