Unsteady Flow Simulation of Leading-Edge Separation in Thin-Airfoil Cascade: A Modification to Turbulence Model
Unsteady Flow Simulation of Leading-Edge Separation in Thin-Airfoil Cascade: A Modification to Turbulence Model
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DOI：
10.1115/gt2015-43849
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发表时间：
2015-06
期刊：
影响因子：
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通讯作者：
A. Tateishi;Toshinori Watanabe;T. Himeno;C. Inoue
中科院分区：
文献类型：
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作者：
A. Tateishi;Toshinori Watanabe;T. Himeno;C. Inoue
采用隐式大涡模拟（ILES）和雷诺平均Navier-Stokes（RANS）方法，采用不同的湍流模型，对亚音速大攻角薄叶栅前缘分离进行了数值模拟。在细网格的ILES模拟中，时均表面压力定性地与实验数据一致。粗糙网格上的RANS和ILES模拟未能捕捉到前缘附近的压力峰值。从频谱分析可以看出，分离泡内的流场是湍流的。在RANS模拟失败的情况下，分离泡更长，前缘附近的湍流能量比ILES结果低得多。在非定常模拟中观察到了旋涡结构的发展及其在再附着点附近的突然减弱。通过比较ILES和RANS计算结果中湍流能量的差异，提出了两种可能的修正方案。结果表明，这些修改改善了RANS模拟的气泡长度和Cp分布，但需要进一步验证和建模才能应用于实际情况。Copyright © 2015 by ASME
Leading edge separation of thin airfoil cascade in subsonic flow at large angle of incidence was simulated by implicit large eddy simulation (ILES) and Reynolds averaged Navier-Stokes (RANS) simulations with various turbulence models. In the ILES simulations with fine grids, the time-averaged surface pressure qualitatively agreed with the experimental data. The RANS and ILES simulations on the coarse mesh failed to capture a peak of pressure near the leading edge. From spectrum analysis, it was observed that the flow-field was turbulent in the separation bubble. In the failed RANS simulations, the separation bubble was much longer and the turbulence energy near the leading edge was much lower than those in the ILES results. The development of lambda-shaped vortex structures and their sudden weakening near the reattachment point was observed in the unsteady simulations. Two possible modifications to existing turbulence models in RANS simulations were proposed based on the comparison of turbulence energy between the ILES and RANS results. It is shown that these modifications improve the bubble length and Cp distributions of RANS simulations, though further validation and modeling are needed for the application to realistic cases.Copyright © 2015 by ASME