基于RANS/LES方法的超声速底部流场数值模拟

分别采用基于两方程k-ω剪切应力输运(SST)湍流模型的延迟DES(DDES)、更改的DDES(MDDES)和改进的DDES(IDDES)方法,并引入可压缩修正,结合三阶MUSCL-Roe和五阶WENO-Roe两种空间离散格式,针对超声速底部的复杂流动现象,开展了数值模拟研究。计算结果表明本文方法能够捕捉到超声速底部流动中丰富的湍流结构,通过分析计算结果对超声速底部的流动机理有了进一步的认识,为下一步的超声速底部流动减阻改进和雷诺平均NavierStokes/大涡模拟(RANS/LES)方法在非定常高可压缩性流动中的应用提供了参考。通过对比分析不同空间离散格式的计算结果研究了数值耗散对计算的影响,五阶WENO-Roe格式的计算结果与实验结果吻合良好;对不同RANS/LES混合方法的计算结果进行了对比分析,结果表明IDDES方法在近壁区的表现优于DDES和MDDES方法。

Numerical simulations of supersonic base flow field based on RANS/LES approaches

Numerical investigation on supersonic base flow is performed using several Reynolds averaged Navier-Stokes (RANS) and large eddy simulation (LES) hybrid methods based on k-ω shear stress transport (SST) model with compressibility correction,including delayed detached eddy simulation (DDES),modified-DDES (MDDES) and improved-DDES (IDDES) approaches.Third-order MUSCL-Roe and fifth-order WENO-Roe spatial scheme are applied in the investigation.The numerical results show plenty of small scale turbulence structure in supersonic base flow.The complex flow physics are comprehensively understood,which provides references for the base aerodynamic drag reduction and the application of RANS/LES hybrid methods to unsteady highly compressible flows in future research.Numerical dissipation effects of two spatial schemes are investigated.Computational results show that fifth-order WENO-Roe scheme is more validated than third-order MUSCL-Roe scheme when compared with experimental data.Furthermore,comparative analysis of the computational results with several RANS/LES hybrid methods is conducted.The results show that IDDES approach has better performance in regions near the wall than DDES and MDDES approaches.