细长旋成体背风面非对称流场的DES模拟

DES Method for Asymmetric Separated Flow on the Leeward Side of Slender Body

利用脱体涡模拟DES方法对细长旋成体非对称绕流进行数值模拟,比较了基于S-A湍流模型的DES与RANS方法对背风面非对称分离涡的数值模拟能力,发现在大迎角非对称涡未破裂情况下,DES与RANS均能模拟出与实验相符的非对称绕流;当迎角增大,背风面非对称涡发生破裂时,RANS无法准确捕捉到背风面流场的非定常性,而DES能准确预测非对称涡的飘起与破裂,并与实验值接近。计算结果表明:与RANS方法相比,DES方法具有更好的模拟大攻角,大分离流动的能力,尤其在非对称流场的分离涡破裂模拟方面具有明显优势,能够更真实模拟出细长旋成体背风面分离涡破裂之后的非定常流动特征。

Turbulent flows over a slender body at different high angles of attack were simulated numerically using DES and RANS approach..The location and strength of separated vortex, flow field and pressure distribution on the surface were compared with DES and RANS based on S- A model. It is clearly found that both models performed well for the steady asymmetrical flows at high angle of attack, however, with further increase in incidence, DES can predict the unsteady characteristic and breakdown in asymmetrical separated vortices around slender leeside. The results of numerical simulation show that the DES model is more suitable for the complex separated flow around the slender body at extremely high angle of attack.