二维进气道不启动流场非定常特性的混合LES/RANS模拟

Investigation on unsteady characteristics of unstarted two-dimensional inlet flow using hybrid LES/RANS method

采用一种混合大涡模拟/雷诺平均Navier-Stokes(LES/RANS)方程模拟方法结合5阶WENO(weighted essentially non-oscillatory)格式对马赫数为3的来流中、内收缩比为1.5的不启动状态下的二维进气道进行了计算,再现了不启动进气道中的非定常流场.计算结果表明:所采用的模拟方法对入口处的平均绝热壁温、摩擦速度和雷诺应力的计算精度较好,进气道不启动流场中激波波系和分离区存在大时空尺度的低频运动,其占主导的特征频率和典型的激波/湍流边界层干扰问题中激波和分离区的低频频率接近,且进气道出现了间歇性的启动状态.

A hybrid large-eddy simulation/Reynolds-averaged Navier-Stokes （LES/ RANS） method together with 5th order WENO （weighted essentially non-oscillatory） scheme were used to caculate an unstarted two-dimensional inlet with contraction ratio of 1.5 in a Math 3 freestream. The unsteady flow field in the unstarted inlet was captured. The result shows that current numerical method can predict mean adiabatic wall temperature, friction velocity and Reynolds stress reasonably well. Some low-frequency motion exist in the shock system and separation zone in the unstarted field at large time-space scale. The dominant frequency is close to its counterpart in classic shock/turbulent boundary layer interaction problem. The inlet switches to started state intermittently.