“回收/调节”方法在混合LES/RANS模拟方法中的应用

Application of recycling/rescaling method in hybrid LES/RANS simulation method

采用一种混合大涡模拟/雷诺平均Navier-Stokes(LES/RANS)模拟方法结合三阶加权基本无振荡(WENO)格式对马赫数为2.88的压缩斜坡流动进行了数值模拟,并采用"回收/调节"方法生成入口湍流脉动边界条件.当采用固定入口边界条件时,湍流边界层会缺乏合理的湍流能量,使之抵抗逆压梯度的能力减弱,会严重高估分离区的大小;而当采用"回收/调节"方法时,可以在10倍来流边界层厚度的距离内激励起湍流大尺度结构,计算得到的流场能够再现激波/湍流边界层干扰流场的非定常特性,时间及展向平均壁面压力和试验值吻合较好.

A hybrid large eddy simulation/Reynolds-averaged Navier-Stokes （LES/ RANS） simulation method together with the third-order weighted essentially non-oscillatory （WENO） scheme were used to compute the flow field of a Math number is 2.88 compression ramp flow. A recycling/rescaling method was used to generate turbulent fluctuating inflow boundary conditions. When fixed inflow boundary conditions were applied, the incoming turbulent boundary layer could not resist the adverse pressure gradient due to lack of reasonable turbulent energy. So the separation zone was overpredicted heavily. When recycling/ resealing method was used, large scale turbulent structures were stimulated in a length ten times the inflow boundary layer thickness. Thus, the results demonstrate the unsteady features of shock/turbulent boundary layer interactions. Time- and spanwise-averaged wall pressure is in good agreement with experimental values.