强迫振动下超声速混合层的掺混特性

Mixing characteristics of supersonic mixing layer induced by forced vibration

利用实验研究与数值仿真相结合的方法,对强迫振动下对流马赫数为0.22的超声速混合层的掺混特性进行了分析,采用动量混合、雷诺应力以及标量混合指标对超声速混合层的掺混效率进行评估.研究结果表明:强迫振动对超声速混合层的掺混特性有重要影响.与无振动下相比,强迫振动使混合层的失稳位置提前,卷起的展向涡尺度变大,加快上下两层流动的混合.同时,强迫振动下,动量混合和标量混合更加充分.振动频率为4 500Hz时,雷诺应力峰值提高约48%,薄平板后缘下游160mm处,动量厚度增长120%.

Through combining an experimental study with numerical simulation,an analysis of mixing characteristics of a supersonic mixing layer was carried out,which was influenced by forced vibration under the condition of convective Mach number 0.22.The indexes of momentum mixing,Reynolds stress and scalar mixing were adopted to assess the mixing efficiency of supersonic mixing layer.The results show that forced vibration has an important effect on the mixing efficiency.Compared with no vibration,forced vibration advances the instability position of mixing layer and enlarges the scales of rolled-up spanwise vortices,which can promote the mixing of upper and lower streams.Meanwhile,with forced vibration,both momentum and scalar are more fully mixed.The peak value of Reynolds stress increases by about 48% when the vibration frequency is 4 500 Hz and the momentum thickness increases by 120%at 160 mm position downstream the trailing edge of thin metal plate.