For the purpose of turbulence drag reduction, a velocity-temperature coupled control method is proposed based on the velocity boundary layer control and the thermal boundary layer. The spatial evolution of supersonic turbulent boundary layer at a Mach number of 2.25, subject to steady blowing with different velocities and temperatures, is investigated using direct numerical simulations. Noting that the wall is isothermal with nearly adiabatic temperature, it is found that the thickness of boundary layer increases by the control of heated blowing, as do the viscous sublayer and the logarithmic zone. Moreover, drag reduction of 20.1% is achieved by heated wall blowing, higher than that of unheated wall blowing, while drag increases 12.2% by the control of cooled wall blowing. Nevertheless, the control efficiency of heated wall blowing is low due to high energy consumption, which needs further study. The reduction of mean viscous shear stress is mainly responsible for the drag reduction mechanism though there is a substantial increase in Reynolds stresses. Compressible Renard-Deck decomposition of $C_f$ indicates that it is the decrease of the spatial growth term that determines the turbulence drag reduction. The strong Reynolds analogies are still valid in all controlled cases. The average streamwise scale of near-wall streaks reduces by introducing heated blowing. Turbulence amplifications are observed in heated cases while turbulence attenuations are observed in cooled cases.

中文翻译：

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超声速湍流边界层受速度-温度耦合控制的直接数值模拟

为了降低湍流阻力，提出了一种基于速度边界层控制和热边界层的速度-温度耦合控制方法。使用直接数值模拟研究了马赫数为2.25的超音速湍流边界层的空间演化，该马赫数受不同速度和温度的稳定吹扫。注意到壁是接近绝热温度的等温壁，发现边界层的厚度通过加热吹气的控制而增加，粘性子层和对数区也是如此。此外，通过加热的壁吹实现的阻力减小为20.1％，高于未加热的壁吹，而通过控制冷却的壁吹实现的阻力增大了12.2％。尽管如此，由于能耗高，吹墙加热的控制效率低，有待进一步研究。尽管雷诺应力显着增加，但平均粘性剪应力的减小主要是减阻机理的原因。可压缩的Renard-Deck分解$C_F$表示决定湍流阻力减小的是空间增长项的减小。强大的雷诺兹比喻在所有受控情况下仍然有效。近壁条纹的平均流向尺度通过引入加热的吹气而减小。在加热情况下观察到湍流放大，而在冷却情况下观察到湍流衰减。