壁面展向周期振动的超声速湍流减阻研究

Research on Drag Reduction of Supersonic Turbulent Flow with Spanwise Wall Oscillation

减小摩擦阻力对改善飞行器的性能具有重要意义,因此以减阻为目的的边界层转捩和湍流的控制因其广阔的应用前景而成为湍流研究的重点之一。采用大涡模拟方法对壁面展向周期振动条件下的超声速平板边界层转捩和湍流进行了数值模拟研究。结果表明,通过改变振幅大小和振动周期,壁面展向振动可减小湍流区域的摩擦阻力,边界层厚度也相应减小。随着振幅和周期的增加,壁面展向振动使边界层内湍流马赫数、流向速度脉动分布呈下降趋势,从而对边界层内湍流脉动的发展起到抑制作用。壁面展向振动还对流场中相干结构的生成具有一定抑制作用,相干结构在流场中的密度相应降低。

Because reducing friction drag is very important for improving aircraft performance,boundary layer transition and turbulence control for the purpose of drag reduction have become one of the focuses of turbulence research due to its broad application.The large eddy simulation of supersonic boundary layer transition and turbulence over a flat-plate with spanwise wall oscillation.It is found that the spanwise wall oscillation can reduce the friction drag and boundary layer thickness in the turbulent area by changing the amplitude and period of oscillation.Due to the increase of amplitude and period,the spanwise wall oscillation can make the distribution of turbulent Mach number and rms streamwise velocity decrease,which inhibits the development of turbulent fluctuations in the boundary layer.Furthermore,it has a certain inhibitory effect on the development of the generation of large-scale coherent structures,resulting in the decrease of the density of large-scale coherent structures in the flowfield.