高超声速三角翼上横流不稳定性的实验研究

Experimental study of crossflow instability in a Mach 6 delta wing flow

本文研究了三角翼迎风面边界层中的非定常横流不稳定性.实验在马赫6低噪声风洞中进行,模型为平板构型,攻角为5°和10°.通过温敏漆技术,观察到在远离头部的区域,边界层转捩阵面光滑且平行于前缘,通过Kulite高频脉动压力传感器得到的功率谱密度曲线中有明显的f≈10 kHz的扰动波信号峰值.利用基于纳米示踪的平面激光散射技术,在平行前缘方向对此区域进行流场可视化,观察到规则的向下游卷起的涡结构,形态与数值模拟中的横流涡形态一致,且涡结构的位置不是固定的,因此该10 kHz的信号为非定常横流波信号.只有在边界层为层流时,才能够观察到明显的10 kHz左右的非定常横流波信号峰值,边界层转捩中或转捩后,脉动压力的功率谱密度曲线为低频成分占主导的宽频分布.提高单位雷诺数,同一压力测点位置得到的横流波幅值先增长至饱和而后衰减.增大攻角时,横流行波幅值增长更加迅速,在较低的雷诺数下就可以增长至饱和.另外,还利用Kulite传感器阵列测量了横流波的相速度和传播角度,文中所测状态下,相速度分布在0.24-0.32倍来流速度之间,传播角度与来流方向夹角在40°-60°之间.并且,增大攻角时,横流波的相速度变大,传播角减小.

In this paper,the traveling crossflow instability in the boundary layer on the windward side of a delta wing is studied.The experiments are carried out in a Mach 6 low-noise wind tunnel,with the angles of attack of the model being 5°and 10°,and the Reynolds number being in a range of 2.43×106-14.21×106 m-1.The wall fluctuation pressure is measured by fast-response Kulite pressure transducers.The power spectrum density(PSD)analysis is conducted to obtain the disturbance waves'development process in the boundary layer.The temperature-sensitive paints(TSPs)and nano-tracer based planar laser scattering(NPLS)technique are also used.From the TSP results,the boundary layer transition near the leading edge of the delta wing is smooth and parallel to the leading edge.A peak around 10 kHz in power spectrum density is detected by the fast-response pressure sensor,which may be caused by the traveling crossflow waves.To verify this dominant mode,an NPLS image in the plane of n=36 mm is obtained.The shapes of vortex structures correspond to the shapes of the crossflow vortices from the numerical simulation.Only when the boundary layer is laminar can the traveling crossflow wave signal be observed from the PSD curves.When the boundary layer is at a transitional or turbulent phase,the low-frequency component is dominant in the PSD curve.With the increase of Reynolds number,the characteristic frequency of the crossflow wave increases,and the wave’s amplitude first increases and then decreases.Moreover,the angle of attack effect is obtained.The increasing of the angle of attack can make the traveling crossflow wave grow faster and saturate,attenuate at the position closer to the leading edge of the delta wing or at a lower Reynolds number.By sensor pairs composed of three Kulite transducers,the phase velocity and the propagation angle of the traveling crossflow wave are investigated.The dimensionless phase velocities of the traveling wave are in ranges of 0.24-0.26 and 0.26-0.32 at 5°and 10°angles of attack,respectively.The propagation angles are at 50°-60°and 40°-55°at the angles of attack of 5°and 10°,respectively.At a larger angle of attack,the traveling wave’s propagation angel is smaller,but the phase velocity is bigger.It may be because the spanwise pressure gradient is higher at a larger angle of attack,and then the crossflow velocity is stronger.