摘要
The high-frequency instability on a cone at 6°angle of attack is measured in a hypersonic quiet wind tunnel with Reynolds number of 6.90×10^(6)m^(−1),and Mach number is 6.Fast-response pressure sensors are used to measure the disturbance waves on the surface of the cone.The nano-tracer-based planar laser scattering(NPLS)technique is used to visualize the coherent structures of the three-dimensional boundary layer.At the plane of azimuthal angle ofθ=30°from the leeward ray,low-and high-frequency disturbance waves with the characteristic frequency of f=10–20 kHz and f=120–140 kHz are detected.From the NPLS image,the regular large-scale traveling crossflow waves structures are observed,which are related to the low-frequency instability.On the top of the traveling crossflow waves,there are a series of small-scale structures,which suggests there is strong shear on the top of the traveling crossflow waves.These small vortices likely are the secondary instability of the traveling crossflow waves,which are associated with the high-frequency instability.The disturbance waves characteristics in different planes are measured using PCB transducers.The result shows that the high-frequency instability occurs in the planes ofθ=15°-60°,and the characteristic frequency is between f=106.97-181.08 kHz.With the increase of azimuthal angle,the characteristic frequency increases obviously,which is related to the thinner boundary layer near the windward side.With the increase of the x-coordinate,the circumferential range of the high-frequency instability gradually widens.
本文在马赫6静风洞中对6◦攻角圆锥边界层中的高频不稳定性进行了研究,实验的单位雷诺数是6:90×10^(6)m^(−1).使用Kulite和PCB脉动压力传感器测量了圆锥壁面的高频脉动压力信号,并使用基于纳米示踪的平面激光散射(NPLS)技术对三维边界层中的相干结构进行测量.结果表明,在圆锥背风面存在低频和高频的扰动波信号,特征频率分别为10-20 kHz和120-140 kHz.由NPLS结果可知,低频信号对应行进横流波结构,高频信号位于行进横流波结构的顶部,为行进横流波的二次不稳定性.另外,使用PCB传感器阵列对高频不稳定性的频率和幅值增长特性进行了研究,得到了高频不稳定性的幅值增长云图.
