高超声速圆锥边界层转捩纹影显示

为发展高超声速边界层转捩的试验研究手段，在中国空气动力研究与发展中心（CARDC）超高速空气动力研究所的FD-14激波风洞上开展了基于纹影显示技术的边界层转捩特性研究。试验模型为半锥角为7°的钝锥，头部钝度R_n有2.0和0.5mm两种。试验的名义马赫数为8和10，单位雷诺数变化范围为1.6×107~4.4×107m-1，高速相机的拍摄帧频20kHz。纹影显示捕捉到了第二模态不稳定波和湍流斑的空间结构。对纹影图像的灰度分布进行了功率谱密度（PSD）分析，结果表明第二模态波长约为边界层厚度的2倍。对纹影图像序列的分析表明，湍流斑波前传播速度大于波尾，并且略大于边界层外缘速度。

Schlieren visualization of hypersonic boundary layer transition on a circular cone

To develop the experimental technique for investigating the hypersonic boundary layer transition, schlieren visualization is used to study the characteristics of the boundary layer transition in the FD-14 shock tunnel at the Hypervelocity Aerodynamics Institute of China Aerodynamics Research and Development Center(CARDC). The test model is a 7° half-angle blunt cone with two different nosetip radiuses, 2.0 and 0.5mm, respectively. The nominal Mach numbers are 8 and 10 and the unit Renolds number varies from 1.6×107 to 4.4×107 m-1. The high-speed camera's frame frequency is 20kHz. Structures of the second mode instability waves and turbulent spots are obtained by schlieren visualization and the power spectral density is analyzed based on the gray scale distribution of schlieren images. Results indicate that the wavelength of the second mode wave is nearly twice as large as the boundary layer thickness. Analysis results of the schlieren image sequence show that the propagation speed of the turbulent spot front is higher than that of the turbulent spot tail, and is slightly higher than the velocity of the boundary layer outer edge.