凹腔作为超燃冲压发动机的一种火焰稳定器受到广泛关注，凹腔剪切层与背景激波系的相互作用影响凹腔火焰稳定器的性能。 为深入分析背景激波系对凹腔流动的影响，设计了长深比为13.3的闭式凹腔，将凹腔模型前缘激波和风洞上壁面干扰作为背景激波系，在Ma=2的直连式风洞中开展了背景激波系与凹腔剪切层的相互作用的试验，采用高速纹影系统对瞬态流场进行了捕捉，重点关注背景激波系和凹腔剪切层的动态变化特性。 采用纹影序列的本征正交分解来研究流场中的主要相干结构，采用快速傅里叶变换和连续小波变换对流场的频率域特征进行了分析。结果表明:在背景激波与剪切层相互作用下，激波结构产生大尺度振荡，凹腔内流动结构产生小尺度脉动。通过对激波位置的傅里叶变换分析，发现激波振荡的主导频率集中在90~400 Hz的范围内。通过对纹影图像的空间傅里叶变换分析，发现5 kHz以下的流场振荡主要由激波振荡引起，5 kHz以上的流场脉动主要由凹腔内流动结构引起。
As a flame stabilizer of scramjet engine, the cavity has attracted much attention. The interaction between cavity shear layer and background waves affects the performance of cavity flame stabilizer. To deeply analyze the influence of background shock wave system on the flow in the cavity, a cavity with an aspect ratio of 13.3 is designed. The leading-edge shock wave of the cavity model and the wall interation shock wave on the upper wall of the wind tunnel are used as the background waves. The interaction between the background waves and the cavity shear layer is carried out in a Ma=2 direct-connected wind tunnel. The high-speed schlieren system is used to capture the transient flow field, focusing on the dynamic characteristics of the background waves and the cavity shear layer. The main coherent structures in the flow field are studied by the snapshot proper orthogonal decomposition of the schlieren sequences. The frequency characteristics of the flow field are analyzed by fast Fourier transform and continuous wavelet transform. The results show that with the interaction between the background waves and the shear layer, the shock-wave structure produces large-scale oscillation and the flow structure in the cavity produces small-scale pulsation. With the Fourier transform analysis of the shock wave position, it is found that the dominant frequency of the shock wave oscillation is mainly concentrated in the range of 100Hz-500Hz. With〓the spatial Fourier transform analysis of the schlieren image, it is found that the flow field pulsation below 5 kHz is mainly caused by shock-wave oscillation, and the flow field pulsation above 5 kHz is mainly caused by the flow structure in the cavity.
郭善广, 付昌钦, 李明啸, 杨恒德.带背景激波系的凹腔流动特性研究[J].空军工程大学学报,2023,24(5):48-55复制