空间发展超音速混合层入口扰动的最不稳定波方法  

Most-unstable wave method for inlet disturbances of spatially developing supersonic mixing layers

作　　者：薛淑艳[1] 张会强[1] 王兵[1] 王希麟[1] 

机构地区：[1]清华大学航天航宅学院,北京100084

出　　处：《清华大学学报（自然科学版）》2011年第5期724-728,共5页Journal of Tsinghua University(Science and Technology)

摘　　要：可压缩混合层的大尺度涡结构及其演化过程与来流扰动密切相关。该文首先对来流扰动为白噪声扰动的二维空间发展超音速平面混合层进行了数值模拟,并对流动初始失稳区域的瞬时y方向速度信号进行Fourier分析,来获得流动最不稳定波频率,以该频率来构造入口扰动。结果表明:与白噪声扰动相比,应用相同均方根的最不稳定波扰动能更有效激发混合层的发展,使流场起涡位置明显提前,使脉动时均统计量更快达到自相似。要达到相同的起涡位置,白噪声扰动均方根是最不稳定波扰动均方根的13倍左右,这与不可压流的350～500倍相比,要小得多。Reasonable predictions of large scale vortex structures and their evolution in a compressible mixing layer are mainly dependent on the inlet disturbance.Numerical results for the instantaneous transverse velocity predicted for a white noise inlet condition were used to calculate the most unstable wave frequency used to form the inlet disturbance by Fourier analysis.The results show that the most unstable wave disturbance can more effectively excite the supersonic mixing layer compared with the white noise disturbance for the same root mean square（RMS） noise level.Also,the position of the vortex roll up significantly moved upstream and the time-averaged properties became self-similar earlier.For the same vortex roll up position,the RMS level of the white noise disturbance was about thirteen times greater than that of the most unstable wave disturbance.For incompressible flows,the ratio was 350～500 times since the noise level for the most unstable disturbance was much smaller.

关 键 词：超音速平面混合层 入口扰动 最不稳定波 白噪声扰动 FOURIER分析 

分 类 号：O357.5[理学—流体力学]