Study of Oscillation Characteristics of Shock Trains Formed in Supersonic Internal Flow and its Suppressing Method

（1）激波与湍流边界层相互作用，在超音速管道内形成激波串和伪激波。通过数值模拟和实验研究了激波串和伪激波的三维流动结构，揭示了复杂的激波结构。（2）用高速摄影结合纹影法对二维跨音速扩压器内产生的多道小激波进行了观测，并记录了每道小激波的运动。将实验结果与假设通道出口压力扰动为正弦函数的计算值进行了比较，实验结果与计算值吻合较好。（3）研究表明，当扰动幅值不大，普通激波下游通道的发散段较长时，出现了多激波斑图。（4）对二维超声速和跨声速扩压器内的自激激波振荡进行了实验研究。结果表明，在激波的中心附近产生了一个压力扰动，并向下游移动。在边界层变得高度湍流的下游区域，产生另一个扰动并引起激波振荡。

(1)Shock trains and pseudo-shocks have been formed insupersonic internal duct flows due to the interaction between a normal shock wave and a turbulent boundary layer. The three dimensional flow structure of the shock trains and pseudo-shocks has been investigated numerically and experimentally, and the complicated shock structure was made clear.(2)Multiple shocklets generated in a two-dimensional transonic diffuser was observed with a high speed camera combined with schlieren method, and the motions of each shock wave have been recorded. The experimental results were compared with the calculated values assuming a pressure disturbance given by the sine function at the channel exit, and it is shown that the experiments agree well with the calculated results.(3)From the above study, it is concluded that the multiple shocklet pattern appears when the amplitude of disturbance is not large and the diverging part of the channel downstream of the ordinary shock wave is long.(4)The self-excited shock wave oscillation in two-dimensional supersonic and transonic diffusers was investigated experimentally. The results show that a pressure disturbance is generated near the stem of the shock wave and it moves downstream. In the downstream region where the boundary layer becomes highly turbulent, another disturbance is generated and it causes the shock wave oscillation.