A Study of Instability Phenomenon in a Supercritical Diffuser Flow

1.在总压比一定的情况下，超临界扩压器内激波的行为可分为绕平均激波位置的稳定振荡和在喉部下游产生激波并向上游运动的不稳定振荡.分析了激波与周期性低频下游压力扰动相互作用的稳定性准则，并将激波下游亚音速流的扩压器效率考虑在内.通过纹影光学方法和压力测量，实验研究了二维圆形扩压器中稳定和不稳定激波的行为.小振幅压力扰动相互作用引起的激波响应和后续运动是激波初始位置马赫数和激波下游亚音速区扩压器效率的函数.得到了扩压器效率与激波马赫数之间的中性稳定性关系曲线，表明该判据与现有的实验结果以及前人的实验结果吻合得很好。

1. The behavior of a shock wave in a supercritical diffuser under a constant overall pressure ratio is classified into a stable oscillation about its mean shock position and an unstable one where a shock wave is generated downstream of its throat and moves upstream and the cycle is repeated.2. An analysis of the stability criterion of a shock wave which interacts with periodic, lowfrequency downstream pressure disturbances has been performed taking the diffuser efficiency of the subsonic flow downstream of a shock wave into consideration.3. The behavior of stable and unstable shock waves in a two-dimensional circular diffuser has been experimentally clarified by a schlieren optical method and by pressure measurements.4. The response and subsequent motion of shock waves by the interaction of small-amplitude pressure disturbances are presended as a function of the Mach number where the shock is initially located and the diffuser efficiency of the subsonic region downstream of the shock.5. The curve of neutral stability which relates the diffuser efficiency to the Mach number of a shock wave is obtained and it is shown that the criterion agrees well with the present experimental results as well as with the previous experimental ones.