Three-Dimensional Structure of Transonic Shear Flow Interacting with Shock Wave

发展了一种激光诱导荧光(LIF)方法来测量与激波相互作用的跨音速剪切流的三维结构和非定常行为。它被应用于激波/边界层和激波/自由剪切层相互作用问题的流动测量。对LIF方法得到的干扰问题的详细数据进行了分析，并与数值模拟进行了比较，以研究跨音速剪切流与激波干扰的非定常三维行为。结果表明：利用基于LIF方法的三维流量测量系统测量了后掠跨声速管道内流场的三维温度分布，揭示了三维激波/边界层相互作用场中高度复杂的流动结构，包括后掠碰撞诱导的三维激波形态、管道壁面激波反射形式和壁面边界层分离结构。结果表明，该测量系统为三维跨音速切变流与激波干扰的诊断提供了有力的诊断工具。将LIF方法应用于超音速空腔流中激波/自由剪切层干扰的非定常三维流动测量。从时均温度和温度脉动的三维分布可以清楚地了解干扰区内的流动现象，即与空腔前缘分离的剪切层、空腔后缘的分离激波和空腔内的旋涡结构。在超音速空腔内发现了三种不同类型的自持流动振荡。

A laser-induced fluorescence (LIF) method has been developed to measure three-dimensional structure and unsteady behavior of transonic shear flows interacting with shock waves. It was applied to flow measurements for the shock-wave/boundary-layr and shock-wave/free-shear-layr interaction problems. Detailed data on the interaction problems obtained by the LIF method were analyzed and compared with numerical simulations to investigate the unsteady three-dimensional behavior of the transonic shear flows interacting with shock waves. As a result, the following conclusions can be drawn :From a three-dimensional temperature distribution measured in a transonic duct flow field with a swept-back bump using a three-dimensional flow measurement system based on the LIF method, highly complicated flow structure in the three-dimensional shock-wave/boundary-layr interaction field was clarified including three-dimensional shock pattern induced by the swept-back bump, shock reflection form on duct walls and flow separation structure in wall boundary layres. It was found that the present measuremennt system offered a powerful diagnoxtic tool for the three-dimensional transonic shear flow interacting with shock waves.The LIF method was applied to an unsteady three-dimensional flow measurement for the shock-wave/free-shear-layr interaction in a supersonic cavity flow. The flow phenomena in the interaction field, namely shear layr separated from the cavity leading edge, detached shock wave at the cabity trailing edge and vortex structure in the cavity were made clear from three-dimensional distributions of time-averaged temperature and temperature fluctuation. Three different types of self-sustained flow oscillation in the supersonic cavity were found out.