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为了认识激波与转捩边界层之间的相互作用,选取压缩拐角模型为研究对象,在高超声速风洞中开展了激波/转捩边界层干扰试验研究。试验在FD-20炮风洞中进行,试验马赫数为8,雷诺数0.5×107~2×107/m。试验采用了薄膜电阻温度计和常规压力传感器,分别测量压缩拐角周围的热流和压力分布。根据干扰区上下游的边界层流态,将试验分为两部分:层流/湍流干扰和转捩/湍流干扰。对比分析了边界层转捩发生在干扰区时的热流分布、压力分布以及脉动热流的非定常特性。研究结果表明,激波/转捩边界层干扰的热流和压力分布特征,不同于常规的层流干扰和湍流干扰,其介于二者之间。层流/湍流干扰的热流和压力分布特征类似于层流干扰;转捩/湍流干扰的热流和压力分布特征类似于湍流干扰。互双谱分析结果表明,当边界层转捩发生在分离区时,转捩脉动与分离泡脉动同时出现并增长。当两者幅值足够大时,转捩脉动会与分离泡脉动发生非线性耦合作用。这种耦合作用会诱导出新的频率特征的脉动结构,从而使分离区内的脉动量显著增加。
In order to understand the interaction between the shock wave and the transitional boundary layer, the compression corner model was selected as the research object and the shock wave / transition boundary layer disturbance experiment was conducted in the hypersonic wind tunnel. The test was carried out in a FD-20 cannon-blasting tunnel with a Mach number of 8 and a Reynolds number of 0.5 × 107 to 2 × 107 / m. The test uses a thin-film resistance thermometer and a conventional pressure sensor to measure the heat flow and pressure distribution around the compressed corner, respectively. According to the boundary layer flow regimes upstream and downstream of the disturbance zone, the experiment is divided into two parts: laminar / turbulent disturbance and turbulence / turbulence disturbance. The heat flow distribution, pressure distribution and unsteady characteristics of pulsating heat flow in the transition zone are compared and analyzed. The results show that the heat flow and pressure distribution characteristics of the shock / transition boundary layer are different from the conventional laminar flow disturbance and turbulent flow disturbance, which lie in between. The laminar / turbulent disturbances have similar heat and pressure distribution characteristics as laminar flow disturbances; the turbulent flow and pressure distribution characteristics of turbulent / turbulent disturbances are similar to turbulent disturbances. Cross-bispectrum analysis showed that when the boundary layer transition occurs in the separation zone, the transitional pulse and the separate bubble pulse appear and grow at the same time. When both amplitudes are large enough, the transitional pulsation will have a nonlinear coupling with the separation bubble pulsation. This coupling induces a pulsating structure of new frequency characteristics, resulting in a significant increase in the amount of pulsation in the separation zone.