一种二元高超声速进气道起动特性的尺度效应研究

对一种二元混压式进气道三维流场进行了数值和实验考察,研究了不同尺度进气道模型自起动性能的变化。结果表明,在相同来流单位雷诺数条件下,随着模型尺度的减小,进气道自起动马赫数有所提高,起动性能有所降低。同时对不同尺度模型进行雷诺数匹配,发现在相同雷诺数下,不同尺度模型的起动性能相近,表明雷诺数是影响不同缩尺模型起动性能不同的主要原因。在可获得的实验结果范围内,数值模拟所得到的自起动结果基本与之相符。此外,对实验中发现在低雷诺数下进气道反而呈现出自起动特征的异常现象进行了初步分析,通过数值模拟比较指出了低雷诺数下来流偏向层流流态,可能会导致进气道呈现一种“起动”状态。

Scale effects on the starting characteristics of a 2D hypersonic inlet

A combined numerical and experimental investigation was carried out for the self-starting characteristics of a 2D hypersonic inlet,with a special focus on the comparison between different scale models.The numerical results show that the self-starting capability is decreased when the model scale is reduced under the same unit Reynolds number condition,during which the corresponding self-starting Mach number may go up remarkably.It was also found that the inlet flow behaves similarly when the Reynolds numbers are close to each other even though the model scales are different in size,which demonstrates that the Reynolds number is a dominant factor characterizing the flow field.The experimental results obtained within the capability of the in-hand shock tunnel show that the agreement with that of the CFD simulation is reasonable. Furthermore,a kind of unexpected“self-starting”configuration was also observed experimentally under very low Reynolds number condition.It is argued,with the help of numerical simulation, that laminar flow is favourable for the occurrence unusual “self-starting”whereas turbulent flow is the opposite,although the mechanism needs to be clarified in the future.