后掠激波边界层干扰的有利影响

Favorable influence of swept shock-boundary layer interactions

本文分析和对比了正激波和后掠激波/边界层干扰的机理,并用几个典型的算例说明了其差别。本文的结果指出,由于后掠的压力梯度方向垂直于激波,并且边界层内速度存在平行于激波的横向分量,会导致边界层内的速度分布形成空间"扭曲",可以阻止部分边界层进入激波后,并使穿过激波的部分边界层气流形成向两侧发散的趋势。这证明利用后掠激波/边界层干扰效应控制边界层是可行的。这也是实现近年来国内外兴起的"无隔道进气道"的关键机理之一。

Swept and normal shock-boundary layer interactions were compared. The interactional differences between several examples are shown and analyzed through the calculated results. The results show that, in the case of swept shock, the velocity vector profile is twisted due to the normal gradient of pressure and the tangent component of velocity. The twisted velocity vector profile forms a conic vortex along the intersection of the swept shock and the side wall. Some portion of boundary layer is involved in the conic vortex and cannot come through the shock. The stronger the conic vortex is, the less the portion of boundary layer part can comes through the shock. Even the small portion of boundary layer part that comes through the shock diverges to the outside due to the normal gradient of pressure and the tangent component of velocity. This leads to much thinner boundary layer after swept shock than that after normal shock. It is shown that swept shock-boundary layer interactions can be used to control boundary layer before inlet. Utilizing this mechanism, most of boundary layer can be get off without boundary layer diverter.