二元进气道非均匀超音来流试验研究

EXPERIMENTAL INVESTIGATION OF 2-D INLET MODEL IN NON-UNIFORM SUPERSONIC FLOW

关键词:  超音速进气道  非均匀流  激波-边界层干扰

Key words:  Supersonic inlet  Non-uniform flow  Shock wave boundary layer interaction

摘要:

介绍一种二元进气道模型在非均匀超音来流中的初步研究结果。试验在DLR小型超音风洞上进行。为造成非均匀来流条件,试验中将部分或全部试验段顶壁附面层引入进气道模型。结果表明,进气斜板产生的头激波与来流附面层相互作用的性状在不同的附面层隔道下变化极大。随隔道高度增加,激波附面层相互作用距离L起初亦增加,当全部附面层被排移后,L大幅度下降。与均匀来流试验结果相比较,当来流顶壁附面层全部被进气道吞入时,该进气道总压恢复σ及质量流率m分别降低18％及15％(M_∞=2.19),同时出口面总压畸变大幅度增加。文章分析了原因及对进气道性能影响的强度。

Abstract:

An experimental Study of a two dimensional inlet model in non-uniform supersonic flow are presented.The experiment were carried out at a nominel Mach number of 2.25 and 2.50 in the DLR’s small supersonic wind tunnel (KUG).The turbulent boundary layer in the top wall of the test Section was fully or partly swallowed by the test inlet model. In this way the influence of incoming flow non-uniformity on inlet performance was investigated. The results indicated that the ramp shock-boundary layer interaction was significantly affected by the behaviour of the boundary layer bleed gap and the flow non-uniformity in the entrance of the inlet model. With the increase of the boundary layer beed gap height, the shock-boundary layer interaction length L was increased at first, then droped rapidlywhen all of the boundary layer was bypassed through the bleed gap.In comparison with the baseline inlet which was operated at the condition of M = 2.25 uniform stream,the inlet stagnation pressure recovery factor & and inlet mass flow rates were reduced nearly 18% and 15% respectively when all of the incoming boundary layer was swallowed by the Inlet. At the same time> the stagnation pressure distortion D and the RMS deflection of the Mach number contour in the inlet measuring station were increased by live to seven times in comparison with that of the baseline inlet. It should be emphasized that the flow patterns in the boundary layer bleed gap had a non-negligible effect on the behaviour of the ramp shock-boundary layer intetract-ion and on the inlet performance. In the boundary layer bleed gap there were two kinds of flow patterns that were dominated by the bleed gap height. The first pattern was subsonic flow at the gap entrance and the second was supersonic entrance flow. The significant decrease of inlet performance was mainty due to the breathing of a low energy boundary layer flow into the test inlet.