Abstract: A kind of S-shaped inlet ingesting a large amount of freestream boundary layer was designed and numerically studied，then compared with the S-shaped inlet without boundary layer ingestion，in order to get its flow characteristics. Results indicate that the flow structure at the entrance is mainly influenced by the flow around blunted cowl body/boundary layer interaction，due to the boundary layer ingestion. In the diffuser，the secondary flow develops into a vortex-pair at the aft of the second bend. Then some fluid within the boundary layer accumulating at the bottom wall is pulled towards the core flow by the vortex-pair，which develops into a region of low total pressure recovery coefficient at the middle and bottom part of the exit plane. Besides，the boundary layer ingestion has the total pressure recovery coefficient reduced by 0.04. As the outlet Mach number increasing，the total pressure recovery coefficient increases at first and then declines，while it decreases monotonously in the S-shaped inlet without boundary layer ingestion.

Key words: Boundary layer ingestion inlet；S-shaped inlet；Flow characteristics；Secondary flow

摘要： 为了深入认识一种吸入大量来流边界层的S弯进气道，在完成其设计的基础上，采用仿真方法对其流动特性展开了研究，并与无边界层吸入的S弯进气道进行了对比。结果表明:由于吸入大量来流边界层，该进气道进口段流场主要受钝体绕流与平板边界层相互干扰作用；在内通道第二弯段后半段，二次流逐渐发展成为对涡，并将堆积在下壁面的低能流卷向截面中间，最终在出口截面的中下半部形成了低总压恢复区。另外，边界层的吸入使得进气道总压恢复系数下降约0.04，且随出口马赫数的升高，总压恢复系数先升高后降低，而在无边界层吸入的S弯进气道中总压恢复系数随之单调降低。

关键词: 边界层吸入式进气道；S弯进气道；流动特性；二次流