流线追踪内转式低音爆进气道的设计方法及流动特征

Designing Method and Flow Characteristic of Streamline-Traced Inward-Turning Low-Boom Inlet

关键词:  音爆强度  曲内收缩流场  零度唇罩角  内转式低音爆进气道  流动特征

Key words:  Sonic boom  Curved generatrix internal flowfield  Zero-angle cowl  Inward-turning low-boom inlet  Flow characteristic

摘要:

为了降低内转式进气道的音爆强度，设计了一种具有曲内收缩前体和零度唇罩角的流线追踪内转式低音爆进气道，采用数值仿真方法初步研究其在不同工况下的流场结构和流动特征。结果表明：由于零度唇罩角，低音爆进气道的唇罩激波微弱，对唇罩外侧的流场影响较小，因此内转式低音爆进气道的音爆显著低于常规内转式进气道，其中在设计马赫数Ma_d=2.2通流状态下相比下降约94.18%；由于内唇罩面向内偏折，导致唇口反射激波强度增加，总压损失增加，内转式低音爆进气道总压恢复系数略低于常规内转式进气道；内转式低音爆进气道的音爆不但与其唇罩角有关，而且与其飞行工况有关，飞行攻角越大、来流马赫数Ma_∞<Ma_d越小，音爆越大；其中，在攻角α=0°时，其音爆比α=6°时减小约86.69%；在Ma_∞=2.2时，其音爆比Ma_∞=1.85下减小约91.93%。

Abstract:

In order to reduce the sonic boom， a streamline-traced inward-turning low-boom inlet was designed， which features curved generatrix internal flowfield and zero-angle cowl. The flow field structure and flow characteristics of the inlet under different operating conditions were studied by numerical simulation. The results show that the shock wave is weak and has little effect on the flow field of cowl exterior due to the zero-angle cowl， and the sonic boom of the inward-turning low-boom inlet is significantly lower than that of the conventional inward-turning inlet， which is about 94.18% lower than that of fully opened state with design Mach number. The reflection shock wave intensity of the inner lip increases due to the cowl internal surface and it results in the increase of the total pressure loss. Therefore， the total pressure recovery coefficient of the inward-turning low-boom inlet is slightly lower than that of the conventional inward-turning inlet. Except for the angle of attack， the sonic boom of the inward-tuning low-boom inlet is associated with the operating conditions with the larger degree of the angle of attack or the lower freestream Mach number（Ma_∞<Ma_d）. The sonic boom of 0°angle of attack is reduced by about 86.69%， compared with the 6°angle of attack. The sonic boom of Ma_∞=2.2 is decreased by about 91.93%， compared to Ma_∞ =1.85.