大内收缩比二元高超声速进气道波系配置特性

Shocks Arrangement of Ramp Compression Hypersonic Inlet with High Internal Contraction Ratio

关键词:  超燃冲压发动机  二元高超声速进气道  波系配置  附面层抽吸

Key words:  Scramjet  Ramp compression hypersonic inlet  Shocks arrangement  Boundary layer bleeding

摘要:

为了发展适应宽飞行范围的高超声速二元进气道设计技术,考察了内收缩比对进气道特性的影响规律,并提出了结合附面层抽吸辅助自起动的大内收缩比进气道波系设计方法,改善了二元进气道低马赫条件下流量捕获低的弱点。研究发现,存在着设计点推力最优进气道内收缩比,而进气道非设计点流量系数随内收缩比而增大。基于最优内收缩比进气道构型,取消外压激波封口约束,通过局部等熵压缩波分散打进内收缩段内部,大幅提高了进气道低马赫流量捕获。并进一步通过合理配置内收缩段抽吸槽,以设计点(马赫6)1%,非设计点(马赫4)3%的流量损失使进气道自起动马赫数降到3.35,改善了内收缩比过大导致的自起动问题。 

Abstract:

The paper presents the shocks arrangement of ramp compression hypersonic inlet with fixed geometry within a range of flight Mach number. The effect of internal contraction ratio was studied based on the inlet optimization design with the objective of scramjet thrust. The design methods for the inlet shocks and bleeding slots were then developed. The result reveals that an optimal inlet internal contraction ratio exists for on-design engine thrust, while the pressure ratio and mass flow capture on off-design condition increase with the internal contraction ratio. An oblique shock can be replaced by isentropic compression waves impinging into the internal duct without focus, which cancels the restriction of shock-on-lip. This modification would dramatically improve the inlet mass capture on off-design point. Moreover, the rational bleeding is proven to be viable for inlet starting, which reduced the inlet self-starting Mach number to 3.35 with a little mass loss. 