马赫数可控的方转圆内收缩进气道非设计点工作特性

Off-design performance characteristics of inward turning inlet with rectangular-tocircular shape transition with controlled Mach number distribution

基于反正切马赫数分布的弥散反射激波中心体轴对称基准流场,设计了方转圆内收缩进气道,并对其进行风洞试验和数值仿真研究,获得该进气道非设计点(Ma=5.0和Ma=7.0)的工作特性和自起动特性。试验结果表明:进气道顶板压力分布具有反正切曲线特征,出口涡流区小且总体性能优良。Ma=5.0和Ma=7.0时出口总压恢复系数分别为0.647和0.443,对应的增压比分别为20.0和32.7。Ma=5.0时,进气道不但可以捕获约90%的自由来流,而且能够自起动(内收缩比高于Kantrowitz限制),下临界反压为64倍来流静压,对应的出口马赫数和总压恢复系数分别为1.32和0.409。上述结果表明,本文设计方法可以获得高性能的矩形转圆内收缩进气道。

Based on the axisymmetric basic flowfield of diffusing reflected shock center body with arc tangent Mach number distribution, an inward turning inlet with rectangular-to-circular shape transition is designed. Wind tunnel experiment and numerical simulation are conducted to obtain the off-design performance characteristics and self-starting characteristics. The experimental results indicate that the top wall pressure distribution is of arc tangent curve. The inlet has good overall per-formance and small vortex region at exit section. For Ma =5.0 and Ma =7.0, the total pressure recovery coefficient of exit section is 0. 647 and 0. 443, respectively, and the corresponding compression ratio is 20.0 and 32.7, respectively. For Ma = 5.0, the inlet could capture about 90 % of the free stream and self-start despite its internal contraction ratio being above the Kantrowitz limit; the lower critical back pressure of the inlet is about 64 times of the free stream static pressure, and the corresponding Mach number and total pressure recovery coefficient of exit section are 1.32 and 0. 409, respectively. The results demonstrate that high-performance inward turning inlets with rectangular-to-circular shape transition can be designed by the method proposed in this paper.