Abstract: In order to investigate the effects of strut angle on the rocket-based combined cycle engine (RBCC) inlet and optimize its design method， the numerical simulation was employed. The influence of various strut angles on the minimum length of internal compression section had been detailed. The numerical simulation presented herein demonstrated the influence of various strut angles on inlet flow field and performance quantitatively and qualitatively in typical conditions. The results show that the increase of the strut angle results in the decrease of the inlet length (the isolator length of Strut_2， Strut_3， Strut_4 and Strut_5 decreases by 47%， 62%， 70%， 75% when compared with Strut_1) and viscous drag force coefficient (the internal compression section viscous drag force coefficient of Strut_2， Strut_3， Strut_4 and Strut_5 decreases by 33%， 45%， 55%， 59% at [Ma∞]=1.5 and decreases by 37%， 50%， 57%， 61% at [Ma∞]=5.5 when compared with Strut_1). But no influence have been imposed on captured mass flow coefficient or flow uniformity. The inlet was optimized according to the preceded analysis in this paper， the starting performance and other performance parameters are improved effectively. The inlet internal drag coefficient decreases by 13.5% while the inlet external drag coefficient decreases by 5.7%. The total pressure recovery coefficient increases by 2.6% while the cycle static temperature ratio increases by 0.5%.

Key words: Rocket-based combined cycle；Inlet；Strut angle；Numerical simulation

摘要： 为研究中心支板顶角对火箭基组合循环发动机(Rocket Based Combined Cycle，RBCC)进气道的影响，优化RBCC进气道设计方法，利用数值模拟对RBCC进气道开展了研究。分析了中心支板顶角变化对进气道内压缩段最小长度的影响，通过数值模拟对中心支板顶角变化对典型工况下进气道的流场特征和性能影响开展了定量及定性的研究。研究结果表明，增加支板顶角可以减小进气道长度(相比于Strut_1，Strut_2至Strut_5的隔离段长度分别减少47%，62%，70%，75%)和粘性阻力系数(相比于Strut_1，在[Ma∞]=1.5时Strut_2至Strut_5内压缩段粘性阻力系数分别减少33%，45%，55%，59%；在[Ma∞]=5.5时Strut_2至Strut_5内压缩段粘性阻力系数分别减少37%，50%，57%和61%)，但并不影响进气道流量系数和流动均匀度。同时根据研究结果对进气道进行优化设计，能有效提高进气道的起动能力及其他性能参数，进气道的内、外压缩段阻力系数分别降低13.5%和5.7%，总压恢复系数和循环静温比分别提高2.6%和0.5%。

关键词: 火箭基组合循环发动机；进气道；中心支板顶角；数值模拟