Abstract: To investigate the operating characteristics of the inlet which is used in combined cycle engine at Mach 0 to 6， a three-channel over-under adjustable inward turning inlet was designed， in order to let the inlet adjust to the wide flight Mach number， the variable geometry design method was used in the top wall of the inward turning inlet， which can adjust the internal contraction ratio of inlet， it is beneficial to easily start the inlet at the lower Mach number and ensure that the inlet has superior performance at design point. Using three-dimensional numerical simulation method， the characteristics of the inlet with different back pressure was investigated at the transition state. The results of the investigation indicate that using the isolator back pressure or the turbine channel back pressure can internally redistribute mass flow and adjust the turbine distortion， when the back pressure of turbine channel increases， the mass flow rate and distortion of turbine channel will decrease， however， the mass flow rate of ramjet channel will increase， the maximum increase is about 23.3% of the original flow. When the isolator back pressure increases， the mass flow rate and distortion of turbine channel will increase， however， the mass flow rate of ramjet channel will decrease， the maximum decrease is about 29.3% of the original flow.

Key words: Combined cycle engine；Over-under；Adjustable inward turning inlet；Characteristics of back pressure；Numerical simulation

摘要： 为了研究工作马赫数范围Ma0～6的组合循环发动机进气道的工作特性，设计了一种三通道内并联型可调内转进气道，为了适应进气道能宽速域正常工作，在内转进气道的顶板压缩面上进行了变几何设计，可以调节进气道的内收缩比，兼顾了进气道低马赫数下的起动性能和高马赫数下气动性能。采用三维数值仿真的方法对进气道在过渡模态下的反压特性进行了分析研究。研究结果表明，可以通过改变隔离段反压或者涡轮通道反压的大小来调节两通道之间的流量分配和涡轮通道出口的稳态畸变；当增加涡轮通道反压时，涡轮通道的流量系数和稳态畸变会逐渐减小，而冲压通道的流量系数会逐渐增大，最大增加量约为原有流量的23.3%；当增加隔离段反压时，涡轮通道的流量系数和稳态畸变会逐渐增大，而冲压通道的流量系数会逐渐减小，最大减小量约为原有流量的29.3%。

关键词: 组合循环发动机 ；内并联型；可调内转进气道；反压特性；数值仿真