| Scramjet is an important propulsion device in the field of modern aviation.With the development of high ultrasonic technology,the compatibility of speed and stability has become an urgent technical problem for scramjet.In addition,some problems such as flow separation,aerodynamic thermal effect and flow internal resistance caused by the interference of shock wave/expansion wave in hypersonic speed have greatly reduced the performance of the engine.Therefore,it is very important to study the flow characteristic,mixing characteristic and combustion characteristic of scramjet deeply.In this paper,the cnr11-r36-plate jet scramjet jointly carried out by Japan space agency and France aerospace research institute was selected as the research object,and its flow characteristics and combustion characteristics were numerically calculated and analyzed based on Fluent ? commercial software.Based on the similarity principle,the open channel flow experimental platform is built to verify the numerical simulation results of cold flow field,which increases the reliability and credibility of numerical calculation.On this basis,the interference process and flow law of shock wave/boundary layer and shock wave/mixed layer under different inlet boundary conditions are analyzed.With the increase of inlet Mach number and total temperature of airflow,the shock wave Angle decreases,the adverse pressure gradient decreases and the flow separation phenomenon disappears gradually.For the mixing layer,the increase of inlet Mach number increases the shock wave intensity,and the reflected shock wave intensity also increases.The reflected shock wave/mixing layer interaction increases the mass,momentum and energy exchange among the fluids enhanced by local turbulence.Finally by changing the boundary conditions and equivalent ratio supersonic combustion characteristics is analyzed,the results show that the plate trailing edge to form recirculation and enhance the flame stability at low speed,with the increase of equivalence ratio at the same time,local lower oxygen content in the mixed gases,the resulting in a decline in the efficiency of the fuel,multi-step simplification reaction mechanism are adopted to simulate the supersonic combustion,small molecule primitive reaction can not be ignored,although initial release quantity of heat low but overall there are some error with the experiment effect is accord with the experiment. |
