Supersonic Mixing and Combustion

Abstract

With the broad range of flying conditions in the hypersonic regime, the processes in the supersonic combustion chamber are subject to large thermodynamic condition variations. At the low range of the hypersonic flight regime, the heat deposition in the combustion chamber is relatively large compared with the incoming flow energy; hence, the heat deposition reduces substantially the air speed and a large pressure rise is experienced with possible flow separations. At the higher range of the hypersonic regime, close to Mach 25, which is considered the upper envelope of airbreathing propulsion, the heat addition may amount to only 10 % of the incoming airflow enthalpy. The heat release effects are less pronounced. The airspeed in the combustion chamber itself may be hypersonic and the heat deposition is distributed over a longer distance following mixing and chemical reactions. The pressure rise associated with combustion is less pronounced and is mostly due to the internal geometry of the combustion chamber. Throughout the flight domain there is a closed coupled interaction between fuel‐air mixing and heat release. In the following chapter, with the recognition that the two elements cannot realistically be uncoupled, a description of the salient features of mixing and combustion is presented.