Scramjet performance for ideal combustion processes

Models used to analyse scramjet engine cycles are typically either very simple or focused on specific combustor geometries. This paper uses a quasi-one-dimensional, inviscid chemical equilibrium solver to examine scramjet engines defined by predetermined combustion processes. This solver is capable of rapidly analysing combustion processes without requiring predefined geometries and is validated against the Hyshot II flight experiment and a constant area combustor ground test. Combustion occurs using constant area, constant pressure, constant Mach number or constant temperature processes. Constant area combustion typically produces the highest specific impulse for given combustor entrance conditions. Maximum pressure and temperature limitations were introduced, and multiple engines with combinations of combustion process were examined. It was found that engines with a combination of all four combustion processes can have lower maximum values of pressure and temperature whilst maintaining high performance compared with constant area combustor engines.