A unified analysis of unsteady flow structures in a supersonic ramjet engine

An integrated numerical analysis has been conducted to study the internal flowfield in a ramjet engine. Emphasis is placed on the establishment of a unified numerical scheme capable of treating both the supersonic inlet diffuser and combustor flows. The theoretical model is based on the complete conservation equations of mass, momentum, energy, and species concentration, with consideration of finite-rate chemical reactions and variable properties. Turbulence closure is achieved using a low-Reynolds number ke two-equation model. Calculations have been carried out for the flowfield in a typical ramjet engine consisting of an axisymmetric mixed-compression supersonic inlet and a coaxial dump combustor. The mutual coupling between the inlet and combustor was carefully examined under various operating conditions. In particular, strong vortices arising from the inlet shock/shock and shock/boundary-layer interactions may convect downstream and affect the combustion dynamics. Large vortical motions, coupled with acoustic motions, were observed in the combustion chamber, which in turn modified the inlet flow structures.