A model of mode transition logic in dual-mode scramjet engines

Intricate process of mode transition exists in dual-mode scramjet engines, mainly amongst three typical operation modes (i.e., scramjet mode, ramjet mode and unstarted mode). Based on the analysis of an original analytical model, four transition boundaries are defined, and several corrections and considerations are carried out to clarify the way how to develop a model of mode transition logic. The complete mode transition logic is presented in a flowchart with a calculated case, and the corresponding implementation method for simulation is specified with programs in the paper. Combining the present mode transition logic unit with the original analytical parts, a dual-mode scramjet engine model for simulation, in which the inlet unstart issue is mainly caused by the interaction between thermodynamic effect and geometrical effect, could be acquired.