Analysis of thermal choking in expanding RBCC duct

Expanding combustor has been validated to realize the best performance of the RBCC engine which has several operating modes. But it is based on the implementation of thermal choking in the duct which was influenced by several factors including expanding angle, heating amount and heating rate etc. A theoretical one dimensional model was developed in this paper to describe the flow in an expanding duct. it is concluded by the one-dimensional analysis that the expanding angle, heating increment and heat release law are of crucial effect on the thermal choking. These factors mainly influence the position of choking throat, the total pressure loss and distribution of the temperature. In order to implement thermal choking in the duct, there must be a certain heat release law, heating increment and a special expanding angle which depends on the given heating law. In order to transit subsonic flow to supersonic flow in expanding duct, the heating rate should change from a bigger value to a smaller one.