Flow and thermal analyses of supercritical hydrocarbon fuel in curved regenerative cooling channel around cavity in rocket based combined cycle engine

Various studies in straight channels have been investigated to promote the development of regenerative thermal protection technique. However, the combined effects of curved structure and pyrolytic reaction of hydrocarbon fuel have not been adequately investigated. In this article, the effects of inlet temperature, unilateral heat flux and pyrolytic reaction on flow and heat transfer processes in a 90° curved channel around cavity are numerically analyzed in fluid-solid coupled and uncoupled models, considering variable thermophysical properties and chemical components. Results show that there is strong secondary flow around the corner of cooling channel and the vortices form a heat transfer deterioration region at the center of bottom wall which results in transverse temperature difference. With increasing inlet temperature, the vortices magnitude is increasing and the transverse nonuniformity of temperature decreases by 60.3%. And when the inlet temperature reaches the value with maximum pyrolytic rate, the increasing heat flux is mostly taken by the pyrolysis reaction which results in insignificant changes of vortices magnitude. The pyrolysis reaction intensifies the stratifications of pressure and density, which correspondingly strengthens the magnification effect of vortices around the corner and decrease the transversal temperature difference.