Flow Characteristics and Heat Transfer of Supercritical n-decane in Novel Nested Channels for Scramjet Regenerative Cooling

A novel kind of regenerative cooling channel, a so-called nested channel, is proposed to further reduce the combustion chamber wall temperature of a scramjet. The supercritical n-decane heat transfer in the horizontal up-channel and horizontal down-channel with different flow directions are numerically investigated. The temperature distribution, flow field, and vortex structure are presented to discuss the thermal performance and flow characteristics. It is found that the nested channel with the same flow direction performs well particularly for the up-channel with the gravity direction points at the heated wall, and the vortices induced by the gravity are beneficial to the heat transfer performance. This feature is also confirmed by the Case B1 (up-channel, parallel-flow) with the n-decane flowing into the heated wall assisted by the nesting inner channel taking more heat away.