Improved thermal performance of cooling channels with truncated ribs for a scramjet combustor fueled by endothermic hydrocarbon

In order to further improve the thermal performance of cooling channels for a scramjet combustor using endothermic hydrocarbon fuel, an array of truncated ribs with various pitches and heights is mounted on one wall. The turbulent flow characteristics and local heat transfer of the ribbed channels are numerically studied and analyzed in the non-chemical zone by a verified SST k-ω turbulence model under the studied Reynolds number ranging from 1800 to 3700. It is found that the quantity and the scope of vortex pairs are increased with increasing the ribs height, and that the velocity of the coolant near the bottom and the turbulence caused by the vortex pairs are the two main factors to affect the thermal transfer. Finally, the thermal performances under a considered range of the rib pitch-to-height ratio between 12.5 and 25 are carefully checked and evaluated. Compared with a cooling channel without truncated ribs at a heat flux of 2.0 MW/m2, the averaged temperature of the ribbed walls can be reduced by 390-511 K.