Numerical investigation of a novel regenerative cooling channel for methane-fueled scramjet

The extreme heating loads in the scramjet thrust chamber and the limited coolant mass flow rate are obstacles to effective thermal performance. This study proposes a novel design for regenerative channels of methane-fueled scramjet engines to optimize thermal performance. Nine cases of semi-circular ribs with radius (0.1, 0.2, and 0.3 mm), rib pitch (12, 8, and 4 mm), and heat fluxes (2.5, 3.5, and 4.5 MW/m2) are analyzed numerically. Additionally, the boundary-layer properties of the methane-fueled channel were investigated over the heat-flux range. Results indicate that the implementation of semi-circular ribs significantly enhances coolant vorticity and mitigates thermal stratification. While the thermal boundary layer thickness in the smooth channel remains constant across heat fluxes from 2.5 to 4.5 MW/m2, the semi-circular ribs actively reduce this layer by intensifying near-wall vorticity, thereby optimizing convective heat transfer. Performance analysis shows that case 4 achieves a 28.5% improvement over the baseline at the lowest heat flux (2.5 MW/m2). Conversely, case 7 provides the peak thermal enhancement, outperforming the smooth channel by 30% at the highest flux of 4.5 MW/m2. Consequently, determining the optimal rib configuration necessitates a balance between manufacturing complexity and specific thermal dissipation requirements.