Parametric study of flow and heat transfer characteristics in a regenerative cooling channel with crescent-shaped ribs under non-uniform heat flux

• A parametric analysis of regenerative cooling channels with crescent-shaped ribs was performed. • Systematic analysis framework for flow and heat transfer mechanisms was established. • The heat transfer enhancement mechanisms of crescent-shaped ribs were analyzed. • The small-sized convex rib with a 60° angle achieves the best performance. • The channel increases the Nusselt number by 42.85% and reduces wall inhomogeneity by 25.89%. Regenerative cooling technology is key for scramjets to cope with extreme thermal loads during operation. Non-uniform heat flux, as an important feature of the propulsive combustion system, poses a serious challenge to the optimization of regenerative cooling. In this study, the flow and heat transfer characteristics in a regenerative cooling channel with crescent-shaped truncated ribs are investigated by means of the L-VEL model. The effects of the rib angle, rib opening orientation and size on the temperature distribution and flow behavior are analyzed. The mechanisms of high-efficiency heat transfer by modified crescent-shaped truncated ribs are comprehensively revealed. It is shown that non-uniform heat flux significantly exacerbates the thermal stratification and heat transfer deterioration (HTD). Concave ribs enhance heat transfer mainly through the higher flow velocity of coolant in the truncated slit and the fluid impingement effect in the front-end of ribs, while convex ribs enhance heat transfer mainly through the turbulence effect caused by vortices in the back-end of ribs. The rib with 60° rib angle, small size and convex structure enhanced the normalized average Nusselt number ( N u ‾ / N u 0 ) by 42.85% compared to the smooth channel, and improved the performance evaluation criterion (PEC) and thermal performance factor (TPF) by factors of 1.199 and 1.271, respectively. This configuration exhibited excellent temperature and buoyancy uniformity, heat transfer enhanced performance and low pressure drop, which outperforms other structural configurations in terms of overall thermal performance.