Numerical study of heat transfer enhancement in regenerative cooling channels with symmetric truncated ribs

Regenerative cooling using hydrocarbon fuels is essential for the thermal protection of hypersonic vehicles. However, the heat transfer deterioration (HTD) severely compromises cooling efficiency. Although micro-ribs have been extensively investigated to suppress HTD, the synergistic coupling mechanism between the intensity and spatial structure of secondary flow still remains unclear. This study performed a systematic numerical investigation on the heat transfer characteristics of n-decane in four channels featuring symmetrical truncated rib arrangements (T-, P-, A-, and V-type). Quantitative analysis of normalized secondary flow intensity (Se/Se0) and integrated heat transfer factor (η) reveals that the synergistic coupling of intensity and spatial structure of secondary flow determines the heat transfer efficiency. The V-type arrangement shows the best performance with a pronounced wall-directed flow structure. It reduces the maximum wall temperature by 22% and increases the average Nu by 111% compared to the smooth channel under the reference condition of Re=3230 , and over the investigated Reynolds numbers, the maximum η reaches about 1.80 at Re=6460. In addition, although the P-type arrangement exhibits a lower secondary flow intensity than the A-type arrangement, its unique biased flow structure successfully compensates for this drawback, resulting in similar heat transfer efficiency. This study provides a theoretical foundation for the topology optimization of ribbed channels for regenerative cooling.