Experimental investigation of heat transfer and structure optimization for regenerative cooling channels using n-decane.

• Single-side heating condition in the experiment is realized by a graphite coating. • Symmetric and asymmetric heating exhibit similar Nusselt numbers. • The data of experiment and temperature prediction method are in good agreement. • The newly proposed optimization method can be used for structural optimization. Regenerative cooling technologies are considered one of the most effective and widely used active thermal protection methods for hypersonic aircraft scramjets. The heat transfer performance of hydrocarbon fuel and the geometric optimization of cooling channels are the key factors to be considered in designing regenerative cooling structures. Therefore, the present study experimentally and numerically investigated the heat transfer characteristics of n-decane in regenerative channels under asymmetric heating conditions and presented a new structure optimization method. The experiment was conducted at 3 MPa and 293 K with a mass flow rate of 0∼2.442 g/s per channel and a heat flux range of 0∼150 kW/m2. Experimental data show that the local Nusselt numbers exhibit a higher sensitivity to changes in mass flow rate compared to heat flux. Compared to symmetric heating, asymmetric heating mainly affects the heat conduction in the solid domain rather than the performance of convective heat transfer. The modified Dittus-Boelter correlation could predict the experimental data with a relative deviation of ±25 %. A rapid temperature prediction method based on heat flux distribution was proposed through heat transfer analysis, and it was utilized with a particle swarm optimization algorithm to conduct structure optimization. [ABSTRACT FROM AUTHOR]