Drag reduction and thermal protection efficiencies of combinational spike and opposing jet with different forebody geometries in hypersonic flows

The extreme aerodynamic heating and shock-dominated flow fields encountered during hypersonic flight present formidable challenges for vehicle integrity. To address these dual challenges, integrated aerodynamic solutions combining spike with opposing jet have been developed, with their efficacy in drag attenuation and thermal mitigation systematically validated through extensive computational and experimental investigations. Nevertheless, current research remains predominantly constrained to simplified hemisphere-cylinder configurations, limiting the generalizability of derived optimization strategies across diverse geometries. This study conducts a comprehensive numerical evaluation of six distinct geometries. The systematic analysis encompasses flow field modulation mechanisms, parametric dependencies on spike dimensions, and angle-of-attack effects on coupled aerodynamic-thermal performance. The results show that a significant geometric dependence exists in both drag reduction and thermal mitigation efficiencies of the combined configurations. Through the integrated application of spike and opposing jet configurations, maximum drag reduction (79.5 %) was achieved in hemisphere-cylinder models, while double-cone geometries exhibited optimal heat flux attenuation at 90.9 %. In contrast, the waverider configuration showed minimal performance improvements. Notable variations in recirculation zone morphology were observed with progressive elongation of the spike apparatus, accompanied by corresponding reductions in surface pressure distribution and thermal loading across all test configurations. Aerodynamic analysis revealed that incremental elevation of the angle of attack from 0° to 8° resulted in progressive augmentation of both drag forces and heat flux intensities. Nevertheless, the spike-jet combination maintained protection for conventional geometries in this angular range, except for the waverider configuration.