In Silico Analysis of Film Cooling in Aerospike Nozzles for Improved Thermal Management and Thrust Efficiency

Aerospike nozzles, with their inherent altitude-compensating performance, are strong candidates for next-generation reusable rocket engines. However, the extreme thermal loads on the spike surface present significant design challenges, particularly under high-thrust operational conditions. This study presents a high-fidelity computational investigation into film cooling strategies for annular aerospike nozzles, emphasizing the interplay between thermal protection, aerodynamic stability, and thrust performance. Using a density-based in silico solver coupled with species transport models, simulations were conducted for hydrogen coolant injection velocities of 0, 100, and 200 m/s. In the absence of cooling, spike wall temperatures exceeded 3800 K, highlighting the severity of thermal loading. At 100 m/s coolant injection, wall temperatures were reduced by over 50% with minimal performance penalties, while injection at 200 m/s achieved >80% temperature reduction but at the cost of significant thrust losses due to coolant-exhaust interaction, flow divergence, and shock-induced instability. Detailed analysis of skin friction and velocity contours revealed that excessive coolant velocities degrade film stability downstream, adversely impacting propulsion efficiency. An injection velocity of 100 m/s emerged as the optimal balance between thermal relief and thrust preservation. These results offer valuable design guidelines for incorporating film cooling in aerospike systems, particularly where regenerative cooling is constrained. The study further identifies opportunities for hybrid cooling approaches, adaptive injection control, and experimental validation under realistic mission profiles to advance reusable propulsion architectures.