Numerical investigation on thermal behaviors of active-cooled strut in RBCC engine

•Numerical model coupling heat transfer in RBCC engine and strut is proposed.•Strut temperature is within the allowable range with current cooling structure.•Impingement flow enhances thermal efficiency at cost of huge pressure drop.•Strut manifold homogenizes flow velocity and lowers the strut temperature. Integrating strut ejector with air-breath engine is an effective method of enhancing fuel/air blend and combustion efficiency. In the present study, a stainless steel strut with active cooling structure is designed for thermal protection in severe combustor environment in Rocket Based Combined Cycle (RBCC) engine. The numerical model is proposed that conjugates turbulent combustion in thrust chamber and convective heat transfer in strut. The flow and thermal behaviors in the strut are evaluated under four mass flow rates of kerosene coolant at the flight condition of Mach 6. The numerical pressures are in good agreement with the experimental data. Results indicate that the strut temperature is maintained within the allowable limit with the designed cooling structure. The highest temperature (1100K) is discovered at the rear of the strut due to the high thermal resistance at the strut corner. The perturbation at leading edge and the flow separation at strut back lead to vorticity augmentation and velocity decrease at the vicinity of strut bound. Both coolant velocity and thermal efficiency increase in the manifold due to the sudden pressure drop at the manifold entrances.