Design and Analysis of a Novel Cloverleaf Combustor for Scramjet Engine

In recent years, there has been an increased interest in the field of scramjet engine and its combustor design studies. Researchers started adopting several new technologies in fulfilling the design requirements of the combustor like mixing characteristics, shock elimination, low total pressure losses, high fuel penetration, and cooling. Among them, the shock eliminating capability and the total pressure losses are some of the key challenges. In this study, a novel idea of the cloverleaf-shaped combustor is proposed to eliminate both the shock and total pressure losses encountered in a scramjet combustor. A baseline circular combustor and the modified cloverleaf combustor have been numerically investigated at Mach 3 using density based K-ω SST (Shear Stress Transport) equations in CFD. The results show that the cloverleaf structure has the tendency to eliminate the shock formation in the combustor thereby helps reducing the total pressure losses incurred in the combustor. Moreover, the reason to use cloverleaf-structured combustor is twofold, one it reduces the shock formation and the other one it provides a 16.58% increase in the flow velocity at which the continuous stabilized combustion can be achieved. Additionally, attempts were made to identify the optimized number of cloverleaf structure by testing three cloverleaf structures to eight cloverleaf structures as briefly discussed.