CFD Analysis of Single and Double Cavity Based Scramjet Combustion with Front Ramp Angle at Mach 2

Modern high speed aerospace propulsion relies on the development of scramjet engines significantly. Design of a supersonic combustor involves the potential problems of proper mixing, flame holding as well as flame stabilization within the very short period. Many techniques were introduced to overcome these problems, of which cavity flame holders has evolved as one of the prominent among them. The presence of cavity forms a recirculation region inside the combustor, which enhances fuel-air mixing and flame holding. The aim of this paper is to analyze and compare cavities of L/D ratio 5 & 10 in single and double cavity configurations with a front ramp angle. The models were designed in ANSYS Design Modeler and the numerical simulation was done in ANSYS FLUENT 13.0 using the two dimensional density based energy equation and kε turbulence model. The contours of static pressure, static temperature, turbulence kinetic energy, total pressure and x-velocity are taken along the combustor length for comparison. Double and closed cavities were more efficient in terms of mixing and flame holding characteristics compared to the corresponding single and open cavities respectively though the total pressure losses are higher for the former models.