Computational Analysis of Flow Field Over Missile Separated from Weapon Bay Cavity at Mach 2 and 5

A parametric analysis was conducted to determine the flow over a missile released from the weapon bay cavity passing at a supersonic speed of Mach 2 in comparison with Mach 5. A weapon bay cavity with specified dimensions and a missile at 2.75m distance from bottom cavity wall was tested in compressible flow RANS solver. Detailed information of complicated aerodynamic characteristics like pressure variation, density variation and Mach number was obtained through CFD simulations to study the variation in flow physics over missile. Pressure fluctuation experienced by missile surface is plotted as coefficient of pressure (Cp) data over a missile kept in supersonic flow of Mach 2 and Mach 5. The flow is compared on the basis of flow interaction between shear layer at anterior edge of cavity and the leading-edge shock generated at nose of the missile body. As flow speed is decreased from Mach 5 to Mach 2, this flow interaction has minimal impact. In this paper, two-dimensional CFD simulations in ANSYS FLUENT are carried out on the missile body at an angle of attack of 0 degree 9and Mach number 2.00 and 5.00 with density-based solver, assuming the ideal gas conditions with k-ℰ turbulence model. The study indicates that with decrease in flow Mach number, the flow characteristics changes between cavity and upper surface of missile. The plot of pressure coefficient distribution over missile surface shows significant variation in flow between cavity and upper missile surface with change in freestream Mach number. Configuration moving at supersonic speed of Mach 2 has less concern with the flow interaction and is rather affected by the detached bow shock wave with higher flow turn angle. Due to the compressible behaviour of the flow, a Prandtl-Meyer expansion fan is observed at shoulder of missile nose tip and also at rear end of missile. The effect of flow interaction between the shear layer at front edge of cavity and system of shock wave is major contributor for change in aerodynamic characteristics for model moving at speed of Mach 5. While for Mach 2, strong detached bow shock wave at leading edge of missile is the primary reason.