Aerothermodynamic Analysis for Axisymmetric Projectiles at Supersonic/Hypersonic Speeds

Abstract

An aerothermodynamic design code for axisymmetric projectiles has been developed using a viscous-inviscid interaction scheme. Separate solution procedures for the inviscid and the viscous (boundary layer) fluid dynamic equations are coupled by an iterative solution procedure. Non-equilibrium, equilibrium and perfect gas boundary layer equations are included. The non-equilibrium gas boundary layer equations assume a binary mixture (two species; atoms and molecules) of chemically reacting perfect gases. Conservation equations for each species include finite reaction rates applicable to high temperature air. The equilibrium gas boundary layer equations assume infinite rate reactions, while the perfect gas equations assume no chemical reactions. Projectile near-wall and surface flow profiles (velocity, pressure, density, temperature and heat transfer) representing converged solutions to both the inviscid and viscous equations can be obtained in less than two minutes on minicomputers. A technique for computing local reverse flow regions is included. Computations for yawed projectiles are accomplished using a coordinate system transformation technique that is valid for small angle-of-attack. Computed surface pressure, heat transfer rates and aerodynamic forces and moments for 1.25 ≤ Mach No. ≤ 10.5 are compared to wind tunnel and free flight measurements on flat plate, blunt-cone, and projectile geometries such as a cone-cylinder-flare.