Analysis of the interaction of a supersonic gas flow with a solid low melting polymer as a ramjet engine propellant

The performance of ramjet engines with a supersonic combustion is one of the main directions of hypersonic aircraft development research is studied. Researchers around the world create special experimental facilities for testing engine models, investigate fuels for ramjet engines and classify new scientific data. Since the ambient temperature and the oxidizer flow temperature in engine air duct are low at the flight altitude of a hypersonic aircraft, low melting materials can be used as a fuel agent in a solid propellant. The main purpose of this work is analysis of heat and mass exchange processes associated with the motion of a supersonic gas flow in an axisymmetric duct described as a combustion chamber of a ramjet engine with a solid polymer. The mathematical model of the problem consists of the unsteady Reynolds-averaged Navier–Stokes equations and the equations of a semiempirical turbulence model. The stated problem was solved by the finite volume method. Initial and boundary conditions are identical to experimental conditions and this makes it possible to verify the results of the numerical solution directly during aerodynamic tests. Gas dynamic parameters for the gas flow in an air duct of a ramjet engine are described, pressure profiles at the gas-solid interface are plotted, and a transient pressure behavior is considered. The results of the solution of a coupled heat transfer problem allow analyzing a dynamic heat exchange pattern in a solid polymeric material (caprolone, polyethylene and polyoxymethylene). It has been found that the effect of a supersonic flow on the surface of a low melting material within one second leads to temperature changes in a solid to a depth of 20% of its total thickness.