Effect of a gas flow structure in an axisymmetric channel on the inhomogeneous temperature field formation in a low-melting cylinder

This paper presents a study of the interaction between high-speed airflow and the surface of a solid low-melting material in a flowing channel of a model body. Both numerical and experimental approaches are used to solve the problem, which allows one to perform a comprehensive analysis of the processes under study.
Numerical simulation conditions correspond to aerodynamic tests in the experimental facility. The unsteady Reynolds-averaged Navier-Stokes (URANS) equations are used to describe a gas flow. When solving the problem, the coupled heat-transfer and turbulence are taken into account. The low-temperature gas-dynamic processes are considered, while the chemical reactions and phase transition are neglected.
As a result of numerical simulations, the flow structure and regime in a flowing channel of the model are determined, as well as the pressure and temperature distributions in the near-wall region of a solid combustible material. The gas flow regime corresponds to an underexpanded jet flow with the separation of the boundary layer and the formation of the intense heat-transfer regions at the initial section of the flowing channel. According to the numerical simulation results, in aerodynamic tests with a Mach number of 6, the melting point is attained in the near-wall region of the solid combustible material (polyethylene, polyoxymethylene, and wax). Aerodynamic tests are carried out to validate the obtained results. Experimental results show that the variation in the flowing channel diameter in the thick-wall cylinder made of polyethylene and polyoxymethylene is induced by thermal expansion. In aerodynamic tests with a wax cylinder, the mass reduction and the fusion of the solid-gas interface are revealed.