Heat Transfer and Thermophysics of Subsonic Dissociated-Air Jets in Flow past a Cylindrical Model in a High-Frequency Induction Plasmatron

Abstract

Heat transfer in the subsonic high-enthalpy air flow in the VGU-4 induction plasmatron is experimentally and numerically investigated for three versions of the sectional discharge channel with the exit section diameters of 30, 40, and 50 mm. The model was a flat-nosed cylinder, 20 mm in diameter. Using a Gamma code the enthalpy h_e and the velocity at the jet axis are numerically reconstructed from the experimental data. The method for approximately determine the enthalpy h_e on the basis of the experimental data and the Fay—Riddell formula for the heat flux is proposed. The effective dimensionless model radius r_eff is introduced, which makes it possible to take account for the dependence of the flow at the outer edge of the boundary layer on the model and discharge channel geometries and the plasmatron operation regime. The value of r_eff is calculated for the VGU-4 operation regimes with a simple cylindrical discharge channel and a sectional channel. The values of the enthalpy h_e calculated using the “exact” and approximate methods are compared: the greatest difference in the h_e values amounts to 6%.