Numerical computation of a chemically non-equilibrium laminar boundary layer in an axially symmetric hypersonic jet at high air-braking temperature

Abstract

THE non-equilibrium boundary layer in a nozzle is considered in the case of air. The formation of five components is assumed as six, reactions occur simultaneously. Profiles of the gas-dynamic parameters are calculated, together with quantities characterizing the wall friction, the thickness of the displacement, and the thickness of the momentum loss. The paper presents computational results on a chemically non-equilibrium laminar boundary layer in a hypersonic jet with ideal conical contour when air flows in it with a braking temperature of 5500°K. The flows in the boundary layer and in the external stream are computed on the assumption that air is a five-component mixture, consisting of atoms of O and N, and molecules O 2, N 2 and NO. Numerical integration of the boundary layer equations was performed by computer for a jet with a cooled, non-catalytic wall. Velocity, temperature, and concentration profiles in the boundary layer were obtained, together with the values of C t ́ √/Re x 1 , ( δ ∗ x )√/Re x , ( δ ∗∗ x )√Re x , characterizing respectively the wall friction, the thickness of the displacement, and the thickness of the momentum loss. Computational data are compared for chemically non-equilibrium and equilibrium boundary layers in a jet with the same air-braking parameters. The complete and simplified expressions necessary for calculating the transport coefficients of multi-component gas mixtures are compared, and the results obtained from the two types of expression are found to be in good agreement over a wide temperature range.