Abstract: The flow in the conical nozzle of Marseille shock tube tunnel (H₀=10.3MJ/kg) is computed by solving 2D-axisymmetric laminar Navier-Stokes equations. The numerical analysis includes computations assuming a chemical / thermal equilibrium, chemical nonequilibrium / themal equilibrium and chemical / thermal nonequilibrium nozzle expansions. The thermochemical nonequilibrium effects are discussed. The results of centerline translational -rotational temperature, vibrational temperature,Mach number, species mass fraction distributions and temperature and velocity transverse profiles near nozzle exit are presented. It is shown that the exit temperature can be increased when speeding up the chemical reaction process. The freezing of vibrational energy can result in a decrease of the exit temperature.

Key words: hypersonic nozzle, viscous flow, numerical simulation, 2D-axisymmetric Navier-Stokes equations, thermochemical nonequilibrium effect