Numerical analysis of shock speed attenuation in expansion tube

Shock speed attenuation in the expansion tube HEK-X was numerically investigated by solving the axisymmetric compressible Navier-Stokes equation with an adaptive mesh refinement technique. The numerical simulation using a thermochemical nonequilibrium model as a real gas effect and the Baldwin-Lomax model was performed to assume a turbulent boundary layer. Numerical simulation results show good agreement with the analytical solution, and the shock speed of the numerical simulation with the Baldwin-Lomax model agrees with the experimental value at the acceleration tube of the expansion tube. It is found that the boundary layer plays a major role in attenuating the shock wave speed at the acceleration tube of the expansion tube in the same way as the shock tube.