| The purpose of the present work is to analyze the effects of viscosity in the Mechanical and Aerospace Engineering Undergraduate Laboratory shock tube at a pressure ratio (p4/p 1) of approximately 1.54. Ten tests were performed at this ratio to check for consistency in the system. The experimental results from this facility were compared with results obtained from the typical shock tube equations, as well as computer simulations in Matlab and GASP. Among these methods, GASP was the only one which took viscosity into consideration. Multiple simulations were run with this program to determine the appropriate grid size (coarse or fine), as well as compare the inviscid and viscous results. The other methods (theory and Matlab) assumed a one-dimensional inviscid flow for simplification of the computation. The results showed that all of the data from the latter three methods matched relatively well for the flow in the center of the shock tube. However, near the wall, the viscous GASP computation showed a variation in density, temperature, and velocity, while the others remained at a constant value. This is due to the no-slip boundary condition at the walls used for the viscous flow. By taking a specific point along the shock tube with viscous flow and comparing the velocity profiles from when the incident wave and when the reflected wave passes, it was discovered that a wall jet was created in the boundary layer. This jet moves in the opposite direction of the mainstream flow and at a much higher speed (more than 20 m/s greater).;Keywords: boundary layer, viscosity, shock tube, GASP... |
