Shock wave turbulent boundary layer interaction is a fundamental phenomenon observed in most of the gas dynamics applications such as wind tunnels, supersonic air intakes, transonic airfoil, nozzle flows, etc. The flow field and shock wave pattern in a constant area duct are analyzed experimentally. The focus of the present study is to present the time-resolved flow characteristics of the multiple shock waves and its oscillations. High-speed Schlieren flow visualization is used to capture the transient shock structure in the wind tunnel constant area test section. A gradient-based image processing was incorporated to capture the shock excursion details. Results indicate that the shock pattern is unsymmetrical in the flow field. The foot of the lambda shock wave in the upper and lower exhibit a difference in axial location and there is a large difference in this value at the mean position when the shock moves in the upstream direction compared to the downstream movement.