Investigation of transonic flow over a bump: Base flow and control

In this paper, a combined experimental and numerical investigation of transonic shock wave/boundary layer interaction over a wall-mounted, circular-arc bump has been undertaken aiming to reveal information regarding the details of the flow and the capability of CFD in predicting such complex, yet fundamental, aerodynamic flows. CFD was first used in an attempt to establish the flow conditions and shape the upper wall of the wind tunnel so that a clear transonic interaction can be obtained. A set of measurements was then conducted to provide surface pressure and flow visualisation data. Numerical simulation of the flow using the URANS approach resulted in fair predictions for the averaged surface pressure, the separation and re-attachment locations and the overall flow topology. The unsteadiness of the flow was, however, under-estimated and for this reason, a coarse LES has also been performed. It was found that LES offered some improvements in predictions though further computations are needed in order to obtain quantitative agreement with the experiments. The data obtained from CFD and experiments resulted in a better understanding of the shock-boundary layer interaction flow. As a second step CFD was used to provide some insight into flow control ideas for this complex flow case