Computational Investigations and Control of Shock Interference

Computational fluid dynamics (CFD) has aided the development, design, and analysis of hypersonic air-breathing propulsion technologies, such as scramjets. The complex flow field in a scramjet isolator has been the subject of intense interest and study for several decades. Many features of this flow field also occur in supersonic wind tunnel nozzles and diffusers. Computational analysis of these topics has frequently provided immense insight into the actual functionality and performance. Research presented in this work supports scientific understand- ing of shock interference and passive control of the adverse effects of shock-wave boundary layer interaction to prevent onset of unstart in a scramjet isolator by computational investigations by using a backpressured isolator and a modified three-dimensional shock-tube to represent scramjet isolator with ram effects pro- vided by high-pressure gas and high-speed flow provided by a supersonic inflow. Computational results for the backpressured isolator have been validated against experimental data. In addition, the modified shock tube provided an opportunity to study the shock interference and shock-boundary layer interaction effects that would occur in a scramjet isolator or a ram-accelerator when the high speed flow from the inlet interacted with the shock produced due to the combustor pressure traveling and meeting in the isolator. An assessment of wall cooling effects on these phenomena is presented for both backpressured isolator and the modified shock-tube.