Simulation of Unstart in Hypersonic Flow with a Dual-Mode Scramjet Model

Abstract

A validated model of hypersonic unstart will prove a valuable tool in diagnosing scramjet design issues and may provide a possible path towards preventing an unstart event in a scramjet. To this end, a computational model of an inlet-isolator was developed to study unstart. This model was compared to experimental data from the UT Austin Mach 5 Wind Tunnel and was shown to accurately reproduce both the fully started and unstarted inlet-isolator flowfields. The use of a body force rather than a moving mesh to initiate unstart is demonstrated, greatly reducing computational complexity to demonstrate unstart. The unstart shock and boundary layer interactions within this model are explored throughout the duration of the unstart process. Precursors to unstart are explored, specifically the wall pressures within the boundary layer, as the unstart system progresses upstream from its source.