RANS Predictions of Inlet/Isolator Unstart at Mach 4

This paper describes several approaches to back pressuring an inlet/isolator model at Mach 4.0 and the differences in unstart predictions using common RANS simulation methods. The CFD codes OVERFLOW and CREATE-AV Kestrel were used for this work. Verification and validation was conducted on a relevant shock-wave-boundary-layer-interaction case with both solvers. Using aftmounted back pressure flaps did not produce a stable pre-combustion shock train. An unstart comparison between CFD codes OVERFLOW and CREATE-AV Kestrel as well as common 2-equation turbulence models was conducted with numerical back pressure. Unstart predictions using a novel louver back pressure mechanism was done with OVERFLOW. There is notable differences in shock train travel and predicted unstart limit due to turbulence modeling, temporal resolution, and use of the 2D simplification.