Compressible streamwise vortices under adverse pressure gradients

Tip vortices appear under various circumstances such as tip leakage in turbomachines, vortex generators, and aircraft engines. In flows that have a high enough swirl and a large enough adverse pressure gradient, the vortex can become unstable and begin to breakdown. This breakdown could contribute to adverse effects such as the loss of lift, nonoptimal flow structures to other aerodynamic components, or to decreased efficiencies within a turbomachine. However, the sensitivity of a vortex experiencing compressible transonic flow under various Mach numbers, Reynolds numbers, pressure gradients, and free stream turbulence is unknown. In this study, a vortex will be analyzed between a freestream velocity of Mach 0.3 and 0.9 and under a variety of Reynolds number and pressure gradients to study the resulting behavior of the vortex. Computational Fluid Dynamics using Reynolds-Averaged Navier-Stokes will be used to gauge an estimated behavior of the vortex under these flows. Select flows were run through a Detached Eddy Simulation model to gauge differences in unsteady behavior. The unsteady simulations predicted vortex breakdown in both the zero and adverse pressure gradient cases while the steady simulations predicted no vortex breakdown of the zero pressure gradient cases. A future study will involve particle image velocimetry within a custom designed test section to experimentally capture the flow field of the vortex.