Participant results from AIAA’s 5th Propulsion Aerodynamics Workshop inlet study are summarized.

What is it about?

The 5th AIAA Propulsion Aerodynamics Workshop (PAW5) was held as part of the Science and Technology Forum between January 9th-10th 2021. The workshop aimed to assess the current capabilities of computational fluid dynamics (CFD) tools to accurately predict complex flow phenomena relevant to the propulsion community. The inlet portion of PAW5 focused on an axisymmetric inlet in crossflow near a ground plane. Eleven participants presented their work for this portion of the workshop, which included results spanning 9 CFD solvers, 13 turbulence models, and 200 solution sets. Simulations were run for 3 crossflow velocities on 4 mesh refinement levels supplied by the PAW5 organizers and included meshes developed by participants themselves. In general, solvers matched test data at the lowest crossflow velocity favorably regardless of mesh refinement, turbulence model, or solver; though, two-equation turbulence models tended to match the distortion metric better than one-equation models. At higher crossflows, interactions between internal flow separation on the windward side of the inlet and the ingested ground vortex hindered accurate predictions by most solvers. Moving the outflow boundary further downstream improved comparisons for some simulations at the highest crossflow velocities, but additional studies are needed to ensure the test configuration is accurately represented.

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Photo by Jacek Dylag on Unsplash

Photo by Jacek Dylag on Unsplash

Why is it important?

When an aircraft is operating in static or near static conditions during taxiing or take-off a vortex can form between the ground and the intake. With engine diameters increasing, intakes are moving non-dimensionally closer to the ground and as a consequence the likelihood of vortex formation during the aircraft operating envelope is set to increase. To date there is little quantitative knowledge therefore a greater understanding is required. Accurately capturing this vortex ingestion under these types of crossflow conditions and predicting performance metrics of interest to the propulsion community is a challenging problem. Assessing the current capabilities of computational fluid dynamics (CFD) flow solvers and modeling techniques is important in order to determine best practices and pitfalls practitioners should leverage and be aware of when analyzing these types of flows.

Perspectives