LES of Impinging Jet Flows Relevant to Vertical Landing Aircraft

The flow-field due to multiple impinging jets from a vertical landing aircraft is highly complex and unsteady. The ability to predict both the mean flow and unsteady excursions is important for the design and development of future aircraft. A Large Eddy Simulation (LES) technique is used to compute two simplified twin impinging jet in cross flow problems. The LES solutions give good agreement with experiment and are a significant improvement over Reynolds Averaged Navier-Stokes solutions. The interaction of the wall jets to form an unsteady fountain that can sometimes reach the intake is observed. There is a disparity in time scales between that needed to resolve the smallest eddies and that for flow to travel through the domain, resulting in the computation needing a large number of time steps to achieve statistically meaningful results. The LES results indicate considerable promise for this type of flow problem, and work is underway to extend the application to full aircraft geometries.