Coupled Flight Simulator and CFD Calculations of Ship Airwake using Kestrel

The coherent vortical wakes of the flow past Navy ships can pose a flight risk to fixed and rotary wing aircraft landing on the deck. Safety can be greatly enhanced by using realistic flight simulators to train pilots. However, flight simulators typically use atmospheric models of turbulence that do not adequately represent the coherent wakes present near ships. Recently air wakes have been calculated using CFD and fed into flight simulators to enhance realism. However, this approach provides only one-way coupling, ignorning the effect of the aircraft on the airwake, such as the effect of the superstructure in modifying ground effect. Also the airwake’s effect on the air vehicle was necessarily a linear model based on a small number of discrete sample points around the aircraft. The current effort successfully couples the CFD solver, HPCMP CREATETM–AV Kestrel, to the U.S. Navy flight simulation executive, CASTLE, resulting in a fully coupled simulation of the rotorcraft and ship airwake. The primary means of coupling is through the rotor blade element model hosted within CASTLEand implemented as a force source in Kestrel. The aerodynamic forces are calculated by CASTLEbased on the Kestrel calculated velocities at the rotor. The coupling takes advantage of the modular nature of Kestrel, using a newly developed component that communicates through named pipes with CASTLE. The paper will present a fully coupled hover case, compared to CASTLE-only simulations, bladeelement momentum disk simulations, and resolved rotor blades to validate the rotor model. Additionally a forward flight case will be presented with the pilot model coupled. Finally, an approach to ship case will be examined.