High Resolution CFD Simulations of Maneuvering Aircraft Using the CREATE-AV/Kestrel Solver

This paper discusses the evaluation of the high-fidelity CFD solver Kestrel to conduct time-accurate, rigid-body, prescribed-motion maneuvers on the F-16C and F-22 from an S&C perspective using computational fluid dynamics (CFD) run on DoD High Performance Computing (HPC) resources. The approach presented herein uses Kestrel to simulate the response of USAF fighter aircraft to prescribed motions, which are specifically designed to take full advantage of the unique capabilities of the CFD environment while minimizing the computational time. Two categories of rigid body, prescribed motion maneuvers are discussed. Flight test maneuvers were performed using both flight test data and maneuver response data from Lockheed Martin's 6-DOF and flying qualities simulation ATLAS. Non-flyable, computational training maneuvers designed to capture both static and dynamic aerodynamics as well as aiding discovery of envelope-limiting, nonlinear aerodynamic phenomena were simulated as forced rotational and/or translational oscillations about one or more axes. Nonlinear, reduced-order aerodynamic models of USAF fighter aircraft with and without stores have been generated through System Identification (SID) of the aforementioned computational training maneuvers. The resulting SID models showed good predictive capabilities when tested against the CFD training data, wind tunnel data, Lockheed Martin performance data, static, time-accurate CFD simulations and flight test maneuvers performed in CFD that were not used to create the models. The necessity of DoD HPC resources to support the USAF T&E community in gathering critical data in a timely manner to rapidly deliver capability to the warfighter is reaffirmed.