Unsteady Aerodynamic Modeling of Aircraft Control Surfaces by Indicial Response Methods

摘要

This study is part of a larger effort to create reduced-order models for aerodynamic forces and moments acting on a maneuvering aircraft with moving control surfaces. The aircraft used in this study was inspired by the T-38 jet trainer and includes elevators, rudder, ailerons, and trailing-edge flaps on the wing for landing and takeoff. A hybrid unstructured overset mesh was generated to move these control surfaces and simulate the unsteady flowfields around the aircraft The static results are first compared to experimental data available at different flap deflection angles, with good agreement obtained at low to moderate angles of attack and deflection angles. Unsteady airloads predictions were then made using the indicial response methods and response functions due to step changes in control surface deflection angles. A time-dependent surrogate model was also used to approximate the response function variation with changes in the angle of attack. The model outputs were then compared with tune-accurate simulations of arbitrary control surface motions within the range of data used for model generation. Very good agreement was found between models and computational-fluid-dynamics data for low and high motion rates at low to moderate deflection angles. The results demonstrated that unsteady effects significantly change the amplitude and phase lags of predicted airloads compared with static (or steady-state) predictions.