Efficient Prediction of Aerodynamic Control Surface Responses Using the Linear Frequency Domain

Abstract

In modern aircraft design the accurate prediction of dynamic control surface deflections is crucial for the evaluation and application of new load alleviation techniques. Time-marching approaches, such as the unsteady Reynolds-averaged Navier–Stokes equations, do provide a complete modeling of the aerodynamic flowfield; however, they are extremely time-consuming and still too expensive for design applications. In this paper a model is presented, which enables the fast and accurate prediction of aerodynamic responses for arbitrary control surface deflections. The model hereby reflects the time signal of the control surface deflection as a superposition of frequency components and computes the dynamic response behavior of the control surface using the linear frequency domain. The frequency responses are precomputed in a surrogate model for a wide parameter space of Mach number, Reynolds number, angle of attack and flap chord ratio, so that a frequency response for a new flight condition can be computed by mere interpolation. After building the surrogate model, the method achieves reduction in computational time of up to six orders of magnitude in comparison to time-marching simulations, while still covering the viscous and unsteady aerodynamic effects in the flow.