Reduced order aerodynamics for delta wing pitching oscillations

An unsteady aerodynamic reduced order model (ROM) based on Volterra Series is presented to identify the aerodynamics of a pitching delta wing. The wavelet multi-resolution analysis is employed to truncate the identification parameters. The identifications of unsteady aerodynamics are carried out in various cases with different mean angles of attack and oscillation amplitude. The results show that the second order nonlinear component of the responses appears in the cases with larger mean angle of attack and/or oscillation amplitude. This nonlinear component suppresses the oscillation amplitude of the aerodynamic responses. The first-order ROM capture the linear component exactly, but have no identification ability for the nonlinear component. Comparatively, The second-order ROM is capable of recognizing both linear and the second-order nonlinear component and significantly improve the prediction accuracy of aerodynamics with higher mean angle of attack and larger oscillation amplitude. In addition, the wavelet multi-resolution analysis is helpful to obtain the low-order approximation of Volterra Series and reduces the algorithm complexity.