NUMERICAL STUDY ON AERODYNAMIC FORCES ON H-SHAPE SECTION UNDER ASYMPTOTIC DIVERGENCE VIBRATION

This paper presents a numerical simulation of nonlinear aerodynamic forces on a H-shape section under an asymptotic divergence oscillation through the integration of computational fluid dynamics (CFD) and continuous wavelet transform (CWT). A H-shape section is forced in either torsional or vertical oscillation and the flow field is computed by using Reynolds-averaged Navier-Stokes (N-S) equations for two dimensional incompressible flow to obtain the aerodynamic forces on the H-shape section. A Renormalization group (RNG) k-ε turbulence model is used to simulate turbulence. The aerodynamic forces are analyzed by CWT based on complex Morlet wavelet. The ridge of the wavelet transform is searched by the snake penalization method. The instantaneous frequencies and amplitudes of the aerodynamic forces are obtained from the ridge. The study reveals that there are high-order harmonic aerodynamic forces of several times forced frequency and complex nonlinear relationship between instantaneous amplitudes of main frequency components of the aerodynamic forces and that of a forced oscillation when a H-shape section is forced in a large amplitude oscillation.