H型断面渐近发散振动气动力特征的数值模拟研究

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

基于计算流体动力学(CFD)数值模拟和连续小波变换的方法研究了渐近发散振动条件下H型断面的非线性气动力。采用二维非定常不可压缩雷诺平均N-S方程结合重整化群(RNG)k-湍流模型计算纯扭转或竖向渐近发散振动条件下的气动力。采用复Morlet小波对气动力进行连续小波变换,结合蛇形罚函数方法提取小波脊。由小波脊识别气动力的各瞬时频率及对应的瞬时振幅。研究表明:H型断面在大振幅振动条件下的气动力存在多倍于强迫振动频率的高次谐波,各频率成份的瞬时振幅与激励瞬时振幅间存在复杂的非线性关系。

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-e 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.