Numerical and Experimental Study of Vortex Induced Vibration on the Thin Symmetric Airfoils

摘要

In this paper, numerical and experimental schemes have been developed for the response of Vortex Induced Vibration (VTV) on the thin symmetric airfoil. VIV occurs where a bluff body interacts with a fluid flow. This phenomenon can be seen in many practical or industrial applications such as heat exchanger tube bundles, marine structures, power transmission lines and airfoils. Due to VTV, the structures could be subjected to very large transverse vibrations which may lead to fatigue failure. Both of methods that used in this research have been applied on the NACA0015 with various models, such as different stiffness, flow velocity and angle of attack. A numerical method, that using finite element based software ANSYS, modal and harmonic (3D) finite element analysis have been developed, is presented to study the VIV. Also experimental method is based on the image processing and direct measurement. The results show that, in VIV the response amplitude depends upon the initial condition. Also there is a frequency with large amplitude which is smaller than the shedding frequency. Therefore in transverse VIV, resonance of the frequency occurs with the 4 th sub harmonic of vortex shedding. This is an important issue in studying resonance.