Abstract
This paper focuses on the coupling between the high fidelity aerodynamic model for the flow field and the modal analysis of a typical wing section to carry out flutter analysis. This coupled aeroelastic model is implemented in one of the most widely used open source CFD codes called OpenFOAM. The model is designed to calculate the structural displacement in the time domain based on the free vibration modes of the structure by constructing the numerical model directly from the modal analysis. Essentially a second order ordinary differential equation is solved for each mode as a function of the generalised coordinates. A density based solver using central difference scheme of Kurganov and Tadmor is used to model the flow field. Two main cases of transonic flow over NACA 64A010 are modelled for a forced pitching oscillation airfoil and a self-sustained aerofoil respectively. The self-sustained two degrees of freedom case is modelled for three different possibilities covering damped, neutral and divergent oscillations. Predicted results show very good agreement with the numerical and experimental data available in the literature.
Highlights
Aeroelasticity is the science of studying the interaction between three main forces namely; elastic, inertia and aerodynamics
The aeroelastic phenomenon, flutter is due to all three types of forces, namely elastic, inertia and aerodynamics
The complexity of flutter analysis arises from the fact that flutter involves very strong coupling between fluid mechanics and structural dynamics
Summary
Aeroelasticity is the science of studying the interaction between three main forces namely; elastic, inertia and aerodynamics. One of the most dangerous aeroelastic instabilities is, flutter It is a selfexcited oscillation of elastic body in fluid stream. This condition is usually defined by two important parameters namely the flutter speed and the flutter frequency. It means that if the aircraft flies at this speed it will have steady harmonic oscillation of constant amplitude This self-excited oscillation will have a frequency which is called the flutter frequency. This point is the most critical point because if for any reason, free stream velocity exceeds the flutter speed, the system will have divergent oscillation and will eventually vibrate in a violent way which could lead to the destruction of the aircraft. An accurate description of the flow field as well as structural dynamic behaviour together with a mechanism of coupling between the two is essential for flutter analysis
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