TABLE OF CONTENTS The design cruising speed of civil aircraft often falls within the transonic region, where the structural loads, and hence aeroelastic behaviour, are greatly affected by the presence and motion of shock waves. Hence, the accurate prediction of flutter characteristics of aerofoils in transonic flow is a critical design consideration for most modern civil and high performance aircraft.
In the pure subsonic or supersonic regimes, it has been a normal industry practice to use linear aerodynamic theory, such that the aerodynamic forces depend upon the body motion in linear fashion, thus permitting uncoupling of the structural and fluid equations (MacNeal Schwendler Corporation, 1995). However, this cannot be applied in the transonic regime due to the high non-linearity of the flow field. The aerofoil thickness was often neglected in linear theory, but the aerofoil geometry plays an important role in the development and motion of shock waves in the transonic region (Bland and Edwards, 1984). There are other non-linear phenomena associated with aeroelastics, for example, aileron buzz or limit cycle oscillations (LCO), and none of these phenomena can be predicted directly by traditional linear theoretical methods, since they are interactions between non-linear aerodynamic forces and structures. Hence, more advanced aeroelastic simulation methods, applicable to transonic flows, are essential.
Computational aeroelastics (and aeroservoelastics) often involves two computational models, namely independent aerodynamic and structural models. In the former, the aircraft surface and the surrounding flow field are discretised, before the governing fluid flow equations are solved. The latter involves solving the structural...
