The Expanding Domain of Aeroelastic Simulation.

The impact of aeroelasticity and structural dynamics on the design of flight vehicles is apparent when considering the entire time- dependent environment in which these vehicles operate. Aircraft are subjected to maneouvre, gust, and landing loads, and must be freeof flutter and other aeroelastic instabilities throughout the flight envelope. Space vehicles are subjected to release transient loads and aeroacoustic loads at lift-off and must be free of control instabilities. Moreover, they must retarget rapidly and quickly settle from a vibratory condition to a quiet functional state. Rotorcraft, because of their highly-flexible rotating parts, are subjected to strong, periodically unsteady aerodynamic excitations, and also the bladings of advanced turbofan engines may strongly suffer from structural vibrations and aeroelastic instabilities. The ability to predict these effects - which belong to the coupled effects - is essential for the design of safe and economically viable high-performance flight vehicles of the future. In this keynote paper, as an introductory contribution to this Forum, current challenging problem areas in aeroelasticity which deal with coupled problems are pointed out and the impetus of unsteady computational aerodynamics in the development of advanced aeroelastic computational simulation is highlighted. The focus is primarily on aeroelasticity at transonic and separated flows and on computational methods aimed at the study of related unsteady airloads, typically referred to as Computational Fluid Dynamics (CFD)