The Effect of the Turbine Airfoil Shape on its Aerodynamic Damping

Designing the low pressure stages of large gas turbines requires extraordinary attention to account for aeroelastic phenomena and its mitigations. A very hazardous phenomenon is fl utter, a self-excited form of vibration, which is caused by fl uid energy transferred into the blade structure. To mitigate fl utter the designer can chose between aerodynamic and mechanical measures. The present work focus on the impact of the blade shape to modify the exciting unsteady pressure fi elds leading to fl utter. Analytical as well as numerical approaches are presented, which examine the link between steady aerodynamics and the vibration induced unsteady pressure. The results of these studies are used to derived guide lines for the design of high-performance airfoils with a reduced fl utter excitation and discussed in the last chapter.