A Parametric Survey of Hydrofoil Strut FlutterDavid W. Taylor Naval Ship Research and Development Center, Ship Performance Department, 1976 - 106 pages In order to explore the fundamental nature of hydrofoil flutter, a hydroelastic instability which is a potential cause of structural failure of lifting surfaces operating at high speeds in water, a series of hydrofoil models was tested in a towing basin. Flutter data were obtained from four surface-piercing hydrofoil strut models with various pod and foil configurations. Flutter occurred in two independent hydroelastic modes having predominantly first bending and first torsion mode shapes, respectively. The unstable modes were found to exist simultaneously in at least one strut. Flutter inception speed of the bending flutter mode was affected by strut submergence and the presence or absence of a foil. Flutter inception speed of the torsional flutter mode was dependent on strut cavitation pattern, strut submergence, pod moment of inertia, pod length, and the presence or absence of a foil. (Author). |
Expressions et termes fréquents
11 SPEED amplitude bending and torsional bending flutter mode bending flutter speed bending mode Beta with Blunt BLUNT BASE PROFILE Blunt Leading Edge chord damping and frequency DAMPING RATIO damping values decreased Experimental Fineness ratio Flutter Condition FLUTTER FREQUENCY Flutter inception speed flutter occurred flutter tested Frequencies for Model FREQUENCY f Hz Frequency of Oscillation Functions of Speed hydroelastic mode inertia lb-in Leading Edge Profile Mass Ratio measured mechanical impedance MODE 1 MODE Model 2T Model Alpha Model Beta moment of inertia NACA Nodal Lines Nondimensional Flutter Speed obtained oscillation Parameters Pod Configuration percent pod-foil potentiometers rapid sweep excitation RATIO Š Resonant Frequencies Second bending shown in Figure spectral analysis Speed for Model SPEED U KNOTS strut cavitation strut elastic axis strut models strut profile Strut Submergence Strut Submergence l/L Torsion Torsion Torsion torsional flutter mode torsional flutter speed visual analysis zero speed πρε