The effect of blade vibration on the unsteady forces developed by an elastic marine propeller is investigated for a controlled laboratory situation. The study involves the development of a theory for a flexible propeller operating in a spatially nonuniform inflow velocity field and a series of experimental tests. Measurements of unsteady propeller forces in a 24-inch water tunnel are presented for two model propellers whose fundamental resonance frequencies are excited by a nonuniform inflow field. Measured unsteady thrust and torque, presented as a function of excitation frequency, show distinctly different elastic effects - one propeller demonstrates a large force amplification near its resonance frequency while the other did not. The simple theoretical model explains the difference as being due to differing amounts of induced hydrodynamic damping; there is a large hydrodynamic damping in one case and a small amount in the other case. Another result of the study is that blade vibration can significantly reduce the unsteady forces transmitted to the propeller shaft over a certain range of excitation frequencies. Calculated forces are in general agreement with the experimental measurements. (de Posamentier)


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    Title :

    Vibrations of a marine propeller operating in a nonuniform inflow


    Additional title:

    Schwingungen eines Schiffspropellers bei unregelmaessiger Zustoemung


    Contributors:

    Publication date :

    1980


    Size :

    133 Seiten


    Type of media :

    Theses


    Type of material :

    Print


    Language :

    English





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