Static and Dynamic Calibration of Propeller Model Fluctuating Force Balances
DAVID W TAYLOR NAVAL SHIP RESEARCH AND DEVELOPMENT CENTER BETHESDA MD BETHESDA United States
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Balance systems and techniques for model-scale measurement of up to six components of the fluctuating propeller forces produced by nonuniform inflow conditions were developed. Balances which achieve a broad nonresonant measuring range along with high signal to noise ratio were developed with two degrees of freedom mechanical designs. Analytic methods employing lumped mass and spring and estimated damping representations have aided in balance design. Devices and methods for statically and dynamically calibrating these balances so that accurate relationships between balance signals and actual propeller forces are described. A dynamic calibration procedure utilizing small electromechanical force inducers attached in place of the test propeller on the rotating balance shaft is used to determine the frequency response of each of the balances force transducers. Interaction effects on transducer signals of force components produced in planes other than the principal transducer plane are small on the latest balance designs. Although relatively satisfactory calibrations were achieved to date with this scheme, improvements in monitoring amplitude and phase of calibrator input forces should be pursued to assure maximum accuracy in calibration.
- Marine Engineering
- Test Facilities, Equipment and Methods