Browsing by Author "Crist, Scott D."

Now showing 1 - 3 of 3
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    The Effect of Dilute Solutions of Drag Reducing Polymers on Radiated Flow Noise
    (St. Anthony Falls Laboratory, 1967-07) Killen, John M.; Crist, Scott D.
    The influence of a drag reducing polymer additive in water on radiated flow noise was experimentally determined. The test facility was a rotating cylinder mounted in the center of a large cylindrical tank which served as an echoic chamber for the sound power measurements. Sound power radiated from the boundary layer of the rotating cylinder was measured for concentrations of 0, 10, 100, and 1000 ppmw of Polyox WSR 301 dissolved in the water. Sound power reductions greater than 20 decibels were noted in a frequency range of 20 to 100 kHz for a concentration of 1000 ppmw. Little influence could be found in a frequency range of 1 to 20 kHz. The effect of polymer additive on the drag coefficient of a rotating cylinder is also shown.
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    A New Facility for Evaluation of Materials Subject to Erosion and Cavitation Damage
    (St. Anthony Falls Laboratory, 1965-03) Ripken, John F.; Killen, John M.; Crist, Scott D.
    For nearly forty years various investigators have attempted to develop and routinely employ test procedures which would realistically evaluate the service resistance of fabricated materials exposed to erosion by water impact. These evaluations were necessary for the design selection of materials for steam turbine blades, for hydraulic machinery, and more recently for underwater ship appendages and for aircraft windshields.
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    A Study of the Influence of Microbubbles on Hydrodynamic Flow Noise
    (St. Anthony Falls Hydraulic Laboratory, 1966-04) Killen, John M.; Crist, Scott D.
    A test facility has been constructed for the measurement of flow noise generated by a rotating cylinder in water. Measurements were made of radiated flow noise in water for a frequency range of 5 to 80 kiloHertz. The surface velocities of the cylinder were varied from 44 to 100 fps. The total air content of the water was varied from 7 to 27 ppm. The radiated flow noise was observed to increase as the sixth power of the surface velocity for low frequencies. For high frequencies, the flow noise increased as the tenth power of the velocity. Release of air bubbles by shear had no effect on radiated flow noise other than to reduce the measured level of the noise.