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Browsing by Author "Killen, John"

Now showing 1 - 6 of 6
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    A Buoyancy-Propelled-Test-Body Laboratory Facility
    (St. Anthony Falls Hydraulic Laboratory, 1974-06) Killen, John
    The physical form of a buoyancy-propelled-test-body facility and some preliminary test results are described. The facility is a 26-meter-high, 1.067-meter-diameter standpipe which can be filled with water or other liquid. An axisymmetric body rises by buoyancy and is guided up the center on a taut restraining cable. Sensors for measurement of velocity and displacement are incorporated into the guide cable. The standpipe is also equipped to provide pull-down and release of the test body, initial acceleration, and stopping. The confined space of a standpipe within the laboratory permits controlled use of drag reducing polymer in the test liquid and nucleus removal to reduce cavitation. The minimal quantity of fluid in motion resulting from this configuration and consequent low level of background noise allow surface pressure fluctuations and radiated noise to be measured. Preliminary measurements of surface pressure fluctuations are reported. The potential of this apparatus for future use is outlined.
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    An Evaluation of Acoustic Techniques for Measuring Gas Bubble Size Distributions in Cavitation Research
    (St. Anthony Falls Laboratory, 1971-05) Schiebe, Frank R.; Killen, John
    The acoustic tone burst attenuation technique for measuring the gas bubble size distribution in water was critically reviewed. The findings reveal that the usefulness of the technique is limited to the bubble volume concentration range between 0.03 and 1.0 parts per million. Furthermore, resolution between size ranges is probably not possible with sufficient accuracy for many purposes.
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    A Feasibility Study of a Field Instrument for the Measurement of Suspended Sediment Concentration
    (St. Anthony Falls Hydraulic Laboratory, 1969-07) Killen, John
    A flow-through instrument system for measuring the concentration of suspended sediments in natural streams is described. The sediment concentration is inferred from the change in electrical resistance of the water due to the presence of sediment. The system appears adaptable to either field or laboratory use. The potentialities of the system have been explored; however, no specific instrument design has been proposed. The range of particle sizes that can be handled in the laboratory instrument is from 9 to 300 microns in diameter at concentrations from 25 to 10,000 ppm by volume. The system is unaffected by variations in temperature, salinity, and contaminants in the flow within practical limits. Conducting particles sometimes alter the calibration, but a separate calibration can be made for sediments containing known proportions of conducting particles.
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    The Influence of Drag Reducing Polymer Additives on Surface Pressure Fluctuations on Rough Surfaces
    (St. Anthony Falls Hydraulic Laboratory, 1971-09) Killen, John; Almo, John
    Experimental measurements were made to determine the effect of drag reducing polymer additives on the surface pressure fluctuations on smooth and rough surfaces in relative motion with water. Changes in surface pressure fluctuation intensity were found to be closely related to changes in surface shear when shear change was caused by the addition of drag reducing polymer, by a change in surface roughness, or by both of these.
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    The Influence of Drag Reducing Polymer on Radiated Noise from Rough Surfaces
    (St. Anthony Falls Hydraulic Laboratory, 1972-01) Killen, John
    Experimental measurements were made of radiated noise from a rough surface moving in water and from the same surface moving in a dilute water solution of a drag reducing polymer. Roughly 10 dB of noise reduction was observed for a concentration of 100 ppmw Polyox 301.
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    A Preliminary Report on the Zero-Crossing-Rate Technique for Average Shear Measurement in Flowing Fluid
    (St. Anthony Falls Laboratory, 1972-11) Wetzel, Joseph M.; Killen, John
    The characteristics of a flush-mounted hot film sensor were investigated in turbulent flows of both water and drag reducing polymer solutions in a 4-inch-diameter pipe. For water flows, a linear relationship was found between the average power supplied to the sensor and the cube root of the wall shear stress. With the addition of polymer additives, the heat transfer rates at a given shear stress were reduced from those found with water alone. Analysis of the heat transfer fluctuations occurring in various flow facilities has shown that the zero crossing rate is related to the wall shear stress and to fluid properties for water, polymer, and air flows. The zero crossing rate is not dependent on hot film sensitivity or contamination. Evaluations of the fluctuation microscale indicated that it had been increased by the addition of drag reducing polymer to the water. Autocorrelation measurements were made of the heat transfer fluctuations, but the limited data for the autocorrelations were not conclusive. Attempts to obtain cross-correlation coefficients between heat transfer and surface pressure fluctuations as measured with a small hydrophone were unsuccessful. The zero crossing rate of the surface pressure fluctuations was found to be related to the local wall shear stress.