Browsing by Author "Olson, Reuben M."

Now showing 1 - 8 of 8
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    Cavitation Testing in Water Tunnels
    (St. Anthony Falls Hydraulic Laboratory, 1954-12) Olson, Reuben M.
    There are direct and indirect measurements reported in the literature which indicate boundary pressures in incipient-bubbling cavitation zones in water ranging as high as a foot or more of water above vapor pressure to below absolute zero (liquid tension). Tests have been conducted to study some of the factors believed to affect the cavitation susceptibility of water in a water tunnel and to determine if the use of a measured pressure instead of vapor pressure in computing the cavitation index would result in more consistent results in tests of incipient-bubbling cavitation on slender bodies. Factors studied included total gas content of the water, the free carbon dioxide, the nitrogen-oxygen ratio, changes in surface tension, colloidal solid nuclei added to the water, temperature, and velocity. The total gas content and temperature were the only known factors which changed the measured cavitation pressure significantly at a given velocity, although one or more unknown factors were effective since tests were seldom reproducible. Incipient cavitation tests of the tunnel test section, and of a 3- and 6-caliber ogive head form, indicated that the incipient cavitation index was more constant when based on a measured pressure than when based on the conventional vapor pressure.
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    Mississippi River Revetment Studies
    (St. Anthony Falls Hydraulic Laboratory, 1952-05) Straub, Lorenz G.; Olson, Reuben M.
    The initial studies conducted on articulated concrete revetment at the St. Anthony Falls Hydraulic Laboratory during 1950 and 1951 were made with a single layer of revetment. The present tests were conducted with a double layer of mattress, placed one on top the other so that the interstices between adjacent blocks were symmetrically staggered. Test runs were made over a 32-ft length of a full-scale double mattress installed over a 15-in. sand bed in a 9-ft test channel with water depths of 2.1 to 3.2 ft and mean velocities of 3.2 to 10.0 fps. Turbulence was induced into the flow stream to simulate the random pressure pulsations which have been measured in revetted areas in the Lower Mississippi River. Pressure measurements indicated that the pressures at the bottom surface of the lower layer of blocks and in the sand beneath them remained essentially constant and that the differential pressures across the double mattress essentially followed the pulsating pressures above the top layer. No underscour of sand was observed after a total of 18.7 hr of test runs at a mean flow velocity of 5-1/2 fps. Some underscour was observed during a similar test at 8-1/2 fps, although pockets scoured and refilled. No settling of the mattress took place. Noticeable underscour occurred during a 1.2-hr test at 10 fps; yet, again, no revetment settling occurred.
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    Mississippi River Revetment Studies
    (St. Anthony Falls Hydraulic Laboratory, 1951-06) Straub, Lorenz G.; Olson, Reuben M.
    Articulated concrete revetment mattresses have been and are being laid on the bed and banks of the Lower Mississippi River to stabilize bends and prevent recession of the banks. Exploratory experiments have been conducted at the St. Anthony Falls Hydraulic Laboratory to study some of the factors believed to contribute towards revetment instability and to explore the process of initial failure of the revetment as indicated by a movement or settling of the revetment mattress.
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    Model Studies of a Water Tunnel with an Air-Bubble Resorber
    (St. Anthony Falls Hydraulic Laboratory, 1952-02) Olson, Reuben M.
    It was proposed that an open- or closed-jet variable pressure water tunnel with an air-bubble resorber be constructed at the David Taylor Model Basin at Carderock, Maryland. This tunnel initially was to have a 36-in. diameter, cylindrical, closed-jet test section about 6.5 ft long and an alternate 36-in. diameter open-jet test section diverging to a 38.25-in. diameter over a length of 4.8 ft. These test sections were to be followed by a 7° conical diffuser, a vaned elbow, a second diffuser, a second elbow, the pump, a third 9° diffuser, a third elbow, an air-bubble resorber 25 ft in diameter and 70 ft high, a fourth vaned elbow, a honeycomb, and a 9-to-l contraction section [1]*. A tapered closed-jet test section was later considered.
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    Model Studies of a Water Tunnel with an Air-Bubble Resorber Supplement I
    (St. Anthony Falls Hydraulic Laboratory, 1952-06) Olson, Reuben M.
    The original closed-jet test section designed for use in a 36-in. water tunnel with an air-bubble resorber was cylindrical and 2.18 diameters long. It was followed by a parabolic transition, 0.5 diameter long, to the 7 degree diffuser cone. The effect of diverging test section with a longer diffuser transition in decreasing the pressure gradients and, as a result, lowering the cavitation indices attainable is discussed in this report. Tests on a one-sixth scale model and analyses indicate that a test section diverging at a total angle of about 0 degrees 9.6' would be expected to have an essentially constant core pressure throughout the length of the test section. This divergence angle followed by a nearly 1-diameter transition should result in a test section which can be operated at cavitation indices as low as 0.025 or 0.030 at velocities of 84.5 fps.
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    Pulp, Paper, and Insulation Mill Waste Analysis
    (University of Minnesota, 1942-03-17) Rowley, Frank B.; Jordan, Richard C.; Olson, Reuben M.; Huettl, Richard F.
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    The Six-Inch Water Tunnel at the St. Anthony Falls Hydraulic Laboratory and Its Experimental Use in Cavitation Design Studies
    (St. Anthony Falls Hydraulic Laboratory, 1956-03) Straub, Lorenz G.; Ripken, John F; Olson, Reuben M.
    A recirculating model water tunnel has been devised at the St. Anthony Hydraulic Laboratory for the purpose of determining prototype design data for use in the planning of various types of cavitation test facilities. The test section of the model is 6 in. in diameter, and various boundary geometries have been studied in their relation to the test stream flow quality. Special emphasis has been given to the cavitation test limits imposed by the test section boundaries and various other tunnel components. This paper describes the basic tunnel, the critical cavitation tests made on the tunnel, and some cavitation studies made in the tunnel. Observations made on closed (cylindrical and diverging), open, and slotted0wall test sections are discussed. A minimum cavitation index of about 0.023 can be achieved in the diverging closed-jet test section at a velocity of 50 fps. Some cavitation studies indicate how the cavitation susceptibility of the tunnel water varies, and show that the critical cavitation index of a slender body is more constant when based on a measured pressure than when based on vapor pressure.
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    A Slotted-Wall Test Section for a Water Tunnel
    (St. Anthony Falls Hydraulic Laboratory, 1955-02) Olson, Reuben M.
    Studies have been under way at the St. Anthony Falls Hydraulic Laboratory to investigate the possibility of including an alternate slotted-wall test section in a proposed 36-in. water tunnel for the David Taylor Model Basin. The experimental program was conducted in a 6-in. model water tunnel previously used in design studies for the 36-in. tunnel, and in a 10-in. free-jet tunnel at the Laboratory. Tests were run on slotted-wall test sections 2.18 and 2.38 test-section diameters in length and indicated that perhaps 2.5 diameters would be the maximum length possible without altering the diffuser following the test section. Axial pressures uniform within 1/2 per cent of the free stream dynamic pressure were obtained for a length of 2 test-section diameters. Velocity profiles in the test section compared favorably with those for a closed-jet test section, being flat within 1 per cent over 90 per cent of the diameter in the upstream portion, and over 80 per cent in the downstream portion of the useful test-section length. It was estimated that the energy losses for this slotted-wall test section would be about 10 per cent greater than for the shorter open-jet test section which will be included in the 36-in. tunnel. The cavitation characteristics were not as good as those for an open-jet tunnel, incipient cavitation occurring at an index: of about 0.6 to 0.9; below 0.5 the reservoir chamber became cloudy. A minimum of optical distortion is expected to result if slots are omitted from the Slotted-wall cylinder near the axis on the viewing side and if flat windows are used for the reservoir barrel. Tests on a hemispherical-nosed body indicated that the 2.4-diameter length was shorter than would be desired for testing bodies whose diameters are one-third the test-section diameter and more than two or three body-diameters in length.