Browsing by Author "Olson, Reuben M."
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Item 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.Item 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.Item 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.