Browsing by Author "Straub, Lorenz G."

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Effect of Inlet Design on Capacity of Culverts on Steep Slopes
(St. Anthony Falls Hydraulic Laboratory, 1954-04) Straub, Lorenz G.; Anderson, Alvin G.; Bowers, Charles E.
The geometry of the inlet has a significant bearing on the relationship headwater elevation and discharge for culverts with a free outlet. The relative importance of inlet design depends upon the location of the control section. The primary purpose of the research reported here was to examine the effect of inlet design upon the head-discharge curve of a model culvert. Two types of flush inlets, selected to represent extreme conditions for flush inlets, were tested--a square-edged inlet and a well rounded inlet. For each inlet the head-discharge curve was measured and the two curves compared. The comparison indicated that for certain conditions an appreciable head-advantage was gained by using a rounded inlet. Observation and analysis of the flow characteristics indicated that this gain phenomenon occurred in the region where for the same head a square-edged inlet caused separation and inhibited full flow, while the rounded inlet promoted full flow in the culvert with a corresponding increase in discharge. In connection with measurements to establish friction factors and entrance losses in the model culvert for use in the analysis of the experimental, a few behavior curves were determined. An analysis of behavior curves is included in Appendix IV. The results obtained were compared with experimental curves and other published curves.
Experimental Studies of Pneumatic and Hydraulic Break Waters
(St. Anthony Falls Hydraulic Laboratory, 1959-08) Straub, Lorenz G.; Bowers, C. E.; Tarapore, Zal S.
Experimental studies were conducted on two similar models of both pneumatic and hydraulic breakwaters, having a length ratio of 4.5:1. Tests of the pneumatic system indicated that the horsepower requirements for a given percentage of attenuation depended only on the wave length, the submergence of the manifold, and the depth of water. Multiple-manifold breakwaters with different spacings between manifolds were tried and found to be of no particular advantage over the one-manifold system. An intermittent bubbler device was also tested very briefly, showing very little difference from the one-manifold data. Tests of the hydraulic system indicated that power requirements varied with wave steepness as well as wave length. Orifice area was a very important parameter as this affected the discharge requirements and the required size of supply piping. The power requirements of the pneumatic system are somewhat less than the hydraulic for average values of wave steepness, but the maximum attenuation achieved was less than the hydraulic.
Hydraulic Data Comparison of Concrete and Corrugated Metal Culvert Pipes
(St. Anthony Falls Hydraulic Laboratory, 1950-07) Straub, Lorenz G.; Morris, Henry M.
Full-scale tests were conducted at the St. Anthony Falls Hydraulic Laboratory of the University of Minnesota primarily for the purpose of obtaining pipe friction and entrance loss coefficients for concrete and corrugated metal culvert pipes, which would be more accurate and dependable than those currently recommended in culvert design literature. Comparison of these test data is presented in this paper and recommendations are given for design values of the coefficients under various flow conditions. The experimental studies were made on new culverts, all of which were installed and maintained with excellent alignment. A high degree of accuracy was possible in these tests for all of the culverts. Sizes up to 3 ft in diameter were investigated. Analytical studies were made of the data obtained from the experimental observations which were significant to basic pipe flow theory where systematic form roughness and large diameters come into consideration.
Hydraulic Model Studies of St. Anthony Falls Spillway
(St. Anthony Falls Hydraulic Laboratory, 1952-08) Straub, Lorenz G.
In the spring of 1952, the maximum measured discharge of the Mississippi River occurred at the St. Anthony Falls Dam of the Northern States Power Company at Minneapolis, Minnesota. As a result of the high flow, considerable damage was done to the spillway surface and to the rock-filled crib supporting the structure. These model tests were initiated by the Northern States Power Company to determine a hydraulic design for a structure to replace the damaged spillway.
Hydraulic Tests on Concrete Culvert Pipes
(St. Anthony Falls Hydraulic Laboratory, 1950-07) Straub, Lorenz G.; Morris, Henry M.
Included in an experimental program conducted at the St. Anthony Falls Hydraulic Laboratory of the University of Minnesota on full-scale culverts was a series of tests on concrete pipes up to 3 ft in diameter. The primary purpose of these tests was to obtain pipe friction and entrance loss coefficients which would be more accurate and dependable than those currently recommended in culvert design literature. the studies were begun in 1946. This paper is confined to a discussion of the concrete culvert test program and the results of the studies. The test series included three concrete culvert pipes, 18 inches, 24 inches, and 36 inches in diameter, respectively. Each pipe was 193 ft long and laid on a slope of 0.20 per cent, except that the 24-in. pipe was on a slope of 0.224 per cent. the pipes tested were all manufactured by the cast-and-vibrated process. Details of the pipe sections are shown on page 22. Friction and entrance loss coefficients were established for the culverts under the usual conditions of field operations: (a) Full flow with submerged inlet and outlet. (b) Part-full flow at uniform depth. The 18-in. and 36-in. diameter pipes were tested for each of the two types of flow with two different entrance conditions; namely, (a) pipe projecting 2 ft into the headwater pool, (b) pipe entrance flush with the headwall. The 24-in. pipe was tested with the projecting entrance only.
Hydraulic Tests on Corrugated Metal Culvert Pipes
(St. Anthony Falls Hydraulic Laboratory, 1950-07) Straub, Lorenz G.; Morris, Henry M.
Experimental studies on culverts conducted at the St. Anthony Falls Hydraulic Laboratory of the University of Minnesota, beginning in 1946, included several series of observations on commercial , corrugated metal culvert pipes, The primary purpose of these large-scale tests was to obtain pipe friction and entrance loss coefficients which would be more accurate and dependable than those currently recommended in culvert design literature. A previous paper in this series gives a discussion of the comparison with the results of parallel studies on concrete culverts. The present paper is confined to a discussion of the corrugated pipe culvert test program and an analysis of the results of the studies. Two types of corrugated metal culverts were tested, namely, the circular and the pipe arch types. In each case, threee different nominal diameter pipe sections were tested--18 in., 24 in., and 36 in., respectively--, making a total of six corrugated metal culverts in the test program. Each pipe was 193 ft long and laid on a slope of 0.20 per cent. For the pipe arch culverts, the identifying dimensions refer to the diameters of circular pipes having the same length of periphery. For example, the 36-in. pipe arch and the 36-in. circular culvert have equal perimeters although their heights, widths, and areas are unequal. Cross sections of the various pipes, with controlling dimensions, appear in Fig. 1. (Note that the corrugation height in each case is 1/2 in. and that all computations have been based on the inside section, that is on the minimum cross-sectional area.) Friction and entrance loss coefficients were established for the culverts under the usual conditions of field operation. With this objective in view, each pipe was tested for the following conditions: (a) Full flow with submerged inlet and outlet. (b) Part-full flow at uniform depth. For each flow condition, several values of head and discharge were used. In addition, five of the culverts were tested with two different entrance conditions; namely, (a) Pipe projecting 2 ft into the headwater pool. (b) Pipe entrance flush with headwall.
Importance of Inlet Design on Culvert Capacity
(St. Anthony Falls Hydraulic Laboratory, 1953-01) Straub, Lorenz G.; Anderson, Alvin G.; Bowers, Charles E.
The design of a culvert inlet has a significant bearing upon the relationship of the head to the discharge of a culvert. Its relative importance hinges upon the type of flow occurring in the culvert, which in turn is governed by the location of the control section. For part-full flow the control may be either at the inlet or the outlet depending on whether the slope is hydraulically steep or mild. In the case of short culverts, control may be at the inlet even for horizontal or mild slopes. For full flow, barrel friction provides the control. The head-discharge curves of culverts having square-edge inlets have been compared with those for culverts having rounded inlets to illustrate the conditions for which a head-advantage may be obtained by using a rounded inlet. These comparisons have been made for three categories of culvert flow: long culverts on steep slopes, long culverts on mild slopes, and short culverts. Dimensionless head-discharge curves have been plotted for culvert flow in each category. For culverts on steep slopes, experimental data have been compared with the computed values and, since the agreement was reasonably good, serve as a basis for the analysis of flow in culverts operating under conditions other than those for which the tests were made. The greatest head-advantage for a particular discharge of the rounded inlet over that of a square-edge inlet was found for those cases in which the control section was located at the inlet. These were long culverts on steep slopes or short culverts where the length was negligible. for long culverts on mild slopes, the head-advantage was far less pronounced.
Lift and Drag on Surface-Peircing Dihedral Hydrofoils in Regular Waves
(St. Anthony Falls Laboratory, 1960-09) Straub, Lorenz G.; Schiebe, F. R.
Experimental measurements were made of the lift and drag of a restrained surface-piercing dihedral hydrofoil in regular head and following seas. Two velocities and a variety of wave lengths and amplitudes were used. The oscillatory lift was predicted with fair success using linearized theory as developed by Ogilvie. The experimental forces were observed to contain harmonic distortion, and comparison of the second harmonic component obtained from nonlinear quasi-steady theory indicated that the calculated values were too low. No theory was available for comparison with the oscillatory drag forces. Tests with a restrained tandem dihedral configuration in smooth water indicated that the performance ratio of the aft foil could be considerably increased for a particular separation of the foils. The optimum separation increased with increasing velocity. A brief series of tests were made in head seas using the optimum foil separation, and little difference between the tandem foils and single foil was noted for the oscillatory lift component.
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.
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.
Resistance to Flow in Two Types of Concrete Pipe
(St. Anthony Falls Hydraulic Laboratory, 1960-12) Straub, Lorenz G.; Bowers, Charles A.; Pilch, Meir
Experimental studies were performed on 24-in. and 36-in. concrete culvert pipe to determine the effect of interior surface finishes and joint irregularities on the frictional resistance of the pipe. Cast and vibrated pipe and machine-tamped pipe were used in the tests. The studies are grouped into several more or less related categories.
Self-Aerated Flow in Open Channels
(St. Anthony Falls Laboratory, 1960) Straub, Lorenz G.; Anderson, Alvin G.
Measurements of distribution of air concentration in self-aerated flows are presented. The experiments were made in a rough channel of sand-grain type surface at various slopes and discharges, and the data were used as a basis for study of the mechanism of entrainment of air and to relate the air content and distribution to the characteristics of the flow. The analysis of the data shows that the air distribution can be adequately described by relationships based on a simplified concept of turbulent transport and thus are functions of the flow characteristics. The maximum depth and the mean velocity are both shown to increase above those of a corresponding nonaerated flow.
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.
The St. Anthony Falls Multi-Purpose Test Channel
(St. Anthony Falls Hydraulic Laboratory, 1956-07) Straub, Lorenz G.; Bowers, C. E.
In its original concept the design of the St. Anthony Falls Hydraulic Laboratory provided for a Multi-Purpose Test Channel which would be a main feature of the gravity flow research facility on the Mississippi River at the Falls. This channel has been used for many test programs and has been progressively developed for a wider range of applications since the completion of the Laboratory structure in 1938. It is now approaching its ultimate development by the installation of towing facilities which are soon to be completed.
Velocity Measurement of Air-Water Mixtures
(St. Anthony Falls Hydraulic Laboratory, 1952-03) Straub, Lorenz G.; Killen, John M.; Lamb, Owen P.
A troublesome aspect of experimental studies of flow phenomena in air-water mixtures has long been that of making accurate velocity measurements. In the pas, bulk-flow measurements have been made variously with surface floats, injected dyes or salt clouds, and relationships between the discharge and depth of flow. Point measurements of velocity have been attempted by measuring stagnation pressures in the air-water mixture. These methods have not been of sufficient accuracy for many purposes. An instrument for making accurate point velocity measurements throughout a section of an aerated flow stream has been invented and developed at the St. Anthony Falls Hydraulic Laboratory. The transit time, between two fixed electrodes, of minute cloudlets of salt solution injected repetitively into the flowing air-water mixture is measured electronically. A rate of 15 injections per sec permits a direct measure of the mean flow velocity over a short stream filament. In the present form of the instrument, this mean velocity is indicated directly on a meter calibrated in feet per second. Measurements can be made in aerated flows with air concentrations exceeding 70 or 80 per cent and at very high velocities. Velocity measurements with the new velocity meter in nonaerated flows check within 1 or 2 per cent of those made with a Pitot tube. The integrated water discharge inan aerated flow stream, taking into account both the measured air distribution and the velocity distribution and making reasonable estimates of the water discharge through the boundary areas have also checked the water discharge through the boundary areas have also checked the water discharge measured directly with an accuracy of 1.5 per cent.

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Browsing by Author "Straub, Lorenz G."