Browsing by Author "Bowers, Charles E."

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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.
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    Hydraulic Model Studies for Whiting Field Naval Air Station
    (St. Anthony Falls Hydraulic Laboratory, 1950-01) Bowers, Charles E.
    The Naval Auxiliary Air Station, Whiting Field, is to have a stormwater disposal system in which the existing pipes and terraces under and in the vicinity of the runways and building area will discharge into paved trapezoidal open channels. Many of the channels join other channels as they pass down the sides of the plateau on which the airfield is located. The grades of the main channels and of many of the lateral channels are such that water flows at supercritical velocities or at velocities greater than that of a gravity wave. The difficulties anticipated in joining two streams of water, one or more of which is flowing at supercritical velocities, led to the request for model studies of several of the channel junctions. The primary objectives in the present study include (1) the development of junction designs for specified operating conditions which would result in reasonably smooth flow downstream of the junction and (2) the determination of the necessary wall heights in the vicinity of the junction. Economic and structural considerations involved in the junction designs were considered in the final selection. Dependent upon the junction design, the discharges, velocities, and related phenomena of the flow in the vicinity of the junction, a hydraulic jump may form in one or both of the inlet channels. This may necessitate a large increase in the height of the sidewalls in the vicinity of the junction. On the other hand, if the flow passes through the junction at velocities greater than the critical, standing waves may form which have a height greatly in excess of a normal freeboard and which continue to oscillate back and forth across the channel for a considerable distance downstream from the junction before being damped by frictional forces. These standing waves necessitate higher sidewalls not only in the vicinity of the junction but for a considerable distance downstream. As available information on junctions of this type is almost nonexistent, it was necessary to resort to model studies in order to determine the flow conditions and the minimum sidewall heights. Two general types of junctions were studied. One type consists of the junction of two large channels in which the lateral and inlet main have comparable discharges. The other type, called terrace outlets, consists of a junction between a main channel and a terrace channel having a relatively small discharge. The maximum discharge ranges from 380 to 960 cfs in the main channels and from 25 to 70 cfs in the terrace channels. The maximum velocity of flow encountered is approximately 30 fps.
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    Hydraulic Model Studies for Whiting Field Naval Air Station Part V
    (St. Anthony Falls Hydraulic Laboratory, 1950-01) Bowers, Charles E.
    The Naval Auxiliary Air Station, Whiting Field, is to have a stormwater disposal system in which the existing pipes and terraces under and in the vicinity of the runways and building area will discharge into paved trapezoidal open channels. Many of the channels join other channels as they pass down the sides of the plateau on which the airfield is located. The grades of the main channels and of many of the lateral channels are such that water flows at supercritica1 velocities or at velocities greater than that of a gravity wave (V > sqrt(gd)). The difficulties anticipated in joining two streams of water, one or more of which is flowing at supercritical velocities, led to the request for model studies of several of the channel junctions.
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    Hydraulic Studies of The Spillway of The Karnafuli Hydroelectric Project East Pakistan
    (St. Anthony Falls Laboratory, 1964-09) Bowers, Charles E.; Tsai, Frank Y.; Kuha, Roy M.
    In August, 1961, while still under construction, the spillway chute of the Karnafuli Hydroelectric Project was severely damaged by flows up to a maximum of 123,000 cfs. A Special Board of Consultants reviewed the damage and considered three possible causes of the damage: (1) seepage uplift pressures, (2) failwater uplift, and (3) impact of logs. An inspection of the site and piezometer records indicated that seepage was not the primary cause. Opinions were divided on the other two items. A revised design of the chute was recommended for construction before the next high water, and recommendations were made for model and prototype studies to assist in an evaluation of the cause of the damage and the adequacy of repairs. A 1:28 scale section model was constructed and tested in the Hydraulic Laboratory of the East Pakistan Water and Power Development Authority. A report of October, 1962, presented the results of these studies together with prototype flow measurements on the reconstructed spillway. The present study was authorized effective October 2, 1962. A comprehensive model of the spillway and associated area was constructed to a scale of 1:132. A section model of one full bay and two half bays was constructed to a scale of 1:60. The model studies involved (1) measurements of flow pattern, log retention, and scour in the comprehensive model , and (2) measurements of temporal mean pressures, fluctuating pressures, log velocities and accelerations, and movement of model chute slabs in the section model. In addition, exploratory data were obtained on full-scale log impacts on a section of slab similar to the original chute. It was concluded that: (1) logs could have caused appreciable damage to the initial chute design, but some other mechanism was needed to remove the slabs; (2) fluctuating pressures associated with the hydraulic jump have caused sufficient uplift to remove the slabs with or without damage logs; (3) the increased thickness and new design of the drainage system the revised chute should provide adequate protection against fluctuating pressures; and (4) consideration should be given to doweling or otherwise holding down the floor of the stilling basin to avoid possible uplift of the basin slabs.
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    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.