Browsing by Author "Bowers, C. E."

Now showing 1 - 6 of 6
  • Thumbnail Image
    Item
    Experimental Studies of Hydraulic
    (St. Anthony Falls Hydraulic Laboratory, 1956-06) Herbich, John B.; Ziegler, Jurgen; Bowers, C. E.
    Experil1lental studies were conducted on both large and small models of hydraulic breakwaters. Data were obtained which indicated that power requirements are function of jet area, jet submergence, attenuation, and wave characteristics. It was concluded that no serious scale effect was obtained over the 1:4.5 scale ratio of the tests. Tests of multiple-manifold systems and the effect of waves striking the breakwater at an angle were limited in scope, but data were obtained providing an indication of the effect of these variables.
  • Thumbnail Image
    Item
    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.
  • Thumbnail Image
    Item
    An Experimental Study of Wave Absorbers
    (St. Anthony Falls Hydraulic Laboratory, 1957-01) Bowers, C. E.; Herbich, John B.
    Large-scale experimental studies were conducted on two types of wave absorbers, as an extension of earlier small-scale work. The first absorber, and the one of primary interest, was a discontinuous permeable absorber with a surface slope of 12 degrees. Two types of permeable materials-- ( a) crushed rock and (b) rectangular bars--were investigated. Several modifications of the basic design were studied, including various thicknesses of permeable layer. On the basis of the experimental studies, an optimum thickness of permeable layer was selected. The use of the rectangular-bar construction was recommended. Brief tests were run on the second type, a short absorber, which was being considered for use around the periphery of a rotating-am basin. The tests indicated that a surface slope of 15 degrees and a thin layer of permeable material produced the best results. The absorber was restricted to a very short length and produced high reflection coefficients, but it materially reduced the settling time of the basin.
  • Thumbnail Image
    Item
    An Experimental Study of Wave Filters
    (St. Anthony Falls Hydraulic Laboratory, 1957-02) Bowers, C. E.; Herbich, John B.
    Wave filters may be employed in laboratory facilities to attenuate oscillatory surface waves reflected from a test model, or to improve the quality of generated waves. When used for these purposes, they are placed between the generator and the test model, usually quite close to the generator. The studies reported herein consisted of experimental tests of the attenuation and reflection characteristics of plate and wire-mesh filters. The results indicated that high attenuations can be achieved with either type filter without serious reflections. The attenuation and reflection depend, in addition to other factors, upon the plate spacing of plate type filters and the porosity of wire-mesh filters. Very dense or closely spaced filters produced high attenuations and high reflections. The best over-all performance was obtained by plate spacings or porosities selected to utilizee a filter length equal to or in excess of the wave length. Reflection produced by plate filters depended, to a considerable extent, on the blockage or reduction in cross-section of the channel, as well as on the ratio of wave length to filter length. Reflections from plate filters were reduced when the filter was constructed of plates of various lengths. The experimental results were compared with available theory. Very good agreement was obtained with the plate-type filter when the spacing was not too small. Brief comparisons between the data on wire-mesh filters and two suggested theories were not successful. The majority of the filter tests were conducted in a relatively small wave channel. limited tests were conducted on wire-mesh filters in a large channel; a comparison of data from the two sources indicated that porosity was not the sole factor affecting the attenuation and that the resistance of the wire mesh probably varied as a function of Reynolds number.
  • Thumbnail Image
    Item
    Laboratory Surface Wave Equipment
    (St. Anthony Falls Hydraulic Laboratory, 1953-11) Ross, James; Bowers, C. E.
    This report is a brief summary of selected literature pertaining to equipment and methods associated with laboratory studies of surface waves. It consists of four parts: (1) Summary or discussion· section. (2) Selected abstracts. (3) Annotated bibliography. (4) Bibliography. The summary section consists of a discussion of available literature on the subject of wave generators, wave filters, wave absorbers, and instrumentation. No attempt has been made to include reference material relating to equipment associated with field studies of waves.
  • Thumbnail Image
    Item
    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.