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035 _a.b10649979
099 9 _aAIT Thesis no.WA-87-1
100 1 _aAbbas, Muhammad Akhtar
245 1 2 _aA study of compound weirs
260 _aBangkok :
_bAsian Institute of Technology,
_c1987
300 _a135 p.
490 1 _aThesis ;
_vno. WA-87-1
500 _aA thesis study submitted in partial fulfillment of the requirements for the degree of Master of Engineering, School of Engineering and Technology
502 _aThesis (M.Eng.) - Asian Institute of Technology, 1987
520 _aParshall flume, standard rectangular weir, and 90° V-notch weir are commonly used as flow measurement devices. All of them show good applicability within a limited range of discharge to be measured. However, in a small watershed area when the rainfall is not uniformly distributed, heavy rainfall in wet season and the low flow during the dry season, ensures considerable fluctuation of the discharges. The existing devices are not appropriate for the flow measurement under such conditions. In such areas, the compound weir is needed for this purpose . The necessity of having accurate information on the performance characteristics of compound weirs has focused attention to study its behaviour under free overfall conditions. A theory is outlined which helps to explain the flow over compound weirs, whose application is shown to be reasonably justified in the present context. Experiments on twelve weirs of three sets are shown to confirm the trends predicted by the theory. A discharge equation of the form Q = K.Hn is formulated, where Q is discharge, K is dimensional constant of proportionality, H is measured head, and n is hydraulic exponent . Such a definitive and unique relationship offers a practical basis for the measurement of discharge in open channels. An accurate method for determining the discharge coefficients is presented and the coefficients are determined for each of the compound weirs. The limits of validity of the results are investigated. The summary of the results is presented in graphic and tabular forms. Finally, sensitivity analysis, by varying the discharge coefficients has been carried out to help identifying the potential importance of these parameters. A comparison of the theoretically determined solution with observations indicates a fair agreement, and allows a simple prediction of all pertinent flow characteristics.
650 0 _aWeirs
700 1 _aWang, Tsan-Wen,
_eChairperson
700 0 _aPrida Thimakorn,
_eCo-Chairperson
700 1 _aBogardi, Janos J.,
_eExamination Committee
700 0 _aPreecha Kamronrithisorn,
_eExamination Committee
710 2 _aThe Government of France,
_eScholarship Donor
810 2 _aAsian Institute of Technology.
_tThesis ;
_vno. WA-87-1
856 _3Full-Text
_uhttp://203.159.5.9/ait-thesis/detail.php?q=B19395
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