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Medzveliya Manana Levanovna -
Moscow State University of Civil Engineering (MGSU)
Candidate of Technical Sciences, Associate Professor, Department of Hydraulic Engineering, Moscow State University of Civil Engineering (MGSU), 26 Yaroslavskoe shosse, Moscow, 129337, Russian Federation;
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.
In the process of calculating and simulating water discharge in free channels it is necessary to know the flow features in case of small values of Reynolds and Weber numbers. The article considers the influence of viscosity and surface tension on the coefficient of a weir flow with sharp threshold. In the article the technique of carrying out experiments is stated, the equation is presented, which considers the influence of all factors: pressure over a spillway threshold, threshold height over a course bottom, speed of liquid, liquid density, dynamic viscosity, superficial tension, gravity acceleration, unit discharge, the width of the course. The surface tension and liquid density for the applied liquids changed a little. In the rectangular tray (6000x100x200) spillway with a sharp threshold was established. It is shown that weir flow coefficient depends on Reynolds number (in case Re < ~ 2000) and Webers number. A generalized expression for determining weir flow coefficient considering the influence of the forces of viscosity and surface tension is received.
DOI: 10.22227/1997-0935.2014.9.100-105
References
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Medzveliya Manana Levanovna -
Moscow State University of Civil Engineering (MGSU)
Candidate of Technical Sciences, Associate Professor, Department of Hydraulic Engineering, Moscow State University of Civil Engineering (MGSU), 26 Yaroslavskoe shosse, Moscow, 129337, Russian Federation;
This e-mail address is being protected from spambots. You need JavaScript enabled to view it
.
The author considers the influences of the forces of viscosity and superficial tension on the discharge ratio in a channel with side narrowing. In the article the equation is presented that takes into account the influence of all the factors: the pressure, the speed of the liquid, liquid density, dynamic viscosity, superficial tension, gravity acceleration, expense per unit of width, width of the course, width of narrowing. Superficial tension and liquid density for the used liquids changed a little.The narrowing in the rectangular tray was achieved by force of flowing liquid between rectangular parallelepipeds, which were attached to the wall of the tray. The dimensions of the rectangular parallelepipeds were: the length L = 200 mm, the width B = 33 mm, and the depth of the mouth b = 34 mm.The findings of the experiment proved that the increase in the Reynolds number causes the increase flow discharge ratio and it approaches the constant value at Re ? 4000.
DOI: 10.22227/1997-0935.2015.6.110-114
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- Medzveliya M.L., Pipiya V.V. Koeffitsient raskhoda vodosliva s shirokim porogom v oblasti malykh naporov [Discharge Ratio of the Broad-crested Weir Flow in the Low Head Area]. Vestnik MGSU [Proceedings of Moscow State University of Civil Engineering]. 2013, no. 4, pp. 167—171. (In Russian)
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