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HYDRAULICS. ENGINEERING HYDROLOGY. HYDRAULIC ENGINEERING

CONDITIONS OF FORMATION OF A FREE FLOW OVER A SHARP CREST WEIR

Vestnik MGSU 1/2013
  • 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 .
  • Pipiya Valeriy Valerianovich - Breesize Trading Limited Candidate of Technical Sciences, Senior Project Engineer, Breesize Trading Limited, 42 Mosfil’movskaya St., Moscow, 119285, Russian Federation; This e-mail address is being protected from spambots. You need JavaScript enabled to view it .

Pages 185-189

The authors consider the viscosity and surface tension forces that produce their influence on the conditions of separation of the stream from a sharp crest weir. The authors have compiled an equation that takes account of the influence of all factors, including liquid pressure over the weir — H, weir height — P, liquid flow velocity — v, liquid density — ρ, dynamic viscosity — μ, surface tension σ, gravity acceleration — g, discharge per the unit of the weir width — q, width of the course — B. The authors have proven that the surface tension and liquid density are different for different types of liquids.As part of the experiment, a sharp crest weir was installed into a rectangular tray (6,000×100×200). The weir height was permanent, and it was equal to P = 60 mm. Experiments were conducted to register the moment of the flow separation from the weir wall. The experiment contemplated gradual pressure rise. The authors demonstrated that the stream separation from the weir wall that had a sharp crest occurred when the Weber’s number reached its critical value os that it was independent from the Reynold’s number.

DOI: 10.22227/1997-0935.2013.1.185-189

References
  1. Al’tshul’ A.D. Gidravlicheskie soprotivleniya [Hydraulic Resistances]. Moscow, Nedra Publ., 1982, 223 p.
  2. Linford A. The Application of Models to Hydraulic Engineering-reservoir Spillways. Water and Water engn. October 1965, pp. 411—417.
  3. D’Alpaos Luigi. Sull’effl usso a stramazzo al di sopra di un bordo in parete s ottile per piccolo Valori del carico. Atte ist. Veneto sci lett. ed arti. Cl, sci mat. e natur. 1976—1977, 135, pp. 169—190.
  4. Lobachev P.V., Makarevich T.N., Myasnikov V.I. Vliyanie vyazkosti i poverkhnostnogo natyazheniya zhidkosti na koeffitsient raskhoda vodoslivov s tonkoy stenkoy [Influence of Viscosity and Surface Tension of Liquids on the Discharge Ratio of Weirs That Have Thin Walls]. Tr. VNII «VODGEO» [Works of Scientific Research Institute of Water Supply, Sewage, Hydraulic Structures and Engineering Hydro-geology]. 1978, no. 73, pp. 129—134.
  5. Chugaev R.R. Gidravlika [Hydraulics]. Moscow, Energiya Publ., 1975, 671 p.
  6. Maxwell C., Weggel R. Surface Tension in Froude Models. J. of Hydraulics Division. ASCE, 1969, March, HY 2, pp. 677—701.
  7. Kisilev P.G. Osnovy mekhaniki zhidkosti [Fundamentals of Liquid Mechanics]. Moscow, Energiya Publ., 1980, 337 p.
  8. Zegzhda A.P. Teoriya podobiya i metodika rascheta gidrotekhnicheskikh modeley [Similarity Theory and Methodology of Analysis of Hydraulic Engineering Models]. Moscow, Gosstroyizdat Publ., 1938, 220 p.
  9. Al’tshul’ A.D. Istechenie iz otverstiy zhidkostey s povyshennoy vyazkost’yu [Outflows of Hyperviscosity Liquids through Holes]. Neftyanoe khozyaystvo [Crude Oil Economy]. 1950, no. 2, pp. 55—60.

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DISCHARGE RATIO OF THE BROAD-CRESTED WEIR FLOWIN THE LOW HEAD AREA

Vestnik MGSU 4/2013
  • 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 .
  • Pipiya Valeriy Valerianovich - Breesize Trading Limited Candidate of Technical Sciences, Senior Project Engineer, Breesize Trading Limited, 42 Mosfil’movskaya St., Moscow, 119285, Russian Federation; This e-mail address is being protected from spambots. You need JavaScript enabled to view it .

Pages 167-171

The authors consider the influence of the Reynolds number on the discharge ratio of the broad-crested weir. The authors provide an overview of their experiment in thearticle. They provide the equation that takes account of each factor of influence, including H — pressure over the broad-crested weir, P — weir height above the bottom, v — liquid velocity, ρ — liquid density, μ — dynamic viscosity, g — superficial tension, σ — gravity acceleration, q — per-unit weir flow, B — width of the weir, L — length of the weir. Superficial tension and liquid density values have minor differences for different fluids.A broad-crested weir flow was organized in the rectangular tray (6,000×100×200). The flow had the following dimensions: weir length L = 40 mm, weir height P = 50 mm, weir width B = 100 mm. The findings of the experiment have proven that the increase in the Reynolds number causes the increase in the broad-crested weir flow discharge ratio (at the pre-set relative pressure) and it approaches the constant value at Re ≈ 2000.

DOI: 10.22227/1997-0935.2013.4.167-171

References
  1. Chugaev R.R. Gidravlika [Hydraulics]. Moscow, Energiya Publ., 1975, 671 p.
  2. Linford A. The Application of Models to Hydraulic Engineering-reservoir Spillways. Water and Water engn. October 1965, pp. 411—417.
  3. Al’tshul’ A.D. Istechenie iz otverstiy zhidkostey s povyshennoy vyazkost’yu [Outflows of Hyper-viscosity Liquids through Holes]. Neftyanoe khozyaystvo [Crude Oil Economy]. 1950, no. 2, pp. 55—60.
  4. Zegzhda A.P. Teoriya podobiya i metodika rascheta gidrotekhnicheskikh modeley [Similarity Theory and Methodology of Analysis of Hydraulic Engineering Models]. Moscow, Gosstroyizdat Publ., 1938, 220 p.
  5. Kisilev P.G. Osnovy mekhaniki zhidkosti [Fundamentals of Liquid Mechanics]. Moscow, Energiya Publ., 1980, 337 p.
  6. Medzveliya M.L., Pipiya V.V. Usloviya obrazovaniya svobodnoy strui na vodoslive s ostrym porogom [Conditions of Formation of a Free Flow over a Sharp Crest Weir]. Vestnik MGSU [Proceedings of Moscow State University of Civil Engineering]. 2013, no. 1, pp. 185—189.
  7. Berezinskiy A.R. Propusknaya sposobnost’ vodosliva s shirokim porogom [Throughput of a Broad-crested Weir]. Moscow – Leningrad, Stroyizdat Publ., 1950, 149 p.
  8. Al’tshul’ A.D. Gidravlicheskie soprotivleniya [Hydraulic Resistances]. Moscow, Nedra Publ., 1982, 223 p.

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