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HYDRAULICS. ENGINEERING HYDROLOGY. HYDRAULIC ENGINEERING

Account for the surface tension in hydraulic modeling of the weir with a sharp threshold

Vestnik MGSU 9/2014
  • 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 .

Pages 100-105

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
  1. Linford A. The Application of Models to Hydraulic Engineering – Reservoir Spillways. Water and Water Engineering. October, 1965, pp. 351—373.
  2. Engel F., Stainsby W. Weirs for Flow Measurement in Open Channels. Part 2. Water and Water Engineering. 1958, vol. 62, no. 747, pp. 190—197.
  3. Kindsvater C., Carter R. Discharge Characteristics of Rectangular Thin-plate Weirs. Transactions ASCE, 1957, vol. 122, pp. 772—822.
  4. Spronk R. Similitude des ecoulements Sur les deversoirs en mince paroi aux faibles charges. Rev. Univers. mines. 1953, vol. 3, no. 9, pp. 119—127.
  5. Hager W. Ausfluss durch vertikale offnungen. Wasser, Energ. Luft. 1988, vol. 80, no. 3—4, pp. 73—79.
  6. Al’tshul’ A.D., Medzveliya M.L. Ob usloviyakh otryva prilipshey strui na vodoslive s ostrym porogom [On the Conditions of Separating the Stuck Flood on the Weir with a Sharp Threshold]. Izvestiya vuzov: Stroitel’stvo [News of the Institutions of Higher Education]. 1991, no. 11, pp. 73—76.
  7. 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.
  8. 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.
  9. Al’tshul’ A.D. Istechenie iz otverstiy zhidkostey s povyshennoy vyazkost’yu [Efflux of Liquids with Elevated Toughness]. Neftyanoe khozyaystvo [Oil Industry]. 1950, no. 2, pp. 55—60.
  10. Jameson A. Flow over Sharp-edged Weirs. Effect of Thickness of Crest . J. Inst. of Civil Engrs. Nov. 1948, vol. 31, no. 1, pp. 36—55. DOI: http://dx.doi.org/10.1680/IJOTI.1948.13377.
  11. D’Alpaos L. Sull’efflusso a stramazzo al di sopra di un bordo in parete sottile perpiccolshi valori del carico. Atti ist. Veneto sci lett. ed arti. Cl, sci mat. e natur. 1976—1977, vol. 135, pp. 169—190.
  12. Shchapov N.M. Gidrometriya gidrotekhnicheskikh sooruzheniy i gidromashin [Hydrometry of Hydraulic Engineering Structures and Hydraulic Units]. Moscow, Leningrad, Gosenergoizdat Publ., 1957, 235 p.
  13. Raju K.G.R., Asawa G.L. Viscosity And Surface Tension Effects On Weir Flow. J. of the Hydraulic Engineering, ASCE. 1977, vol. 103, no. 10, pp. 1227—1231.
  14. Rosanov N., Rosanova N. Some Problems of Modeling Water Outlet Structures with Free — Surface Flow. Proc. 19 IAHR congr. New-Delhi, 1981, vol. 5, pp. 81—91.
  15. Molitor D.A. Hydraulics of Rivers, Weirs and Sluices. 1st ed. New York : John Wiley & Sons; London : Chapman & Hall, Limited. 1908. 178 p.

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Effect of the physical properties of a liquid on discharge coefficient in case of efflux from under the gate

Vestnik MGSU 10/2014
  • 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 .
  • Volgina Lyudmila Vsevolodovna - Moscow State University of Civil Engineering (MGSU) andidate of Technical Sciences, Associate Professor; +7 (495) 287-49-14, ext. 14-18, 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 .

Pages 147-152

Hydraulic engineering models are usually calculated according to Fraud law. Though in the process of small size models operation also viscosity and service tension forces become essential and we can’t neglect them.
The article considers the influence of viscosity and surface tension on discharge coefficient in case of efflux from under the gate. In the article the technique of carrying out experiments is stated, the equation is presented, which considers the influence of all factors: pressure, speed of liquid, liquid density, dynamic, superficial tension, gravity acceleration, unit discharge, width of the course, opening height. The surface tension and the liquid density for the used liquids changed a little. The gate was established in a rectangular trough (6000×100×200).
It is shown that with the increase of Reinolds number (at a relative opening a/H = 00,04…0,03 and Webers number
We > 250) the discharge coefficient rises and no longer depends on the Reinolds number, at Re > 2000 and Webers number (at constant values of Reinolds numbers) practically does not influence the discharge coefficient.

DOI: 10.22227/1997-0935.2014.10.147-152

References
  1. Allen J. Scale Models in Hydraulic Engineering. London, Longmens Green, 1947, 440 p.
  2. Benedini M. Lo stramazzo Bazin in canali di grandi dimensioni. Energia electr., 1966, vol. 43, no. 7, pp. 412—423.
  3. Maxwell W., Hall C., Weggel J. Surface Tension in Froude Models. J. of Hydraulics Division, ASCE. 1969, vol. 95, no. 2, pp. 677—704.
  4. Martynov I.P. Istechenie iz-pod ploskogo shchita [Efflux from under Flat Panel]. Nauchnye zapiski Moskovskogo gidromeliorativnogo instituta im. Vil'yamsa [Proceedings of Moscow Hydrotechnological Institute Named after Williams]. 1959, vol. 21, pp. 263—272. (in Russian)
  5. Spronk R. Similitude des ecoulements Sur les deversoirs en mince paroi aux faibles charges. Rev. Univers. Mines. 1953, vol. 3, no. 9, pp. 119—127.
  6. D’Alpaos L. Sull’efflusso a stramazzo al di sopra di un bordo in parete s ottile per piccolo Valori del carico. Atti ist.Veneto sci lett. ed arti. Cl, sci mat. e natur. 1976—1977, vol. 135, pp. 169—190.
  7. 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)
  8. Linford A. The Application of Models to Hydraulic Engineering — Reservoir Spillways. Water and Water Engn. Oct. 1965, pp. 351—373.
  9. Engel F.V.A., Stainsby W. Weirs for Flow Measurement in Open Channels. Part 2. Water and Water Engng. 1958, vol. 62, no. 747, pp. 190—197.
  10. Raju R., Asawa G.L. Viscosity and Surface Tension Effects on Weir Flow. J. of the Hydraulics Div., ASCE. 1977, vol. 103, no. 10, pp. 1227—1231.
  11. Lenz A.T. Viscosity and Surface Tension Effects on V-Notch Weir Coefficients. Transactions, ASCE. 1943, vol. 108, no. 1, pp. 351—373.
  12. Al'tshul' A.D. Istechenie iz otverstiy zhidkostey s povyshennoy vyazkost'yu [Efflux of the Liquids with Raised Viscosity from the Holes]. Neftyanoe khozyaystvo [Oil Industry]. 1950, no. 2, pp. 55—60. (in Russian)
  13. Ob usloviyakh otryva prilipshey strui na vodoslive s ostrym porogom [On the Conditions of Separating the Stuck Flood on the Weir with a Sharp Threshold]. Izvestiya vuzov: Stroitel'stvo [News of the Institutions of Higher Education]. 1991, no. 11, pp. 73—76. (in Russian)
  14. Medzveliya M.L. Uchet poverkhnostnogo natyazheniya pri gidravlicheskom modelirovanii vodosliva s ostroy kromkoy [Account For The Surface Tension In Hydraulic Modeling Of The Weir With A Sharp Threshold]. Vestnik MGSU [Proceedings of Moscow State University of Civil Engineering]. 2014, no. 9, pp. 100—105. (in Russian)
  15. Rel'tov B.F. Ob istechenii iz-pod vertikal'nogo shchita v gorizontal'nyy lotok [On the Efflux from under Vertical Gate into Horizontal Triugh]. Izvestiya VNIIG [News of All-Russian Scientific and Research Institute of Hydraulic Engineering]. 1934, vol. 11, no. 23, pp. 29—41. (in Russian)

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