DESIGNING AND DETAILING OF BUILDING SYSTEMS. MECHANICS IN CIVIL ENGINEERING

DEGREE-BASED VELOCITY DISTRIBUTION INSIDE FLAT AND ROUND TURBULENT FLOWS

Vestnik MGSU 7/2012
  • Skrebkov Gennadiy Petrovich - Chuvash State University named after I.N. Ul’yanov (ChGU) Candidate of Technical Sciences, Associate Professor, Department of Heat and Hydraulic Engineering; +7 (8352) 58-79-26, Chuvash State University named after I.N. Ul’yanov (ChGU), 15 Moskovskiy prospekt, Cheboksary, 428015, Russian Federation; This e-mail address is being protected from spambots. You need JavaScript enabled to view it .
  • Fedorov Nikolay Anfimovich - Chuvash State University named after I.N. Ul’yanov (ChGU) assistant lecturer, Department of Heat and Hydraulic Engineering; +7 (8352) 67-33-26, Chuvash State University named after I.N. Ul’yanov (ChGU), 15 Moskovskiy prospekt, Cheboksary, 428015, Russian Federation; This e-mail address is being protected from spambots. You need JavaScript enabled to view it .

Pages 90 - 95

The authors propose a general method of identification of exponent within the distribution of velocities of round and flat flows. Resulting formulas do not contain any empirical corrections, and they are confirmed by the experimental data.
Resulting degree-based velocity profiles comply with the results of measurements of flat flows, whereas any disagreement between experiment-based points and their analysis-based counterparts do not exceed any acceptable experimental errors.
The practical equivalence of degree-based and logarithmic velocity profiles may serve as a supplementary condition that makes it possible to identify the degree value without the involvement of any empirical corrections.
The degree-based velocity profile of round flows may be calculated according to the expression .\[n=0,9\sqrt{\lambda }\]. or \[n=1,25\sqrt{{{\lambda }_{\text{}}}},\].. the degree-based velocity profile of flat flows is equal to \[n=1,76\sqrt{{{\lambda }_{\text{}}}},\] as both formulas enjoy experimental and theoretical substantiations.

DOI: 10.22227/1997-0935.2012.7.90 - 95

References
  1. Schiller L. Dvizhenie zhidkostey v trubakh [Movement of Fluids in Pipes]. ONTI Publ., Moscow, 1936, p. 230.
  2. Shevelev F.A. Issledovanie osnovnykh gidravlicheskikh zakonomernostey turbulentnogo dvizheniya v trubakh [Investigation of Basic Hydraulic Laws of the Turbulent Flow in Pipes]. Gosstroyizdat Publ., Moscow, 1953, p. 208.
  3. Nunner W. W?rme?bergang und Druckabfall in rauhen R?hren,VDI Forschungsheft, 1956, no. 45.
  4. Al‘tshul‘ A.D. Gidravlicheskie poteri na trenie v truboprovodakh [Hydraulic Friction Loss in Pipes]. Moscow-Leningrad, Gosenergoizdat Publ., 1963, 256 p.
  5. Bryanskaya Yu.V., Markova I.M., Ostyakova A.V. Gidravlika vodnykh i vzvesenesushchikh potokov v zhestkikh i deformiruemykh granitsakh [Hydraulics of Water and Suspension Flows in Rigid and Deformable Boundaries]. Moscow, ASV Publ., 2009, 264 p.
  6. Loytsyanskiy L.G. Mekhanika zhidkosti i gaza [Fluid and Gas Mechanics]. Moscow, Nauka Publ., 1978, 736 p.
  7. Bogomolov A.I., Borovkov V.S. Mayranovskiy T.G. Vysokoskorostnye potoki so svobodnoy poverkhnost’yu [High-speed Flows with Free Surface]. Moscow, Stroyizdat Publ., 1979, p. 344.
  8. Skrebkov G.P. Parashchenko I.E. O velichine postoyannykh logarifmicheskogo profilya skorosti pri dvizhenii potoka mezhdu gladkimi stenkami [The Value of the Permanent Logarithmic Velocity Profile of the Flow between Smooth Walls]. Izvestiya vuzov. Stroitel’stvo i arkhitektura [Bulletin of Institutions of Higher Education. Construction and Architecture]. Novosibirsk, 1983, no. 2, pp. 88—92.
  9. Skrebkov G.P. O gidravlicheskom soprotivlenii rusel ploskomu potoku [About Hydraulic Resistance of Watercourses to Flat Flows]. Proceedings of VNIIG named after B.E. Vedeneeva, 1981, vol.145, pp. 87—92.
  10. Skrebkov G.P., Parashchenko I.E. Issledovanie kinematicheskoy struktury potoka i pristennogo treniya v trapetseidal’nykh kanalakh so stenkami odinakovoy i raznoy sherokhovatosti [Investigation of the Kinematic Structure of the Flow and Wall Friction in the Trapezoidal Channel with the Walls of Identical and Different Roughnesses]. Vodnye resursy [Aquatic Resources]. 1989, no. 2, pp. 91—96.
  11. Laufer J. Investigation of Turbulent Flow in a Two-Dimensional Channel. NACA, Rep. 1053, 1951, pp. 1—33.
  12. Subbotin V.N. Issledovanie osrednennykh gidrodinamicheskikh kharakteristik turbulentnogo potoka v pryamougol’nom kanale [The Study of Averaged Hydrodynamic Characteristics of the Turbulent Flow in a Rectangular Channel]. Obninsk, Institute of Physics and Power Engineering, Preprint, 1973, no. 455.

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Solution of the problem of pipes freezing with account for external heat exchange

Vestnik MGSU 1/2015
  • Samarin Oleg Dmitrievich - Moscow State University of Civil Engineering (MGSU) Candidate of Technical Sciences, Assistant Professor, Department of the Heating and Ventilation, Moscow State University of Civil Engineering (MGSU), 26 Yaroslavskoye shosse, Moscow, 129337, Russian Federa- tion; This e-mail address is being protected from spambots. You need JavaScript enabled to view it .

Pages 90-96

The author considered the problem statement on the pipes freezing in emergency regimes of building engineering systems and external pipe nets using liquid water as working fluid under boundary conditions of the 3rd type. This problem is a high-priority task now because of actualization of building standards in Russian Federation and because of the increasing requirements to safety and security of heat supply. That’s why it is very important to find a simple but accurate enough dependence for the freezing time in pipe nets. The system of differential and algebraic equations of external heat exchange and internal heat transfer with account for heat ingress from hydraulic friction at water flow and Stephan’s condition on the freezing front is presented. The analytical solution of the given system is obtained as a quadrature for the dependence of the current coordinate of the freezing front. The results of numerical calculation of the corresponding integral are shown and their comparison with the former author’s researches concerning the solution of the considered problem at the boundary conditions of the 1st type is conducted. It is shown that the account of intensity of external heat exchange causes retarding of freezing because of adding thermal resistance on the external surface of the pipe. The former author’s conclusion on the existence of the ultimate water velocity, when freezing doesn’t take place, is verified. The area of use of the presented dependence is found. The obtained model contains is easy to use in engineering practice, especially during preliminary calculations. The presentation is illustrated with numerical and graphical examples.

DOI: 10.22227/1997-0935.2015.1.90-96

References
  1. Karev D.S., Mel’nikov V.M. Matematicheskoe modelirovanie teplovykh setey zakrytykh sistem tsentralizovannogo teplosnabzheniya [Mathematical Simulation of Heat Supply Nets in Closed Systems of District Heating]. Vestnik MGSU [Proceedings of Moscow State University of Civil Engineering]. 2011, no. 7, pp. 444—451. (In Russian)
  2. Gabrielaitiene I. Numerical Simulation of a District Heating System with Emphases on Transient Temperature Behavior. Environmental Engineering : Pap. of the 8th Inter. Conf. May 19—20, 2011, Vilnius, Lithuania. 2011, vol. 2, pp. 747—754.
  3. Gorshkov A.S. Energoeffektivnost’ v stroitel’stve: voprosy normirovaniya i mery po snizheniyu energopotrebleniya zdaniy [Energy Efficiency in Construction: Problems of Standardizing and Measures to Decrease Energy Consumption of Buildings]. Inzhenerno-stroitel’nyy zhurnal [Magazine of Civil Engineering]. 2010, no. 1, pp. 9—13. (In Russian)
  4. Gagarin V.G., Kozlov V.V. Trebovaniya k teplozashchite i energeticheskoy effektivnosti v proekte aktualizirovannogo SNiP «Teplovaya zashchita zdaniy» [The Requirements to the Thermal Performance and Energy Efficiency in the Project of the Updated Snip “Thermal Performance of the Buildings”]. Zhilishchnoe stroitel’stvo [Housing Construction]. 2011, no. 8, pp. 2—6. (In Russian)
  5. Kapalo P. Energy Efficiency Buildings Energy for Hot Water. Visnik Nacionaľnogo universitetu Ľvivska politechnika [News of Technical University of Košice]. 2008, no. 627, pp. 223—225.
  6. Citterio M., Cocco M., Erhorn-Cluttig H. Thermal Bridges in the EPBD Context: Overview on MS Approaches in Regulations. EPBD Buildings Platform. 2008. Available at: http://www.buildup.eu/sites/default/files/P064_EN_ASIEPI_WP4_IP1_p3073.pdf/. Date of access: 18.05.2014.
  7. Dylewski R., Adamczyk J. Economic and Ecological Indicators for Thermal Insulating Building Investments. Energy and Buildings. 2012, no. 54, pp. 88—95. DOI: http://dx.doi.org/10.1016/j.enbuild.2012.07.021.
  8. Parfent’ev N.A., Parfent’eva N.A. Matematicheskoe modelirovanie teplovogo rezhima konstruktsiy pri fazovykh perekhodakh [Mathematical Simulation of the Thermal Regime of Constructions under Phase Transitions]. Vestnik MGSU [Proceedings of Moscow State University of Civil Engineering]. 2011, no. 4, pp. 320—322. (In Russian)
  9. Lapina N.N., Pushkin V.N. Chislennoe reshenie odnomernoy ploskoy zadachi Stefana [The Numerical Solution of One-Dimensional Planar Stephan’s Problem]. Vestnik Donskogo gosudarstvennogo tekhnicheskogo universiteta [Vestnik of DSTU. Theoretical and Scientific-Practical Journal of Don State Technical University]. 2010, vol. 10, no. 1, pp. 16—21. (In Russian)
  10. Akimov M.P., Mordovskoy S.D., Starostin N.P. Vozdeystvie podzemnogo truboprovoda teplosnabzheniya na vechnomerzlye grunty Kraynego Severa [The Influence of Buried Heat Supply Pipe on Constantly Frozen Soils of the Extreme North]. Vestnik Severo-Vostochnogo federal’nogo universiteta im. M.K. Ammosova [Vestnik of Yakutsk State University named after M.K. Ammosov]. 2012, vol. 9, no. 2, pp. 19—23. (In Russian)
  11. Akimov M.P., Mordovskoy S.D., Starostin N.P. Chislennyy algoritm dlya issledovaniya vliyaniya beskanal’nogo podzemnogo truboprovoda teplosnabzheniya na vechnomerzlye grunty [The Numerical Algorithm for the Research of the Influence of Non-Channel Underground Heat Supply Pipe on Constantly Frozen Soils]. Matematicheskie zametki YaGU [Mathematical notes of North-Eastern Federal University in Yakutsk]. 2010, vol. 17, no. 2, pp. 125—131. (In Russian)
  12. Dos Santos G.H., Mendes N. Combined Heat, Air and Moisture (HAM) Transfer Mod-El for Porous Building Materials. Journal of Building Physics. 2009, vol. 32, no. 3, pp. 203—220.
  13. Miseviciute V., Martinaitis V. Analysis of Ventilation System’s Heat Exchangers Inte-gration Possibilities for Heating Season. Environmental engineering : Pap. of 8th conf. of VGTU. 2011, vol. 2, pp. 781—787.
  14. Kuznetsov G.V., Polovnikov V.Yu. Analiz teplovykh poter’ teplotruboprovodov v usloviyakh vzaimodeystviya s vlazhnym vozdukhom [Analysis of Heat Losses of the Heat Supply Pipes in Case of Interaction with Moist Air]. Energosberezhenie i vodopodgotovka [Energy Saving and Water Treatment]. 2009, no. 2, pp. 37—39. (In Russian)
  15. Malyavina E.G., Ivanov D.S. Raschet trekhmernogo temperaturnogo polya grunta s uchetom promerzaniya pri opredelenii teplopoter’ [Calculation of Three-Dimensional Temperature Field of the Soil in View of Freezing While Estimating Heat Losses]. Vestnik MGSU [Proceedings of Moscow State University of Civil Engineering]. 2011, vol. 1, no. 3, pp. 371—376. (In Russian)
  16. Malyavina E.G., Ivanov D.S. Opredelenie teplopoter’ podzemnoy chasti zdaniya raschetom trekhmernogo temperaturnogo polya grunta [Estimation of Heat Losses of the Underground Part of a Building by Calculating Three-Dimensional Temperature Field of the Soli]. Vestnik MGSU [Proceedings of Moscow State University of Civil Engineering]. 2011, no. 7, pp. 209—215. (In Russian)
  17. Parfent’eva N.A., Samarin O.D. Reshenie zadachi Stefana pri promerzanii truboprovodov [Solution of the Stephan’s Problem in Case of Pipe Freezing]. Vestnik MGSU [Proceedings of Moscow State University of Civil Engineering]. 2007, no. 1, pp. 67—70. (In Russian)
  18. Parfent’eva N.A., Samarin O.D., Kashintseva V.L. O primenenii i reshenii zadachi Stefana v stroitel’noy teplofizike [On Applying and Solving the Stephan’s Problem in Building Thermal Physics]. Vestnik MGSU [Proceedings of Moscow State University of Civil Engineering]. 2011, no. 4, pp. 323—328. (In Russian)
  19. Samarin O.D. Raschet poter’ napora v polimernykh trubakh [Calculation of Head Losses in Plastic Pipes]. Santekhnika [Sanitary Engineering]. 2014, no. 1, pp. 22—23. (In Russian)
  20. Makhov L.M., Samarin O.D. O raschete poter’ davleniya v elementakh sistem vodyanogo otopleniya [On Calculation of Pressure Losses in the Elements of Water Heating Systems]. Vestnik MGSU [Proceedings of Moscow State University of Civil Engineering]. Special issue. 2009, no. 2, pp. 439—443. (In Russian)

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