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Symulacja komputerowa (CFD) burzliwego pola prędkości w strumieniu wlotowym ze standardowej turbiny Rushtona
Języki publikacji
Abstrakty
The velocity field around the standard Rushton turbine was investigated by the Computational Fluid Dynamics (CFD) calculations and compared with results obtained from the Laser Doppler Anemometry (LDA) measured in a pilot plant baffled cylindrical vessel. For calculations the Large Eddy Simulation (LES) approach was employed. The impeller motion was modeled using the Sliding Mesh technique (SM). The mean ensemble-averaged velocity profiles and root mean square values of fluctuations were compared in the radial discharge jet from the standard Rushton turbine under turbulent regime of flow of agitated liquid. There were found two subregions in the discharge stream and the values of the axial profiles of the radial component of the fluctuating velocity are rather same determined from the LES calculations and from the LDA measurements in the second one ZEF (zone of established flow) of the impeller discharge stream, but they differ in the first region ZFE (zone of flow establishment) in the impeller vicinity, although they exhibit the same shape. The impeller power number derived from calculations shows also good agreement with values introduced in literature with a significant influence of the thickness of the impeller disc.
Pole prędkości wokół standardowej turbiny Rushtona przeanalizowano metodą CFD (Computer Fluid Dynamics) i porównano z wynikami uzyskanymi za pomocą laserowej anemometrii dopplerowskiej (LDA) w doświadczalnym zbiorniku cylindrycznym z przegrodami. W obliczeniach wykorzystano technikę LES (Large Eddy Simulation). Ruch mieszadła zamodelowano z zastosowaniem techniki SM (Sliding Mesh). Średnie ważone profile prędkości i średnie kwadratowe wartości fluktuacji porównano z promieniowym strumieniem cieczy wypływającej z turbiny Rushtona w warunkach burzliwego przepływu cieczy mieszanej. W strumieniu wypływającym z mieszadła wyodrębniono dwa podobszary, a przebiegi profili promieniowych składowych fluktuacji prędkości były zbliżone, zarówno otrzymane w wyniku obliczeń LES, jak i z pomiarów LDA w drugiej strefie przepływu ustabilizowanego w sąsiedztwie wirnika, chociaż wykazywały ten sam kształt. Liczba mocy mieszadła, otrzymana w wyniku obliczeń, wykazała dobrą zgodność z wartościami podawanymi w literaturze, przy znaczącym wpływie grubości tarczy mieszadła.
Słowa kluczowe
Czasopismo
Rocznik
Tom
Strony
73--84
Opis fizyczny
Bibliogr. 22 poz., il., wykr., wz.
Twórcy
autor
- Institute of Hydrodynamics AS CR, Prague, Czech Republic
autor
- Department of Process Engineering, Faculty of Mechanica l Engineering, Czech T echnical University in Prague, Czech Republic
autor
- Institute of Hydrodynamics AS CR, Prague, Czech Republic
Bibliografia
- [1] Ben-Nun R., Sheintuch M., Characterizing turbulent jet properties of radial discharge impeller: potential core, spreading rate and averaged flow field parameters, 9th European Congress of Chemical Engineering, The Hague (NL), April 2013.
- [2] Yeoh S., Papadakis G., Yianneskis M., Numerical Simulation of Turbulent Flow Characteristics in a Stirred Vessel Using the LES and RANS Approaches with the Sliding/Deforming Mesh Methodology, Chemical Engineering Research and Design, vol. 82, no. 7, 2004, pp. 834-848.
- [3] Joshi J.B., Nere N.K., Rane C.V., Murthy B.N., Mathpati C.S., Patwardhan A.W., Ranade V.V., CFD simulation of stirred tanks: Comparison of turbulence models (Part I: Radial flow impellers), The Canadian Journal of Chemical Engineering, vol. 89, no. 1, 2011, pp. 23-82.
- [4] Joshi J.B., Nere N.K., Rane C.V., Murthy B.N., Mathpati C.S., Patwardhan A.W., Ranade V.V., CFD simulation of stirred tanks: Comparison of turbulence models (Part II: Axial flow impellers, multiple impellers and multiphase dispersions), The Canadian Journal of Chemical Engineering, vol. 89, no. 4, 2011, pp. 754-816.
- [5] Coroneo M., Montante G., Paglianti A., Magelli F., CFD prediction of fluid flow and mixing in stirred tanks: Numerical issues about the RANS simulations, Computers & Chemical Engineering, vol. 35, no. 10, 2011, pp. 1959-1968.
- [6] Bakker A., Laroche R., Wang M., Calabrese R., Sliding Mesh Simulation of Laminar Flow in Stirred Reactors, Chemical Engineering Research and Design, vol. 75, no. 1, 1997, pp. 42-44.
- [7] Gimbun J., Rielly C.D., Nagy Z.K., Derksen J.J., Detached eddy simulation on the turbulent flow in a stirred tank, AIChE Journal, vol. 58, no. 10, 2012, pp. 3224-3241.
- [8] Derksen J., Van den Akker H., Large eddy simulations on the flow driven by a Rushton turbine, AIChE Journal, vol. 45, pp. 209-221, FEB 1999.
- [9] Derksen J., Long-time solids suspension simulations by means of a large-eddy approach, Chemical Engineering Research and Design, vol. 84, JAN 2006, pp. 38-46.
- [10] Bakker A., Oshinowo L., Modelling of Turbulence in Stirred Vessels Using Large Eddy Simulation, Chemical Engineering Research and Design, vol. 82, no. 9, 2004, pp. 1169-1178.
- [11] Jahoda M., Moštěk M., Kukuková A., Machoň V., CFD modeling of liquid homogenization in stirred tanks with one and two impellers using large eddy simulation, Chemical Engineering Research and Design, vol. 86, 2007, pp. 616-625.
- [12] Li Z., Hu M., Bao Y., Gao Z., Particle Image Velocimetry Experiments and Large Eddy Simulations of Merging Flow Characteristics in Dual Rushton Turbine Stirred Tanks, Industrial & Engineering Chemistry Research, vol. 51, no. 5, 2012, pp. 2438-2450.
- [13] Li Z., Bao Y., Gao Z., PIV experiments and large eddy simulations of single-loop flow fields in Rushton turbine stirred tanks, Chemical Engineering Science, vol. 66, no. 6, 2011, pp. 1219-1231.
- [14] Gillissen J.J., Van den Akker H.E., Direct numerical simulation of the turbulent flow in a baffled tank driven by a Rushton turbine, AIChE Journal, vol. 58, no. 12, 2012, p. 3878-3890.
- [15] Kolář V., Filip P., Curev A., Hydrodynamics of radially discharging impeller stream in agitated vessels, Chemical Engineering Communications, vol. 27, 1984, pp. 313-326.
- [16] Drbohlav J., Fořt I., Máca K., Ptáček J., Turbulent characteristics of discharge flow from turbine impeller, Coll. Czech. Chem. Commun., vol. 43, 1978, pp. 3148-3161.
- [17] Fořt I., Möckel H.O., Drbohlav J., Hrach M., The flow of liquid in a stream from the standard turbine impeller, Coll. Czech. Chem. Commun., vol. 44, 1979, pp. 700-710.
- [18] Obeid A., Fořt I., Bertrand J., Hydrodynamic characteristics of flow in systems with turbine impeller, Coll. Czech. Chem. Commun., 48, 1983, p. 568-577.
- [19] Talaga J., Fořt I., The velocity field in the discharge stream from a rushton turbine impeller, 14th European Conference on Mixing, Warszava, 10‒13 September 2012.
- [20] Venneker B.C., Derksen J.J., Van den Akker H.E.A., Turbulent flow of shear-thinning liquids in stirred tanks - The effects of Reynolds number and flow index, Chemical Engineering Research and Design, vol. 88(7), 2010, pp. 827-843.
- [21] Bujalski W., Nienow A.W., Chatwin S., Cooke M., The dependency on scale of power numbers of Rushton disk turbine, Chemical Engineering Science, vol. 42(2), 1987, pp. 317-326.
- [22] Beshay K.R., Kratěna J., Fořt I., Brůha O., Power Input of High-Speed Rotary Impellers, Acta Polytechnica, vol. 41, no. 6, 2001, pp. 18-23.
Uwagi
EN
This research has been subsidized by the research project No. GA CR P101/12/2274 and RVO: 67985874.
Typ dokumentu
Bibliografia
Identyfikator YADDA
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