3D simulation of gas-laden liquid flows in centrifugal pumps and the assessment of two-fluid CFD methods
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Vol. 2, No. 4, 2020, 00–00 https://doi.org/10.1007/s42757-020-0080-4
3D simulation of gas-laden liquid flows in centrifugal pumps and the assessment of two-fluid CFD methods Markus Hundshagen1 (), Michael Mansour2,3, Dominique Thévenin2, Romuald Skoda1 1. Chair of Hydraulic Fluid Machinery, Ruhr University Bochum, Universitätsstr. 150, 44801 Bochum, Germany 2. Lab. of Fluid Dynamics & Technical Flows, University of Magdeburg “Otto Von Guericke”, Universitätsplatz 2, 39106 Magdeburg, Germany 3. Mechanical Power Engineering Department, Faculty of Engineering, Mattaria, Helwan University, 11718 Cairo, Egypt
Abstract
Keywords
An assessment of a two-fluid model assuming a continuous liquid and a dispersed gas phase for 3D computational fluid dynamics (CFD) simulations of gas/liquid flow in a centrifugal research
3D CFD
pump is performed. A monodisperse two-fluid model, in conjunction with a statistical eddyviscosity turbulence model, is utilized. By a comprehensive measurement database, a thorough
centrifugal pump
diffuser gas/liquid flow
assessment of model inaccuracies is enabled. The results on a horizontal diffuser flow reveal that the turbulence model is one main limitation of simulation accuracy for gas/liquid flows. Regarding pump flows, distinctions of single-phase and two-phase flow in a closed and semi-
Article History
open impeller are figured out. Even single-phase flow simulations reveal challenging requirements
Revised: 6 May 2020
on a high spatial resolution, e.g., of the rounded blade trailing edge and the tip clearance gap flow. In two-phase pump operation, gas accumulations lead to coherent gas pockets that are predicted partly at wrong locations within the blade channel. At best, a qualitative prediction of
Accepted: 4 June 2020
gas accumulations and the head drop towards increasing inlet gas volume fractions (IGVF) can be obtained. One main limitation of two-fluid methods for pump flow is figured out in terms of
© The Author(s) 2020
Received: 13 March 2020
Research Article
the violation of the dilute, disperse phase assumption due to locally high disperse phase loading within coherent gas accumulations. In these circumstances, bubble population models do not appear beneficial compared to a monodisperse bubble distribution. Volume-of-Fluid (VOF) methods may be utilized to capture the phase interface at large accumulated gas cavities, requiring a high spatial resolution. Thus, a hybrid model, i.e., a dispersed phase two-fluid model including polydispersity for flow regions with a dilute gas phase, should be combined with an interphase capturing model, e.g., in terms of VOF. This hybrid model, together with scaleresolving turbulence models, seems to be indispensable for a quantitative two-phase pump performance prediction.
1
Introduction
Centrifugal pumps are employed in many technical applications, especially when reliable and flexible pump performance is needed. Often, their conveying task is not limited to pure liquids, since also mixtures, e.g., liquid and gas, must be deliver
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