Research Papers: Flows in Complex Systems

Numerical Simulations and Analysis of a Low Consumption Hybrid Air Extractor

[+] Author and Article Information
Marc Sanchez, Adrien Toutant, Françoise Bataille

University of Perpignan Via Domitia,
Tecnosud-Rambla de la Thermodynamique,
Perpignan 66100, France

Contributed by the Fluids Engineering Division of ASME for publication in the JOURNAL OF FLUIDS ENGINEERING. Manuscript received October 10, 2016; final manuscript received July 25, 2017; published online September 11, 2017. Assoc. Editor: Wayne Strasser.

J. Fluids Eng 139(12), 121106 (Sep 11, 2017) (10 pages) Paper No: FE-16-1666; doi: 10.1115/1.4037507 History: Received October 10, 2016; Revised July 25, 2017

Hybrid low pressure air extractors are an economic way to enhance indoor air quality. The evaluation of their energetic performances needs the analysis of flow parameters that is typically done with wind tunnel data and numerical simulations. The purpose of this study is to analyze, numerically and experimentally, the flow and the energetic performances of a hybrid rooftop extractor. This innovative extractor has two main features: it works at low difference of pressure, below 50 Pa, and its fan is placed far above the duct outlet, out of the fluid flow. The hybrid extractor works following three modes of operation: stack effect, Venturi effect, and fan rotation. The two first modes of operation allow large energy saving. To analyze the three modes of operation, three sets of corresponding Reynolds-averaged Navier–Stokes (RANS) simulations are developed. The first one allows us to estimate the pressure drop due to the geometry of the air extractor. The second one is used to check the ability of the extractor to generate a suction into the duct in the presence of wind. The final one involves multiple reference frame (MRF) modeling in order to study the flow when the electric motor drives the fan. The numerical simulation configurations are validated with experimental data. A good behavior of the extractor is found for simulations of stack effect mode and Venturi effect mode. The stack effect and the Venturi effect allows the hybrid extractor to work most of the time without electric power. Finally, energetic comparisons are given.

Copyright © 2017 by ASME
Your Session has timed out. Please sign back in to continue.


Khan, N. , Su, Y. , and Riffat, S. B. , 2008, “ A Review on Wind Driven Ventilation Techniques,” Energy Build., 40(8), pp. 1586–1604. [CrossRef]
Ismail, M. , and Abdul Rahman, A. , 2010, “ Comparison of Different Hybrid Turbine Ventilator (HTV) Application Strategies to Improve the Indoor Thermal Comfort,” Int. J. Environ. Res., 4(2), pp. 297–308.
Lai, C.-M. , 2003, “ Experiments on the Ventilation Efficiency of Turbine Ventilators Used for Building and Factory Ventilation,” Energy Build., 35(9), pp. 927–932. [CrossRef]
Revel, A. , 1998, “ Testing of Two Wind Driven Roof Ventilators,” INSEARCH Limited, Sydney, Australia, Technical Report No. E98/42/041. http://www.svswindventilators.com/Testing%20of%20Hurricane%20Ventilators%20Vs.%20Spherical%20Vane%20Ventilators.pdf
Khan, N. , Su, Y. , Riffat, S. B. , and Biggs, C. , 2008, “ Performance Testing and Comparison of Turbine Ventilators,” Renewable Energy, 33(11), pp. 2441–2447. [CrossRef]
De Gids, W. , and Den Ouden, H. P. L. , 1987, “ Three Investigations of the Behavior of Ducts for Natural Ventilation in Which an Examination is Made of the Influence of Location and Height of the Outlet, of the Built-Up Nature of the Surroundings and of the Form of the Outlet,” TNO, The Hague, The Netherlands.
Hughes, B. R. , and Abdul Ghani, S. A. A. , 2008, “ Investigation of a Windvent Passive Ventilation Device Against Current Fresh Air Supply Recommendations,” Energy Build., 40(9), pp. 1651–1659. [CrossRef]
Hughes, B. R. , and Abdul Ghani, S. A. A. , 2009, “ A Numerical Investigation Into the Effect of Windvent Dampers on Operating Conditions,” Energy Build., 44(2), pp. 237–248. [CrossRef]
Hughes, B. R. , and Abdul Ghani, S. A. A. , 2010, “ A Numerical Investigation Into the Effect of Windvent Louvre External Angle on Passive Stack Ventilation Performance,” Energy Build., 45(4), pp. 1025–1036. [CrossRef]
Serag-Eldin, M. A. , 2009, “ Prediction of Performance of a Wind-Driven Ventilation Device,” J. Wind Eng. Ind. Aerodyn., 97(11–12), pp. 560–572. [CrossRef]
Kim, J.-H. , Kim, J.-W. , and Kim, K.-Y. , 2011, “ Axial-Flow Ventilation Fan Design Through Multi-Objective Optimization to Enhance Aerodynamic Performance,” ASME J. Fluids Eng., 133(10), p. 101101. [CrossRef]
Pfeiffer, A. , Dorer, V. , and Weber, A. , 2008, “ Modelling of Cowl Performance in Building Simulation Tools Using Experimental Data and Computational Fluid Dynamics,” Build. Environ., 43(8), pp. 1361–1372. [CrossRef]
Van Hooff, T. , Blocken, B. , Aanen, L. , and Bronsema, B. , 2011, “ A Venturi-Shaped Roof for Wind-Induced Natural Ventilation of Buildings: Wind Tunnel and CFD Evaluation of Different Design Configurations,” Build. Environ., 46(9), pp. 1797–1807. [CrossRef]
Van Hooff, T. , Blocken, B. , Aanen, L. , and Bronsema, B. , 2012, “ Numerical Analysis of the Performance of a Venturi-Shaped Roof for Natural Ventilation: Influence of Building Width,” J. Wind Eng. Ind. Aerodyn., 104–106, pp. 419–427. [CrossRef]
Blocken, B. , Van Hooff, T. , Aanen, L. , and Bronsema, B. , 2011, “ Computational Analysis of the Performance of a Venturi-Shaped Roof for Natural Ventilation: Venturi-Effect Versus Wind-Blocking Effect,” Comput. Fluids, 48(1), pp. 202–213. [CrossRef]
Montazeri, H. , Montazeri, F. , Azizian, R. , and Mostafavi, S. , 2010, “ Two-Sided Wind Catcher Performance Evaluation Using Experimental, Numerical and Analytical Modeling,” Renewable Energy, 35(7), pp. 1424–1435. [CrossRef]
Montazeri, H. , 2011, “ Experimental and Numerical Study on Natural Ventilation Performance of Various Multi-Opening Wind Catchers,” Build. Environ., 46(2), pp. 370–378. [CrossRef]
Lien, S.-T. J. , and Ahmed, N. A. , 2010, “ Numerical Simulation of Rooftop Ventilator Flow,” Build. Environ., 45(8), pp. 1808–1815. [CrossRef]
Farahani, A. , Adam, N. , and Ariffin, M. , 2010, “ Simulation of Airflow and Aerodynamic Forces Acting on a Rotating Turbine Ventilator,” Am. J. Eng. Appl. Sci., 3(1), p. 159. [CrossRef]
BSI, 2005, “ Ventilation for Buildings. Performance Testing of Components/Products for Residential Ventilation. Cowls and Roof Outlet Terminal Devices,” British Standards Institution, London, Standard No. EN-13141-5. http://www.din.de/en/getting-involved/standards-committees/nhrs/projects/wdc-proj:din21:243256600
ISO, 2008, “ Industrial Fans. Performance Testing Using Standardized Airways,” International Organization for Standardization, Geneva, Switzerland, Standard No. ISO-5801. https://www.iso.org/standard/39542.html
Ferziger, J. H. , and Perić, M. , 1996, Computational Methods for Fluid Dynamics, Vol. 3, Springer, Berlin. [CrossRef]
Shih, T.-H. , Zhu, J. , and Lumley, J. L. , 1993, “ A Realizable Reynolds Stress Algebraic Equation Model,” NASA Lewis Research Center, Cleveland, OH, Technical Report No. NASA-TM-105993. https://ntrs.nasa.gov/search.jsp?R=19930007407
Strasser, W. , 2009, “ Cyclone-Ejector Coupling and Optimisation,” Prog. Comput. Fluid Dyn., 10(1), pp. 19–31. [CrossRef]
Launder, B. E. , and Spalding, D. B. , 1974, “ The Numerical Computation of Turbulent Flows,” Comput. Methods Appl. Mech. Eng., 3(2), pp. 269–289. [CrossRef]
Liu, H.-L. , Ren, Y. , Wang, K. , Wu, D.-H. , Ru, W.-M. , and Tan, M.-G. , 2012, “ Research of Inner Flow in a Double Blades Pump Based on Openfoam,” J. Hydrodyn., Ser. B, 24(2), pp. 226–234. [CrossRef]
Vanyo, J. P. , 1993, Rotating Fluids in Engineering and Science, Elsevier, Amsterdam, The Netherlands.
Ballesteros-Tajadura, R. , Velarde-Suárez, S. , Hurtado-Cruz, J. P. , and Santolaria-Morros, C. , 2006, “ Numerical Calculation of Pressure Fluctuations in the Volute of a Centrifugal Fan,” ASME J. Fluids Eng., 128(2), pp. 359–369. [CrossRef]
Ballesteros-Tajadura, R. , Velarde-Suárez, S. , and Hurtado-Cruz, J. P. , 2008, “ Noise Prediction of a Centrifugal Fan: Numerical Results and Experimental Validation,” ASME J. Fluids Eng., 130(9), p. 091102. [CrossRef]
Gonzalez, J. , Fernandez, J. , Blanco, E. , and Santolaria, C. , 2002, “ Numerical Simulation of the Dynamic Effects Due to Impeller-Volute Interaction in a Centrifugal Pump,” ASME J. Fluids Eng., 124(2), pp. 348–355. [CrossRef]
Corsini, A. , Delibra, G. , and Sheard, A. G. , 2013, “ A Critical Review of Computational Methods and Their Application in Industrial Fan Design,” ISRN Mech. Eng., 2013, p. 625175. [CrossRef]
Hamidreza, T. , Masoud, B. , and Mohammad, T. R. , 2012, “ An Investigation on Turbocharger Turbine Performance Parameters Under Inlet Pulsating Flow,” ASME J. Fluids Eng., 134(8), p. 081102. [CrossRef]
Tallgren, J. A. , Sarin, D. A. , and Sheard, A. G. , 2004, “ Utilization of CFD in Development of Centrifugal Fan Aerodynamics,” International Conference on Fans, London, Nov. 9–10, Vol. 4, p. 99.
Pluviose, M. , 2004, “ Similitude des turbomachines hydrauliques,” Techniques De L’ingénieur, Saint-Denis, France, Report No. TIB173DUO.
Wang, S. K. , 2001, Handbook of Air Conditioning and Refrigeration, McGraw-Hill, New York.
Neal, D. , and Foss, J. , 2007, “ The Application of an Aerodynamic Shroud for Axial Ventilation Fans,” ASME J. Fluids Eng., 129(6), pp. 764–772. [CrossRef]


Grahic Jump Location
Fig. 1

Schematic view of the studied geometry

Grahic Jump Location
Fig. 2

Numerical domains for pressure drop mode and dynamic mode (cubic domain with bold bounds), static mode (parallelepipedic domain with thin bounds), and boundary conditions

Grahic Jump Location
Fig. 3

Effect of the mesh on the vertical velocity (m s−1) inside the MRF area. The coarse mesh is on the left, the intermediate mesh is at the top, and the fine mesh is on the right. Each cross represents a cell.

Grahic Jump Location
Fig. 4

Mesh for pressure drop mode simulations: (a) cut section in the fan and (b) detail of blades

Grahic Jump Location
Fig. 5

Dimensionless pressure drop as a function of Reynolds number

Grahic Jump Location
Fig. 6

Nondimensionalized velocity field magnitude and nondimensionalized static pressure at Re = 188,462 for pressure drop mode: (a) nondimensionalized velocity (U/Ub) and (b) nondimensionalized pressure ΔPs/(0.5ρUb2)

Grahic Jump Location
Fig. 7

Dimensionless static extraction as a function of Reynolds number

Grahic Jump Location
Fig. 8

Nondimensionalized velocity field magnitude and nondimensionalized static pressure at Re = 22,772 and U = 8 m s−1 for static mode: (a) U/U and (b) ΔPs/(0.5ρU∞2)

Grahic Jump Location
Fig. 9

Dimensionless pressure as a function of Reynolds number

Grahic Jump Location
Fig. 10

Efficiency of the extractor as a function of Reynolds number

Grahic Jump Location
Fig. 11

Relative velocity (m s−1) for dynamic mode, seen from below

Grahic Jump Location
Fig. 12

Streamlines (a), and velocity vectors (b) of the flow below the fan: (a) swirling flow below the fan and (b) flow between the fan and the guard, (z = 1.67 m)

Grahic Jump Location
Fig. 13

Line plot of velocities depending of the radius (a), and position of the different part of the extractor following the radius (b): (a) line plot of the vertical velocity and tangential velocity against the radius at z = 1.67 m and (b) schematic view of the extractor



Some tools below are only available to our subscribers or users with an online account.

Related Content

Customize your page view by dragging and repositioning the boxes below.

Related Journal Articles
Related eBook Content
Topic Collections

Sorry! You do not have access to this content. For assistance or to subscribe, please contact us:

  • TELEPHONE: 1-800-843-2763 (Toll-free in the USA)
  • EMAIL: asmedigitalcollection@asme.org
Sign In