Members of the aerospace fan community have systematically developed computational methods over the last five decades. The complexity of the developed methods and the difficulty associated with their practical application ensured that, although commercial computational codes date back to the 1980s, they were not fully exploited by industrial fan designers until the beginning of the 2000s. The application of commercial codes proved to be problematic as, unlike aerospace fans, industrial fans include electrical motors and other components from which the flow will invariably separate. Consequently, industrial fan designers found the application of commercial codes challenging. The decade from 2000 to 2010 was focused on developing techniques that would facilitate converged solutions that predicted the fans’ performance characteristics over the stable part of their operating range with reasonable accuracy, using a practical computational effort. In this paper, we focus on elucidating aspects of the flow physics that one cannot easily study in a laboratory environment, discussing the challenges involved and the relative merits of the available modelling techniques. The paper ends with a discussion of the practical problems associated with the use of commercial codes in a development environment and finally the legislation that is driving the need for aerospace style computation methods. 1. Introduction Industrial fan designers have historically relied on empirical design methodologies based upon an Euler analysis of velocity triangles [1], empirical correlations [2], experimental fluid dynamics [3], and fan noise measurements [4, 5]. Engineers have developed these empirical design methodologies over many decades, with each industrial fan manufacturer developing its own proprietary empirical correlations that aid in applying the basic methodology in specific applications. Unlike aerospace fan designers, industrial fan designers have to apply their design methodologies into a wide range of different applications. At one extreme are the cooling fans required for electronic equipment that can be no more than a few centimetres in diameter [6], and at the other extreme are fans absorbing up to 25 MW in induced draft power plant applications [7]. It is this breadth of application that has resulted in the different empirical approaches adopted by competing industrial fan manufacturers, each treating their proprietary empirical approaches as a source of competitive advantage. The historic view that the empirical approaches to industrial fan design constitute a form
References
[1]
B. Lakshminarayana, Fluid Dynamics and Heat Transfer of Turbomachinery, Wiley-Interscience, New York, NY, USA, 1996.
[2]
N. A. Cumpsty, Compressor Aerodynamics, Krieger Publishing Company, Malabar, Fla, USA, 2004.
[3]
C. Tropea, A. L. Yarin, and J. F. Foss, Eds., Springer Handbook of Experimental Fluid Mechanics, Springer, Paris, France, 2007.
[4]
W. K. Blake, Mechanics of Flow-Induced Sound and Vibration, Volume 1: General Concepts and Elementary Sources, Academic Press, Orlando, Fla, USA, 1986.
[5]
W. K. Blake, Mechanics of Flow-Induced Sound and Vibration, Volume 2: Complex Flow-Structure Interactions, Academic Press, Orlando, Fla, USA, 1986.
[6]
L. Huang and J. Wang, “Acoustic analysis of a computer cooling fan,” Journal of the Acoustical Society of America, vol. 118, no. 4, pp. 2190–2200, 2005.
[7]
S. Bianchi, A. Corsini, and A. G. Sheard, “Demonstration of a stall detection system for induced draft fans,” Proceedings of the Institution of Mechanical Engineers A, vol. 227, pp. 272–284, 2013.
[8]
Commission Regulation (EU), No. 327/2011, Official Journal of the European Union, June 2011, http://www.amca.org/UserFiles/file/COMMISSION%20REGULATION%20%28EU%29%20No%20327-2011.pdf.
[9]
A. Hauer and J. Brooks, “Fan motor efficiency grades in the European market,” AMCA Inmotion, no. 2, pp. 14–20, 2012.
[10]
U.S. Department of Energy, Energy Conservation Standards Rulemaking Framework for Commercial and Industrial Fans and Blowers, U.S. Department of Energy, 2013.
[11]
S. L. Gho, “AMCA grows in Asia,” AMCA Inmotion, no. 3, 2013.
[12]
J. H. Horlock and J. D. Denton, “A review of some early design practice using computational fluid dynamics and a current perspective,” Journal of Turbomachinery, vol. 127, no. 1, pp. 5–13, 2005.
[13]
P. K. Kundu and I. M. Cohen, Fluid Mechanics, Elsevier Academic Press, Oxford, UK, 4th edition, 2008.
[14]
P. A. Davidson, Turbulence, An Introduction for Scientists and Engineers, Oxford University Press, Oxford, UK, 2004.
[15]
K. Hanjali？, S. Kenjeres, M. J. Tummers, and H. J. J. Jonker, Analysis and Modelling of Physical Transport Phenomena, VSSD, Delft, The Netherlands, 2008.
[16]
P. A. Durbin and B. A. Pettersson Reif, Statistical Theory and Modelling for Turbulent Flows, John Wiley & Sons, Chichester, UK, 2001.
[17]
C. Hirsch, Numerical Computation of Internal and External Flows, Butterworth-Heinemann, Oxford, UK, 2007.
[18]
S. B. Pope, Turbulent Flows, Cambridge University Press, Cambridge, UK, 2000.
[19]
P. R. Spalart and S. R. Allmaras, “A one-equation turbulence model for aerodynamic flows,” in Proceedings of the 30th Aerospace Sciences Meeting and Exhibit, AIAA Paper 92-0439, Reno, Nev, USA, January 1992.
[20]
G. Rábai and J. Vad, “Validation of a computational fluid dynamics method to be applied to linear cascades of twisted-swept blades,” Periodica Polytechnica, Mechanical Engineering, vol. 49, no. 2, pp. 163–180, 2005.
[21]
S. ？ari？, B. Kniesner, A. Mehdizadeh, S. Jakirli？, K. Hanjali？, and C. Tropea, “Comparative assessment of hybrid LES/RANS models in turbulent flows separating from smooth surfaces,” in Advances in Hybrid RANS-LES Modelling, Notes on Numerical Fluid Mechanics and Multidisciplinary Design, S. H. Peng and W. Haase, Eds., vol. 97, pp. 142–151, 2008.
[22]
W. P. Jones and B. E. Launder, “The prediction of laminarization with a two-equation model of turbulence,” International Journal of Heat and Mass Transfer, vol. 15, no. 2, pp. 301–314, 1972.
[23]
D. C. Wilcox, “Reassessment of the scale-determining equation for advanced turbulence models,” AIAA Journal, vol. 26, no. 11, pp. 1299–1310, 1988.
[24]
D. C. Wilcox, Turbulence Modelling for CFD, DCW Industries, La Canada, Canada, 1993.
[25]
F. R. Menter, “Zonal two-equation k-w turbulence model for aerodynamic flows,” in Proceedings of the 24th Fluid Dynamics Conference, AIAA Paper 1993-2906, Orlando, Fla, USA, July 1993.
[26]
F. R. Menter, “Two-equation eddy-viscosity turbulence models for engineering applications,” AIAA Journal, vol. 32, no. 8, pp. 1598–1605, 1994.
[27]
M. Pinelli, C. Ferrari, A. Suman, M. Morini, and M. Rossini, “Fluid dynamic design and optimization of a double entry fan driven by tractor power take off for mist sprayer applications,” in Proceedings of the Fan 2012 Conference, Senlis, France, April 2012.
[28]
A. Corsini and F. Rispoli, “Flow analyses in a high-pressure axial ventilation fan with a non-linear eddy-viscosity closure,” International Journal of Heat and Fluid Flow, vol. 17, pp. 108–155, 2005.
[29]
A. G. Sheard, A. Corsini, S. Minotti, and F. Sciulli, “The role of computational methods in the development of an aero-acoustic design methodology: application in a family of large industrial fans,” in Proceedings of the 14th International Conference on Modelling Fluid Flow Technologies, pp. 71–79, Budapest, Hungary, September 2009.
[30]
A. Corsini and F. Rispoli, “Using sweep to extend the stall-free operational range in axial fan rotors,” Proceedings of the Institution of Mechanical Engineers A, vol. 218, no. 3, pp. 129–139, 2004.
[31]
A. Corsini and A. G. Sheard, “Tip end-plate concept based on leakage vortex rotation number control,” Journal of Computational and Applied Mechanics, vol. 8, pp. 21–37, 2007.
[32]
A. Corsini, F. Rispoli, and A. G. Sheard, “Development of improved blade tip endplate concepts for low-noise operation in industrial fans,” Proceedings of the Institution of Mechanical Engineers A, vol. 221, no. 5, pp. 669–681, 2007.
[33]
A. Corsini, F. Rispoli, and A. G. Sheard, “Aerodynamic performance of blade tip end-plates designed for low-noise operation in Axial flow fans,” Journal of Fluids Engineering, vol. 131, no. 8, Article ID 0811011, 13 pages, 2009.
[34]
A. Corsini, F. Rispoli, and A. G. Sheard, “Shaping of tip end-plate to control leakage vortex swirl in axial flow fans,” Journal of Turbomachinery, vol. 132, no. 3, Article ID 031005, 9 pages, 2010.
[35]
J. Vad and C. Horváth, “Study on the effects of axial clearance size on the operation of an axial flow electric motor cooling fan,” in Proceedings of the 10th European Turbomachinery Conference, Lappeenranta, Finland, April 2013.
[36]
A. Corsini, G. Delibra, and A. G. Sheard, “Leading edge bumps in reversible axial fans,” in Proceedings of 58th American Society of Mechanical Engineers Gas Turbine and Aeroengine Congress, Paper No. GT2013-94853, San Antonio, Tex, USA, June 2013.
[37]
F. S. Lien, W. L. Chen, and M. A. Leschziner, “Low-Reynolds-number eddy-viscosity modelling based on non-linear stress-strain/vorticity relations,” in Proceedings of the 3rd Symposium on Engineering Turbulence Modelling and Measurements, Crete, Greece, May 1996.
[38]
S. Lee, S. Heo, and C. Cheong, “Prediction and reduction of internal blade-passing frequency noise of the centrifugal fan in a refrigerator,” International Journal of Refrigeration, vol. 33, no. 6, pp. 1129–1141, 2010.
[39]
S. J. van der Spuy, T. W. von Backstr？m, and D. G. Kr？ger, “An evaluation of simplified methods to model the performance of axial flow fan arrays,” R & D Journal of the South African Institution of Mechanical Engineering, vol. 26, pp. 12–20, 2010.
[40]
A. Corsini, F. Rispoli, A. G. Sheard, and P. Venturini, “Numerical simulation of coal-fly ash erosion in an induced draft fan,” Journal of Fluids Engineering, vol. 135, Article ID 081303, 12 pages, 2013.
[41]
D. Borello, A. Corsini, F. Rispoli, and A. G. Sheard, “Large eddy simulation of a tunnel ventilation fan,” Journal of Fluids Engineering, vol. 135, Article ID 071102, 9 pages, 2013.
[42]
M. Popovac and K. Hanjali？, “Compound wall treatment for RANS computation of complex turbulent flows and heat transfer,” Flow, Turbulence and Combustion, vol. 78, no. 2, pp. 177–202, 2007.
[43]
T. J. Craft, B. E. Launder, and K. Suga, “Development and application of a cubic eddy-viscosity model of turbulence,” International Journal of Heat and Fluid Flow, vol. 17, no. 2, pp. 108–115, 1996.
[44]
W. L. Chen, F. S. Lien, and M. A. Leschziner, “Computational prediction of flow around highly loaded compressor-cascade blades with non-linear eddy-viscosity models,” International Journal of Heat and Fluid Flow, vol. 19, no. 4, pp. 307–319, 1998.
[45]
K. Hanjali？, M. Popovac, and M. Had？iabdi？, “A robust near-wall elliptic-relaxation eddy-viscosity turbulence model for CFD,” International Journal of Heat and Fluid Flow, vol. 25, no. 6, pp. 1047–1051, 2004.
[46]
P. A. Durbin, “Separated flow computations with the k-epsilon-v-squared model,” AIAA Journal, vol. 33, pp. 659–664, 1995.
[47]
B. E. Launder and N. D. Sandham, Eds., Closure Strategies for Turbulent and Transitional Flows, Cambridge University Press, Cambridge, UK, 2002.
[48]
K. Hanjali？ and B. Launder, Modelling Turbulence in Engineering and the Environment: Second-Moment Routes to Closure, Cambridge University Press, Cambridge, UK, 2011.
[49]
D. Borello, K. Hanjali？, and F. Rispoli, “Prediction of cascade flows with innovative second-moment closures,” Journal of Fluids Engineering, vol. 127, no. 6, pp. 1059–1070, 2005.
[50]
K. Hanjali？ and S. Jakirli？, “Contribution towards the second-moment closure modelling of separating turbulent flows,” Computer and Fluids, vol. 27, pp. 137–156, 1998.
[51]
K. Hanjali？ and S. Jakirli？, “A model of stress dissipation in second-moment closures,” Applied Scientific Research, vol. 51, pp. 513–518, 1993.
[52]
P. A. Durbin, “A Reynolds stress model for near-wall turbulence,” Journal of Fluid Mechanics, vol. 249, pp. 465–498, 1993.
[53]
D. Borello, K. Hanjali？, and F. Rispoli, “Computation of tip-leakage flow in a linear compressor cascade with a second-moment turbulence closure,” International Journal of Heat and Fluid Flow, vol. 28, no. 4, pp. 587–601, 2007.
[54]
T. Kobayashi and M. Yoda, “Modified k-epsilon model for turbulent swirling flow in a straight pipe,” JSME International Journal, vol. 30, no. 259, pp. 66–71, 1987.
[55]
G. F. Sander and D. G. Lilley, “The performance of an annular vane swirler,” in Proceedings of the AIAA/SAE/ASME 19th Joint Propulsion Conference, Paper No. AIAA-83-1326, Seattle, Wash, USA, 1983.
[56]
C. G. Speziale, S. Sarkar, and T. B. Gatski, “Modelling the pressure-strain correlation of turbulence. An invariant dynamical systems approach,” Journal of Fluid Mechanics, vol. 227, pp. 245–272, 1991.
[57]
F. S. Lien and P. A. Durbin, “Non linear k-ε-v2 modelling with application to high lift,” in Proceedings of the CTR Summer Program, Stanford University, 1996.
[58]
R. B. Langtry and F. R. Menter, “Transition modeling for general CFD applications in aeronautics,” in Proceedings of the 43rd AIAA Aerospace Sciences Meeting and Exhibit, AIAA Paper No. 2005-522, pp. 15513–15526, Reno, Nev, USA, January 2005.
[59]
F. R. Menter, R. B. Langtry, S. V？lker, and P. G. Huang, “Transition modelling for general purpose CFD codes,” Flow, Turbulence and Combustion, vol. 77, pp. 277–303, 2006.
[60]
F. R. Menter, R. Langtry, and S. Volker, “Transition modelling for general purpose CFD codes,” Flow, Turbulence and Combustion, vol. 77, pp. 277–303, 2006.
[61]
W. Piotrowski, W. Elsner, and S. Drobniak, “Transition prediction on turbine blade profile with intermittency transport equation,” in Proceedings of the 53rd American Society of Mechanical Engineers Gas Turbine and Aeroengine Congress, Paper No. GT2008-50796, Berlin, Germany, June 2008.
[62]
Y. Yang, A. Lucius, and G. Brenner, “3D unsteady CFD simulation of the pressure fluctuation in a centrifugal fan,” in Proceedings of the Fan 2012 Conference, Senlis, France, April 2012.
[63]
J. D. Denton and W. N. Dawes, “Computational fluid dynamics for turbomachinery design,” Proceedings of the Institution of Mechanical Engineers C, vol. 213, no. 2, pp. 107–124, 1999.
[64]
J. D. Denton, Extension of the Finite Volume Time Marching Method to Three Dimensions, VKI Lecture Series 1979-7, VKI, Rhode-St-Genèse, Belgium, 1979.
[65]
M. Vanella, U. Piomelli, and E. Balaras, “Effect of grid discontinuities on large-eddy simulation statistics and flow fields,” Journal of Turbulence, vol. 9, article 32, 2008.
[66]
G. D. Thiart and T. W. von Backstr？m, “Numerical simulation of the flow field near an axial flow fan operating under distorted inflow conditions,” Journal of Wind Engineering and Industrial Aerodynamics, vol. 45, no. 2, pp. 189–214, 1993.
[67]
J. M. F. Oro, K. M. A. Díaz, C. S. Morros, and E. B. Marigorta, “Unsteady flow and wake transport in a low-speed axial fan with inlet guide vanes,” Journal of Fluids Engineering, vol. 129, no. 8, pp. 1015–1029, 2007.
[68]
I. A. Brailko, V. I. Mileshin, M. A. Nyukhtikov, and S. V. Pankov, “Computational and experimental investigation of unsteady and acoustic characteristics of counter—rotating fans,” in Proceedings of the ASME Heat Transfer/Fluids Engineering Summer Conference, Parts A and B, vol. 2 of Paper No. HT-FED2004-56435, pp. 871–879, Charlotte, NC, USA, July 2004.
[69]
D. Wolfram and T. H. Carolus, “Experimental and numerical investigation of the unsteady flow field and tone generation in an isolated centrifugal fan impeller,” Journal of Sound and Vibration, vol. 329, no. 21, pp. 4380–4397, 2010.
[70]
P. N. Son, J. Kim, and E. Y. Ahn, “Effects of bell mouth geometries on the flow rate of centrifugal blowers,” Journal of Mechanical Science and Technology, vol. 25, no. 9, pp. 2267–2276, 2011.
[71]
D. Angeli, “HPC enabling of OpenFOAM for CFD applications,” in Proceedings of the OpenFOAM @ Mimesis and Numerical Simulation of the Mont Blanc Tunnel Workshop, CINECA, Bologna, Italy, November 2012.
[72]
A. Betz, Introduction to the Theory of Flow Machines, Pergamon Press, Oxford, UK, 1966, (D. G. Randall, Translation).
[73]
C. J. Meyer and D. G. Kr？ger, “Numerical simulation of the flow field in the vicinity of an axial flow fan,” International Journal for Numerical Methods in Fluids, vol. 36, no. 8, pp. 947–969, 2001.
[74]
J. N. S？rensen and W. Z. Shen, “Numerical modelling of wind turbine wakes,” Journal of Fluids Engineering, vol. 124, pp. 393–399, 2002.
[75]
P. Venturini, Modelling of particle-wall deposition in two-phase gas-solid flow [Ph.D. thesis], Sapienza Università di Roma, Rome, Italy, 2010.
[76]
L. L. Baxter, Turbulent transport of particles [Ph.D. thesis], Brigham Young University, Provo, Utah, USA, 1989.
[77]
W. Tabakoff, R. Kotwal, and A. Hamed, “Erosion study of different materials affected by coal ash particles,” Wear, vol. 52, pp. 161–173, 1979.
[78]
A. Ghenaiet, “Numerical study of sand ingestion through a ventilating system,” in Proceedings of the World Congress on Engineering, vol. 2, London, UK, July 2009.
[79]
L. He and J. D. Denton, “Three-dimensional time-marching inviscid and viscous solutions for unsteady flows around vibrating blades,” Journal of Turbomachinery, vol. 116, no. 3, pp. 469–476, 1994.
[80]
J. G. Marshall and M. Imregun, “A review of aeroelasticity methods with emphasis on turbomachinery applications,” Journal of Fluids and Structures, vol. 10, no. 3, pp. 237–267, 1996.
[81]
E. Envia, A. G. Wilson, and D. L. Huff, “Fan noise: a challenge to CAA,” International Journal of Computational Fluid Dynamics, vol. 18, no. 6, pp. 471–480, 2004.
[82]
F. R. Menter and Y. Egorov, “A scale-adaptive simulation model using two-equation models,” in Proceedings of the 43rd AIAA Aerospace Sciences Meeting and Exhibit, AIAA Paper No. 2005-1095, pp. 271–283, Reno, Nev, USA, January 2005.
[83]
F. R. Menter and Y. Egorov, “The scale-adaptive simulation method for unsteady turbulent flow predictions, part 1: theory and model description,” Flow, Turbulence and Combustion, vol. 85, no. 1, pp. 113–138, 2010.
[84]
F. R. Menter and Y. Egorov, “The scale-adaptive simulation method for unsteady turbulent flow predictions, part 2: application to complex flows,” Flow, Turbulence and Combustion, vol. 85, no. 1, pp. 139–165, 2010.
[85]
D. Borello, G. Delibra, K. Hanjali？, and F. Rispoli, “Large-eddy simulations of tip leakage and secondary flows in an axial compressor cascade using a near-wall turbulence model,” Proceedings of the Institution of Mechanical Engineers A, vol. 223, no. 6, pp. 645–655, 2009.
[86]
L. Davidson, “Large eddy simulation: a dynamic one-equation subgrid model for three-dimensional recirculating flow,” in Proceedings of the 11th International Symposium on Turbulent Shear Flow, vol. 3, pp. 26.1–26.6, Grenoble, France, 1997.
[87]
H. Jasak, “OpenFOAM: a year in review,” in Proceedings of the 5th OpenFOAM Workshop, Gothenburg, Sweden, June 2010.
[88]
A. Frederic, N. Mehitoua, and S. Marc, “Code_Saturne: a .finite volume code for the computation of turbulent incompressible flows—industrial applications,” IJFV International Journal on Finite Volumes, vol. 1, pp. 1–62, 2004.
[89]
M. S. Eldred, A. A. Giunta, B. G. van Bloemen Waanders, S. F. Wojtkiewicz, W. E. Hart, and M. P. Alleva, “DAKOTA, a multilevel parallel object-oriented framework for design optimization, parameter estimation, uncertainty quantification, and sensitivity analysis,” Sand Report SAND2001-3796, Sandia National Laboratories, Livermore, Calif, USA, 2002.
[90]
I. Spisso, “HPC Enabling of OpenFOAM for CFD Applications,” in Parametric and Optimization Study: OpenFOAM and Dakota, Proceedings of Workshop, CINECA, Bologna, Italy, November 2012.
