Commenced in January 2007
Frequency: Monthly
Edition: International
Paper Count: 32127
CFD-Parametric Study in Stator Heat Transfer of an Axial Flux Permanent Magnet Machine

Authors: Alireza Rasekh, Peter Sergeant, Jan Vierendeels


This paper copes with the numerical simulation for convective heat transfer in the stator disk of an axial flux permanent magnet (AFPM) electrical machine. Overheating is one of the main issues in the design of AFMPs, which mainly occurs in the stator disk, so that it needs to be prevented. A rotor-stator configuration with 16 magnets at the periphery of the rotor is considered. Air is allowed to flow through openings in the rotor disk and channels being formed between the magnets and in the gap region between the magnets and the stator surface. The rotating channels between the magnets act as a driving force for the air flow. The significant non-dimensional parameters are the rotational Reynolds number, the gap size ratio, the magnet thickness ratio, and the magnet angle ratio. The goal is to find correlations for the Nusselt number on the stator disk according to these non-dimensional numbers. Therefore, CFD simulations have been performed with the multiple reference frame (MRF) technique to model the rotary motion of the rotor and the flow around and inside the machine. A minimization method is introduced by a pattern-search algorithm to find the appropriate values of the reference temperature. It is found that the correlations are fast, robust and is capable of predicting the stator heat transfer with a good accuracy. The results reveal that the magnet angle ratio diminishes the stator heat transfer, whereas the rotational Reynolds number and the magnet thickness ratio improve the convective heat transfer. On the other hand, there a certain gap size ratio at which the stator heat transfer reaches a maximum.

Keywords: Axial flux permanent magnet, CFD, magnet parameters, stator heat transfer.

Digital Object Identifier (DOI):

Procedia APA BibTeX Chicago EndNote Harvard JSON MLA RIS XML ISO 690 PDF Downloads 1349


[1] H. Hakala, “Integration of Motor and Hoisting Machine Changes the Elevator Business,” Proceedings of International Conference on Electrical Machines (ICEM), vol. 3, pp. 1242-1245, 2000.
[2] C. Ruschettia, C. Verucchib, G. Bossioa, C. De Angeloa, G. García, “Rotor demagnetization effects on permanent magnet synchronous machines,” Energy Conversion and Management, vol. 7, pp. 1–8, 2013.
[3] S. Scowby, R. Dobson, M. Kamper, “Thermal modelling of an axial flux permanent magnet machine,” Appl. Thermal Eng, vol. 24, pp. 193–207, 2004.
[4] G. Airoldi, J. Bumby, C. Dominy, G. Ingram, C. Lim, K. Mahkamov, N. Brown, A. Mebarki, M. Shanel, “Air flow and heat transfer modeling of an axial flux permanent magnet generator,” World Acad. Sci., Eng. Technol, vol. 58, pp. 809–813, 2009.
[5] P. Moradnia, M. Golubev, V. Chernoray, H. Nilsson, “Flow of cooling air in an electric generator model-An experimental and numerical study,” Applied energy, vol. 114, pp. 644-653, 2014.
[6] J. Pyrhönen, P. Lindh, M. Polikarpova, E. Kurvinen, “Heat-transfer improvements in an axial-flux permanent-magnet synchronous machine,” Applied Thermal Engineering, vol. 76, pp. 245-251, 2015.
[7] Y.C. Chong, D.A. Magahy, J. Chick, M.A. Mueller, D.A. Staton, A.S. McDonald, “Numerical modelling of an axial flux permanent magnet machine for convection heat transfer,” Renewable Power Generation (RPG) IET Conference, pp. 1-6, 2011.
[8] C.H. Lim, G. Airoldi, J.R. Bumby, R.G. Dominy, G.I. Ingram, K. Mahkamov, N.L. Brown, A. Mebarki, M. Shanel, “Experimental validation of CFD modelling for heat transfer coefficient predictions in axial flux permanent magnet generators,” International Journal of Thermal Sciences, pp. 50, 2451-2463, 2011.
[9] Z.X. Yuan, N. Saniei, X.T. Yan, “Turbulent heat transfer in the stationary disk in a rotor-stator system,” Int. J. Heat Mass Transf. vol. 46, pp. 2207-2218, 2003.
[10] D.A. Howey, A.S. Holmes, K.R. Pullen, “Radially resolved measurement of stator heat transfer in a rotor–stator disc,” International Journal of Heat and Mass Transfer, vol. 53 pp. 491–501, 2010.
[11] A. Rasekh, P. Sergeant, J. Vierendeels, “A parametric-CFD study for heat transfer and fluid flow in a rotor-stator system,” 11th World congress on Computational Mechanics (WCCM XI) pp. 1-9, 2014.
[12] A. Rasekh, P. Sergeant, J. Vierendeels, “Convective heat transfer prediction in disk-type electrical machines,” Applied Thermal Engineering, vol. 91, pp. 778-790, 2015.