Effect of Blade Design Parameters on Air Flow through an Axial Fan


Faculty of Mechanical Engineering, Semnan University, Semnan, Iran


The objective of this paper is the numerical study of the flow through an axial fan and examining the effects of blade design parameters on the performance of the fan. The axial fan is extensively used for cooling of the electronic devices and servers. Simulation of the three-dimensional incompressible turbulent flow was conducted by numerical solution of the (RANS) equations for a model. The SST- k-ω and k-ε turbulence models are applied in the simulations which are done using CFX software. The comparison between available experimental data and simulation results indicates that the SST k-ω model gives more accurate results than the k-ε model. The results also show that in separation regions and vortices, the pressure will decrease. Hub area and blade root contain large vortices. The effects of changes in the blade geometry and the number of blades on the fan performance are studied in detail. For the primary fan model with the different number of blades (4, 5, and 6), the maximum mass flow rate of 800 CFM is obtained. Hence, the number of blades had negligible effects on the maximum flow rate. By 3o% decreasing in the chord of the blades, the maximum mass flow rate of the fan with the different number of blades (5, 6 and 8) will be reduced to 500 CFM. Therefore, in order to increase the maximum mass flow rate, the chord and the width of blades should be increased. On the other hand, by increasing blades from 4 to 6 in the primary model, the maximum outlet pressure has been increased by 32%. Furthermore, it was found that in high flow rates, an increment in the number of blades had no effect on the produced static pressure.


1.     Ayremlouzadeh, H. and Ghafouri, J., "Computational fluid dynamics simulation and experimental validation of hydraulic performance of a vertical suspended api pump (research note)", International Journal of Engineering-Transactions B: Applications,  Vol. 29, No. 11, (2016), 1612-1620.
2.     Vazifeshenas, Y., Farhadi, M., Sedighi, K. and Shafaghat, R., "Numerical simulation of cavitation in mixed flow pump", International Journal of Engineering-Transactions C: Aspects,  Vol. 28, No. 6, (2015), 956-962.
3.     Amanifard, N., "Stall vortex shedding over a compressor cascade (research note)", International Journal of Engineering-Transactions A: Basics,  Vol. 18, No. 1, (2004), 29-36.
4.     Ghorbanian, K. and Amanifard, N., "A numerical investigation on the unstable flow in a single stage of an axial compressor", International Journal of Engineering-Transactions A: Basics,  Vol. 16, No. 2, (2003), 171-180.
5.     Krishna, S.R., Krishna, A.R. and Ramji, K., "Reduction of motor fan noise using CFD and caa simulations", Applied acoustics,  Vol. 72, No. 12, (2011), 982-992.
6.     Hu, B.-b., OuYang, H., Wu, Y.-d., Jin, G.-y., Qiang, X.-q. and Du, Z.-h., "Numerical prediction of the interaction noise radiated from an axial fan", Applied acoustics,  Vol. 74, No. 4, (2013), 544-552.
7.     Scheit, C., Karic, B. and Becker, S., "Effect of blade wrap angle on efficiency and noise of small radial fan impellers—a computational and experimental study", Journal of Sound and Vibration,  Vol. 331, No. 5, (2012), 996-1010.
8.     Hurault, J., Kouidri, S., Bakir, F. and Rey, R., "Experimental and numerical study of the sweep effect on three-dimensional flow downstream of axial flow fans", Flow Measurement and Instrumentation,  Vol. 21, No. 2, (2010), 155-165.
9.     Lin, S.-C. and Huang, C.-L., "An integrated experimental and numerical study of forward–curved centrifugal fan", Experimental Thermal and Fluid Science,  Vol. 26, No. 5, (2002), 421-434.
10.   Pathak, Y.R., Baloni, B.D. and Channiwala, D.S., "Numerical simulation of centrifugal blower using CFX", International Journal of Electronics, Communication & Soft Computing Science and Engineering,  (2012), 242-247.
11.   Denton, J.D., "Some limitations of turbomachinery CFD", ASME Paper No. GT2010-22540,  (2010), 735-745.
12.   Foss, J., Neal, D., Henner, M. and Moreau, S., "Evaluating CFD models of axial fans by comparisons with phase-averaged experimental data". (2001), SAE Technical Paper.
13.   Chen, Y.-C., Chen, C.-L. and Dong, Q., "CFD modeling for motor fan system", in Electric Machines and Drives Conference. IEMDC'03. IEEE International, Vol. 2, (2003), 764-768.
14.   Beiler, M. and Carolus, T., "Computation and measurement of the flow in axial flow fans with skewed blades", Transactions-American Society of Mechanical Engineers Journal of Turbomachinery,  Vol. 121, (1999), 59-66.
15.   Estevadeordal, J., Gogineni, S., Copenhaver, W., Bloch, G. and Brendel, M., "Flow field in a low-speed axial fan: A dpiv investigation", Experimental Thermal and Fluid Science,  Vol. 23, No. 1, (2000), 11-21.
16.   ZHANG, D.-s., SHI, W.-d., Bin, C. and GUAN, X.-f., "Unsteady flow analysis and experimental investigation of axial-flow pump", Journal of Hydrodynamics, Ser. B,  Vol. 22, No. 1, (2010), 35-43.
17.   Shigemitsu, T., Fukutomi, J. and Okabe, Y., "Performance and flow condition of small-sized axial fan and adoption of contra-rotating rotors", Journal of Thermal Science,  Vol. 19, No. 1, (2010), 1-6.
18.   Lee, K.-S., Kim, K.-Y. and Samad, A., "Design optimization of low-speed axial flow fan blade with three-dimensional rans analysis", Journal of Mechanical Science and Technology,  Vol. 22, No. 10, (2008), 1864-1869.
19.   Venter, S. and Kröger, D., "The effect of tip clearance on the performance of an axial flow fan", Energy Conversion and Management,  Vol. 33, No. 2, (1992), 89-97.
20.   Vad, J. and Bencze, F., "Three-dimensional flow in axial flow fans of non-free vortex design", International Journal of Heat and Fluid Flow,  Vol. 19, No. 6, (1998), 601-607.
21.   Li, X., Spence, S., Chen, H., Chu, W. and Gibson, L., "Flow control by slot position and noise baffle in a self-recirculation casing treatment on an axial fan-rotor", International Journal of Rotating Machinery,  Vol. 2017, (2017), 143-151.
22.   ANSYS Inc, ANSYS-CFX, Release 16, Documentation, Reference Guide, (2016).