Contra-rotating small-sized axial fans are used as cooling fans for electric
equipment. In the case of the contra-rotating rotors, the blade row distance
between front and rear rotors is a key parameter for the performance and stable
operation. The wake and potential interference occur between the front
and rear rotors and leakage flow from the front rotor tip influences on the
flow condition of the rear rotor near the shroud when the blade row distance
is small. Therefore, it is important to clarify the flow condition between front
and rear rotors. The fan static pressure curves were obtained by the experimental
apparatus and the numerical analysis was also conducted to investigate
the internal flow between front and rear rotors. The leakage flow from the
front rotor tip reaches the leading edge of the rear rotor when the blade row
distance is small as L = 10 mm and the pressure fluctuations at the leading
edge of the rear rotor tip becomes larger than those at other radial positions.
In the present paper, the vorticity contour between front and rear rotors is
shown and pressure fluctuations related to the leakage flow from the front rotor
is investigated using the numerical analysis result. Then, suitable blade
row distance for the contra-rotating small sized axial fan is discussed based on
the internal flow condition.
References
[1]
Hata, T. and Nakamoto, S. (2010) Energy Saving Service for Data Centers. Journal of the Japan Society for Precision Engineering, 76, 272-275. (In Japanese)
https://doi.org/10.2493/jjspe.76.272
[2]
Furukawa, A., Shigemitsu, T. and Watanabe, S. (2007) Performance Test and Flow Measurement of Contra-Rotating Axial Flow Pump. Journal of Thermal Science, 16, 7-13. https://doi.org/10.1007/s11630-007-0007-4
[3]
Furukawa, A., Cao, Y., Okuma, K. and Watanabe, S. (2000) Experimental Study of Pump Characteristics of Contra-Rotating Axial Flow Pump. Proceedings of the 2nd International Symposium on Fluid Machinery and Fluid Engineering, Beijing, 67, 245-252.
[4]
Nouri, H., Ravelet, F., Bakir, F., Sarraf, C. and Rey, R. (2012) Design and Experimental Validation of a Ducted Counter-Rotating Axial-Flow Fans System. Journal of Fluids Engineering, 134, 104504. https://doi.org/10.1115/1.4007591
[5]
Shigemitsu, T., Furukawa, A., Okuma, K. and Watanabe, S. (2002) Experimental Study on Rear Rotor Design in Contra-Rotating Axial Flow Pump. Proceedings of 5th JSME/ KSME Fluids Engineering Conference, Nagoya, 17-21 November, 2002, 1453-1548.
[6]
Wang, C. and Huang, L. (2014) Passive Noise Reduction for a Contrarotating Fan. Journal of Turbomachinery, 137, 031007. https://doi.org/10.1115/1.4028357
[7]
Sanders, A.J., Papalia, J. and Fleeter, S. (2002) Multi-Blade Row Interactions in a Transonic Axial Compressor: Part I—Stator Particle Image Velocimetry (PIV) Investigation. Journal of Turbomachinery, 124, 10-18.
https://doi.org/10.1115/1.1411973
[8]
Nouri, H., Danlos, A., Ravelet, F., Bakir, F. and Sarraf, C. (2013) Experimental Study of the Instationary Flow between Two Ducted Counter-Rotating Rotors. Journal of Engineering for Gas Turbines and Power, 135, 022601.
https://doi.org/10.1115/1.4007756
[9]
Shigemitsu, T., Fukutomi, J. and Okabe, Y. (2010) Performance and Flow Condition of Small-Sized Axial Fan and Adoption of Contra-Rotating Rotors. Journal of Thermal Science, 19, 1-6. https://doi.org/10.1007/s11630-010-0001-0
[10]
Ito, T., Minorikawa, G., Nagamatsu, A. and Suzuki, S. (2006) Experimental Research for Performance and Noise of Small Axial Flow Fan (Influence of Parameter of Blade). Transactions of the JSME, 72, 670-667. (In Japanese)
https://doi.org/10.1299/kikaib.72.670
[11]
Shigemitsu, T., Fukutomi, J. and Shimizu H. (2012) Influence of Blade Row Distance on Performance and Flow Condition of Contra-Rotating Small-Sized Axial Fan. International Journal of Fluid Machinery and Systems, 5, 161-167.
https://doi.org/10.5293/IJFMS.2012.5.4.161
