Structure of Tip Leakage Flow in a Forward-Swept Axial-Flow Fan Operating at Different Loading Conditions

  • 발행 : 2004.03.01


An experimental analysis using three-dimensional Laser Doppler Velocimetry(LDV) measurement and computational analysis using the Reynolds stress model in FLUENT are conducted to give a clear understanding of the effect of blade loading on the structure of tip leakage flow in a forward-swept axial-flow fan operating at the maximum efficiency condition ($\Phi$=0.25) and two off-design conditions ($\Phi$=0.21 and 0.30). As the blade loading increases, the onset position of the rolling-up of tip leakage flow moves upstream and the trajectory of tip leakage vortex center is more inclined toward the circumferential direction. Because the casing boundary layer becomes thicker and the mixing between the through-flow and the leakage jet with the different flow direction is enforced, the streamwise vorticity decays more fast with the blade loading increasing. A distinct tip leakage vortex is observed downstream of the blade trailing edge at $\Phi$=0.30, but it is not observed at $\Phi$=0.21 and 0.25.



  1. Lauchle, G. C., MacGillivray, J. R. and Swanson, D. C., 1997, Active control of axial-flow fan noise, J. Acoust. Soc. America, Vol. 101, pp.341-349
  2. Quinlan, D. A. and Bent, D. A., 1998, High frequency noise generation in small axial flow fans, J. Sound Vibration, Vol. 218, pp. 177-204
  3. Wagner, J. H., Dring, R. P. and Joslyn, H. D., 1983, Axial compressor middle stage secondary flow study, NASA-3701
  4. Pandya, A. and Lakshminarayana, B., 1983, Investigation of the tip clearance flow inside and at the exit of a compressor rotor passage- Part I: mean velocity field, ASME J, Eng. Power, Vol. 105, pp.1-12
  5. Myung, H. J. and Baek, J. H., 1999, Mean velocity characteristics behind a forwardswept axial-flow fan, JSME Int. J. (B), Vol. 42, pp. 476-488
  6. FLUENT, 2001, User's guide Ver.6, Fluent Inc
  7. Myung, H. J., Baek, J. H., Rew, H. S. and Lee, I. S., 1999, Turbulence chracteristics of a leakage vortex in an axial-flow fan, Proc. of KFMA Meeting, Seoul, Korea, pp. 227-233
  8. Myung, H. J. and Baek, J. H., 1999, Measurement of the flow behind an axial-flow fan using three-dimensional LDV, Proc. of SAREK Meeting, Seoul, Korea, pp.563-567
  9. Myung, H. J., Baek, J. H. and Lee, I.S., 2000, A study of the flows of an axial flow fan, Proc. 1st National Cong. Fluids Eng., Muju, Korea, pp.667-670
  10. Lee, G. H., Myung, H. J. and. Baek, J. H., 2003, Structure of tip leakage flow in a forwardswept axial-flow fan, Flow, Turbulence and Combustion, Vol. 70, pp.241-265
  11. GAMBIT, 2001, User's guide Ver.2, Fluent Inc