Journal article Open Access
K. Vasudeva Karanth; N. Yagnesh Sharma
Generally flow behavior in centrifugal fan is observed to be in a state of instability with flow separation zones on suction surface as well as near the front shroud. Overall performance of the diffusion process in a centrifugal fan could be enhanced by judiciously introducing the boundary layer suction slots. With easy accessibility of CFD as an analytical tool, an extensive numerical whole field analysis of the effect of boundary layer suction slots in discrete regions of suspected separation points is possible. This paper attempts to explore the effect of boundary layer suction slots corresponding to various geometrical locations on the impeller with converging configurations for the slots. The analysis shows that the converging suction slots located on the impeller blade about 25% from the trailing edge, significantly improves the static pressure recovery across the fan. Also it is found that Slots provided at a radial distance of about 12% from the leading and trailing edges marginally improve the static pressure recovery across the fan.
Boyce, M.P., Gas Turbine Engineering Hand Book, Gulf Professional Publishing, Third Edition, USA, 2006, pp. 238 - 239.
Reacock, R. E., "Boundary-Layer Suction to Eliminate Corner Separation in Cascades of Aerofoils", Research report, University Engineering Department, Cambridge, 1965.
Khan, M.M.S., Cornelius, K.C. and Tassa, Y., "Effect of suction on boundary-layer flow over a 2-D slot", American Institute of Aeronautics and Astronautics, Aerospace Sciences Meeting, 20th, Orlando, FL, Jan. 11-14, 1982, 11 p
Seal, C.V. and Smith, C.R., "The control of turbulent end-wall boundary layers using surface suction", Experiments in Fluids, Springer Publications, Volume 27, Number 6 , November, 1999, pp. 484-496
Raghunathan, S. and Cooper, R.K., "Passive Boundary Layer Control with Slots in Short Diffusers", ASME Journal of Fluids Engineering, 3, Vol. 122, 2000, pp. 177-179.
Wursthorn, S. and Schnerr, G.H., "Numerical investigations of cavitation control in pumps", Journal of Applied Mathematics and Mechanics, vol. 80, 2000, pp. S663-S664
Hubrich, K., Bolcs, A. and Ott, P., "Boundary Layer Suction via a Slot in a Transonic Compressor: Numerical Parameter Study and First Experiments", Proceedings of ASME Turbo Expo 2004 Power for Land, Sea, and Air GT2004-53758, 2004, Austria
Shojaefard, M.H., Noorpoor, A.R, Avanesians, A. and Ghaffarpour, M., "Numerical Investigation of Flow Control by Suction and Injection on a Subsonic Airfoil", American Journal of Applied Sciences, Science Publications, 2 (10), 2005, pp. 1474-1480.
Atik, H., Kim, C.Y., Van-Dommelen, L. and Walker, J.D.A., "Boundary-layer Separation Control on a Thin Airfoil using Local Suction", Journal of Fluid Mechanics Cambridge University Press, 535 , 2005, pp. 415-443.  Gajjar, J.S.B. and Smith, F.T., "Vortices and flow reversal due to suction slots", Philosophical Transactions of the Royal Society, Vol. 363, No. 1830, 2005, pp. 1199 - 1208.  Dovgal, A. and Sorokin, A., "Application of flow suction for controlling the shedding of large-scale vortices at boundary-layer separation", Journal of Applied Mechanics and Technical Physics, Volume 47, Number 4, 2006, pp. 510-514  Song, Y., Chen, F., Yang J. and Wang, Z., "A Numerical Investigation of Boundary Layer Suction in Compound Lean Compressor Cascades", ASME Journal of Turbomachinery, 5, Volume 128, Issue 2, 2006, pp. 357 - 366.  Atik, H. and van Dommelen, L., "Autogenous Suction to Prevent Laminar Boundary-Layer Separation". Journal of Fluids Engineering 1, Vol. 130, Issue 1, 2008, 011201 (8 pages)  Gbadebo, S.A., Cumpsty, N.A. and Hynes T.P., "Control of Three- Dimensional Separations in Axial Compressors by Tailored Boundary Layer Suction", ASME Journal of Turbomachinery , 1, Volume 130, Issue 1, 2008, 011004 (8 pages)  Fatsis, A., Pierret, S. and Van den Braembussche, R., "Threedimensional unsteady flow and forces in centrifugal impellers with circumferential distortion of the outlet static pressure", ASME Journal of Turbomachinery, 119, 1997, pp. 94-102.  Sorokes, J.M., Borer, J.C. and Koch, J.M., "Investigation of the circumferential static pressure non-uniformity caused by centrifugal compressor discharge volute", 98 GT 326, International Gas Turbine & Aeroengine Congress & Exhibition, Stockholm, 1998, Sweden,  Hillewaert, K. and Van den Braembussche, R.A., "Numerical simulation of impeller-volute interaction in centrifugal compressors", ASME Journal of Turbomachinery, 121, 1999, pp. 603-608.  Shi, F. and Tsukamoto, H., "Numerical Study of Pressure Fluctuations Caused by Impeller-Diffuser Interaction in a Diffuser Pump Stage", Transactions of the ASME, 9, Vol. 123, 2001, pp. 466 - 474.  Sofiane, K., Smaïne, K., Farid, B. and Robert, R., "Flow Study in the Impeller-Diffuser Interface of a Vaned Centrifugal Fan", ASME Journal of Fluid Engineering, 5, vol. 127, 2005, pp. 495 - 502.  Meakhail, T. and Par,k S.O., "A Study of Impeller-Diffuser-Volute Interaction in a Centrifugal Fan", ASME Journal of Turbo machinery, 127, 2005, pp. 84 - 90.  Fluent 6.3, Fluent Inc., 2006.  Patankar, S.V., Numerical Heat Transfer and Fluid Flow, Tailor and Francis, 1980, pp. 90-92.