In this study, we tried to improve the performance by giving a pre-swirling flow to the radial inflow that occurred in the semi-opened axial fan. In addition, the flow fields of rotor outlet were clarified experimentally, and the effect of pre-swirling flow was considered. The experiment was carried out using a performance test wind tunnel with a square cross section of 880 mm. Three types of casings were prepared, in which the blade tip protruded 0%, 20%, and 40% of the meridional chord length. They were called R25, R15, and R05, respectively, in the casing bellmouth model code. Guide blades for generating a pre-swirling flow were installed on the vertical wall surface of the casing. In addition, a vertical wall was installed 60% upstream of the meridional chord length as an obstacle to prevent axial inflow. The velocity fields of the rotor outlet were measured using a hot-wire anemometer. From the results, the pre-swirling flow did not significantly affect the fan performance. When there was no obstacles wall upstream, there was a partial increase in efficiency, but the difference was not so large. When there was an obstacle wall upstream, the efficiency increased overall in the case of R15, but in the case of R05, the efficiency increased only in the low flow rate region, and conversely decreased in the high flow rate region. By observing the blade outlet flow fields when the performance was improved, it was confirmed that the influence of the tip leakage vortex was weakened.
References
[1]
Liu, N.T., Jiang, C.Y., Huang, L.X. and Wang, C. (2021) Effect of Porous Casing on Small Axial-Flow Fan Noise. Applied Acoustics, 175, 107808. https://doi.org/10.1016/j.apacoust.2020.107808
[2]
Obayashi, W., Aono, H., Tatsukawa, T., Fujii, K., Takeda, K., Takemi, K. and Murakami, N. (2021) Numerical Simulations and Data Analyses to Identify Aerodynamic Noise Sources Emitted from Small Axial Fan. Proceedings of ASME Fluid Engineering Division Summer Meeting, 10-12 August 2021, 7 p. https://doi.org/10.1115/FEDSM2021-65995
[3]
Yo, P.X., Bai, J.Q. and Han, X. (2021) Optimization of Low Noise Blade of Small Axial Fan at Low Reynolds Number. INTER-NOISE and NOISE-CON Congress and Conference Proceedings, 21, 236-256. https://doi.org/10.3397/IN-2021-1380
[4]
Fukuda, T., Masuda, Y., Fukue, T., Sugimoto, Y., Hatakeyama, T., Ishizuka, M. and Koizumi, K. (2021) CFD-Based Investigation of Effects of Obstruction in Front of Small Axial Cooling Fan and Deterioration of Supply Flow Rate. Proceedings of ASME 2021 International Technical Conference and Exhibition on Packaging and Integration of Electronic and Photonic Microsystems, 26-28 October 2021, 7 p. https://doi.org/10.1115/IPACK2021-72976
[5]
Shiomi, N., Kinoue, Y. and Setoguchi, T. (2018) Changes of Performance and Flow Fields of Semi-Opened Propeller Fan In-Stalled in Narrow Space. Proceedings of 29th International Symposium on Transport Phenomena (ISTP29), Honolulu, 30 October-2 November 2018, 5 p.
[6]
Shiomi, N., Kinoue, Y. and Setoguchi, T. (2019) Effect of Bellmouth Geometry on Inlet Flow Fields of Small Fan. Proceedings of 15th Asian International Conference on Fluid Machinery (AICFM15), Busan, 25-27 September 2019, 6 p.