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Investigation study on the flow-induced noise by winglet and shroud shape of an axial flow fan at an outdoor unit of air conditioner

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Abstract

Axial flow fans of outdoor units are equipped with specially shaped winglets and shroud for reduction of the flow-induced noise. In this study, the unsteady state flow field and the characteristics of the flow-induced noise according to the application of the sweptback tip winglets and 30 % covered shroud in an axial flow fan of an outdoor unit of air conditioner were experimentally and numerically analyzed. To analyze the unsteady flow field, large eddy simulation (LES) reflecting the geometry of complicated outdoor unit was performed; and the LES results were used by simplified Ffowcs Williams and Hawkings (FW-H) equation in order to calculate the noise numerically. As a result, asymmetric flow characteristics inside the outdoor unit by the mount and the shape of blade tip and shroud were found to cause inconsistent movement of the tip leakage vortex, which was revealed to change the characteristics of the flow-induced noise.

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Abbreviations

D :

Diameter of fan (m)

D hub :

Diameter of fan’s hub (m)

R :

Radius of fan (m)

H fan :

Height of fan (m)

δ :

Tip clearance (m)

h winglet :

Height of winglet (m)

ρ :

Density of air (kg m−3)

c 0 :

Sound speed (m s−1)

p fluid :

Static wall pressure by fluid flow (Pa)

r :

Distance between observer and noise source (m)

y + :

Non-dimensional wall distance

x :

Locations of observer

y :

Locations of noise source

M r :

Convective Mach number

A st :

Aeroacoustic source strength

t :

Time (s)

ω :

Vorticity (s−1)

Q :

Volume flow rate of fan (m3 s−1)

K sa :

Specific noise level (dB)

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Acknowledgments

This work was supported by the Industrial Technology Innovation Program (Advanced Technology Center, 10051890) funded by the Ministry of Trade, Industry & Energy, and supported by the Korea Institute of Energy Technology Evaluation and Planning (KETEP) and the Ministry of Trade, Industry & Energy (MOTIE) of the Republic of Korea (No. 20172010 105200).

Author information

Authors and Affiliations

  1. Technical Research Lab., CEDIC Co., 145 Gasan digital 1-ro, Geumcheon-gu, Seoul, 08506, Korea

    Tae-Gyun Lim & Wan-Ho Jeon

  2. Air Solution Lab., LG Electronics Co. Ltd., 51 Gasan-digital-1-ro, Geumcheon-gu, Seoul, 08592, Korea

    Jae Hyuk Jung

  3. School of Mechanical Engineering, Yonsei University, 50 Yonsei-ro, Seodaemun-gu, Seoul, 03722, Korea

    Won-Gu Joo

  4. Department of Mech. Eng., Faculty of Science and Engineering, Hosei University, Tokyo, 184-8584, Japan

    Gaku Minorikawa

Authors
  1. Tae-Gyun Lim
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  2. Jae Hyuk Jung
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  3. Wan-Ho Jeon
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  4. Won-Gu Joo
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  5. Gaku Minorikawa
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Corresponding author

Correspondence to Won-Gu Joo.

Additional information

Recommended by Editor Yang Na

Tae-Gyun Lim received his Ph.D. at the Hosei University in 2018. He currently works at the Technical Research Lab. of CEDIC Co. Ltd. with a focus on the field of aerodynamics and aeroacoustics. His major research interests are computational analysis for incompressible/compressible fluid flow and flow-induced noise.

Jae Hyuk Jung received his Ph.D. degrees at Yonsei University in 2020. He currently works at the Air Solution Lab. of LG Electronics Co., since 2011. His main research field is high-efficiency, low-noise design of fans used in air conditioners and air purifiers.

Wan-Ho Jeon received his master’s and Ph.D. degrees at KAIST in 1994 and 1999, respectively. He worked in LG Electronics with a focus on aeroacoustic analysis and low-noise fan design. He has published over 100 scientific papers in CFD, aeroacoustics, and fan design. He currently works at CEDIC Co. Ltd., particularly in the areas of CFD, aeroacoustics, noise reduction, and development of FlowNoise S/W.

Won-Gu Joo has received his B.S. and M.S. degrees from Mechanical Engineering at Yonsei University in 1981 and 1987, respectively. He moved to Whittle Laboratory in University of Cambridge, United Kingdom for his Ph.D. and received the degree from Engineering on October 1994. Since September 1995, he has been working at the Department of Mechanical Engineering in Yonsei University as currently an Associate Professor. His research interests include aerodynamic design, loss mechanism, unsteady flow and non-uniform flow interactions in turbomachinery.

Gaku Minorikawa received his Ph.D. at the Tokyo Institute of Technology in 2000. He has worked as a Professor at the Department of Mechanical Engineering in Hosei University since 1999. His major research interests are fan noise control, sound quality, microturbomachinery design, standardization work of noise, and vibration measurement for small fans.

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Lim, TG., Jung, J.H., Jeon, WH. et al. Investigation study on the flow-induced noise by winglet and shroud shape of an axial flow fan at an outdoor unit of air conditioner. J Mech Sci Technol 34, 2845–2853 (2020). https://doi.org/10.1007/s12206-020-0617-2

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  • DOI: https://doi.org/10.1007/s12206-020-0617-2

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