• Title/Summary/Keyword: Aerodynamic noise

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Aeolian Noise from High Voltage Insulators (초고압 송전용 애자의 풍소음 특성)

  • Chu, Jang-Hee;Kim, Sang-Beom;Shin, Koo-Yong;Lee, Seong-Doo;Lee, Dong-Il
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 2000.06a
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    • pp.1842-1847
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    • 2000

  • In this paper, a review is attempted for understanding of aeolian noise from high voltage insulators and their aerodynamic noise characteristics were investigated using the low noise wind tunnel. The noise from the insulators was dependent upon the wind speed and their orientation relative to the wind direction. The noise spectrum revealed sharp peak which was found the cavity resonance frequency.

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Noise Analysis and Reduction Methods of the All-in One Window Ventilation System (창호일체형 환기장치의 소음분석 및 저감방안)

  • Park, Chan-Jae;Haan, Chan-Hoon
    • The Journal of the Acoustical Society of Korea
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    • v.32 no.1
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    • pp.43-55
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    • 2013

  • The window ventilation system based on the heat recovery device was developed which make air ventilation possible without opening the windows. However, mechanical and aerodynamic noises were come to pass which annoyed people in rooms. In the present study, noise of new window ventilation system was measured in both general room and anechoic chamber. Also, the noise path was detected to find cause of noise generation and vulnerable area of the device. Sound absorptive and insulation materials were applied to mitigate the noise. Finally, an alternative noise control method was suggested which can satisfy with the indoor noise standards. As a result, it was shown that the cause of noise was the low transmission loss in the ventilation system. As a result, it was shown that the main noise source of the ventilation system was the blower and the major cause of noise was the low transmission loss of the ventilation system. It is also concluded that the noise levels complies with the noise standards of 40 dBA when 2 mm rubber sheet is applied inside the ventilation system.

  • https://doi.org/10.7776/ASK.2013.32.1.043 인용 PDF KSCI

PERFORMANCE ASSESSMENT OF THE RANS TURBULENCE MODELS IN PREDICTION OF AERODYNAMIC NOISE FOR AIR-CONDITIONER INDOOR UNIT (에어컨 실내기의 공력소음 예측을 위한 RANS 난류모델의 성능 평가)

  • Min, Y.H.;Kang, S.;Hur, N.;Lee, C.;Park, J.
    • Journal of computational fluids engineering
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    • v.17 no.4
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    • pp.81-86
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    • 2012

  • The objective of the present study is to investigate the effects of various turbulence models on the aerodynamic noise of an air-conditioner (AC) indoor unit. The results from URANS (unsteady Reynolds-averaged Navier-Stokes) simulations with the standard k-$\varepsilon$, k-$\omega$ shear stress transport (SST) and Spalart-Allmaras (S-A) turbulence models were analyzed and compared with the noise data from the experiments. The frequency spectra of the far-field acoustic pressure were computed using the Farrasat equation derived from the Ffowcs Williams-Hawkings (FW-H) equation based on the acoustic analogy model. Two fixed fan casings and the rotating cross-flow fan were used as the source surfaces of the dipole noise in the Farrasat equation. The result with the standard k-$\epsilon$ model showed a much better agreement with the experimental data compared to the k-w SST and S-A models. The differences in the pressure spectra from the different turbulence models were discussed based on the instantaneous vorticity fields. It was found that the over-estimated power spectra with the k-w SST and S-A models are related to the emphasized small-scale vortices produced with these models.

  • https://doi.org/10.6112/kscfe.2012.17.4.081 인용 PDF KSCI