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소형 터보홴 설계인자와 음질의 상관관계에 의한 설계 최적화
김휘중(Kim, Hooi-Joong),정용규(Jung, Young-Gyu),이정수(Lee, Jung-Soo),이승배(Lee, Seung-Bae) 한국소음진동공학회 2006 한국소음진동공학회 논문집 Vol.16 No.5
The state-of-the-art of low-noise fan design usually includes the consideration of optimal sound level and sound quality. The influential design parameters of the noise level by the centrifugal fan were selected based on the preliminary test. The centrifugal fans were designed according to the experiment plan method by specifying the selected design parameters. The experiment with these machined mock-up's of centrifugal impellers suggested the major design parameters among many, having impacts upon the indices of sound quality (e.g. loudness, sharpness, roughness and fluctuation strength) at the same operation point. With the response surface method, the major design parameters selected thereafter were analyzed to estimate each contribution upon the sound quality of the centrifugal fan, and the optimal values were drawn by the consideration of the sound quality levels and their regression equations. In addition, the validity of the regression equations was numerically verified by means of the coefficient of determination. Furthermore, the mechanism by which the centrifugal fan impeller influences the determinants of its sound quality was suggested.
축대칭 물체의 경계층 유동소음에 대한 실험적 연구 ( I ) - 축대칭 물체 전두부 및 실린더 벽면 섭동압력 -
이승배,김휘중,권오섭,이상권,Lee, Seung-Bae,Kim, Hooi-Joong,Kwon, O-Sup,Lee, Sang-Kwon 대한기계학회 2000 大韓機械學會論文集B Vol.24 No.7
The axisymmetric bodies considered in this study have hemispherical and ellipsoidal noses. The near-field pressure fluctuations over each nose model at $Re_D=2.43{\times}10^5$ were investigated in the laminar separation region and developing turbulent boundary layers using a 1/8' pin-holed microphone sensor. The wall pressure fluctuations were also measured in an axisymmetric boundary layer on a cylinder parallel to mean flow at a momentum thickness Reynolds number of 850 and a boundary layer thickness to cylinder radius ratio of 1.88.
이승배,김휘중,Lee, Seungbae,Kim, Hooi-Joong 대한기계학회 1999 大韓機械學會論文集B Vol.23 No.6
The wall pressure fluctuations of a turbulent boundary layer over a flat plate have been investigated in an anechoic wind tunnel facility. The anechoic wind tunnel consists of acoustically-lined duct, muffler, and splitter-type silencer for noise suppression and vanes for reducing head losses involved. To improve spectra characteristics in high frequency range, a 1/8" pressure-type microphone sensor, which has a pin-holed cap of various diameters, was employed in this experiment. It was shown that the pin-holed microphone sensor with a dimensionless diameter $d^+$ of 7.1 resolved the high frequency pressure fluctuations most effectively among ones with various pin-hole diameters. The measured wall pressure spectra in terms of three types of scaling parameters were in good agreement with other experimental and numerical results. The pressure events of high amplitude were found to contribute to total fluctuating pressure energies in the turbulent boundary layer significantly and supposed to radiate to the far-field effectively.
축대칭 물체의 경계층 유동소음에 대한 실험적 연구(II) - 전두부 천이제어 및 방사소음 -
이승배,김휘중,권오섭,이상권,Lee, Seung-Bae,Kim, Hooi-Joong,Kwon, O-Sup,Lee, Sang-Kwon 대한기계학회 2000 大韓機械學會論文集B Vol.24 No.10
The oscillatory excitation with a Strouhal number of 2.65 ncar the stagnation zone of hemispherical nose model was employed to control the laminar separation bubble and the transition to turbulence. The effects of oscillatory excitation upon the separation bubble and the transition were addressed in terms of kurtosis/skewness and time-frequency analyses. The measured noise spectrum of radiated sound from the turbulent boundary layer on the axi-symmetric infinite cylinder is compared with that by Sevik's wave-number white approximations. The noise sources in TBL on axi-symmetric cylinder and the caling of their far-field sound are also discussed.