Department News
Application of cylindrical nearfield acoustical holography ~
Seminar Date
2003-04-29
Author
안지영
Date
2003-04-29
Views
1484
1. 제 목 : Application of cylindrical nearfield acoustical holography to the
visualization of aeroacoustic sources
2. 연 사 : 이무형
3. 일 시 : 2003년 5월 1일 (목) 11:00 - 12:00
4. 장 소 : 301동 1512호
5. 요 약 :
Since Nearfield Acoustical Holography was first proposed in the 1980’s, it has been used to study many sound radiation problems. However, most applications were focused on sound radiation from vibrating structures. The purpose of this study was to develop methods for visualizing the sound radiation from aeroacoustic sources in order to identify their source strength distribution, radiation patterns and to quantify the performance of noise control solutions. Here, the NAH procedure based on the use of the virtual coherence method was used for that purpose. In a practical holographic measurement of sources comprising either partially correlated or uncorrelated subsources, it is necessary to use a number of reference microphones so that the sound field on the hologram surface can be decomposed into incoherent partial fields before holographic projection. In this study, procedures are described for: determining the number of reference microphones required when visualizing partially correlated aeroacoustic sources; performing source non-stationarity compensation; and applying regularization. The procedures have been demonstrated by application to a ducted fan.
6. 약 력 :
박사과정 Purdue University, West Lafayette, Indiana, U.S.A. (2000.8 ~ )
연구원 현대자동차 (1995.2 ~ 2000.6)
석사 서울대학교 기계설계학과 (1995.2)
학사 서울대학교 기계설계학과 (1993.2)
7. 문 의 : 기계항공공학부 강연준 교수 (880-1691)
visualization of aeroacoustic sources
2. 연 사 : 이무형
3. 일 시 : 2003년 5월 1일 (목) 11:00 - 12:00
4. 장 소 : 301동 1512호
5. 요 약 :
Since Nearfield Acoustical Holography was first proposed in the 1980’s, it has been used to study many sound radiation problems. However, most applications were focused on sound radiation from vibrating structures. The purpose of this study was to develop methods for visualizing the sound radiation from aeroacoustic sources in order to identify their source strength distribution, radiation patterns and to quantify the performance of noise control solutions. Here, the NAH procedure based on the use of the virtual coherence method was used for that purpose. In a practical holographic measurement of sources comprising either partially correlated or uncorrelated subsources, it is necessary to use a number of reference microphones so that the sound field on the hologram surface can be decomposed into incoherent partial fields before holographic projection. In this study, procedures are described for: determining the number of reference microphones required when visualizing partially correlated aeroacoustic sources; performing source non-stationarity compensation; and applying regularization. The procedures have been demonstrated by application to a ducted fan.
6. 약 력 :
박사과정 Purdue University, West Lafayette, Indiana, U.S.A. (2000.8 ~ )
연구원 현대자동차 (1995.2 ~ 2000.6)
석사 서울대학교 기계설계학과 (1995.2)
학사 서울대학교 기계설계학과 (1993.2)
7. 문 의 : 기계항공공학부 강연준 교수 (880-1691)