• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
• /
• 2010.05a
• /
• pp.336-337
• /
• 2010

본 연구는 현대자동차 무향 풍동(HAWT)에서 나온 실험치를 범용 CFD software인 SC/Tetra를 활용하여 모사하였다. 이를 위해서 우선 현대자동차 무향 풍동(HAWT)의 입력 경계층을 설정하고, grid test를 통해 최적의 격자를 찾고, 이에 맞는 난류 모델을 선정하였다. 입력 경계조건 설정, 격자 선정, 난류 모델 선정을 완료 후 나온 경계조건을 활용하여 실제 모델에 적용하여 현대 자동차 무향 풍동(HAWT)에서 나온 결과와 SC/Tetra에서 나온 결과와 비교 분석 하였다.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
• /
• 1995.04a
• /
• pp.298-304
• /
• 1995

유동이 있는 경우 발생하는 소음에 대한 실험적 연구는 풍동과 무향실이 결합된 음향풍동에서 수행될 수 있다. 이러한 음향풍동은 팬, 수축부, 수집부, 확산부 그리고 무향실에 주의해서 설계되어야 하고 특히 각 부분에서 발생할 수 있는 이차소음을 최소화하도록 설계되어야 한다. 최종적으로 소음기와 흡음재를 이용해서 팬소음과 이차소음의 전파를 줄인다. 본 음향풍동은 개방형 흡입식(open suction type)으로 시험부에서 유속 62.8m/s, 난류강도 0.1%이하, 배경소음 50-55dB 이하로 설계되었다. 이러한 조건을 만족시키기 위하여 하니콤과 6장의 스크린이 있는 정체실과, 21:1의 수축비를 갖는 수축부를 이용하여 난류강도를 낮추고, 흡음재와 90도 각도의 모서리 그리고 공명형과 소산형 소음기로 소음의 전파를 줄였다.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
• /
• 2001.05a
• /
• pp.34-40
• /
• 2001

Aeroacoustic technology to improve the acoustic comfort in high-speed became a major topic in vehicle development process. Although most of wind noise reduction and sound quality improvements are possible with full vehicle, the countermeasures should be applied at the early design stage. Acoustic holography technology was used to identify the external wind noise sources of a vehicle in Hyundai Aeroacoustic Wind Tunnel. Microphone self-noise reduction techniques and several reference microphone positions are investigated in order to obtain proper results.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
• /
• 1997.04a
• /
• pp.573-580
• /
• 1997

본 고에서는 공력음향학에 대한 여러 분야 중에서 최근 국내에서 관심 있게 연구되어온 분야에 대하여 그 연구 내용과 연구 방법 등을 소개하고자 한다. 먼저 전형적인 유체의 소음원에 대해서 설명하고, 이에 대한 수치적 해석방법과 무향풍동을 이용한 실험, 그리고 본 음향학 이론에 대한 응용 사례들에 대해서 간략히 소개하고자 한다.

• Proceedings of the KSME Conference
• /
• 2002.08a
• /
• pp.759-762
• /
• 2002

Automobile aeroacoustics Is a developing area of technology where experimental and theoretical tools are being continuously refined to understand, analyze and modify the noise-generating mechanisms in the vehicle flow. Main sources of ground vehicle exterior noise are the tires (tire/road interaction) and the unsteady flow field around the vehicle. In this study, the sound source localization of a rolling tire was applied to the measurement of radiated sound by using an acoustic mirror system. A possible flow pattern that develops is suggested based on detailed wind tunnel investigations with a rotating wheel in contact with a moving belt.

• Proceedings of the KIEE Conference
• /
• 2002.07a
• /
• pp.497-499
• /
• 2002

가공선로 표지물로 사용되는 구에서 발생하는 소음의 특성을 조사하였다. 현재 한전에서 사용하고 있는 표지용 구의 크기는 직경 62cm이며 두께가 3mm인 합성수지로 만든 반구를 접합부분에 요철형상으로 결합하도록 되어있다. 현장에서 발생하는 소음 스펙트럼을 측정하여, 무향 풍동에서 측정한 구형 셀에서 발생하는 스퍽트럼과 비교하였다. 백색음을 입사하여 구형 셀의 크기에서 발생하는 기본음의 스펙트럼을 조사하였다.

• Transactions of the Korean Society of Mechanical Engineers B
• /
• v.23 no.6
• /
• pp.722-733
• /
• 1999

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.

• Proceedings of the Acoustical Society of Korea Conference
• /
• autumn
• /
• pp.219-220
• /
• 2004

최근 중대형 세단이나 SW 차량의 썬루프 개구량이 증대되고 사양의 고급화가 진행되면서 기존의 판형 디플렉터를 대신하여 새로이 튜브형 디플렉터의 이용이 늘어나고 있다. 본 연구에서는 실차 무향 풍동을 이용한 실차 썬루프 바람소리 실험을 통하여 튜브형 디플렉터의 특성을 확인하였다. 튜브형 디플렉터의 성능에 영향을 줄 수 있는 인자들의 최적화를 통하여 초기 설계 사양 및 경쟁차보다 우수한 썬루프 바람소리 성능을 얻을 수 있었다.

• Transactions of the Korean Society for Noise and Vibration Engineering
• /
• v.14 no.12
• /
• pp.1241-1248
• /
• 2004

This paper presents an acoustic source localization technique on 2D cavity model in flow using a phased microphone array. Investigation was performed on cavity flows of open and closed types. The source distributions on 2D cavity flow were investigated in an anechoic open-jet wind tunnel. The array of microphones was placed outside the flow to measure the far field acoustic signals. The optimum sensor placement was decided by varying the relative location of the microphones to improve the spatial resolution. Pressure transducers were flush-mounted on the cavity surface to measure the near-filed pressures. It is shown that the propagated far field acoustic pressures are closely correlated to the near-field pressures and their spectral contents are affected by the cavity parameter L/D.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
• /
• 2003.05a
• /
• pp.701-708
• /
• 2003

This paper presents an acoustic source localization technique on 2D cavity model in flow using a phased microphone way. Investigation was performed on cavity flows of open and closed types. The source distributions on 2D cavity flow were investigated in anechoic open-jet wind tunnel. The array of microphones was placed outside the flow to measure the far field acoustic signals. The optimum sensor placement was decided by varying the relative location of the microphones to improve the spatial resolution. Pressure transducers were flush-mounted on the cavity surface to measure the near-filed pressures. It is shown that the propagated far field acoustic pressures are closely correlated to the near-field pressures. It is also shown that their spectral contents are affected by the cavity parameter L/D.