Measurement of the sunroof buffeting noise with an automatic deflector-traversing device

Kook, H.; Shin, Seong-Ryong; Ih, Kang-Duck

doi:10.1007/s12541-010-0001-8

Cited by 11 publications

(5 citation statements)

References 5 publications

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“…Thus far, the most stable and practical passive control technique for sunroof buffeting reduction is to install a deflector near the leading edge of the sunroof opening. There are different types of deflectors, such as the castle type, the tubular type (Kook, 2008; Kook et al, 2009, 2010), the mesh type (Oettle et al, 2015), and the flat type (Karbon and Singh, 2002; An and Singh, 2006). The noise reduction effect of the conventional castle type deflector used in the vehicle of this study is rather poor.…”

Section: Passive Control Of Sunroof Buffetingmentioning

confidence: 99%

Computational investigation and passive control of vehicle sunroof buffeting

Zhang

et al. 2019

Journal of Vibration and Control

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A computational fluid dynamics simulation method based on large eddy simulation is presented and applied to compute the sunroof buffeting of a sport utility vehicle. The simulation result, i.e. the buffeting level curve, coincides well with the road test. The simulation method is then employed to investigate the sunroof buffeting of a vehicle during the development process in the range of 30 km/h–90 km/h. The results show that the most severe sunroof buffeting occurs at 70 km/h, which corresponds to the resonant frequency of the cabin. Flow field visualizations reveal that strong pressure fluctuations are generated inside the cabin due to vortex shedding from the leading edge and impinging onto the trailing edge of the sunroof opening, which explains the mechanism of sunroof buffeting. A new deflector with a gap and a notched upper edge is designed to replace the original castle type deflector. The simulation results show that the newly designed deflector can reduce the buffeting level to 97.9 dB; that is, the sunroof buffeting is completely eliminated. Moreover, the phenomenon of sunroof buffeting reduction is explained by comparing and analyzing the flow field between the newly designed deflector and the original deflector.

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Section: Passive Control Of Sunroof Buffetingmentioning

confidence: 99%

Computational investigation and passive control of vehicle sunroof buffeting

Zhang

et al. 2019

Journal of Vibration and Control

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“…The aerodynamic noise generated by aircraft at a high speed, such as by landing gear 1 and airfoil slats, 2 are some of main noise sources in aeronautical aeroacoustics. 3 For a ground vehicle at a low speed, this noise is associated with the buffeting noise produced by the sunroofs, 4,5 side windows 6 or other body cavities. All these noises are induced by the interaction between the vortex streets in the turbulent wake or between the vortices and the solid body edge.…”

Section: Introductionmentioning

confidence: 99%

Numerical study of the flow-induced sunroof buffeting noise of a simplified cavity model based on the slightly compressible model

Wang

Deng

Yang

et al. 2013

Proceedings of the Institution of Mechanical Engineers, Part D:

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Numerical computation was conducted to investigate the flow-induced sunroof buffeting noise at low Mach numbers. In order to avoid the stiffness problem which occurs in solving the compressible fluid equations at low Mach numbers, new governing equations were derived with the assumption that there is a slight compressibility effect. The mechanisms of the flow-induced sunroof buffeting noise were investigated by considering a three-dimensional model cavity. Extensive wind tunnel tests were conducted to verify the computational scheme developed in the present study. The results demonstrated that strong pressure fluctuations will be generated inside the cavity and that the modal resonant frequencies are in good agreement with the Rossiter formula and experimental data. Moreover, the results reveal that the sunroof buffeting noise is attributed to the periodicity of flow separation, vortex shedding, vortex impingement and pressure wave feedback, with the addition of the Helmholtz resonance locked effect. Therefore, the current computational approach was validated to have the capability to predict the flow-induced buffeting noise in low-Mach-number flows.

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“…The most frequently used method for controlling sunroof buffeting noise is a static wind deflector placed near the upstream edge of the sunroof opening. For small and mid-sized sunroofs, an appropriately designed wind deflector can control the sunroof buffeting noise (Kook et al, 2010). In general, a larger opening area produces a louder sunroof buffeting noise.…”

Section: Introductionmentioning

confidence: 99%

Development of an active deflector system for sunroof buffeting noise control

Kook

Shin

Cho

et al. 2013

Journal of Vibration and Control

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Sunroof buffeting noise is annoying to drivers and passengers. The conventional method for suppressing sunroof buffeting noise is to use passive deflectors. A recent trend has been large sunroof openings, such as panoramic sunroofs, in accordance with customer preferences for a feeling of openness. Since sunroof buffeting noise tends to become louder as the sunroof opening area becomes larger, a conventional passive deflector may not be a solution in this case, and a new effective method for reducing the sunroof buffeting noise is required. Previous work showed that a strong, self-sustained tonal noise, generated from a Helmholtz resonator exposed to a grazing flow, could be significantly reduced by closedloop control of an active deflector installed near the upstream edge of the resonator opening. The active deflector system is a cascade of a microphone sensor mounted inside the cavity, controller, power amplifier, and deflector mechanism vibrated by a voice coil actuator. Since the acoustic pressure inside the cavity is influenced by the shear layer modified by the active deflector, the active deflector and acoustic response of the cavity form a closed-loop control system. The main objective of the present study is to implement this technology on a real vehicle and evaluate whether the technology can be utilized to suppress sunroof buffeting noise. A simple active deflector system was assembled and installed in a compact-sized hatchback car with a sunroof opening length of 460 mm. The active deflector system was tested both in a wind tunnel and on a proving ground. The test results showed that the active deflector reduced the sunroof buffeting noise by as much as 25 dB. The active deflector was shown to be stable and robust regardless of changes in the wind speed and wind yaw angle.

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Measurement of the sunroof buffeting noise with an automatic deflector-traversing device

Cited by 11 publications

References 5 publications

Computational investigation and passive control of vehicle sunroof buffeting

Computational investigation and passive control of vehicle sunroof buffeting

Numerical study of the flow-induced sunroof buffeting noise of a simplified cavity model based on the slightly compressible model

Development of an active deflector system for sunroof buffeting noise control

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