Wind Noise Measurements for Automotive Mirrors

Chen, Kuo-Huey; Johnson, Jim; Dietschi, U. D.; Khalighi, Bahram

doi:10.4271/2009-01-0184

Cited by 16 publications

(7 citation statements)

References 2 publications

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“…The two mirror models (shown in Figure 1) will be referred to as GMT360 and GMX320 which represent a truck and a sedan mirror, respectively. Figure 2 shows the experimental setup and the locations of various pressure taps and microphones at which pressures were measured [10,11]. The mirrors are mounted on a specially designed table for the experiments and the simulations as shown in the figure.…”

Section: Model Description and Simulation Methodology 21 Mirror Modelsmentioning

confidence: 99%

“…Adequate prediction of surface pressure distributions is necessary for accurate simulations of noise originated from the dipole sources. Considerable attention has, therefore, been paid in this work to compare the predicted surface pressure distributions with those measured in the wind tunnel [10,11]. In the experiments, the static pressure was measured along the centerline (along the dark line in Figure 2b at the reflecting surface of the mirror models (not presented in this paper).…”

Section: Surface Pressure Distributionsmentioning

confidence: 99%

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Simulations of Flow and Noise Generated by Automobile outside Rear-View Mirrors

Khalighi

Snegirev

Shinder

et al. 2012

International Journal of Aeroacoustics

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Numerical simulations of the flow and noise generated by two different automotive outside rearview mirrors are investigated. The mirrors were mounted on the top of a specially designed table for simulations and wind tunnel tests. A decoupled two-stage methodology is applied that requires CFD simulations to collect pressure variations at solid surfaces followed by an acoustic post-processing of the data recorded. For the flow simulations, URANS (Unsteady RANS), DES (Detached Eddy Simulation) and LES (Large Eddy Simulation) turbulence modeling approaches are used. This study is part of an ongoing project to develop a transient CFD procedure to accurately predict wind noise generated by the exterior surfaces of a moving ground vehicle. The Curle's formulation in low Mach number limit is used to calculate the acoustic pressure generated by the pressure fluctuations at solid walls. Reasonable agreement (within 5 dB) between measurements and predictions has been achieved both for the flow and sound characteristics (with denser mesh quality). It is found that the URANS and DES approaches underestimate surface pressure fluctuations and therefore, result in underestimated sound pressure levels. The LES approach on the other hand (particularly with the dynamic subgrid viscosity model) provides better agreement for the time-averaged surface pressure distributions and for the sound pressure levels.

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Section: Model Description and Simulation Methodology 21 Mirror Modelsmentioning

confidence: 99%

Section: Surface Pressure Distributionsmentioning

confidence: 99%

Simulations of Flow and Noise Generated by Automobile outside Rear-View Mirrors

Khalighi

Snegirev

Shinder

et al. 2012

International Journal of Aeroacoustics

Self Cite

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“…Kato et al (7) measured the fluctuating surface pressure on a generic body and the far-field sound pressure in detail, and clarified the characteristics of a large-scale flow structure. Chen et al (8) also measured the surface pressure on real mirrors and the far-field sound pressure. Iida et al (9) noticed a tonal noise generated from mirrors of real shapes with a bump, and the feedback mechanism of noise generation was made clear by experimental measurements.…”

Section: Introductionmentioning

confidence: 99%

Direct Numerical Prediction of Aerodynamic Noise Emitted from a Generic Automobile Rear-View Mirror

Doi

Miyoshi

Hamamoto

et al. 2012

JFST

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We numerically simulated the aerodynamic noise generated from the unsteady flow around a generic model of automobile rear-view mirrors in this study. This generic model is made by cutting a hemispherical cylinder into half lengthwise, and placed on a flat plate. The governing equations employed in the present numerical simulation are the compressible Navier-Stokes equations, where no additional models of sound generation and propagation are used. Results show that acoustic pressure waves are generated from the disturbed wake of the mirror model and propagate into the far field. In addition, the spatial distribution of the sound pressure level (SPL) in the far field has a similar tendency to that of the experimental data. These results show that useful data on aerodynamic noise can be obtained by the simple computational method presented in this study, and utilized to make a preliminary design to reduce the aerodynamic noise.

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“…For these complex flow conditions, several studies have shown the source of wind noise from an external rear-view mirror. Chen et al conducted sound pressure measurements around two single mirrors on a table that minimized boundary layer effects [6]. It was found that the noisiest sound pressure level was observed in the separated wake region on the plate.…”

Section: Introductionmentioning

confidence: 99%

Surface flow and wake characteristics of automotive external rear-view mirror

Kim

Park

Han

2011

Proceedings of the Institution of Mechanical Engineers, Part D:

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To observe surface flow and wake structure around an automotive external rear-view mirror, the pressure distribution over the mirror skin and the velocity vector fields in the cross-sectional planes were measured using a pressure scanning system and hot-wire anemometry in a blow-down wind tunnel. Surface flow visualization was also used to investigate boundary layer flow over the mirror surface. It was found that the pressure coefficient became negative over the whole of the surface area, with the exception of the proximity of the stagnation point of the mirror housing, implying the surface flow acceleration along the curved mirror contour. The minimum pressure on the surface of the mirror glass appeared near the outside edge region, which seemed to be the origin of the vortex envelope. Velocity vector fields showed that a conical envelope of the vortex sheet developed with its centre trailing toward the body frame. It was also demonstrated that visualizations over the mirror housing surface and the driver side vehicle skin show good agreement with the pressure distribution of the mirror housing surface and the trail of the vortex sheet in the mirror wake.

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Wind Noise Measurements for Automotive Mirrors

Cited by 16 publications

References 2 publications

Simulations of Flow and Noise Generated by Automobile outside Rear-View Mirrors

Simulations of Flow and Noise Generated by Automobile outside Rear-View Mirrors

Direct Numerical Prediction of Aerodynamic Noise Emitted from a Generic Automobile Rear-View Mirror

Surface flow and wake characteristics of automotive external rear-view mirror

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