Investigation for the Effect of the External Noise Sources onto the Interior Aerodynamic Noise

Hamamoto, Naoki; Okutsu, Yasuhiko; Yanagimoto, Kazuo

doi:10.4271/2013-01-1257

Cited by 6 publications

(2 citation statements)

References 10 publications

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“…Through investigations done on passenger car, the noise caused by the rearview mirror has been investigated at a certain extent. 5–9 Because of the difference mentioned above, the conclusion drawn from passenger car cannot be extended to coach. As a result, how to understand the aerodynamic noise of rearview mirror area of coaches is the focus of this study.…”

Section: Introductionmentioning

confidence: 99%

Numerical and experimental research on flow and aerodynamic noise characteristics of coach

Chang

Yang

2020

Proceedings of the Institution of Mechanical Engineers, Part D:

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The researches on flow and aerodynamic noise characteristics of coaches are urgently needed to improve with the rapid development of new energy coaches. In this paper, tests in model wind tunnel and numerical calculations were carried out to study the phenomenon of flow and aero-noise on 1:25 scale model coach. Based on large eddy simulation (LES) and detached eddy simulation (DES), reliable numerical calculation method of flow and aero-noise on coach was established and verified. It is found that the maximum difference on turbulent pressure between test and LES is less than 10 dB(A) while that of DES is about 20 dB(A). Due to the results got from 1:25 scale model, the W_LES_HOA model is used to obtain the flow field and sound field information outside the coach. To find out the different propagation characteristics of turbulent pressure pulsation and acoustic pressure, proper orthogonal decomposition (POD) and band-pass filter analysis are used for further analysis. For rearview mirror, the energy of first mode is 6.1%, and only the first nine modes have an energy for more than 3.0%. By the reconstruction of first four modes, it can be seen that the complicated transverse vortex shedding couples with A pillar vortex and reaches the body surface. However, the coupling of turbulent pressure can only be seen clearly under low frequency around 250 Hz while the coupling of acoustic pressure can be seen under 750 Hz. Meanwhile, with the analysis of low frequency round 250 Hz and 500 Hz, the change of flow field generated by airflow impingement on the windward surface and A pillar makes the front of the coach becomes the main sources of aerodynamic sound sources.

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Section: Introductionmentioning

confidence: 99%

Numerical and experimental research on flow and aerodynamic noise characteristics of coach

Chang

Yang

2020

Proceedings of the Institution of Mechanical Engineers, Part D:

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“…Recently Nouzawa, Li and Nakamura [6] have studied the mechanism of aerodynamic noise generated from front pillar and door mirror. Hamamoto, Okutsu and Yanagimoto [7] have investigated the effect of the external aerodynamic noise sources onto the interior noise around the front pillar where longitudinal vortices exist. Numerical approaches have also been conducted with delta wings and actual vehicles (Haruna, Hashiguchi, Kamimoto and Kuwahara [8], Takeda and Ogawa [9], Ogawa and Li [10]).…”

Section: Introductionmentioning

confidence: 99%

Aerodynamic Sound Radiated from Longitudinal and Transverse Vortex Systems Generated around the Leading Edge of Delta Wings

Ogawa¹,

Takeda²,

Kawate³

et al. 2016

OJFD

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Flow around the front pillar of an automobile is typical of a flow field with separated and reattached flow by a vortex system. It is known that the vortex system causes the greatest aerodynamic sound around a vehicle. The objective of the present study is to clarify the relationship between vortical structures and aerodynamic sound by the vortex system generated around the front pillar. The vortex system consists of the longitudinal and the transverse system. The characteristics of the longitudinal vortex system were investigated in comparison with the transverse one. Two vortex systems were reproduced by three-dimensional delta wings. The flow visualization experiment and the computational fluid dynamics (CFD) captured well the characteristics of the flow structure of the two vortex systems. These results showed that the longitudinal with the rotating axis along mean flow direction had cone-shaped configuration whereas the transverse with the rotating axis vertical to mean flow direction had elliptic one. Increasing the tip angles of the wings from 40 to 140 degrees, there first exists the longitudinal vortex system less than 110 degrees, with the transition region ranging from 110 to 120 degrees, and finally over 120 degrees the transverse appears. The characteristics of aerodynamic sound radiated from the two vortex systems were investigated in low Mach numbers, high Reynolds number turbulent flows in the lownoise wind tunnel. As a result, it was found that the aerodynamic sound radiated from both the longitudinal and the transverse vortex system was proportional to the fifth from sixth power of mean flow velocity, and that the longitudinal vortex generated the aerodynamic sound larger than the transverse.

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Wind Noise

Al¹

2018

Noise and Vibration Control in Automotive Bodies

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Investigation for the Effect of the External Noise Sources onto the Interior Aerodynamic Noise

Cited by 6 publications

References 10 publications

Numerical and experimental research on flow and aerodynamic noise characteristics of coach

Numerical and experimental research on flow and aerodynamic noise characteristics of coach

Aerodynamic Sound Radiated from Longitudinal and Transverse Vortex Systems Generated around the Leading Edge of Delta Wings

Wind Noise

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