Method of Analyzing the Wind Tunnel Test Data Measured with Directional Microphone Systems

Nagakura, Kiyoshi

doi:10.2219/rtriqr.42.104

Cited by 9 publications

(8 citation statements)

References 4 publications

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“…We measured acoustic-source distribution using a directional microphone system (ellipsoid-shaped acoustic mirror (12) ). The ellipsoidal reflector used here had a diameter of 1.7 m and the test wind velocity was 50 m/s.…”

Section: 2 Measurement Of Noise-source Distribution By a Directionmentioning

confidence: 99%

“…In low-frequency bands where resonance occurs, the entire train-car gap was observed to be an acoustic source, but for noise in high-frequency bands, the positions of acoustic sources could be isolated in detail thanks to the high resolution of the directional microphone system (12) . In particular, for high-frequency bands in which no resonance peak sounds are observed, acoustic source distributions having very similar features were obtained over a broad range of bands.…”

Section: Acoustic Source Distributionsmentioning

confidence: 99%

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Experimental Investigation of Aerodynamic Noise Generated by a Train-Car Gap

Mizushima

Takakura²,

Kurita

et al. 2007

JFST

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To investigate the mechanism of noise generation by a train-car gap, which is one of a major source of noise in Shinkansen trains, experiments were carried out in a wind tunnel using a 1/5-scale model train. We measured velocity profiles of the boundary layer that approaches the gap and confirmed that the boundary layer is turbulent. We also measured the power spectrum of noise and surface pressure fluctuations around the train-car gap. Peak noise and broadband noise were observed. It is found that strong peak noise is generated when the vortex shedding frequency corresponds to the acoustic resonance frequency determined by the geometrical shape of the gap, and that broadband noise is generated at the downstream edge of the gap where vortexes collide. It is estimated that the convection velocity of the vortices in the gap is approximately 45% of the uniform flow velocity.

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Section: 2 Measurement Of Noise-source Distribution By a Directionmentioning

confidence: 99%

Section: Acoustic Source Distributionsmentioning

confidence: 99%

Experimental Investigation of Aerodynamic Noise Generated by a Train-Car Gap

Mizushima

Takakura²,

Kurita

et al. 2007

JFST

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show abstract

“…Finally, the method for estimating the contributions of the localized noise sources to the far field noise level has been proposed on the basis of the wind tunnel test data measured with the directional microphone with the ellipsoidal mirror. For further details, refer to the literature 3) published in this Quarterly Report.…”

Section: T T T T Tatsuomentioning

confidence: 99%

RTRI's Large-scale Low-noise Wind Tunnel and Wind Tunnel Tests

Maeda

Kondo

2001

QR of RTRI

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“…In particular, these noise characteristics tend to increase even more when driving inside a Transportation Environmental Research Team, Korea Railroad Research Institute, Uiwang-si, South Korea tunnel. 1,2 Therefore, many studies have been conducted to reduce the flow noise of between-cars sections.…”

Section: Introductionmentioning

confidence: 99%

Noise reduction in high-speed train gangways using fairings and side barriers

Noh

2014

Advances in Mechanical Engineering

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Interior noise in high-speed trains creates passenger discomfort and fatigue. In particular, the noise generated around the gangway between carriages tends to be easily transmitted to the passenger spaces due to the large noise component in the low-frequency region. In addition, the noise from the between-cars space around the gangway exterior tends to increase significantly when the high-speed train is travelling inside a tunnel. Therefore, this study analyses the cause of the noise generated in the gangways and identifies an effective method for reducing it. First, the mechanism for noise generation around the gangways was determined by computational flow noise analysis using a simple two-dimensional cavity model. From this simulation, it was confirmed that noise is generated when air flow enters the cavity. To investigate the influence of noise reduction in the between-cars section, blocking the airflow indirectly by installing fairings or directly by using side barriers was proposed. These noise reduction methods were examined by flow noise analysis, and then applied to an actual high-speed train. The interior noise was measured, and the results show that the use of side barriers was effective in reducing interior noise by 10 dB or more. In particular, a high noise reduction effect was exhibited in the low-frequency region. Therefore, this study verifies that directly blocking the inflow into the between-cars section is an effective noise reduction method.

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Method of Analyzing the Wind Tunnel Test Data Measured with Directional Microphone Systems

Cited by 9 publications

References 4 publications

Experimental Investigation of Aerodynamic Noise Generated by a Train-Car Gap

Experimental Investigation of Aerodynamic Noise Generated by a Train-Car Gap

RTRI's Large-scale Low-noise Wind Tunnel and Wind Tunnel Tests

Noise reduction in high-speed train gangways using fairings and side barriers

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