Perforated exit regions for the reduction of micro-pressure waves from tunnels

Honglin Wang, Alan E Vardy, Dubravka Pokrajac

Research output: Contribution to journalArticle

8 Citations (Scopus)
4 Downloads (Pure)

Abstract

The effectiveness of long, perforated exit regions in reducing pressure disturbances from railway tunnels is assessed. Such disturbances always occur, but their amplitudes are usually small. For the particular case of high speed trains, they can reach levels that would cause annoyance in the absence of suitable counter-measures. This risk is especially large in the case of long tunnels. The mechanisms causing the disturbances are described and the potential effectiveness of perforated exit regions as a counter-measure is demonstrated. It is shown that the effectiveness is sensitive to the number, size and distribution of pressure relief holes along the exit region, but that the most important parameter is the combined area of all of the holes. This parameter controls the balance between external disturbances alongside the perforated region and disturbances beyond the exit portal. It is also shown that the amplitudes of the external disturbances are strongly dependent upon the amplitude and duration of wavefronts arriving at the exit region as well as upon their steepness. This contrasts with the behaviour found for tunnels with simple exit portal regions.
Original languageEnglish
Pages (from-to)139-149
Number of pages11
JournalJournal of Wind Engineering and Industrial Aerodynamics
Volume146
Early online date25 Sep 2015
DOIs
Publication statusPublished - Nov 2015

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Tunnels
Wavefronts

Keywords

  • rail tunnel
  • micro-pressure wave
  • perforated exit region
  • pressure gradient
  • wavefront steepness
  • counter-measures
  • sonic boom

Cite this

Perforated exit regions for the reduction of micro-pressure waves from tunnels. / Wang, Honglin; Vardy, Alan E ; Pokrajac, Dubravka.

In: Journal of Wind Engineering and Industrial Aerodynamics, Vol. 146, 11.2015, p. 139-149.

Research output: Contribution to journalArticle

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abstract = "The effectiveness of long, perforated exit regions in reducing pressure disturbances from railway tunnels is assessed. Such disturbances always occur, but their amplitudes are usually small. For the particular case of high speed trains, they can reach levels that would cause annoyance in the absence of suitable counter-measures. This risk is especially large in the case of long tunnels. The mechanisms causing the disturbances are described and the potential effectiveness of perforated exit regions as a counter-measure is demonstrated. It is shown that the effectiveness is sensitive to the number, size and distribution of pressure relief holes along the exit region, but that the most important parameter is the combined area of all of the holes. This parameter controls the balance between external disturbances alongside the perforated region and disturbances beyond the exit portal. It is also shown that the amplitudes of the external disturbances are strongly dependent upon the amplitude and duration of wavefronts arriving at the exit region as well as upon their steepness. This contrasts with the behaviour found for tunnels with simple exit portal regions.",
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author = "Honglin Wang and Vardy, {Alan E} and Dubravka Pokrajac",
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