The manner in which step-wavefronts reflect from perforated and flared extension tubes attached to the end of a simple tube is analyzed by using a numerical scheme based on the unidirectional method of characteristics. It is shown that the reflected wavefront can be longer than twice the length of the perforated tube, but that it cannot exceed twice the length of a flared extension. This difference is attributed to the non-linear response of flows through the ventilating holes to changes in the internal pressure. The optimum amount of ventilation is shown to vary with the square-root of the magnitude of the incident wavefront. Little dependence on the axial distribution of the ventilating holes is found. The use of such regions next to the exit portal of a railway tunnel is shown to be less advantageous than similar regions leading to the entrance portal.

  • Availability:
  • Corporate Authors:

    Academic Press Incorporated

    24-28 Oval Road
    London NW1 7DX,   England 
  • Authors:
    • VARDY, A E
  • Publication Date: 1978-8

Media Info

Subject/Index Terms

Filing Info

  • Accession Number: 00190302
  • Record Type: Publication
  • Source Agency: Engineering Index
  • Files: TRIS
  • Created Date: May 26 1979 12:00AM