UNSTEADY FLOW IN TUNNELS

Theoretical predictions are made for attenuation, dispersion, and characteristic impedance of long-wavelength small-amplitude waves in turbulent flow in cylindrical lines or tunnels. A lower limit for attenuation and dispersion results from assuming a turbulent viscosity profile across the tube which remains constant throughout the cycle. An upper limit results from assuming a turbulent viscosity profile which fluctuates during the cycle, maintaining the steady-flow values. An experimental apparatus was nearly completed to check the theory and resolve the transition from upper limit to lower limit. The theory indicates that a relatively simple constant-inertance-resistance model is useful at much higher frequencies than in laminar flow, including most problems of normal vehicle acceleration and deceleration in tunnels, but is totally unacceptable at very high frequencies such as those which result when a vehicle passes rapidly through a sharp or gradual change in the tunnel area. (Author)

• Corporate Authors:

  Massachusetts Institute of Technology

  Engineering Projects Laboratory
  Cambridge, MA  United States 
• Authors:
  • Brown, F T
  • Shah, R P
• Publication Date: 1967-9-30

Media Info

• Pagination: 108 p.

Subject/Index Terms

• TRT Terms: Aerodynamics; High speed rail; Intelligent transportation systems; Pneumatic conveyors; Pressure waves; Tubing; Tunnels; Wave motion
• Old TRIS Terms: Advanced systems; Tube systems; Tube vehicles
• Subject Areas: Bridges and other structures; Operations and Traffic Management; Railroads;

Filing Info

• Accession Number: 00039006
• Record Type: Publication
• Source Agency: National Technical Information Service
• Contract Numbers: C-85-65t
• Files: TRIS
• Created Date: Nov 24 1973 12:00AM