A Novel Multiscale Methodology for Simulating Tunnel Ventilation Flows During Fires

In the past decade over four hundred people worldwide have died as a result of fires in road, rail and metro tunnels. This paper applies a novel and fast modeling approach to simulate tunnel ventilation flows during fires. The complexity and high cost of full computational fluid dynamics (CFD) models and the inaccuracies of simplistic zone or analytical models are avoided by efficiently combining mono-dimensional (1D) and CFD three dimensional (3D) modeling techniques. A simple 1D network approach is used to model tunnel regions where the flow is fully developed (far field), and a detailed CFD representation is used where flow conditions require 3D resolution (near field). This multi-scale method has previously been applied to simulate tunnel ventilation systems including jet fans, vertical shafts and portals and it is applied in this paper to include the effect of fire. Both direct and indirect coupling strategies are investigated and compared for steady state conditions. The methodology has been applied to a modern tunnel of 7 m diameter and 1.2 km in length. Different fire scenarios ranging are investigated with a variable number of operating jet fans. Comparison of cold flow cases with fire cases provides a quantification of the fire throttling effect, which is seen to be large and to reduce the flow by more than 30%. The paper places emphasis on the discussion of the different coupling procedures and the control of the numerical error. Compared to the full CFD solution, the maximum flow field error can be reduced to less than a few percent, but providing a reduction of two orders of magnitude in computational time. The much lower computational cost is of great engineering value, especially for parametric and sensitivity studies required in the design or assessment of ventilation and fire safety systems.

  • Availability:
  • Authors:
    • Colella, Francesco
    • Rein, Guillermo
    • Torero, Jose L
  • Publication Date: 2011-1

Language

  • English

Media Info

  • Media Type: Digital/other
  • Features: Appendices; Figures; References; Tables;
  • Pagination: pp 221-253
  • Serial:

Subject/Index Terms

Filing Info

  • Accession Number: 01361011
  • Record Type: Publication
  • Files: TRIS
  • Created Date: Jan 25 2012 2:21PM