In this study, the critical velocity was investigated with various aspect ratios (0.5, 0.667, 1.0, 1.5, 2.0) of the tunnel cross-section in tunnel fires. Reduced-scale experiments were carried out under the Froude scaling using ethanol pool fire. Temperatures were measured under the ceiling and vertical direction along the center of the tunnel. The effects of aspect ratio on critical velocity were analyzed from smoke movement. It has been found that the critical velocity increases with aspect ratio, where the aspect ratio is height/ width for a tunnel of rectangular cross-section. This study used new dimensionless velocity and dimensionless heat release rate parameters considering aspect ratio of the tunnel. The critical velocity varied with the one-third power of the heat release rate for under-medium fires. The results of this study are compared with other small-scale and full-scale experiments. A good agreement has been obtained.
Chow, W.K. (1996). Simulation of Tunnel Fires Using a Zone Model , Tunnelling and Underground Space Technology, 11(2): 221–236 .
2.
Ingason, H. (1999). Effects of Ventilation on Smoke Spread in Tunnels , In: Proceedings of the 1st International Conference on Tunnel Fires and One Day Seminar on Escape from Tunnels, pp. 407–416 , Lyon, France.
3.
Opstad, K. , Aune, P. and Henning, J.E. (1997). Fire Emergency Ventilation Capacity for Road Tunnels with Considerable Slope, 9.ICAVVT, pp. 535–543Aosta .
4.
Riess, I. , Bettelini, M. and Brandt, R. (2000). Sprint – A Design Tool for Fire Ventilation, 10.ISAVVT, pp. 629–637, Boston .
5.
Riess, I. , Bettelini, M. and Brandt, R. (2001). Smoke Extraction in Tunnels with Considerable Slope , In: 4th International Conference Safety in Road and Rail Tunnels, pp. 503–512 , Madrid.
6.
Woodburn, P.J. and Britter, R.E. (1996). CFD Simulations of a Tunnel Fire-Part I , Fire Safety Journal, 26: 35–62 .
7.
Woodburn, P.J. and Britter, R.E. (1996). CFD Simulations of a Tunnel Fire-Part II , Fire Safety Journal, 26: 63–90 .
8.
Beard, A.N. , Drysdale, D.D. and Bishop, S.R. (1995). A Non-linear Model of Major Fire Spread in a Tunnel , Fire Safety Journal, 24: 333–357 .
9.
Beard, A.N. , Drysdale, D.D. and Bishop, S.R. (1996). Predicting the Effect of Design Parameter Variations on Major Fire Spread in a Tunnel , International Communications in Heat and Mass Transfer, 23: 495–504 .
10.
Kunsch, J.P. (2002). Simple Model for Control of Fire Gases in a Ventilated Tunnel , Fire Safety Journal, 37: 67–81 .
11.
Kurioka, H. , Oka, Y. , Satoh, H. and Sugawa, O. (2003). Fire Properties in Near Field of Square Fire Source with Longitudinal Ventilation in Tunnels , Fire Safety Journal, 38: 319–340 .
12.
Vauquelin, O. and Mégret, O. (2002). Smoke Extraction Experiments in Case of Fire in a Tunnel , Fire Safety Journal, 37: 523–533 .
13.
Carvel, R.O. , Beard, A.N. , Jowitt, P.W. and Drysdale, D.D. (2001). Variation of Release Rate with Forced Longitudinal Ventilation for Vehicle Fires in Tunnels , Fire Safety Journal, 36: 569–596 .
14.
Carvel, R.O. , Beard, A.N. and Jowitt, P.W. (2001). The Influence of Longitudinal Ventilation Systems of Fires in Tunnels , Tunnelling and Underground Technology, 16: 3–21 .
15.
Heselden, A.J.M. (1976). Studies of Fire and Smoke Behaviour Relevant to Tunnels , In: 2nd International Symposium on Aerodynamics and Ventilation of Vehicle Tunnels, Paper J1, Cambridge, UK.
16.
Atkinson, G.T. and Wu, Y. (1996). Smoke Control in Sloping Tunnels , Fire Safety Journal, 27: 335–341 .
17.
Oka, Y. and Atkinson, G.T. (1996). Control of Smoke Flow in Tunnel Fires , Fire Safety Journal, 25: 305–322 .
18.
Wu, Y. and Bakar, M.Z.A. (2000). Control of Smoke Flow in Tunnel Fires Using Longitudinal Ventilation Systems – A Study of the Critical Velocity , Fire Safety Journal, 35: 363–390 .
19.
Kurioka, H. , Oka, Y. , Satoh, H. and Sugawa, O. (2003). Fire Properties in Near Field of Square Fire Source with Longitudinal Ventilation in Tunnels , Fire Safety Journal, 38: 319–340 .
20.
Quintiere, J.G. (1989). Scaling Applications in Fire Research , Fire Safety Journal, 15: 3–29 .
21.
Hu, L.H. , Li, Y.Z. , Huo, R. , Yi, L. , Shi, C.L. and Chow, W.K. (2004). Experimental Study on the Rise-time of Buoyant Fire Plume Fronts Induced by Pool Fires , Journal of Fire Science, 22: 69–86 .
22.
Tewarson, A. (1988). Smoke Point Height and Fire Properties of Materials, NIST-GCR-88-555, National Institute of Standards and Technology, Available from National Technical Information Services, Springfield, VA 22161, USA .
23.
Tewarson, A. (2004). Combustion Efficiency and its Radiative Component , Fire Safety Journal, 39: 131–141 .
24.
Edward, K.B. , Harold, E.N. and David, D.E. (1997). Simplified Fire Growth Calculation, In: Fire Protection Handbook, 18th edn, NFPA FPH1897, Section 11, Chapter 10.
25.
Lacroix, D. (1998). The New PIARC Report on Fire and Smoke Control in Road Tunnels , In: 3rd International Conference on Safety in Road and Rail Tunnels, pp. 185–197 , Nice, France.
26.
Lee, S.R. , Kim, C.I. and Ryou, H.S. (2004). An Experimental Study of Smoke Movement in Tunnel Fires with a Vertical Shaft , Korean Journal of Air-Conditioning and Refrigeration Engineering, 16(2): 135–141 .
27.
Copper, L.Y. , Harkleroad, M. , Quintiere J. and Rinkinen, W. (1982). An Experimental Study of Upper Hot Layer Stratification in Full-Scale Multiroom Fire Scenarios , Journal of Heat Transfer, 104: 741–749 .
28.
Bettis, R.J. , Jagger, S.F. and Wu, Y. (1993). Interim Validation of Tunnel Fire Consequence Models; Summary of Phase 2 Tests, The Health and Safety Laboratory Report IR/L/FR/93/11, The Health and Safety Executive, UK .
29.
Bettis, R.J. , Jagger, S.F. , Macmillan, A.J.R. and Hambleton, R.T. (1994). Interim Validation of Tunnel Fire Consequence Models; Summary of Phase 1 Tests, The Health and Safety Laboratory Report IR/L/FR/94/2, The Health and Safety Executive, UK .
30.
Art Bendelius (1996). Memorial Tunnel Fire Ventilation Test Programme, One Day Seminar of Smoke and Critical Velocity in Tunnels, London, UK .
