THERMAL SCIENCE

International Scientific Journal

Thermal Science - Online First

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Ventilation performance and pollutant flow in a unidirectional-traffic road tunnel

ABSTRACT
To develope a reliable method for modelling fire case scenarios within the road tunnels and observing the effects of the skewed velocity, experimental and numerical approach is used. Experimental results obtained from a laboratory tunnel-model installation, are used to define geometry and boundary conditions. The result for the overall ventilation performance is compared to the available cases, for empty tunnel and stationary bi-directional vehicle traffic. For a unidirectional traffic road tunnel, in traffic-loaded conditions, with a ventilation system based on axial ducted fans, the numerical simulation is used to determine the flow and temperature fields, the ventilation efficiency (efficiency of momentum transfer), and to assess the shape of the velocity distribution. The effect that a skewed velocity distribution can have on the resulting thermal (T) and pollutant fields (CO2), smoke backlayering and stratification, is evaluated using numerical simulations, for the model-scale tunnel fire conditions. The effect of two possible limiting shapes of the velocity distribution, dependent only on the location of the fire with respect to the nearest upstream operating fans, is analyzed. The numerical results for a fire scenario are a starting point in assessing the feasibility of a laboratory model fire-scenario experiment, what is planned as the next step in this research.
KEYWORDS
PAPER SUBMITTED: 2016-03-21
PAPER REVISED: 2016-03-22
PAPER ACCEPTED: 2016-03-30
PUBLISHED ONLINE: 2016-05-21
DOI REFERENCE: https://doi.org/10.2298/TSCI160321117S
REFERENCES
  1. F. Tarada, Design, testing and application of an energy-efficient longitudinal ventilation system, in: 14th International Symposium on Aerodynamics and Ventilation of Tunnels, Dundee, Scotland, Vol. 3, 2002, pp. 1067-1070.
  2. F. Tarada, R. Brandt, Impulse ventilation for tunnels - a state of the art review, in: 13.th International Symposium on Aerodynamics and Ventilation of Vehicle Tunnels, New Brunswick, New Jersey, May 2009, Vol. 3, 2009, pp. 1067-1070.
  3. M. Sekularac, Analiza strujnih polja slozenih sistema ventilacije saobracajnih tunela, PhD thesis (in serbian). engl. Analysis of flow fields in complex ventilation systems of traffic tunnels, PhD thesis, University of Montenegro, Faculty of Mechanical Engineering.
  4. P. Levoni, D. Angeli, E. Stalio, E. Agnani, G. Barozzi, M. Cipollone, Fluid-dynamic characterisation of the Mont Blanc tunnel by multi-point air ow measurements, Tunneling and Underground Space Technology (48) (2015) 110-122.
  5. M. Sekularac, Experimental determination of tunnel ventilation ducted fan performance, Thermal Science 53 (4) (2014) 1237-1242.
  6. V. Betta, F. Cascetta, M. Musto, G. Rotondo, Fluid dynamic performance of traditional and alternative jet fans in tunnel longitudinal ventilation systems, Tunneling and Underground Space Technology (25) (2010) 415-422.
  7. F. Colella, G. Rein, V. Verda, R. Borchellini, Multiscale modeling of transient flows from fire and ventilation in long tunnels, Computers and Fluids (51) (2011) 16-29.
  8. Ansys, Fluent solver theory guide, Ansys 2013.
  9. L. Barbato, F. , Cascetta, M. Musto, R. G., Fire safety investigation for road tunnel ventilation systems - an overview, Tunneling and Underground Space Technology (43) (2011) 253-265.
  10. Y.Wu, M. Bakar, Control of smoke flow in tunnel fires using longitudinal ventilation systems - a study of the critical velocity, Fire Safety Journal 35 (2000) 363-390.