CFD SIMULATION OF LONGITUDINAL VENTILATION SYSTEMS IN A SCALED SHORT TUNNEL


KARAASLAN S. , Hepkaya E., YÜCEL N.

ISI BILIMI VE TEKNIGI DERGISI-JOURNAL OF THERMAL SCIENCE AND TECHNOLOGY, vol.33, no.1, pp.63-77, 2013 (Journal Indexed in SCI) identifier identifier

  • Publication Type: Article / Article
  • Volume: 33 Issue: 1
  • Publication Date: 2013
  • Title of Journal : ISI BILIMI VE TEKNIGI DERGISI-JOURNAL OF THERMAL SCIENCE AND TECHNOLOGY
  • Page Numbers: pp.63-77

Abstract

In this study, a horseshoe cross-sectioned, short tunnel was considered. To simulate fire scenarios, a rectangular fire pool was placed in centreline of the tunnel floor. At different cross-sections of the tunnel, jet fan groups were installed and each fan group includes three jet fans. In order to simulate the fire induced smoke, the species transport model was used. Fires with 10 and 50 MW were considered for the simulations. The effects of LVS (Longitudinal Ventilation System) on the smoke movement and temperature distribution were numerically investigated by using the commercial CFD code FLUENT. Especially, simulations were conducted for the worst scenarios. After the fire induced smoke filled a big part of the tunnel, in order to determine the optimal ventilation approaches, combination of different fan groups were operated with various pressure jumps. From the simulations, it was observed that the smoke propagation was faster than the long tunnel studies found in the literature. It was also observed that the smoke velocity increases toward the tunnel entrance in the backlayer. In order to prevent this uncontrolled smoke movement, the best charge velocities and operation order of jet fan groups were determined numerically. It was observed that the operation order of fan groups, pressure jump values of fans and start time of the fans are important parameters to extinguish.