The accuracy of mapping the airstream of jet fan ventilators by fire dynamics simulator

Abstract

Jet fan ventilators are often applied for smoke control and support for pollutant dispersal in large enclosures, especially in tunnels and car parks. In the design phase, computational fluid dynamics techniques are most often used to verify the fire safety level afforded by the application of jet fans. However, reliable design based on computational fluid dynamics requires a validation of jet fan airstream modeling. To predict these flows, this investigation evaluated the performance of four turbulence models using large-eddy simulations by comparing the simulation results with the experimental data of both horizontal and sloped jet fan guide vanes. The axial velocity was examined and simulations were prepared with fire dynamics simulator software, from the National Institute of Standards and Technology, which is the most popular program for fire simulations, although it is often criticized for inaccurate mapping of ventilation jet fan airstreams. In addition, this investigation analyzed the computing costs of the simulations, according to the fire dynamics simulator version and grid size, showing that the old version of software (fire dynamics simulator 4) was much faster than new one (fire dynamics simulator 6), and that changing grid size from 30 to 15 cm does not significantly change results.

Acknowledgments

Fläkt Woods Sp. z o.o. (Warsaw, Poland) is kindly acknowledged for the providing the jet fan that was used in the experiments.