Numerical investigation of the flow characteristics around two tandem propane fires in a windy environment

Abstract

Investigation of wind-blown fires is highly applicable to fire safety of scenarios associated with burning industrial fuel tanks in wind and wildland fires. This paper conducts a numerical study on the flow characteristics around two propane fire sources in the tandem arrangement under cross wind. The heat release rate, cross wind velocity and fuel source spacing were changed. The results showed that in still air, as the fuel source spacing increases, the flame interaction gradually weakens. The corresponding shapes of flow velocity vector field experience three stages: a whole circular shape, two interacting circular shapes, and two separate circular shapes. As for the wind conditions, in the span wise direction, due to the impact of Rayleigh-Taylor instability, the counter-rotating vortex pair can be generated at the downstream of the fire sources. Under the influences of the counter-rotating vortex pair and blockage effect, a wake regime through flow entrainment is formed, which can reduce the longitudinal air flow velocity along the downstream centerline of fire sources. In the vertical direction, under the impact of fire-wind enhancement, the local flow velocity there can exceed free stream velocity. When the velocity is relatively small, there will be a reverse flow region around the downstream fire source. In addition, the blockage effect shows a non-monotonous trend with the increase of wind velocity.