Doorway flow from a reduced scale isothermal air/helium approach

International audienceThis paper deals with an experimental study of buoyancy-induced gas flow at a doorway-like opening as part of a fire smoke propagation application. The experimental approach is based on a reduced scale air/helium protocol, which allows a wide range of density conditions to be studied. The flow at the opening has been studied for wide ranges of density (0.17-1.22) kg/m(3), flow rate (20-600) l/min and doorway width (0.4-14) cm usually associated with smoke propagation in life-size applications. The data set consists of measurements of flow thicknesses, spilling angles and laser tomography visualizations. The results show that flow behaviour is in harmony with the basic Bernoulli theory commonly applied to this type of flow. The value of the flow coefficient obtained with several density conditions corresponds to the behaviour found by Emmons for a given flow density. The magnitude of the spilling angle has been investigated and its dependency on the Froude number has been demonstrated. The opening width has a significant effect on flow behaviour and the associated spill plume. The reduction of the opening width enhances the mechanism of air entrainment and modifies the position of the transition height at which plume cross sections change from being rectangular to circular in shape. Published by Elsevier Masson SAS