Fire testing with buoyancy equivalent heat release rates

When conducting smoke extraction tests the fire simulation method must be able to simulate the characteristic properties of a real fire. However, the realistic simulation of the plume is of essential importance.

Hot fire gases rising from the fire source form a highly turbulent convective flow in form of a plume. Ambient air is mixed constantly at the borders of the jet into the fire gas. The generated smoke gas mass flow depends from the fire intensity, the turbulence intensity in the plume and the height and the circumference of the plume up to the smoke gas layer. The fire intensity results from the thermal power per area, the so called specific heat release rate (DIN 18232-2) and the increasing fire area and the extent, respectively, of the fire development.

Real fire simulation of the plume only due to combustion cannot be used in rooms with relatively low ceilings and/or with temperature sensitive built in components under the ceiling. For theses applications I.F.I. developed a special smoke generator with equivalent heat release by adding light gases. The basic version generates an uplift of a fire of 0.5 MW heat release. Special spoilers provide the necessary lateral  turbulence and velocity distribution of the plume. The attainable heat release can be increased by adding further elements and the increase of the fire can be simulated due to the delayed activation of the different channels.

The visualisation of the fire gases and the smoke propagation in the plume as well as under the ceiling is achieved by adding fog generated by a harmless and non-polluting fog fluid.