LEIF's New Thermal Tunnel

This is a large piece of equipment with unique characteristics in Portugal and Europe, which makes it possible to study the interaction between fire and its environment, namely the atmosphere, under various conditions of vertical stability of the boundary layer. The Thermal Tunnel has three air ducts in which it is possible to create a flow with variable speed and temperature, between 10 ºC and 45 ºC, thus being able to physically simulate the conditions of fire propagation in a stable, neutral or unstable atmosphere.

General view of the Thermal Tunnel, during tests at the Forest Fire Research Laboratory.

On April 9 and 14, a series of preliminary tests were carried out to develop the experimental methodologies needed to use this unique piece of equipment. These tests, carried out with forest fuel beds made up of dry undergrowth, showed a variation in the interaction between the fire and the atmosphere, reflected in a greater vertical development of the flames in the case of an unstable atmosphere compared to a stable one.

Side view of the flame front in a stable (left) and unstable (right) boundary layer situation.

It was also found that the average speed of spread in the unstable atmosphere increased by around 70% compared to the stable atmosphere. This result shows the importance of the interaction between the fire and the environment in the propagation of a fire front.

The study of the dynamics of this behavior will be developed within the scope of the LARGE-FIRES project, funded by FCT, which CEIF will develop over the next three years, in conjunction with the Centre for Environmental and Marine Studies (CESAM) at the University of Aveiro.

The Thermal Tunnel was purchased as part of the Infrastructures project, funded by the Central Region Coordination and Development Commission, and also received financial support from REN.