Parameters of the laboratory model terrestrial forest fire created from the needles of pine (Pinus nigra)
The work deals with the monitoring of selected parameters in the model of terrestrial forest fire, which originated in forest litter (natural challenged material). A needle of black pine (Pinus nigra) was used as a fuel. For the model there was developed forest fire apparatus – wind tunnel, which simulates terrestrial forest fire on the basic model Superior Técnico in Lisbon (Portugal). In the apparatus, there is possibility to placing a sample on the basis of changes of coniferous litter and regulate the speed of the airflow over the layer of litter. The work reviews the effects of air velocity depending on time and temperature of coniferous leaf litter on the wind tunnel and the speed of flame propagation along the coniferous litter layer. In the article, there are original work results which show a significant effect of air flow over the surface of coniferous litter on a fire and the flame propagation speed after layer of litter. Threshold limits of the flow rate of air are in the range <0.5 m.s-1, 1.0 m.s-1>, in which there is an increase in linear speed of the spread of fire of 2 to 2.5 times. Subsequently, the linear speed of spread for models of terrestrial forest fire appeared significantly comparable at air speed 1.0 cm.s-1 and 2.5 cm.s-1. But time which shows spread of fire at specified speed has been reduced by 60% from the time of fire development at a speed of 0.5cm.s-1.