An analysis, based on two different series of model scale tests, of the effects of ventilation on maximum heat release rate and fire growth rates is presented. In both model scale test series, wood cribs of different porosity, size and numbers were used. Both ambient free burn tests and tests inside a model-scale tunnel were performed. The tunnels varied from 0.3 m to 0.6 m in width and from 0.2 m to 0.4 m in height. The longitudinal velocity varied between 0.22 m/s and 1.12 m/s.
The tests show that for a higher porosity wood crib and higher velocities than 0.45 m/s, an increasing ventilation rate increases the maximum heat release rate in the range of 1.3 to 1.7 times the value measured outside the tunnel under ambient conditions. For the lower porosity wood crib and higher velocities, the corresponding increase in the maximum heat release rates was 1.8 and 2.2, respectively. For the case with a velocity of 0.67 m/s, the linear fire growth rate increased by a factor of 5–10 times compared to the free burn case, depending on the dimensions of the tunnel cross-section.