Influence of fire heat release rate (HRR) evolutions on fire-induced pressure variations in air-tight compartments

International audienceThe paper presents experimental results indicating the influence of the fire heat release rate (HRR) evolution on the fire-induced pressure variation in air-tight compartments, which increasingly appear in modern buildings. The fire evolution is stipulated according to a power law with variations in fire growth rate coefficient, maximum steady state HRR, fire growth exponent and fire duration. It is illustrated that the higher the fire growth rate coefficient, the higher the over-pressure/under-pressure peaks become. The peak values approach a maximum level when the fire growth rate coefficient exceeds a certain level (0.0926 kW/s2 in the present cases). Besides, the over-pressure and under-pressure peak values increase monotonously with the increase of the maximum steady state HRR. For cases with fire growth exponent below 1, the pressure reaches peak values before the HRR reaches a steady state (maximum value or zero) because the net heat gained in the gas phase already reaches its peak values then. In cases with fire growth exponent above 1, the pressure reaches peak values at the moment when the HRR reaches the steady state. Finally, in one test low-frequency oscillatory behavior is illustrated for the first time with gaseous fuel. The present work indicates the significance of the fire-induced pressure risk and provides data for model validation