Abstract. An experimental and numerical comparison of new full-scale atrium fire tests in the 20 m cubic atrium with four different heat release rates (1.7 MW, 2.3 MW, 3.9 MW and 5.3 MW) is presented. Different exhaust conditions (steady and transient extraction rates) and different make-up air configurations (symmetric and asymmetric) are assessed. Temperature measurements in the near (fire plume) and far field (close to the walls) have been recorded by means of 59 thermocouples. The smoke layer interface is also estimated by means of a thermocouple tree with 28 measurements using the least-square and the n-percent methods. The simulations have been conducted using FDS (version 6, Release Candidate 3). The comparison with the simulations shows average discrepancies lower than 32% and 11%, for the near and far field temperatures, respectively. A discrepancy lower than 5% (1 m) is obtained by both methods for the smoke layer height when the steady state is reached. Finally, a slower response to an increment on the exhaust rate is predicted on the smoke layer, being more perceptible for high heat release rates.

No abstract

In case of fire, atria constructive features favor the spread of smoke, becoming its management a challenge. Thus, the effect of different venting conditions on the dynamics of atrium fires is studied herein. Five full-scale fire experiments have been numerically analyzed to explore the influence of the make-up air. Due to the lack of experiments that exists in atria extensive modeling to extract more knowledge is required. Subsequently, 84 simulations with FDS v6 have been carried out, considering different vent areas (air velocity from 0.4 m/s to 5.3 m/s) and configurations, two Heat Release Rate values (2.5 and 5 M W ), and two pan locations. It is demonstrated that make-up air velocities lower than the prescribed limit of 1 m/s may induce adverse conditions, being recommended to assess the complete fire scenario with even lower values, depending on the inlets distribution, in terms of smoke production. The results also show that asymmetric configurations are prone to induce circulation around the flame which can generate fire whirls. Thus, this numerical study links two fire types allowing the connection of pool fires to fire whirls, which completely differ in behaviour, for the sake of design of fire safety.

No abstract

No abstract