Computational Study of Impingement Heat Transfer under a Turbulent Slot Jet

Optimizing extinguishing angle of 6MF-30 pneumatic extinguisher for wildland fire-fighting based on CFD and experiments

The 6MF-30 pneumatic extinguisher is a widely utilized and efficient tool for combating wildland fires. However, using incorrect extinguishing angles can diminish its effectiveness. This study aimed to determine the optimal extinguishing angle for the 6MF-30 pneumatic extinguisher by conducting computational fluid dynamics simulations and experimental verification. The findings revealed that ground roughness did not significantly affect the optimal extinguishing angle or the attenuation of jet velocity near the fan outlet region. The study determined that an optimal extinguishing angle of 37° applies to lossless ground, natural grassland, grassland with artificial disturbance, and enclosed grassland. Furthermore, among the selected angles, the highest rate of jet velocity reduction was observed at 45°, whereas the slowest reduction occurred at 20° and 25°. These findings offer valuable insights and recommendations for enhancing the efficacy of wildland fire-fighting when employing the 6MF-30 pneumatic extinguisher.

Evaluation of source model coupled computational fluid dynamics (CFD) simulation of the dispersion of airborne contaminants in a work environment

Dispersion of airborne contaminants in indoor air was evaluated employing physical measurement, empirical models, and computer simulation methods. Field data collected from a tray of evaporating solvent in the laboratory were compared with computational fluid dynamics (CFD) simulations coupled with evaporation models. The results indicated that mathematical models of evaporation can be coupled with CFD simulations to produce reasonable qualitative predictions of airborne contaminant levels. The airflow pattern within a room is primarily determined by the room layout and the position of the air supply diffusers. Variations in ventilation rate did not alter the airflow pattern, thus generating a characteristic concentration profile of the airborne contaminants.