Simulations of dust dynamics around a cone hood in updraft conditions

Source avec lien : Logachev, K. I., Ziganshin, A. M., & Averkova, O. A. (2018). Simulations of dust dynamics around a cone hood in updraft conditions. Journal of Occupational and Environmental Hygiene, 15(10), 715‑731.

Aucune étude n’a encore porté sur l’efficacité d’une hotte d’extraction face à un flux d’air ascendant avec des particules de poussière en suspension. Le but de cet article est de déterminer l’effet de la vitesse d’entrée, de la vitesse d’aspiration et de la vitesse de sédimentation terminale des particules de poussière sur le coefficient d’aspiration en combinaison avec la longueur de la hotte et l’angle d’inclinaison.

A cone hood is an efficient device for capturing dust releases generated by a variety of process equipment. For stationary airflow conditions, a circular cone hood with a round flange is the most efficient design. The goal of this article is to determine the effect that inflow velocity, suction velocity, and terminal settling velocity of dust particles have on the aspiration coefficient in combination with hood length and inclination angle. No studies have yet addressed the efficiency of an exhaust hood facing an updraft flow of air with suspended dust particles. To simulate the moving fluid, we used the discrete vortices method accounting for flow separation at sharp edges of the cone hood. A custom test bench was built to validate the velocity field distribution around the exhaust hood. To evaluate capture efficiency, we determined the aspiration coefficient using plotted limiting trajectories of dust particles by solving equations of particle dynamics numerically in view of gravity and streamlining airflow patterns. In order to validate our estimate of the aspiration coefficient, we compared our findings with regularities identified by earlier researchers for a simpler problem of dust-air mixture approaching a circular exhaust opening. The following conditions were considered: the ratio of updraft velocity to the exhaust hood suction velocity varying between 0.01 and 0.5; the ratio of dust particle terminal velocity to the suction velocity varying between 0.000625 and 0.2; flange angle varying between 0° and 90°; and the ratio of flange length to the exhaust opening radius varying between 1 and 4. Using regularities discovered by us, exhaust hood designs can be tailored to a variety of application conditions in terms of dust release capture efficiency.

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