Characterization of Jet-Contaminant Interaction Flow in Chemical Decontamination

Abstract

Abstract : A numerical simulation and study are presented for characterization of the flow interaction of a water jet with a chemical contaminant droplet on a plane wall, which occurs in chemical decontamination processes. Two models are developed for this analysis, namely, one-fluid flow and two-fluid flow, both governed by the two-dimensional Navier-STokes equations. Emphases of the study are on the evolution of the contaminant droplet and the effects of various flow parameters. Computer plots of the movement of the droplet are present. Computed results show that a jet impingement at 45-60 degrees from the contaminated wall can perform in the most effective and most efficient way in displacing the contaminant. The results also show that an increase in the jet velocity or the cross-sectional area of the jet can greatly improve the cleaning power. However, for a given jet flow rate, it is more advantageous to adopt a jet spray composed of a number of small high-speed jets than one consisting of a single large low- speed jet. The jet-contaminant interactions taking place in confined geometries, such as cavities and corners of two perpendicular walls, are also examined. We have found that an inclined jet is more effective than a normal jet for decontaminating such geometries. In all of the flow cases studied, the impact pressure on the impingement wall far exceeds the steady-state stagnation pressure of the jet.