Experimental investigation on the pollutant dispersion driven by a condensed-phase explosion in an urban environment

Abstract

The atmospheric dispersion in an urban or industrial environment is well documented in the literature. However, there is a lack of knowledge about the dispersion triggered by rapid and short phenomena such as explosions. The presented research provides information about the pollutant dispersion caused by a condensed-phase detonation in an urban environment. Experimental campaigns are conducted inside a subsonic wind tunnel at a 1:200 reduced scale. An explosion leading to the dispersion of solid particles is experimentally simulated in free field and in a straight street under a controlled neutral urban atmospheric boundary layer. Exploding-bridge-wire detonators are used to disperse a micro-talc powder. The pollutant dispersion and the overpressure caused by the explosion are measured respectively through a fast response optical measurement technique and fast response pressure sensors. The effects of key parameters on the dispersion are investigated. Two gram-scale detonators are used to analyze the effects of the explosion energy. The effect of the powder is studied through two masses of a micro-talc powder. Additionally, the transition between the predominance of the effect of the explosion and the predominance of the effect of the wind is analyzed with three wind velocities. The velocity field of the dispersion is obtained for each time step through Large Scale Particle Image Velocimetry. Similarly, the dispersion is investigated inside a T-junction to highlight the effect of an urban configuration on the pollutant release. This project provides a strong experimental database about dispersion driven by an explosion. A better understanding of the phenomenon can be used to improve industrial safety and security through more reliable predictions.