Density Field Measurements of a Micro–explosion Using BOS

The flow field dynamics associated with blast waves can be better understood by generating controlled micro-explosions in the laboratory. In recent years microexplosions have also found interesting trans-disciplinary applications like food preservation, wood science, drug delivery, gene therapy and bio-medical applications [1], [2]. The blast waves produced by sudden release of energy are normally characterized by a supersonic shock front followed by an exponential type decay of its physical properties. Unlike shock waves that attenuate as they expand spherically, the shock wave from an internal blast can change its propagation properties depending on the physical barriers. The micro-blast provides a challenging case for application of novel flow diagnostic techniques in measuring flow properties. This learning can be scaled up to large scale explosions [3]. One such property is the density field, which although highly informative, is quite difficult to capture. The Background Oriented Schlieren (BOS) technique provides the capability of capturing the three dimensional density fields [4], [5]. This is an attempt to quantify the density flow field of a micro-explosion for the first time using BOS. In this study, a micro-explosion is generated using NONEL tube and the detonating device. The spatio-temporally evolving density field is captured at several instants by means of a precise triggering circuit used to control the illumination and imaging. The density field so obtained can be used for understanding both basic physics associated with explosive driven shock wave propagation as well as validation data attempts to model explosive driven shock wave propagation.