Blast Wave Interaction with Generic Objects and the Measurement of Blast Wave Reattachment Distances
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ORIGINAL CONTRIBUTION
Blast Wave Interaction with Generic Objects and the Measurement of Blast Wave Reattachment Distances Santanu Dey1,2 • Thangadurai Murugan1,2 • Dipankar Chatterjee1,2
Received: 24 January 2018 / Accepted: 15 June 2020 Ó The Institution of Engineers (India) 2020
Abstract The interaction of blast waves with inanimate and biological structures has remained a subject of interest in order to understand their responses to the blast exposure. In this article, the interaction of blast wave with three generic objects namely sphere, cylinder and cone is studied through numerical simulation. The blast wave is generated in a shock tube by limiting its driver section length. The numerical simulation is carried out by solving the Euler equations using ANSYS-Fluent CFD software. The main focus here is to find the typical object shape for which the blast wave gets regenerated earlier at the rear of the object after reflection and diffraction. It is observed that the reattachment occurs first in case of a sphere, followed by the cone and finally the cylinder. Keywords Blast wave reattachment CFD Blast wave interaction Shock tube Vortex ring
Introduction The blast wave generated from high explosives is extremely harmful especially when one is very close to the explosive core or at a location of the constructive interference. It wraps around any objects and buildings [1] like an acoustic wave. Therefore, persons or objects stay behind the objects are not necessarily protected from a blast which & Dipankar Chatterjee [email protected] 1
CSIR-Central Mechanical Engineering Research Institute, Durgapur 713209, India
2
Academy of Scientific and Innovative Research, Ghaziabad 201002, India
happens on the opposite side of the building. The intensity of the blast is characterized by the peak overpressure and the impulse, i.e., positive overpressure multiplied by its duration. The intensity/strength of the blast wave behind the objects depends on the nature of the objects, such as regular or irregular, surface topology, number of reflective and diffractive surfaces, etc. The blast wave after wrapping around the object propagates radially outwards, and its strength and speed are initially less compared to the blast wave expanding in the free field along other directions. However, this blast wave gets regenerated at a downstream location after passing over the objects. The measured blast wave reattachment distances will show the level of blast wave being mitigated/attenuated through the structures without examining the blast wave diffraction, and reflection taking place over the objects in detail. It helps in design and optimization of blast wave mitigating/attenuating devices. Scientists use sophisticated mathematical models for predicting the response of the objects subjected to a blast wave in designing the efficient barriers and safer buildings [2]. Accordingly, the understanding of blast wave interaction with inanimate and biological objects is extremely important in avoiding or reducing the ex
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