The Blast Waves From Unconfined Axisymmetric Vapour-Cloud Explosions
Raju, Manthena Surya Narayana
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https://hdl.handle.net/2142/70620
Description
Title
The Blast Waves From Unconfined Axisymmetric Vapour-Cloud Explosions
Author(s)
Raju, Manthena Surya Narayana
Issue Date
1982
Department of Study
Aeronautical and Astronautical Engineering
Discipline
Aeronautical and Astronautical Engineering
Degree Granting Institution
University of Illinois at Urbana-Champaign
Degree Name
Ph.D.
Degree Level
Dissertation
Keyword(s)
Engineering, Aerospace
Abstract
This dissertation presents a systematic study of the blast waves produced by axisymmetric detonation waves and constant velocity as well as accelerating deflagration waves propagating through homogeneous axisymmetric clouds whose energy density approximate that of a typical hydrocarbon-air mixture. The behavior of the blast wave was studied in a compressible medium surrounding a flammable mixture during and after the propagation of a heat addition wave which models the detonation or deflagration process. In this study the non-steady, two-dimensional fluid dynamic equations of motion were integrated using Godunov's computational scheme subject to appropriate boundary conditions. The actual combustion process was replaced by a simple heat-addition working fluid model developed by Strehlow and coworkers. The results yielded the fluid dynamic and thermodynamic fields associated with the propagation of the blast wave. Particular attention was concentrated in determining the blast parameters, i.e. peak overpressure and impluse, using the numerical calculations for various cloud geometries and flame velocities. A general acoustic monopole source theory was also used in determining the peak overpressure and impulse produced by the low velocity deflagration of non-spherical axisymmetric clouds. Reasonable agreement was found between the values obtained from the numerical calculations and the linear-acoustic theory for low velocity flames.
The results indicate that deflagrative combustion of extended clouds is very ineffective in producing damaging blast waves when compared with the spherical blast wave generated by an equivalent cloud of identical fuel-air mixture. On the contrary, a high pressure burst and detonative combustion of axisymmetric clouds exhibit pronounced directional blast effects with very high overpressures near the source volume. From the results of this study, it appears likely that large flame accelerations and velocities close to detonation are needed for the combustion of an extended cloud to produce a damaging blast wave.
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