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Detonation Diffraction Through an Abrupt Area Expansion


Schultz, Eric (2000) Detonation Diffraction Through an Abrupt Area Expansion. Dissertation (Ph.D.), California Institute of Technology. doi:10.7907/96F1-QR61.


The problem of a self-sustaining detonation wave diffracting from confinement into an unconfined space through an abrupt area change is characterized by the geometric scale of the confinement and the reaction scale of the detonation. Previous investigations have shown that this expansion associated with a detonation transitioning from planar to spherical geometry can result in two possible outcomes depending upon the combustible mixture composition, initial thermodynamic state, and confining geometry. Competition between the energy release rate and expansion rate behind the diffracting wave is crucial. The sub-critical case is characterized by the rate of expansion exceeding the energy release rate. As the chemical reactions are quenched, the shock wave decouples from the reaction zone and rapidly decays. The energy release rate dominates the expansion rate in the super-critical case, maintaining the coupling between the shock and reaction zone which permits successful transition across the area change. A critical diffraction model has been developed in the present research effort from which the initial conditions separating the sub-critical and super-critical cases can be analytically determined. Chemical equilibrium calculations and detonation simulations with validated detailed reaction mechanisms provide the model input parameters. Experiments over a wide range of initial conditions with single- and multi-sequence shadowgraphy and digital chemiluminescence imaging support the model derivation and numerical calculations. Good agreement has been obtained between the critical diffraction model and experimental results.

Item Type:Thesis (Dissertation (Ph.D.))
Subject Keywords:Aeronautics and Planetary Science
Degree Grantor:California Institute of Technology
Division:Engineering and Applied Science
Major Option:Aeronautics
Minor Option:Planetary Sciences
Awards:William F. Ballhaus Prize, 2000.
Thesis Availability:Public (worldwide access)
Research Advisor(s):
  • Shepherd, Joseph E.
Thesis Committee:
  • Hornung, Hans G. (chair)
  • Beck, James L.
  • Ingersoll, Andrew P.
  • Shepherd, Joseph E.
  • Sturtevant, Bradford
Defense Date:20 April 2000
Funding AgencyGrant Number
National Defense Science and Engineering Graduate (NDSEG) Fellowship ProgramUNSPECIFIED
NASA Small Business Technology Transfer (STTR)UNSPECIFIED
Office of Naval Research (ONR). Multidisciplinary Research Program of the University Research Initiative (MURI)UNSPECIFIED
Record Number:CaltechETD:etd-11122003-180459
Persistent URL:
Default Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:4528
Deposited By: Imported from ETD-db
Deposited On:13 Nov 2003
Last Modified:25 Jul 2022 19:19

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