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Detonation Initiation by Annular Jets and Shock Waves

Shepherd, Joseph E. (2005) Detonation Initiation by Annular Jets and Shock Waves. GALCITFM, FM2005.001. California Institute of Technology , Pasdena, CA. (Unpublished)

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The objective of this research is to experimentally determine the feasibility of initiating detonation in fuel-air mixtures using only the energy in hot, compressed air. The existing 6-inch shock tube at Caltech was used to create hot, high-pressure air behind a reflected shock wave. The hot air created an imploding annular shock wave when it jetted through an annular orifice into a 76-mm-diameter, 1-m-long tube attached to the end of the shock tube. A special test section with an annular opening covered by a diaphragm is attached to the end wall of the shock tube. The test section is filled with a combustible gas mixture and initially isolated from the shock tube by both a sliding valve and a very thin diaphragm. The sliding valve is opened immediately prior to the shock tube operation and the diaphragm is ruptured promptly when the shock wave arrives at the end of the shock tube. The test tube was filed with either stoichimetric ethylene-oxygen or propane-oxygen diluted with nitrogen. Piezoelectric pressure transducers and ionization gauges were used to determine the type of combustion event initiated by the annular jet of hot air. The stagnation conditions in the shock tube and the amount of dilution with nitrogen in the test section were varied to find the critical conditions for the onset of detonation in each test mixture. Less sensitive (high dilution) mixtures required larger stagnation pressures in order to initiate a detonation. We were unable to initiate either ethylene or propane-air mixtures within our facility limits. Extrapolation of the low-dilution data indicates that very high stagnation pressures (> 16 bar) are required to initiate detonation in fuel-air mixtures.

Item Type:Report or Paper (Technical Report)
Shepherd, Joseph E.0000-0003-3181-9310
Additional Information:© 2005 California Institute of Technology. Final Report for Award ONR N00014-03-0931.
Group:Graduate Aeronautical Laboratories (Fluid Mechanics), GALCIT
Funding AgencyGrant Number
Office of Naval Research (ONR)N00014-03-0931
Other Numbering System:
Other Numbering System NameOther Numbering System ID
GALCIT Report FM2005.001
Series Name:GALCITFM
Issue or Number:FM2005.001
Record Number:CaltechAUTHORS:20141111-164815139
Persistent URL:
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:51620
Deposited On:12 Nov 2014 21:39
Last Modified:22 Nov 2021 18:48

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