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Title: A kinetic approach to detonation in gaseous hydrogen- and hydrocarbon-oxygen systems
Author: Bradley, Christopher Matthew
ISNI:       0000 0004 2737 3544
Awarding Body: Imperial College London
Current Institution: Imperial College London
Date of Award: 1997
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This work concerns detonation in enclosed gaseous systems. It asserts an improved understanding of the detonation cell, and in particular of the relationship between cell size and induction time - the time between the passage of the front of the shock wave which the detonation supports, and that of the onset of the reaction of a critical reaction intermediate, as characterised by a maximum in the concentration of that species. Computer modelling has built on the work of Asewando (1994a), who produced a predictive thermodynamic model describing quasi-equilibrium conditions at the shock and Chapman-Jouguet planes. This, together with an improved database of thermodynamic data, and a database of kinetic reaction schemes, has been combined with an efficient finite-difference modelling routine, using a flexible grid size, to produce induction time predictions. These predictions are fitted to an Arrhenius-type equation which is used, with an improved geometric description of the detonation cell based on the technique of Vasiliev & Nikolayev (1978), to identify cell sizes. This approach is applied to several non-sooting systems, and to the propane-oxygen system in both sooting and non-sooting regimes. To validate these predictions, experimental results for detonation cell size and velocity have been obtained for the hydrogen-oxygen, ethylene-oxygen, and acetylene-oxygen-20% argon systems in a 2-inch diameter round detonation tube; velocity measurements in the first two of these systems agree with those of previous researchers. Some measurements of cell size have been achieved in fuel rich soot-forming systems using novel materials; results include trials of several materials which were found to be unsuitable. The formation of soot has been studied in a range of fuel-rich hydrogen-acetylene-16% oxygen mixtures; measured cell sizes show clearly the effects of two apparent modes of soot formation. Predictions for some of these systems constitute significant improvements on values from previously published models (Nettleton (1987))
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available