The structure of deflagration to detonation transition in gases is studied through high-resolution numerical simulations. Quasi-steady wave structures have been shown to play an important role in this transition process in previous theoretical studies assuming an Arrhenius single-step reaction model with asymptotically high activation energy. In chapter 2, these are considered in the context of numerical simulations and analysis tools are developed to automatically identify quasi-steady structures within one-dimensional simulation results. These tools are applied to simulations of shock-induced transition in order to reveal the evolution of the waves in time and demonstrate their persistence and scaling over a range of both activation energy and energy release rate. An extension of the system of equations to multiple ideal gases is considered in chapter 3. Particular attention is paid to the method of the numerical solution of this model to avoid errors produced at material interfaces, and an approximate Riemann-problem solution derived to allow for solution of the model by the Weighted Average Flux method. This model is validated for inert flows by the simulation of two-dimensional Richtmeyer-Meshkov experiments. The model is further extended to model reactivity flow by considering the reactant and product gases as two constituents of the system and modelling the conversion between these by a simple one-step reaction mechanism. The complete reactive multi-gas model is then applied to simulations of two-dimensional shock-flame interactions resulting in multidimensional DDT, and the DDT event in these simulations examined in detail. Finally, in chapter 4, the role of chemistry modelling for the DDT process is investigated.
| Identifer | oai:union.ndltd.org:bl.uk/oai:ethos.bl.uk:596472 |
| Date | January 2006 |
| Creators | Bates, Kevin Robert |
| Publisher | University of Cambridge |
| Source Sets | Ethos UK |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
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