Use this URL to cite or link to this record in EThOS: http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.591054
Title: Modelling and large eddy simulation (LES) of vented hydrogen-air deflagrations
Author: Keenan , James
Awarding Body: University of Ulster
Current Institution: Ulster University
Date of Award: 2013
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Abstract:
Venting of deflagrations remains the most cost effective method to reduce the possible adverse effects of accidental combustion that may occur in equipment and structures housing hydrogen. The HySAFER Centre at the University of Ulster (UU) is working towards understanding the underlying physical phenomena and predicting various hydrogen combustion scenarios through a Large Eddy Simulation (LES) modelling approach. The research undertaken focused on further testing and validating the UU turbulent burning velocity (TBV) model, against different types of experimental scenarios that it had not yet been tested against. The experiments selected for analysis were performed at the FM Global 63.7m3 1arge scale explosion test chamber. These experiments consisted of the ignition of flammable hydrogen-air mixtures, initially contained within the chamber. Differing ignition locations and vent sizes were considered. Numerical simulations were conducted using the UU-TBV model. This model describes the interplay between different physical mechanisms affecting the turbulent burning rate. These mechanisms are the influence of pressure, temperature and density on the laminar burning velocity, flow turbulence, turbulence generated by the ftame front itself, preferential diffusion in stretched flames and the fractal growth of turbulent flame surface area. The initial application of this model did not reproduce all details of the experimental pressure transients described by the FM Global experiments. Following appropriate investigations it was concluded that the most likely missing contribution to the enhancement of combustion in the UU-TBV model compared to the experiments was the Rayleigh Taylor (RT) instability. Therefore the UU-TBV has been extended to include RT instability. A heat transfer model and an updated method to calculate the turbulent burning velocity was also added. Comparison of simulation results against experimental data was then undertaken showing how the inclusion of RT instability and these additions improved the UU-TBV model. Finally appropriate recommendations for future areas of researched have also been suggested.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID: uk.bl.ethos.591054  DOI: Not available
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