Vendra, Chandra Madhav Rao (2014) Large eddy simulations of turbulent flame deflagration with wall interactions. (PhD thesis), Kingston University, .
Abstract
Large Eddy Simulation (LES) are performed for premixed gas phase turbulent deflagrations in confinements with particular modeling emphasis to capture proper flame behaviour i.e. quenching and acceleration near the obstacles/solid surfaces. Flamelet based Coherent Flame Model (CFM) is adopted for simulating turbulent flame deflagration. Conservation equation for Flame Surface Density (FSD) is considered to account for the non-equilibrium transport of FSD. Modeling improvements in terms of flow-wall and flame-wall interactions are implemented in the governing equations of CFM, which serve as wall boundary closures for numerical combustion simulations with wall interactions. The enthalpy loss factor considering the non-isobaric condition is used in the present study to accurately capture the region where flame is affected by the presence of wall. Model constants for the flame-wall interaction are determined in a posteriori test. The CFM solver along with flow and flame-wall interactions is been developed in OpenFOAM framework. The solver has been first validated for a non-reacting channel flow simulations with the DNS data. Validation study for the flow-wall interaction is performed by considering the periodic hill configuration in a channel. DNS of a ‘V’-flame in a channel flow is used as posteriori test to fix the flame-wall model constants. The numerical predictions of the CFM solver with wall interactions are assessed by simulating the turbulent flame deflagrations in a quench mesh, repeated obstructed channel and in a model hydrogen storage facility. Numerical results establish that the wall interaction models have improved the predictions and are able to account for change in characteristics of the turbulent premixed flame and turbulence length scales in the near-wall region.
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