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Showing 1 to 20 of 72 for “"Premixed flames"”.
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Propagation of spherically expanding premixed flames
The propagation of spherically expanding premixed flames is investigated, in both confined and unconfined scenarios. In the unconfined case, the flame propagates at nearly isobaric conditions and the flame displacement speed eventually reaches a constant value whereas in the confined case there is …
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Propagation of premixed flames in confined channels
The propagation of premixed flames in confined channels is investigated. In the unconfined case, the structure of the flame and the flame speed for the adiabatic planar flame have been numerically obtained and confirmed with the existing theory. It is seen that in the unconfined case, the flame …
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Dynamics of premixed flames in closed vessels
Submission original under an indefinite embargo labeled 'Open Access'. The submission was exported from vireo on 2025-10-20 without embargo terms
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Extinction in turbulent swirling non-premixed flames
… and global extinction in turbulent swirling non-premixed flames with Large Eddy Simulation (LES) and sub-grid scale Conditional Moment Closure (CMC) model. The first part of this thesis describes the derivations of the three dimensional conservative CMC governing equations and their finite volume …
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Propagation and topology in turbulent premixed flames
… the phenomenon of self-interaction in turbulent premixed flames is investigated. This refers to the self-intersection of a highly curved flame iso-surface, which leads to local annihilation at the point of intersection as the enveloped mixture is depleted. With a rise in turbulence intensity, the …
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Computations of Turbulent Premixed Flames Using Conditional Moment Closure
Lean premixed combustion is at present one of the most promising methods to reduce emissions and to maintain high efficiency in combustion systems. As the emission legislation becomes more stringent, modelling of turbulent premixed combustion has become an important tool for designing efficient and …
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A new theory of premixed flames in near-stoichiometric mixtures
In this dissertation, a new model of premixed flames in near-stoichiometric mixtures is derived. Unlike most previous theories, which are valid only for very lean or very rich, i.e. off-stoichiometric conditions, our model remains valid over the entire spectrum of mixture compositions, from lean to …
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Scalar dissipation rate based flamelet modelling of turbulent premixed flames
Lean premixed combustion has potential for reducing emissions from combustion devices without compromising fuel efficiency, but it is prone to instabilities which presents design difficulties. From emissions point of view reliable predictions of species formation rates in the flame zone are …
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Hydrogen Enrichment Effects on Thermoacoustics of Turbulent Partially Premixed Flames
… Large Eddy Simulations (LES) for a partially premixed swirl stabilised methane-air flame in a GTMC. Simulations are also performed for cases with methane-hydrogen blends revealing a similar bimodal instability, where the frequency of thermo acoustic oscillations differs significantly from the …
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Numerical simulations of perforated plate stabilized premixed flames with detailed chemistry
… investigate perforated-plate stabilized laminar premixed flames. The developed code is used to examine the impact of the operating conditions and the perforated plate design on the steady flame characteristics. It is also used to numerically investigate the response of these flames to imposed …
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The Role of Swirl in the Flow Structure and Response of Premixed Flames
… Combustion needs to be optimised and lean premixed combustion is an attractive approach to face this challenge. Unfortunately, lean premixed flames are often unstable as they may operate close to the flame blow off limit. Therefore, a suitable method of stabilisation is required. Swirlers …
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Development of novel laser diagnostic techniques for the quantitative study of premixed flames
… the determination of flamefront properties in premixed flames that can serve as input data for computational fluid dynamical (CFD) models in technical combustion. The work comprises of a number of related studies, to address problems of relevance in the field of combustion research. The first …
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Numerical investigation of effects of pressure and chemistry on characteristics of turbulent premixed flames
Turbulent premixed flames are used in many energy conversion and propulsion devices. The efficiency and performance of these devices are affected by operating conditions, which also affect the highly nonlinear turbulence-chemistry interactions (TCIs). Previous fundamental studies characterize TCIs …
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A Study of the Dynamics of Laminar and Turbulent Fully and Partially Premixed Flames
… order models for the dynamics of laminar flat flames, swirl stabilized turbulent flames, and in evaluating the effects of the variation in fuel composition on flame dynamics. The laminar flat flame study was conducted on instrument grade methane, propane, and ethane flames for four total flow …
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Interplay between background turbulence and Darrieus-Landau instability in premixed flames via a model equation
… effect of the Darrrieus Landau instability on a premixed flame in a turbulent environment is investigated using a model equation known as the Michelson Sivashinsky equation, in both one and two dimensions. The equation is externally forced with noise representative of weak turbulence in the flow …
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An investigation into the origin, measurement and application of chemiluminescent light emissions from premixed flames
… species CH* and OH* are studied in premixed methane combustion to investigate the possible application of their light emissions in gas turbine combustion monitoring systems. The interpretation of integrated and local chemiluminescence measurements are shown to give important …
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Characteristics of flame-turbulence interactions in freely propagating turbulent premixed flames under decaying and forced isotropic turbulence conditions
Turbulent premixed flames observed in energy conversion and propulsion applications are characterized by highly nonlinear, unsteady, and multi-scale processes. Previous numerical studies of freely propagating flames have utilized either forced or decaying background isotropic turbulence to provide …
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The use of chemiluminescence for the detection of temperature and fuel-to-air ratio in turbulent premixed flames
… ratio has been developed for turbulent premixed flames. This method utilizes chemiluminescent signals to make correlations with flame temperature and equivalence ratio. Emissions from two radical groups are used for the correlations: an OH system at 309 nm and a CH system at 431 nm. The …
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An experimental investigation of the effect of temporal equivalence ratio fluctuations on NO<sub>x</sub> emissions in premixed flames
… ratio on the NO<sub>x</sub> emissions of a premixed methane-air flame was measured in a burner. The NO<sub>x</sub> emissions are compared among steady flames with spatially uniform equivalence ratio distributions, steady flames with spatially nonuniform equivalence ratio distributions, and …
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Turbulent flame propagation characteristics of high hydrogen content fuels
… in the use of combustors operating under lean, premixed conditions. Operating lean (excess air) lowers the level of nitrous oxides (NOx) emitted to the environment. In addition, concerns over climate change due to increased carbon dioxide (CO2) emissions and the need for energy independence in …
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