Global ETD Search
Search theses and dissertations gathered from participating repositories worldwide. Every result links back to the library that holds it. No account is needed.
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Showing 1 to 20 of 49 for “"non-premixed"”.
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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 …
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Sooting behaviour of turbulent non-premixed jet flames.
Soot measurements using planar laser-induced incandescence (LII) have been performed in three commercial propane-fired flames produced by simple jet (SJ), precessing jet (PJ-P) and bluff-body jet (BB) burners. The flames span a wide range of different global mixing rates for the same nozzle …
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Physical Insights of Non-Premixed MILD Combustion using DNS
… Simulation (DNS) is used to study turbulence, premixed flames and MILD combustion to obtain these additional physical insights. In a first stage, the scale-locality of the energy cascade is analysed by applying a multiscale analysis methodology, called the bandpass filter method, on DNS of …
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A Parallel Solution-Adaptive Method for Turbulent Non-Premixed Combusting Flows
… and applied to the predictions of turbulent non-premixed compressible combusting flows for both two and three space dimensions. The parallel solution-adaptive algorithm solves the system of partial-differential equations governing turbulent compressible flows of reactive thermally perfect …
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An Original Method for Computing Complex Non-Premixed Flows in Chemical Equilibrium
… molecular species densities, as is the case for non-equilibrium flow calculations. The method is suited for applications to mixing flows in rocket engine combustors, where, due to the typical low convective speed, chemical reaction is best modeled as an equilibrium process. Equilibrium …
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Novel Approach for Computational Modeling of a Non-Premixed Rotating Detonation Engine
… analyses are generally modeled with perfectly premixed fuel injection and do not capture the effects of improper mixing arising due to discrete injection of fuel and oxidizer into the chamber. To model realistic injection in a 2-D analysis, the current work uses an approach in which, a …
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Flow Field and Soot Formation Characteristics in Swirl-stabilized Non-premixed Turbulent Flames
… experimentally in turbulent swirl-stabilized non-premixed flames using three different fuels: methane, ethanol and aviation Jet A-1. The studied flames were confined and stabilized in a model gas turbine combustor with a swirl number of ~0.55. Soot volume fraction, fv, and primary soot …
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Large eddy simulation of a fuel-rich turbulent non-premixed reacting flow with radiative heat transfer
… (β- PDF) for the simulation of turbulent non-premixed reacting flow, in particularly for the predictions of soot and NO production, and to investigate the radiative heat transfer during combustion process applying Discrete Ordinates Method (DOM). LES seeks the solution by separating the …
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Extinction strain rates of n-butanol, 2-butanol and iso-butanol in counterflow non-premixed flamelets
The extinction strain rates of three butanol isomers, (n-butanol, sec-butanol and iso-butanol) were studied experimentally in a counterflow burner, and computationally using a one-dimensional numerical model. The experimental results provided an insight in how the difference between molecular …
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Flame Stabilisation in the Transition to MILD Combustion
… investigated experimentally and numerically in premixed reactors and non-premixed flames. In this study, definitions of MILD combustion are compared and contrasted, with the phenomenological premixed description of MILD combustion extended to describe non-premixed flames. A simple criterion is …
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CFD modelling and validation of a large 2-stroke marine diesel engine
… models predict the same best flow field and non-equilibrium wall function produces the best heat transfer results. Following this, the spray breakup models were evaluated through the constant volume spray chamber test. The Stochastic Secondary Droplet (SSD) model was verified as the best one …
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Large Eddy Simulation of Boundary Layer Combustion
Numerical simulations of turbulent non-premixed flames occurring in the presence of solid surfaces is a prevalent topic of interest due to the complexity of the near wall physics and the technical modeling challenges it presents. Near wall combustion phenomena is relevant in a variety of combusting …
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An Experimental Study of Soot Formation in Dual Mode Laminar Wolfhard-Parker Flames
… of laminar underventillated ethylene non-premixed flames in hot vitiated environments was performed using a modified Wolfhard-Parker co-flowing slot burner. The burner could be operated in "single mode" with a cold air/oxygen mixture as the oxidizer for the non-premixed flame or in …
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Blow-off in gas turbine combustors
… to the extinction and the blow-off events of non-premixed and spray flames stabilized on an axisymmetric bluff body in a confined swirl configuration. The comparison of flames of different canonical types in the same basic aerodynamic field allows insights on the relative blow-off behaviour. …
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Conditional source-term estimation methods for turbulent reacting flows
… Navier Stokes (RANS) simulation of non-premixed autoigniting jets. Despite the scatter observed in the experimental data, the predictions of ignition delay from both methods agree reasonably well with the measurements. The discrepancy between predictions of these two methods can be …
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Autoignition and emission characteristics of gaseous fuel direct-injection compression-ignition combustion
… stochastic nature of the autoignition process of non-premixed methane jets. Examination of the convergence of the ensemble-averaged OH-PLIF images showed that increasing the number of repeat experiments was the most effective way to achieve a more converged result. A combustion model, which …
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Turbulent combustion simulation in realistic gas-turbine combustors
… study of two combustion models based on a non-premixed assumption or a partially premixed assumption using the previously proposed models Zimont Turbulent Flame Speed Closure (ZTFSC) and Extended Coherent Flamelet Method (ECFM)) is presented in a first step. Comprehensive chemical reactions …
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Simulations of turbulent swirl combustors
… and can therefore be considered as canonical problems. At high enough forcing frequencies, double ring vortices are shed from the air pipe exit. Various harmonics of the pulsating frequency are observed in the spectra and their relation with the vortex shedding is investigated through …
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Flameholding methods for compact hypersonic systems
… possible for the hypermixer geometries alone. Non-premixed oxygen enrichment was tested as an alternative in an axisymmetric Mach 3.5 flowpath. It was observed that oxygen enrichment had significant capability to promote stable scram-mode combustion with low losses in total pressure from …
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Bio-butanol fuel atomization and combustion processes
… namely butanol electrostatic sprays, butanol non-premixed flames, and butanol kinetic modeling in view of the emergence of methods of production of this fuel from biological sources. Butanol electrospray (e-spray) phenomenology was investigated through high-speed visualization and compared …
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