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 40 for “"turbulent flame"”.
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Mechanisms of turbulent flame propagation
… are reported of premixed hydrogen-air turbulent burning velocities, made by the double kernel method during explosions. Turbulence was created by four high speed fans driven by electric motors within the explosion vessel. This arrangement created a central region of uniform, isotropic …
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A study of turbulent flame propagation
Thesis: M.S., Massachusetts Institute of Technology, Department of Mechanical Engineering, 1982
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The bending effect in turbulent flame propagation
In the present thesis, the sensitivity of flame propagation to the turbulent motion of burning gases is investigated. The long-standing issue of the 'bending effect' is focused upon, which refers to the experimentally-observed inhibition of flame propagation velocity at high intensities of …
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Turbulent flame propagation characteristics of high hydrogen content fuels
… tools to better understand the physics of turbulent flame propagation in highly stretch sensitive premixed flames in order to predict their behavior at conditions realistic to the environment of gas turbine combustors. This thesis presents the results of an experimental study into the flame …
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Turbulent flame development in a high-pressure combustion vessel
… of this work was to extend the range of turbulent burning velocities presented in the literature by performing new measurements at elevated pressures over a range of turbulent velocities, u' (r. m. s. deviation from the mean velocity). The influence of equivalence ratio was investigated …
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Large eddy simulations of premixed turbulent flame dynamics : combustion modeling, validation and analysis
… To achieve these objectives, lean premixed flames are generally preferred as they achieve efficient and clean combustion. A drawback of lean premixed combustion, however, is that the flames are more prone to dynamics. The unsteady release of sensible heat and flow dilatation in combustion …
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Turbulent flame microstructure, dynamics, and thermoacoustic instability in swirl-stabilized premixed combustion : measurements, statistics, and analysis
… amplification of the noise inherent in a turbulent combustion system, and that the frequency-based response of the flame is a function of the flame geometry. In the first part of the thesis, we focus on the flame geometry, identifying several discrete transitions that take place in the …
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Propagation of large scale premixed turbulent flames
We examine premixed turbulent combustion within the context of a hydrodynamic model derived from physical first principles. This is an asymptotic model that exploits the multi-scale nature of the problem, characterized by two disparate length scales: the diffusion length scale representing the …
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Fundamental studies of flame propagation in lean-burn natural gas engines
… characteristic time required for steady premixed flame propagation has three components: time for autoignition to occur, time for peak temperature to be achieved following autoignition, and time for steady flame propagation in the premixed fuel/air mixture to be achieved. The autoignition time …
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Flame propagation model for the CFR engine under knocking and non-knocking conditions
… octane measurement and is often equated to the turbulent flame speed of the fuel. The objective of this project is to develop a combustion model using the turbulent flame propagation concept that can be used to study the influence of the underlying flame speed behaviour during combustion. The …
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Fundamental studies of premixed combustion
… a fundamental study of spherical premixed flame propagation,originating at a point under both laminar and turbulent propagation. Schlieren cine photography has been employed to study laminar flame propagation, while planar mie scattering (PMS) has elucidated important aspects of turbulent …
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Flameholding methods for compact hypersonic systems
Methods of flameholding enhancement for ethylene-fueled compact hypersonic systems were characterized using high-speed pressure measurements and imaging in the high-enthalpy supersonic facility ACT-II. “Hypermixer” geometries consisting of tapered wedges with and without expansion-ramp vortex …
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Simulation of an algorithm for the active control of combustion noise
… control of combustion noise generated by a turbulent flame produced by an open burner is developed in this thesis. The simulation includes (1) an autoregressive model of real combustion noise, (2) a feedback loop based on the "observer" method, (3) a model of the transfer function between …
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Multi-dimensional Flow and Combustion Diagnostics
Turbulent flows and turbulent flames are inherently multi-dimensional in space and transient in time. Therefore, multidimensional diagnostics that are capable of resolving such spatial and temporal dynamics have long been desired; and the purpose of this dissertation is to investigate three such …
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Propagation and topology in turbulent premixed flames
… this work, 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 …
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Influences of the Darrieus-Landau instability on premixed turbulent flames
… its inventors. The instability, which prevents flames from being too flat, was thought to lead immediately to turbulent flames. Recent studies, initiated by weakly nonlinear analyses and extended by two-dimensional simulations suggest that this is not the case. It was established that the flame, …
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Heat Transfer Characterization in Jet Flames Impinging on Flat Plates
… of a flat Aluminium plate being impinged by a turbulent flame jet. Heat transfer coefficient distribution at the surface is computed from the measured heat flux and temperature data using a reference method and a slope method. The heat transfer coefficient (h) has a nearly bell shaped radial …
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The structure and stability of expanding and converging near-stoichiometric flames
… stability of expanding and converging premixed flames is investigated theoretically. These configurations are inherently unsteady and represent simple examples of positively (expanding) and negatively (converging) stretched flames. A new model is employed in this study that incorporates both …
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