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Showing 1 to 19 of 19 for “"Laminar flame speed"”.
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Modelling spherical flame propagation in a closed volume
… combustion behaviour of alternative fuels. The laminar flame speed of a combustible mixture is a well defined combustion characteristic that influences the efficiency and performance of many combustion processes. An example of where flame speed has a strong impact on the performance of a …
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Research on late-robust combustion
… study was carried out in which charge motion or laminar flame speed was varied. Two sets of tests were done. The first consisted of using an air jet mounted in the intake port to generate charge motion at a spark-timing sweep from 20⁰ BTC to 200 ATC. Two jet orientations were tested with the …
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A fractal analysis of premixed turbulent flames
… behavior of lean premixed wrinkled turbulent flames was investigated over a range of turbulence conditions. For this purpose a turbulent combustion rig was designed and built in which the turbulence intensity and scale could be independently varied by means of a set of grids. The relative …
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Investigation of a prototype industrial gas turbine combustor using alternative gaseous fuels
… Before examination of the actual burner, the laminar flame speed was measured for a range of gases. The measurement technique was based on Schlieren imaging which is a measure of the density gradient through a flame surface. A Bunsen type burner was used to measure the angle of a conical flame …
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The effects of changes in engine geometry on the breathing and combustion in a spark ignition engine
… attempt has been made to relate the turbulent to laminar flame speed ratio to the engine's physical parameters. These results compare well with previously published work by other workers.
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Transient Phenomena in Annular Combustors
… a wide data set including stability limits, flame regimes and physical mechanisms of ignition and extinction. The first part of the investigation focused on the lean blow-off (LBO). Experiments were carried out on a premixed annular combustor, comprising a variable number of injectors, …
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Combustion lean limits fundamentals and their application to a SI hydrogen-enhanced engine concept
… of lean combustion. Due to hydrogen's high laminar flame speed, adding a hydrogen-rich mixture with gasoline into the engine helps stabilize combustion, extending the lean limit. This work studies the fundamental behavior of lean combustion in a spark ignition (SI) engine, identifying the …
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Experimental investigation of unconfined bluff body stabilised flames with vapourised kerosene fuels
… have increasingly implemented lean premixed flames as they facilitate low NOx and soot emissions. In most modern transport vehicles, combustion occurs under highly turbulent conditions. However, stabilizing lean premixed flames within the high Reynolds number conditions of practical devices …
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Combustion characteristics of alternative liquid fuels
… on the deflagration properties of biodiesel. The laminar flame speeds of Palm Methyl Esters (PME) and blends of PME with conventional fuels are determined using the jet-wall stagnation flame configuration. The same technique is also used to measure the laminar flame speed of diesel, Jet-A1, …
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Feasibility studies of the exhaust-gas reforming of hydrocarbon and alcohol fuels
… exercise was the calculation of reformed fuel laminar flame speed, and hence heat-release duration and commencement values. The results of the simulations have enabled comparisons of predicted engine thermal efficiency and pollutant emission levels for reformed and conventional fuelling …
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Measurement of ignition delay time of jet fuels in shock tube for the development of the chemical kinetic mechanism
… cost. Validation against independent laminar flame speed measurements and shock-tube species profiles confirms that the regularized mechanisms retain balanced fidelity across ignition, flame propagation, and intermediate chemistry, while revealing specific larger unsaturated and …
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Application of Crossed-Plane Tomography and Stereo Particle Image Velocimetry for Three-Dimensional Analysis of Premixed Turbulent Flames
… methods have been used to measure instantaneous flamelet surface normal vectors in premixed turbulent flames to study the wrinkling of flamelet surfaces and the internal structure of the flamelet. CPLT was applied to measure flamelet orientations of premixed turbulent V-flames with increasing …
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Modified source-type flame model and vorticity generated by the flame and bluff bodies
… model is developed to simulate the wrinkled laminar flame sheet flapping in weakly turbulent premixed combustion. The wrinkled laminar flame sheet is represented by a discrete distribution of volume sources called source disks. These source disks are utilized to produce the acceleration of …
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The influence of fuel properties on threshold combustion in aviation gas turbine engines
… evaporation is compromised. The influence of flame speed and chemical ignition delays were investigated. Laminar flame speed was shown not to correlate with LBO, discrediting its use as a proxy for reaction rate. The study showed a correlation between the lean blowout behaviour of jet fuels …
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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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Lean Premixed Prevaporised Combustion for Microturbines
… Thus, this thesis explores the fuel flexibility, flame stability, structures, gas emissions, and droplet behaviour in LPP combustion at conditions relevant for microturbines. The first part of the thesis examines the effect of fuel choice using zero- and one-dimensional combustion simulations. The …
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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, …