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Showing 1 to 20 of 40 for “"premixed flame"”.
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Nonlinear thermoacoustic oscillations of a ducted laminar premixed flame
… of oscillation in a numerical model of a ducted premixed flame, the bifurcations that lead to these oscillations and the influence of external forcing on these oscillations. Criteria for the existence and stability of limit cycles in single mode thermoacoustic systems are derived analytically. …
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Hydrodynamic stability of a premixed flame subjected to transverse shear
Flame instabilities arise intrinsically in combustion systems and have important implication in the operation of engineering devices. The primary intrinsic instability of premixed combustion is caused by thermal gas-expansion, known as the hydrodynamic or the Darrieus-Landau (DL) instability. …
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Modeling study of premixed flame suppression and extinction by water mists, A
Includes bibliographical references (pages 145-152).
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Relation between flame speed and stretch for a premixed flame in a stagnation point flow
The student, Midhun Joy, submitted this Thesis for approval on 2017-12-11 at 14:52.
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Impact of fuel and oxidizer composition on premixed flame stabilization in turbulent swirling flows : dynamics and scaling
… high-speed chemiluminescence to examine the flame macrostructure; high-speed Particle Image Velocimetry and OH Planar Laser Induced Fluorescence to probe the flow and flame microstructure. Numerical simulations were used to complement experiments and examine the complex three-dimensional …
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Swirl-stabilized lean-premixed flame combustion dynamics: An experimental investigation of flame stabilization, flame dynamics and combustion instability control strategies
… in the development of next generation lean premixed combustor technology. Combustion instability is the coupling between unsteady heat release and combustor acoustic modes where one amplifies the other in a feedback loop. This is a complex phenomenon which involves unsteady chemical kinetic, …
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Soot formation in vitiated-air diffusion flames
… using optical techniques in dual mode diffusion flames. A dual mode flame is defined as a diffusion fuel jet that burns in the wake of a premixed flame. The premixed flame combustion products simulate a vitiated-air environment: the air is preheated, rich in radicals, and depleted in oxygen. A …
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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 varying …
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Analytical and Computational Study of Flame Acceleration in Tubes: Effect of Wall Friction
Premixed flame acceleration is especially strong in the case of flame propagation in tubes or channels. Being a reasonably simple configuration to investigate fundamental flame properties, combustion tubes have numerous practical applications such as safety issues in mines, subways and power …
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Composite propellant combustion with low aluminum agglomeration
… at 75/25:FAP/binder (by mass) is found to have premixed flame conditions that produce minimal agglomeration (without ignition) of 15-µm Al. Coarse AP (CAP) is added to the system in the form of either particles (200 or 400 µm) or pressed-AP laminates (simulated CAP). In the 2-D laminate system …
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One-dimensional numerical model for evaporation and oxidation of hydrocarbon fuels
… a thin liquid fuel layer exposed to an incoming premixed flame. In particular, the model is applied to predict the total evaporation and ensuing oxidation of a liquid layer under repeated cycles. Methanol was used as a baseline fuel. Simplifications in the flow, geometry, and operating conditions …
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DNS of inhomogeneous reactants premixed combustion
… combustion, called the inhomogeneous reactants premixed combustion. The present study investigates the effects of inhomogeneous reactants on premixed combustion, specifically on the interactions of an initially planar flame with field of inhomogeneous reactants. Unsteady and unstrained laminar …
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Acoustical behavior of a turbulent, ducted, premixed, hydrogen- flame burner
… is to characterize the structure of the flame as an acoustic source. Data describing the farfield and duct terminating conditions allow for the testing of combustion noise models. The acoustic farfield of a premixed flame burner is documented for various power levels and air-to-fuel …
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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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Development of Reduced-Order Flame Models for Prediction of Combustion Instability
Lean-premixed combustion has the advantage of low emissions for modern gas turbines, but it is susceptible to thermoacoustic instabilities, which can result in large amplitude pressure oscillations in the combustion chamber. The thermoacoustic limit cycle is generated by the unsteady heat release …
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Flame synthesis of carbon nanotubes and metallic nanomaterials
… of this study was to examine the potential of a premixed flame for the synthesis of carbon nanotubes with the view that flame synthesis may prove a means of continuous production at low-cost. The specific approach focused on the formation of metallic nanoparticles in flames; identification of …
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Reduction of convective heat transfer from reacting flows by application of electric fields
… of heat transfer from a rod-stabilized diffusion flame and a step-stabilized premixed flame was investigated. The fuel examined was propane. Inlet velocity for the diffusion mode was a nominal value of 3.4 m/s with nominal air/fuel ratios of 420, 320, and 270. Inlet velocities ranged from 4.5 to …
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Ion-Currents in Oxyfuel Cutting Flames Exposed to External Bias Voltages
… throughout the preheating process of premixed methane-oxygen (CH4-O2) oxyfuel cutting flame subject to electric bias voltages. As such, the equations describing combustion, electrochemical transport for charged species, and potential are solved through a commercially available …
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An Experimental Investigation of JP-7 and n-Heptane Extinction Limits in an Opposed Jet Burner
… strain rate on a laminar, counterflow, non-premixed flame. The extinction limit relates to the ability to maintain combustor operation, and the extinction limit data for pure fuel versus air systems provide a relative reactivity scale for use in the design of flame holders. Extinction limit …
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Edge-Flames and Combustion at the Microscale
… relevant to the dynamic behavior of laminar flames in devices whose critical dimensions are at or below classical quenching limits. The behavior of premixed and nonpremixed edge-flames in tune-periodic counterflows is modeled using a constant-density approximation and a single-step Arrhenius …
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