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Showing 1 to 20 of 141 for “"Equivalence Ratio"”.
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Spatially Resolved Equivalence Ratio Measurements Using Tomographic Reconstruction of OH*/CH* Chemiluminescence
Thermoacoustic instabilities in gas turbine operation arise due to unsteady fluctuations in heat release coupled with acoustic oscillations, often caused by varying equivalence ratio perturbations within the flame field. These instabilities can cause irreparable damage to critical turbine …
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Thermoacoustic Effects of a Variable Equivalence Ratio in a Single Element Methane Combustor
… the thermoacoustic effects of controlling the equivalence ratio of a single-element natural gas combustor were modeled and analyzed. The project used Fidelity Pointwise for meshing, ANSYS Fluent for modeling, ERAU VEGA HPC for computing, and MATLAB for acoustic analysis. A numerical model of …
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Predicting toxic gas concentrations resulting from enclosure fires using the local equivalence ratio concept linked to fire field models
… either ignore the prediction of toxic gas generation or require the use of detailed chemistry to predict toxic gas generation. These detailed chemistry models require considerable data which is not generally available for most common building materials. The main objective of the study presented …
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An experimental investigation of the effect of temporal equivalence ratio fluctuations on NO<sub>x</sub> emissions in premixed flames
The effect of temporal variations in equivalence 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 …
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Equivalence Ratio Gradient Effects on Local Flame Front Topology and Heat Release Rate in Stratified, Iso-Octane/Air Turbulent V-Flames
… reactant mixtures of varying mean gradients in equivalence ratio (ϕ) and a unique windowing approach was devised in which 3-pentanone tracer planar laser induced fluorescence (PLIF) was used to determine an analysis region of interest (ROI) within the flame. Iso-contours of equivalence ratio …
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Exergy Based SI Engine Model Optimisation. Exergy Based Simulation and Modelling of Bi-fuel SI Engine for Optimisation of Equivalence Ratio and Ignition Time Using Artificial Neural Network (ANN) Emulation and Particle Swarm Optimisation (PSO).
… is employed to identify parameters such as equivalence ratio and ignition time for optimising of the engine performance, based upon maximising ¿total availability¿. In the optimisation process, the engine exhaust gases standard emission were applied including brake specific CO (BSCO) and …
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Willans Line Based Equivalent Consumption Minimization Strategy for Charge Sustaining Hybrid Electric Vehicle
… which uses backward facing models and an equivalence ratio to calculate the lowest total fuel power consumption. The equivalence ratio quantifies the fuel power to battery power conversion process of the hybrid electric vehicle components and therefore quantifies electric power consumption …
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Experimental and Theoretical Investigation of Flame Propagation Through Compositionally Stratified Methane -Air Mixtures
… an optically accessible test chamber and its equivalence ratio distribution in the fresh mixture was measured with both acetone PLIF and Raman spectroscopy. For a flame propagating from stoichiometric to leaner methane-air mixtures, the flame speed was shown to be higher than the one …
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CFD investigation on hydrogen enrichment effect to dual-fuel direct injection diesel engine
… use in driving heavy duty machines and power generation plants due to the 40% higher efficiency and torque compared to the Spark Ignition (SI) engines. Bulk of previous studies on the use of alternative fuels; hydrogen-natural gas blends (HCNG) used port injection and experimentally were …
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The generation of carbon monoxide in compartment fires
… production rates can be correlated with the equivalence ratio in what is known as the Global Equivalence Ratio concept (GER). Due to the simplification in these past experiments, it was not known if the GER concept was valid for compartment fires. Therefore, there was a need to determine if …
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A Method for Measuring Spatially Varying Equivalence Ratios with Application to Thermoacoustics
… angle camera images. To determine fuel/air ratios, the ratio of excited radical species (OH*/CH*) emissions using chemiluminescence can be employed. Following the process of high-resolution tomography reconstructions in this work allowed for flame tomography coupled with chemiluminescence …
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The use of chemiluminescence for the detection of temperature and fuel-to-air ratio in turbulent premixed flames
… method for the determination of temperature and equivalence 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 …
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Turbulent flame development in a high-pressure combustion vessel
… from the mean velocity). The influence of equivalence ratio was investigated for a fixed u'= 2 m/s at 0.5 MPa for methane, a 70 % methane/ 30 % hydrogen mixture, methanol, isooctane and a gasoline (Shell dutch-pura). The mixtures were varied from the lean ignition limit to rich limit up to …
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The Role of Fuel Droplets in Laminar Flame Propagation
… simulation. The twin premixed counterflow configuration was used to measure reference flame speed as a function of strain rate and nominal equivalence ratio (φ_0) for acetone/air mixtures. Two opposing stagnation flames were studied: a gaseous flame with prevaporised fuel, and a spray flame with …
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The impact and fate of aqueous sodium nitrate on hydrocarbon flames
… chloride/air flames as a function of equivalence ratios that experienced diffusion of air from the surroundings. The flames were stabilized on a slotted, uncooled burner. The data set was divided into profiles of relative sodium atom concentrations, temperatures, and selected stable …
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Numerical Simulation of UVA Ramjet/Scramjet Hypersonic Engine with Hydrogen-Air Combustion Using Wind-US
… case and two reacting cases with different equivalence ratios, all with clean, non-vitiated air supply. The strong sensitivity of the simulation results to the choice of turbulent Schmidt number is demonstrated. For low equivalence ratio, excellent agreement with experimental data is …
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Experimental Investigation of a Lean, Premixed Gas Turbine Combustor Using Advanced Laser Diagnostics
… Four operating conditions were examined---two equivalence ratios, 0.6 and 0.7, and two combustor pressure drops, 3% and 5%. Time-resolved images were acquired at two axial locations for each test condition, revealing a combustion flow field dominated by large-scale turbulent structures. …
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The Effects of Porous Inert Media in a Self-Excited Thermoacoustic Instability: A Study of Heat Release and Reduced Order Modelling
… strategy requires early-stage design considerations such as reduced order modeling, which is often used to study a systems' stability response to geometric changes and mitigation approaches. These reduced order models rely on flame transfer functions (FTF) which numerically represent the …
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Experimental investigation on traversing hot jet ignition of lean hydrocarbon-air mixtures in a constant volume combustor
… and ethylene-air mixtures in the lean equivalence ratio range of 0.8 to 0.4. Ignition delay times and ignitability of these combustible mixtures as affected by jet traverse speed, equivalence ratio, and fuel type are investigated in this study.
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An Experimental Investigation of Self-Excited Combustion Dynamics in a Single Element Lean Direct Injection (LDI) Combustor
… NOx/CO emission standards have led to engine operation in a narrow, lean regime. While premixed or partially premixed combustor configurations such as the Lean Premixed Pre-vaporized (LPP), Rich Quench Lean burn (RQL), and Lean Direct Injection (LDI) have shown a potential for reduced NOx …
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