On Lean Turbulent Combustion Modeling

This paper investigates a lean methane-air flame with different chemical reaction mechanisms, for laminar and turbulent combustion, approached as one and bi-dimensional problem. The numerical results obtained with Cantera and Ansys Fluent software are compared with experimental data obtained at CORIA Institute, France. First, for laminar combustion, the burn temperature is very well approximated for all chemical mechanisms, however major differences appear in the evaluation of the flame front thickness. Next, the analysis of turbulence-combustion interaction shows that the numerical predictions are suficiently accurate for small and moderate turbulence intensity

Accurate measurements and analysis of the thermal structure of turbulent methane/air premixed flame

WOS:000377911100042International audienceThis paper provides further experimental and numerical results concerning the premix turbulent combustion of lean methane-air mixture. For V-shaped flame, the experimental data were acquired by two-dimensional Rayleigh scattering technique. The main purpose of this investigation is to obtain quantitative information on the instantaneous thermal structure of the flame front for both laminar and turbulent conditions. Four values for turbulence intensity have been considered. The flame surface density is closely related to the two-dimensional temperature gradient. For turbulent combustion, a general decreasing trend of averaged temperature gradient was observed. However, this tendency is inverted for very high turbulence intensity when the instantaneous temperature gradient presents high fluctuations. The flame front thickness PDF and the curvature PDF decrease with the turbulence intensity. The joint PDF of curvature and the maximum of the progress variable's gradient have the tendency to rotate counterclockwise with the increase of turbulence intensity. Negative curvature brings more energy in preheat zone of flame and enhances combustion; consequently the temperature gradients increase. (C) 2016 Published by Elsevier Ltd

Biodiesel from Recycled Sunflower and Palm Oil—A Sustainable Fuel for Microturbo-Engines Used in Airside Applications

An experimental assessment of burning behavior of some aviation fuel and biodiesel obtained from waste oil mixture has been performed within this paper. The biodiesel was obtained from sunflower and palm waste oil (SFP) and the mixtures consisted of 10, 30 and 50% biodiesel in regular aviation fuel. The aviation fuel is a mixture of Jet A fuel + 5% Aeroshell 500 oil (called Ke) with the oil being added for turbo-engine’s lubrication. So, the used fuels were: Ke, Ke + 10% SFP, Ke + 30% SFP, Ke + 50% SFP. In first step, SFP was characterized in terms of: density, kinematic viscosity, flash and freezing points and calorific power. Also a deeper analysis was made by using FTIR for all the fuels involved in the experiments. The second step consisted of assessing the chemical reactions that occur during the burning process. Thus starting from the known elemental analysis, the air needed for a stoichiometric reaction has been calculated for each fuel mixtures. Also the resulting CO2 and water has been calculated from the reactions. The third step consisted of experimental testing the burning behavior of the above mentioned fuels on a micro turbo-engine. The used engine was Jet Cat P80® provided by Gunt Hamburg, Barsbüttel, Germany. The variation of: rpm vs. time, burning temperature vs. time and fuel debit vs. rpm are presented for starting and yield procedures. The tests have been conducted at 8 different working regimes of the engine. For each regime, an 1 min testing period was chose, during which burning temperature vs. rpm, fuel debit vs. rpm and thrust force vs. rpm were monitored. For maximum regime, only calculus for burning, thermal efficiencies and specific consumption have been made. As a main conclusion, the engine working behavior was steady throughout the entire range of rpm and for all the blends fed, thus the studied fuel blends may be considered as sustainable fuel for applications that are using micro turbo-engines with main advantages related to pollution and raw materials allowing the production of this type of fuel

Thermal Structure of Laminar Methane/Air Flames: Influence of H 2 Enrichment and Reactants Preheating

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