Turbulent Premixed Flame Modeling Using the Algebraic Flame Surface Wrinkling Model: A Comparative Study between OpenFOAM and Ansys Fluent

Hereafter, we used the Algebraic Flame Surface Wrinkling (AFSW) model to conduct numerical simulations of the Paul Scherrer Institute (PSI) high-pressure, turbulent premixed Bunsen flame experiments. We implemented the AFSW model in OpenFOAM and in Ansys Fluent, and we compared the outcome of both solvers against the experimental results. We also highlight the differences between both solvers. All the simulations were performed using a two-dimensional axisymmetric model with the standard k−ϵ turbulence model with wall functions. Two different fuel/air mixtures were studied, namely, a 100%CH4 volumetric ratio and a 60%CH4+ 40%H2 volumetric ratio. The thermophysical and transport properties of the mixture were calculated as a function of temperature using the library Cantera (open-source suite of tools for problems involving chemical kinetics, thermodynamics, and transport processes), together with the GRI-Mech 3.0 chemical mechanism. It was found that the outcome of the AFSW model implemented in both solvers was in good agreement with the experimental results, quantitatively and qualitatively speaking. Further assessment of the results showed that, as much as the chemistry, the turbulence model and turbulent boundary/initial conditions significantly impact the flame shape and height.

Multispectral Mid-Infrared Camera System for Accurate Stand-Off Temperature and Column Density Measurements on Flames

Accurate measurement of temperature in flames is a challenging problem that has been successfully addressed by hyperspectral imaging. This technique is able to provide maps of not only temperature T (K) but also of column density Q (ppm·m) of the main chemical species. Industrial applications, however, require cheaper instrumentation and faster and simpler data analysis. In this work, the feasibility and performance of multispectral imaging for the retrieval of T and QCO2 in flames are studied. Both the hyperspectral and multispectral measurement methods are described and applied to a standard flame, with known T and QCO2, and to an ordinary Bunsen flame. Hyperspectral results, based on emission spectra with 0.5 cm−1 resolution, were found in previous works to be highly accurate, and are thus considered as the ground truth to compare with multispectral measurements of a mid-IR camera (3 to 5 μm) with a six interference filter wheel. Maps of T and Q obtained by both methods show that, for regions with T ≳1300 K, the average of relative errors in multispectral measurements is ∼5% for T (and can be reduced to ∼2.5% with a correction based on a linear regression) and ∼20% for Q. Results obtained with four filters are very similar; results with two filters are also similar for T but worse for Q.

Experimental Study on the Effect of Nano Additives γAl2O3 and Equivalence Ratio to Bunsen Flame Characteristic of Biodiesel from Nyamplung (Calophyllum Inophyllum)

Nano γAl2O3 has been one of the nanometal oxides that has improved the characteristics of biodiesel. The effect of γAl2O3 nanoparticles addition on premixed flame combustion is investigated with an experiment on the laminar flame speed of Calophyllum inophyllum methyl ester 30% and 70% petrodiesel mixtures, at atmospheric pressure and preheated temperature T = 473K. The γAl2O3 nanoparticles added to CIME30 biodiesel were 0ppm, 100ppm, 200ppm, and 300ppm. Experiments were carried out on a bunsen burner. The equivalent ratio of the mixture between ϕ = 0.67 to 1.17. Experiments revealed that the addition of nanoparticles to CIME30 biodiesel expands the flammability limit and increases the laminar flame speed. CIME30 without nanoparticles, flame stable between ϕ = 0,76 -1,17. CIME30 with nanoparticles, flame stable between ϕ = 0,67 -1,17. Combustion of CIME30 required a lot of air. The highest laminar flame speed occurred at the equivalent ratio ϕ = 0.83. The highest laminar flame speed of CIME30 0, 100, 200, and 300 ppm were 30.77, 34.50, 35.90, 38.45 cm/s respectively. The higher the nano γAl2O3 concentration the higher the laminar flame speed. This occurs due to the catalytic effect of γAl2O3 on biodiesel and its mixtures.

Effect and mechanism of C2HF5 on premixed flame of runaway gas (syngas) in lithium-ion batteries

Lithium-ion battery is a new type of clean energy. Due to manufacturing defects, improper use, unexpected accidents and other reasons, lithium-ion battery thermal runaway fire and explosion accidents are frequently re-ported, and its safety has become an important issue to be solved. In this paper, the effect of second-generation halon substitute C2HF5 on runaway gas premix flame of lithium-ion battery are studied by experiments and numerical simulations.The bunsen burner was used to measure the changing trend of the premixed flame velocity of the runaway gas/air under different equivalent ratios and different concentrations of C2HF5. The results show that the flame velocity is in good consistency with the model under the conditions of lean flame and low inhibitor addition.The promotion effect of inhibitors on combustion has been verified by bunsen flame. Compared with CH4, C2HF5 is more suitable for inhibiting syngas flame of lithium-ion batteries, and the effect on the rich flames is better than lean flames.