Effects of stretch and preferential diffusion on tip opening of laminar premixed Bunsen flames of syngas/air mixtures

Wang, Jinhua; Wei, Zhilong; Shu, Yu; Jin, Wu; Xie, Yongliang; Zhang, Meng; Huang, Zuohua

doi:10.1016/j.fuel.2015.01.078

Cited by 32 publications

(10 citation statements)

References 30 publications

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“…OH* chemiluminescence is a convenient and widely applied combustion diagnostic technique; however, for Bunsen flames with large molecular weight fuels, flame tip opening phenomenon occurs under slight fuel-rich conditions (around φ > 1.15–1.2). Under these conditions, OH* chemiluminescence has difficulty in obtaining the whole flame contours due to local quenching at the cusp of the flame. − Kerosene-PLIF has the advantage of visualizing the contours of the unburned fronts of kerosene/mixtures, such as Jet A-1, which is free from the influence of local quenching located in the burned gas. , Hence, in the present work, kerosene-PLIF is applied to validate the suitable flame contours definition for the OH* chemiluminescence technique when the flame-opening phenomenon conditions are present.…”

Section: Introductionmentioning

confidence: 99%

Experimental Investigation of Laminar Flame Speed Measurement for Kerosene Fuels: Jet A-1, Surrogate Fuel, and Its Pure Components

Modica

et al. 2018

Energy Fuels

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The present work investigated the laminar flame speed measurement of kerosene-relevant fuel, including Jet A-1 commercial kerosene, and surrogate kerosene fuel and its pure components (n-decane, n-propyl benzene, and propyl cyclohexane) using a high-pressure Bunsen flame burner. The OH* chemiluminescence technique and the kerosene-PLIF technique were used for flame contours detection in order to calculate the laminar flame speed. The experiments were first conducted for n-decane/air flame at T = 400 K, φ = 0.6−1.3, and atmospheric pressure conditions in order to validate the whole experimental system and measurement methodology. The laminar flame speed of Jet A-1/air, surrogate/air, and pure kerosene component (n-decane, n-propyl benzene, and propyl cyclohexane) was then measured under large operating conditions, including temperature T = 400−473 K, pressure P = 0.1−1.0 MPa, and equivalence ratio φ = 0.7−1.3. It was found that these three pure components of kerosene have very similar laminar flame speed. By comparing the experimental results of surrogate kerosene and Jet A-1 commercial kerosene, it was observed that the proposed surrogate kerosene, i.e., mixtures of 76.7 wt % ndecane, 13.2 wt % n-propyl benzene, and 10.1 wt % propyl cyclohexane, can appropriately reproduce the flame speed property of Jet A-1 commercial kerosene fuel. The experimental results were further compared with simulation results using a skeletal kerosene mechanism.

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Section: Introductionmentioning

confidence: 99%

Experimental Investigation of Laminar Flame Speed Measurement for Kerosene Fuels: Jet A-1, Surrogate Fuel, and Its Pure Components

Modica

et al. 2018

Energy Fuels

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“…Quintino et al and Xiang et al assessed the effect of CO 2 on the combustion characteristics of CH 4 /air flames using CANTERA with USC‐Mech chemical‐kinetic mechanism and PREMIX code with the GRI‐Mech 3.0 chemical reaction mechanism, respectively. Furthermore, researchers performed numerical simulations of laminar premixed bunsen flames with different base fuels as well as the chemical mechanisms. While these studies have been performed in‐depth, and, additionally, there is available literature on the usage of GRI‐Mech 3.0 chemical mechanism in order to study the combustion characteristics of biogas/air flames, the results were obtained based on the full mechanisms imposing a heavy computational burden.…”

Section: Introductionmentioning

confidence: 99%

Enhancement of biogas/air combustion by hydrogen addition at elevated temperatures

et al. 2019

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Summary In this study, combustion characteristics of various biogas/air mixtures with hydrogen addition at elevated temperatures were experimentally investigated using bunsen burner method. Methane, CH4, was diluted with different concentrations of carbon dioxide, CO2, 30 to 40% by volume, to prepare the biogas for testing. It is followed by the hydrogen, H2, enrichment within the range of 0 to 40% by volume and the temperature elevation of unburned gas till 440 K. Blowoff velocities were measured by lowering the jet velocity until a premixed flame could be stabilized at the nozzle exit, while laminar burning velocities were calculated by analyzing the shape of the directly captured premixed bunsen flames. The results showed that hydrogen had a positive effect on the blowoff velocity for all three fuel samples. Nonlinear growth of the blowoff velocity with hydrogen addition was associated to the dominance of methane‐inhibited hydrogen combustion process. It was also observed that the increase in the initial temperature of the unburned mixture led to a linear increase of the blowoff velocity. Moreover, specific changes in flame structure such as flame height, standoff distance, and the existence of tip opening were attributed to the change in the blowoff velocity. The effect of CO2 content in the mixture was examined with regards to laminar burning velocity for all compositions. The outcome of the experiment showed that the biogas mixture with higher content of CO2 possessed lower values of laminar burning velocity over the wide range of equivalence ratios. A reduced GRI‐Mech 3.0 was used to simulate the combustion of biogas/air mixtures with different compositions using ANSYS Fluent. The numerically simulated stable conical flames were compared with the experimental flames, in terms of flame structure, showing that the reduced GRI‐Mech 3.0 was suitable for modeling the combustion of biogas/air mixtures.

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“…Also, they found that the increase in the equivalence ratio of the mixture and the length/ depth ratio of the cavity increases the flame splitting limits. Wang et al 16 experimentally and numerically investigated the effects of preferential diffusion and stretch on the tip opening of the laminar premixed syngas (H 2 −CO) flame. The results showed that the strong negative stretch at the tip intensifies the preferential diffusion at the flame tip, which leads to tip opening at lean mixture conditions.…”

Section: Introductionmentioning

confidence: 99%

Tip Opening of Burner-Stabilized Flames

et al. 2018

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The tip-opening mechanism of burner-stabilized flames is investigated computationally using premixed propane + air mixtures. The temperature, net production rate, and reaction rates are investigated for rich mixtures. The flame tip structure was analyzed on the basis of reaction rates to understand the conditions of the equivalence ratio at which the tip-opening phenomenon occurs. Numerical predictions of tip opening are in good agreement with experimental observations. The study revealed that the tip-opening phenomenon starts at ϕ = 1.4. As the mixture becomes rich, the tip opening was found to increase. When the flame tip opens, the volumetric heat release rate at the tip was found to be less than 50% of the heat release rate at the flame shoulder. An increase in the flame tip thickness was observed around 30% from equivalence ratios of 1.3–1.4. The effect of the temperature on the propane burner flame structure is studied by performing simulations at three different mixture inlet temperatures of 300, 350, and 400 K. When the temperature of the unburnt gas mixture increases, the propane–air tube burner flame tip opening begins at more fuel-rich conditions compared to that of the mixture at ambient temperature. A detailed sensitivity analysis was carried out to identify the reactions having large sensitivities.

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Effects of stretch and preferential diffusion on tip opening of laminar premixed Bunsen flames of syngas/air mixtures

Cited by 32 publications

References 30 publications

Experimental Investigation of Laminar Flame Speed Measurement for Kerosene Fuels: Jet A-1, Surrogate Fuel, and Its Pure Components

Experimental Investigation of Laminar Flame Speed Measurement for Kerosene Fuels: Jet A-1, Surrogate Fuel, and Its Pure Components

Enhancement of biogas/air combustion by hydrogen addition at elevated temperatures

Tip Opening of Burner-Stabilized Flames

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