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Omer L Gulder - One of the best experts on this subject based on the ideXlab platform.
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influence of m xylene addition to jet a 1 on spray structure flow field and soot production in turbulent swirl stabilized spray Flames in a model combustor
Combustion and Flame, 2020Co-Authors: Taylor M Rault, Rahul B Vishwanath, Omer L GulderAbstract:Abstract Spray combustion of Jet A-1 and a Jet A-1/10% m-xylene blend was investigated to assess the influence of m-xylene addition on the spray characteristics and soot formation in a swirl-stabilized model combustor with dimensions of 94 mm × 94 mm cross-section and 188 mm length. Keeping the thermal power output constant at 10 kW, globally fuel lean Flames were established for the neat Jet A-1 and 10% m-xylene blend fuels. The velocity field of the model combustor, spray characteristics, and soot volume fraction and primary particle size were measured, respectively, using stereoscopic particle image velocimetry, a Fraunhofer diffraction based droplet sizer, and auto-compensating laser-induced incandescence. Addition of m-xylene to Jet A-1 caused measurable differences in the flow field and the spray characteristics under identical air and fuel flow rates. Soot concentrations were modified throughout the Flame by the addition of m-xylene, resulting in significant alterations in the cumulative soot loading within the spray Flame Envelope. In both Flames, peak soot volume fractions were detected in the lower central portion of the combustor at the base of the inner recirculation zone and in the upper portion of the combustor in the fuel shear layer. Our results demonstrate the nontrivial influence of altered distillation characteristics (and other physical properties) of the fuel, induced by m-xylene addition, on flow field structure and spray properties. Potential mechanisms for the influence of changing flow field and spray characteristics, in addition to m-xylene doping of the Jet A-1, on soot processes are discussed.
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PRESSURE DEPENDENCE OF SOOT FORMATION IN DIFFUSION FlameS
2020Co-Authors: Hyun I Joo, Omer L GulderAbstract:ABSTRACT The effects of pressure on soot formation and the structure of the temperature field were studied in co-flow methane-air laminar diffusion Flames over a wide pressure range, from atmospheric to 6 MPa (60 atm) in a high-pressure combustion chamber. The selected fuel mass flow rates provided diffusion Flames in which the soot was completely oxidized within the visible Flame Envelope and the Flame was stable at all pressures considered. The spatially resolved soot volume fraction and soot temperature were measured by spectral soot emission as a function of pressure. The visible (luminous
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effects of carbon dioxide and nitrogen addition on soot processes in laminar diffusion Flames of ethylene air at high pressures
Fuel, 2017Co-Authors: Ahmet E Karatas, Omer L GulderAbstract:Abstract An experimental assessment of the influence of carbon dioxide and nitrogen dilution on sooting characteristics of laminar ethylene diffusion Flames at pressures up to 20 atm is presented. Two dilution rates, defined as the ratio of mass flow of the fuel to that of the diluent gas, of 1:2 and 1:3 were used at all pressures with a fixed ethylene mass flow rate. A wider range of nitrogen dilution, from 1:1 to 1:4, was investigated at 10 atm. In the pressure range of interest and with the mass flow rates of fuel and diluents, resulting Flames were stable and nonsmoking. Spectrally-resolved line-of-sight soot radiation measurements were obtained to infer the radial soot and temperature distributions within the Flame Envelope through an Abel inversion process. The sooting propensity, in terms of maximum soot yield, was found to be significantly lower with carbon-dioxide dilution in the pressure range of 1–15 atm but approached to comparable values to those with nitrogen-dilution at 20 atm. The implication of this finding is that the chemical suppression effect of carbon dioxide dilution, which was proven at atmospheric pressure previously, exists also at elevated pressures up to 15 atm and becomes relatively small at higher pressures. Variation of the maximum soot yields with pressure indicated that carbon dioxide-diluted Flames show a relatively stronger dependence to pressure as compared to nitrogen-diluted Flames. Temperatures decreased with increasing pressure as expected due to increasing radiative heat loss, and the peak temperatures were observed near the Flame tips as a result of the heat release from soot oxidation.
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numerical and experimental study of soot formation in laminar diffusion Flames burning simulated biogas fuels at elevated pressures
Combustion and Flame, 2014Co-Authors: Marc R J Charest, Omer L Gulder, C P T GrothAbstract:Abstract The effects of pressure and composition on the sooting characteristics and Flame structure of laminar diffusion Flames were investigated. Flames with pure methane and two different methane-based, biogas-like fuels were examined using both experimental and numerical techniques over pressures ranging from 1 to 20 atm. The two simulated biogases were mixtures of methane and carbon dioxide with either 20% or 40% carbon dioxide by volume. In all cases, the methane flow rate was held constant at 0.55 mg/s to enable a fair comparison of sooting characteristics. Measurements for the soot volume fraction and temperature within the Flame Envelope were obtained using the spectral soot emission technique. Computations were performed by solving the unmodified and fully-coupled equations governing reactive, compressible flows, which included complex chemistry, detailed radiation heat transfer and soot formation/oxidation. Overall, the numerical simulations correctly predicted many of the observed trends with pressure and fuel composition. For all of the fuels, increasing pressure caused the Flames to narrow and soot concentrations to increase while Flame height remained unaltered. All fuels exhibited a similar power-law dependence of the maximum carbon conversion on pressure that weakened as pressure was increased. Adding carbon dioxide to the methane fuel stream did not significantly effect the shape of the Flame at any pressure; although, dilution decreased the diameter slightly at 1 atm. Dilution suppressed soot formation at all pressures considered, and this suppression effect varied linearly with CO 2 concentration. The suppression effect was also larger at lower pressures. This observed linear relationship between soot suppression and the amount of CO 2 dilution was largely attributed to the effects of dilution on chemical reaction rates, since the predicted maximum magnitudes of soot production and oxidation also varied linearly with dilution.
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sooting behaviour of n heptane laminar diffusion Flames at high pressures
Combustion and Flame, 2013Co-Authors: Ahmet E Karatas, Gorngrit Intasopa, Omer L GulderAbstract:Abstract The effect of pressure on sooting behaviour of n-heptane is studied in co-flow n-heptane/air laminar diffusion Flames at pressures above atmospheric in a high pressure combustion chamber. The fuel is diluted with either nitrogen or helium to keep a non-smoking Flame at elevated pressures, and the selected fuel mass flow rate of n-heptane provided diffusion Flames in which the soot was completely oxidized within the visible Flame Envelope. The Flame stability proved to be a challenge and stable Flames were possible only at certain pressures for a sufficiently long duration to permit measurements. The soot volume fractions and temperatures were measured by spectral soot emission as a function of pressure for nitrogen-diluted n-heptane Flames at 2, 5 and 7 atm. For helium-diluted n-heptane Flames, line of sight soot emission data at 3, 4, and 5 atm are presented at two heights above the burner exit. Comparison of limited nitrogen-diluted n-heptane data to previous measurements of soot yields indicate that soot formation in diffusion Flames of n-heptane seems to be slightly more sensitive to pressure than that in aliphatic gaseous fuel diffusion Flames within the pressure range considered in this work.
Hyun I Joo - One of the best experts on this subject based on the ideXlab platform.
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PRESSURE DEPENDENCE OF SOOT FORMATION IN DIFFUSION FlameS
2020Co-Authors: Hyun I Joo, Omer L GulderAbstract:ABSTRACT The effects of pressure on soot formation and the structure of the temperature field were studied in co-flow methane-air laminar diffusion Flames over a wide pressure range, from atmospheric to 6 MPa (60 atm) in a high-pressure combustion chamber. The selected fuel mass flow rates provided diffusion Flames in which the soot was completely oxidized within the visible Flame Envelope and the Flame was stable at all pressures considered. The spatially resolved soot volume fraction and soot temperature were measured by spectral soot emission as a function of pressure. The visible (luminous
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unified behaviour of maximum soot yields of methane ethane and propane laminar diffusion Flames at high pressures
Combustion and Flame, 2011Co-Authors: Omer L Gulder, Gorngrit Intasopa, Hyun I Joo, Paul M Mandatori, Decio S Bento, Marie E VaillancourtAbstract:Abstract Soot concentration and temperature distributions within the Flame Envelope of laminar diffusion Flames of methane and ethane at elevated pressures were measured in a high-pressure combustion chamber. Methane measurements were made with two different fuel flow rates: 0.43 mg/s (0.32 mg/s carbon flow rate) for the pressure range of 15–60 atm, and 0.83 mg/s for the pressure range of 5–20 atm (0.62 mg/s carbon flow rate). For the ethane Flames, the flow rate was 0.78 mg/s (0.62 mg/s carbon flow rate) and the pressure range was 2–15 atm. From the soot concentration distribution, soot yields were calculated as a function of Flame height and pressure. Maximum soot yields from the current study and the previous measurements in similar Flames with methane, ethane, and propane Flames were shown to display a unified behaviour. Maximum soot yields, when scaled properly, were represented by an empirical exponential function in terms of the reduced pressure, actual pressure divided by the critical pressure of the fuel. The maximum soot yield seems to reach a plateau asymptotically as the pressure exceeds the critical pressure of the fuel.
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soot formation and temperature field structure in co flow laminar methane air diffusion Flames at pressures from 10 to 60 atm
Proceedings of the Combustion Institute, 2009Co-Authors: Hyun I Joo, Omer L GulderAbstract:Abstract The effects of pressure on soot formation and the structure of the temperature field were studied in co-flow methane–air laminar diffusion Flames over a wide pressure range, from 10 to 60 atm in a high-pressure combustion chamber. The selected fuel mass flow rate provided diffusion Flames in which the soot was completely oxidized within the visible Flame Envelope and the Flame was stable at all pressures considered. The spatially resolved soot volume fraction and soot temperature were measured by spectral soot emission as a function of pressure. The visible (luminous) Flame height remained almost unchanged from 10 to 100 atm. Peak soot concentrations showed a strong dependence on pressure at relatively lower pressures; but this dependence got weaker as the pressure is increased. The maximum conversion of the fuel’s carbon to soot, 12.6%, was observed at 60 atm at approximately the mid-height of the Flame. Radial temperature gradients within the Flame increased with pressure and decreased with Flame height above the burner rim. Higher radial temperature gradients near the burner exit at higher pressures mean that the thermal diffusion from the hot regions of the Flame towards the Flame centerline is enhanced. This leads to higher fuel pyrolysis rates causing accelerated soot nucleation and growth as the pressure increases.
Ahmet E Karatas - One of the best experts on this subject based on the ideXlab platform.
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effects of carbon dioxide and nitrogen addition on soot processes in laminar diffusion Flames of ethylene air at high pressures
Fuel, 2017Co-Authors: Ahmet E Karatas, Omer L GulderAbstract:Abstract An experimental assessment of the influence of carbon dioxide and nitrogen dilution on sooting characteristics of laminar ethylene diffusion Flames at pressures up to 20 atm is presented. Two dilution rates, defined as the ratio of mass flow of the fuel to that of the diluent gas, of 1:2 and 1:3 were used at all pressures with a fixed ethylene mass flow rate. A wider range of nitrogen dilution, from 1:1 to 1:4, was investigated at 10 atm. In the pressure range of interest and with the mass flow rates of fuel and diluents, resulting Flames were stable and nonsmoking. Spectrally-resolved line-of-sight soot radiation measurements were obtained to infer the radial soot and temperature distributions within the Flame Envelope through an Abel inversion process. The sooting propensity, in terms of maximum soot yield, was found to be significantly lower with carbon-dioxide dilution in the pressure range of 1–15 atm but approached to comparable values to those with nitrogen-dilution at 20 atm. The implication of this finding is that the chemical suppression effect of carbon dioxide dilution, which was proven at atmospheric pressure previously, exists also at elevated pressures up to 15 atm and becomes relatively small at higher pressures. Variation of the maximum soot yields with pressure indicated that carbon dioxide-diluted Flames show a relatively stronger dependence to pressure as compared to nitrogen-diluted Flames. Temperatures decreased with increasing pressure as expected due to increasing radiative heat loss, and the peak temperatures were observed near the Flame tips as a result of the heat release from soot oxidation.
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sooting behaviour of n heptane laminar diffusion Flames at high pressures
Combustion and Flame, 2013Co-Authors: Ahmet E Karatas, Gorngrit Intasopa, Omer L GulderAbstract:Abstract The effect of pressure on sooting behaviour of n-heptane is studied in co-flow n-heptane/air laminar diffusion Flames at pressures above atmospheric in a high pressure combustion chamber. The fuel is diluted with either nitrogen or helium to keep a non-smoking Flame at elevated pressures, and the selected fuel mass flow rate of n-heptane provided diffusion Flames in which the soot was completely oxidized within the visible Flame Envelope. The Flame stability proved to be a challenge and stable Flames were possible only at certain pressures for a sufficiently long duration to permit measurements. The soot volume fractions and temperatures were measured by spectral soot emission as a function of pressure for nitrogen-diluted n-heptane Flames at 2, 5 and 7 atm. For helium-diluted n-heptane Flames, line of sight soot emission data at 3, 4, and 5 atm are presented at two heights above the burner exit. Comparison of limited nitrogen-diluted n-heptane data to previous measurements of soot yields indicate that soot formation in diffusion Flames of n-heptane seems to be slightly more sensitive to pressure than that in aliphatic gaseous fuel diffusion Flames within the pressure range considered in this work.
C P T Groth - One of the best experts on this subject based on the ideXlab platform.
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numerical and experimental study of soot formation in laminar diffusion Flames burning simulated biogas fuels at elevated pressures
Combustion and Flame, 2014Co-Authors: Marc R J Charest, Omer L Gulder, C P T GrothAbstract:Abstract The effects of pressure and composition on the sooting characteristics and Flame structure of laminar diffusion Flames were investigated. Flames with pure methane and two different methane-based, biogas-like fuels were examined using both experimental and numerical techniques over pressures ranging from 1 to 20 atm. The two simulated biogases were mixtures of methane and carbon dioxide with either 20% or 40% carbon dioxide by volume. In all cases, the methane flow rate was held constant at 0.55 mg/s to enable a fair comparison of sooting characteristics. Measurements for the soot volume fraction and temperature within the Flame Envelope were obtained using the spectral soot emission technique. Computations were performed by solving the unmodified and fully-coupled equations governing reactive, compressible flows, which included complex chemistry, detailed radiation heat transfer and soot formation/oxidation. Overall, the numerical simulations correctly predicted many of the observed trends with pressure and fuel composition. For all of the fuels, increasing pressure caused the Flames to narrow and soot concentrations to increase while Flame height remained unaltered. All fuels exhibited a similar power-law dependence of the maximum carbon conversion on pressure that weakened as pressure was increased. Adding carbon dioxide to the methane fuel stream did not significantly effect the shape of the Flame at any pressure; although, dilution decreased the diameter slightly at 1 atm. Dilution suppressed soot formation at all pressures considered, and this suppression effect varied linearly with CO 2 concentration. The suppression effect was also larger at lower pressures. This observed linear relationship between soot suppression and the amount of CO 2 dilution was largely attributed to the effects of dilution on chemical reaction rates, since the predicted maximum magnitudes of soot production and oxidation also varied linearly with dilution.
Paul M Mandatori - One of the best experts on this subject based on the ideXlab platform.
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unified behaviour of maximum soot yields of methane ethane and propane laminar diffusion Flames at high pressures
Combustion and Flame, 2011Co-Authors: Omer L Gulder, Gorngrit Intasopa, Hyun I Joo, Paul M Mandatori, Decio S Bento, Marie E VaillancourtAbstract:Abstract Soot concentration and temperature distributions within the Flame Envelope of laminar diffusion Flames of methane and ethane at elevated pressures were measured in a high-pressure combustion chamber. Methane measurements were made with two different fuel flow rates: 0.43 mg/s (0.32 mg/s carbon flow rate) for the pressure range of 15–60 atm, and 0.83 mg/s for the pressure range of 5–20 atm (0.62 mg/s carbon flow rate). For the ethane Flames, the flow rate was 0.78 mg/s (0.62 mg/s carbon flow rate) and the pressure range was 2–15 atm. From the soot concentration distribution, soot yields were calculated as a function of Flame height and pressure. Maximum soot yields from the current study and the previous measurements in similar Flames with methane, ethane, and propane Flames were shown to display a unified behaviour. Maximum soot yields, when scaled properly, were represented by an empirical exponential function in terms of the reduced pressure, actual pressure divided by the critical pressure of the fuel. The maximum soot yield seems to reach a plateau asymptotically as the pressure exceeds the critical pressure of the fuel.
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soot formation in laminar ethane diffusion Flames at pressures from 0 2 to 3 3 mpa
Proceedings of the Combustion Institute, 2011Co-Authors: Paul M Mandatori, Omer L GulderAbstract:Abstract The effects of pressure on soot formation and the structure of the temperature field were studied in co-flow ethane-air laminar diffusion Flames over the pressure range of 0.1–3.34 MPa in a high pressure combustion chamber. The selected fuel mass flow rate provided diffusion Flames in which the soot was completely oxidized within the visible Flame Envelope and the Flame was stable at all pressures considered. The spatially resolved soot volume fraction and soot temperature were measured by spectral soot emission as a function of pressure. The visible (luminous) Flame height remained almost unchanged from 1.52 to 3.34 MPa, whereas it increased considerably from atmospheric to 1.52 MPa. Flame cross-sectional area, measured at the Flame height of 5 mm either bounded by maximum Flame temperature or maximum soot volume fraction contours, showed an inverse dependence on pressure. Peak carbon conversion to soot, defined as the percentage of fuel’s carbon content converted to soot, showed a strong dependence on pressure at lower pressures; but this dependence grew weaker as the pressure was increased. This dependence can be expressed as a pressure scaling in the form of a power law. However, the exponent of pressure was not constant: it was about 2.2 for pressures between 0.2 and 0.51 MPa, about 1.1 for pressures between 0.51 and 1.52 MPa, and about 0.4 for pressures between 1.52 and 3.34 MPa. Averaged Flame temperatures decreased with increasing pressure as a result of enhanced heat loss from the Flame by soot radiation. The maximum temperature gradients increased with pressure at lower Flame heights; at higher locations in the Flame, after an initial increase at the lower pressure range, gradients reached a plateau at about 1.5–2.0 MPa.