@article{kailasanathan_yelverton_fang_roberts_2013, title={Effect of diluents on soot precursor formation and temperature in ethylene laminar diffusion flames}, volume={160}, ISSN={["1556-2921"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-84872855275&partnerID=MN8TOARS}, DOI={10.1016/j.combustflame.2012.11.004}, abstractNote={Soot precursor species concentrations and flame temperature were measured in a diluted laminar co-flow jet diffusion flame at pressures up to eight atmospheres while varying diluent type. The objective of this study was to gain a better understanding of soot production and oxidation mechanisms, which could potentially lead to a reduction in soot emissions from practical combustion devices. Gaseous samples were extracted from the centerline of an ethylene–air laminar diffusion flame, which was diluted individually with four diluents (argon, helium, nitrogen, and carbon dioxide) to manipulate flame temperature and transport properties. The diluted fuel and co-flow exit velocities (top-hat profiles) were matched at all pressures to minimize shear-layer effects, and the mass fluxes were fixed over the pressure range to maintain constant Reynolds number. The flame temperature was measured using a fine gauge R-type thermocouple at pressures up to four atmospheres. Centerline concentration profiles of major non-fuel hydrocarbons collected via extractive sampling with a quartz microprobe and quantification using GC/MS + FID are reported within. The measured hydrocarbon species concentrations are vary dramatically with pressure and diluent, with the helium and carbon dioxide diluted flames yielding the largest and smallest concentrations of soot precursors, respectively. In the case of C2H2 and C6H6, two key soot precursors, helium diluted flames had concentrations more than three times higher compared with the carbon dioxide diluted flame. The peak flame temperature vary with diluents tested, as expected, with carbon dioxide diluted flame being the coolest, with a peak temperature of 1760 K at 1 atm, and the helium diluted flame being the hottest, with a peak temperature of 2140 K. At four atmospheres, the helium diluted flame increased to 2240 K, but the CO2 flame temperature increased more, decreasing the difference to approximately 250 K.}, number={3}, journal={COMBUSTION AND FLAME}, author={Kailasanathan, Ranjith Kumar Abhinavam and Yelverton, Tiffany L. B. and Fang, Tiegang and Roberts, William L.}, year={2013}, month={Mar}, pages={656–670} }
 @article{yelverton_roberts_2008, title={Effect of dilution, pressure, and velocity on smoke point in laminar jet flames}, volume={180}, ISSN={["1563-521X"]}, DOI={10.1080/00102200801931570}, abstractNote={Smoke point measurements of diluted methane and ethylene flames were made in a co-flowing laminar jet diffusion flame at pressures up to 8 atm. The smoke point corresponds to the fuel flow rate where the soot production is exactly offset by the soot oxidation, and as such is sensitive to changes in rates of production or oxidation. Flame height in these flames was measured as a function of pressure, diluent, and dilution level as well as both fuel exit velocity profile (i.e., plug or parabolic) and fuel/air velocity ratio. As pressure increases, the smoke point became less sensitive to diluent or dilution level. In addition to heat capacity and thermal diffusivity differences between CO2 and He for example, the large differences in kinematic viscosity was shown to play an important role in the diluent's ability to suppress the fuel's propensity to form soot.}, number={7}, journal={COMBUSTION SCIENCE AND TECHNOLOGY}, author={Yelverton, T. L. Berry and Roberts, W. L.}, year={2008}, pages={1334–1346} }
 @article{yelverton_roberts_2008, title={Soot surface temperature measurements in pure and diluted flames at atmospheric and elevated pressures}, volume={33}, ISSN={["1879-2286"]}, DOI={10.1016/j.expthermflusci.2008.06.014}, abstractNote={Soot surface temperature was measured in laminar jet diffusion flames at atmospheric and elevated pressures. The soot surface temperature was measured in flames at one, two, four, and eight atmospheres with both pure and diluted (using helium, argon, nitrogen, or carbon dioxide individually) ethylene fuels with a calibrated two-color soot pyrometry technique. These two dimensional temperature profiles of the soot aid in the analysis and understanding of soot production, leading to possible methods for reducing soot emission. Each flame investigated was at its smoke point, i.e., at the fuel flow rate where the overall soot production and oxidation rates are equal. The smoke point was chosen because it was desirable to have similar soot loadings for each flame. A second set of measurements were also taken where the fuel flow rate was held constant to compare with earlier work. These measurements show that overall flame temperature decreases with increasing pressure, with increasing pressure the position of peak temperature shifts to the tip of the flame, and the temperatures measured were approximately 10% lower than those calculated assuming equilibrium and neglecting radiation.}, number={1}, journal={EXPERIMENTAL THERMAL AND FLUID SCIENCE}, author={Yelverton, T. L. Berry and Roberts, W. L.}, year={2008}, month={Oct}, pages={17–22} }