Measurement of smoke point in laminar jet diffusion flames at atmospheric and elevated pressures

by 1980- Berry, Tiffany Leigh

Berry, Tiffany Leigh. Measurement of Smoke Point in Laminar Jet Diffusion Flames at Atmospheric and Elevated Pressures. Under the Direction of Dr. William L. Roberts. Using a Burke-Schumman modeled co-flow burner, a quartz chimney, and a pressure vessel with good optical access, the smoke points in pure and diluted fuels were measured in a laminar jet diffusion flame. Ethylene and methane, burning in a velocity matched, over-ventilated co-flow of air, were tested over the ranges of 1 to 8 atmospheres and 2 to 16 atmospheres, respectively. Various diluents (nitrogen, argon, helium, and carbon dioxide) were added individually to the pure fuels to observe the effects they have on the smoke points and the adiabatic flame temperatures at atmospheric and elevated pressures. These diluents were chosen to allow a wide range of flame temperatures and fuel Lewis numbers to be investigated. For a given fuel flow rate, the dilution level was increased until the flame ceased emitting visible soot (defined as the smoke point). The height of the flame was then measured and the adiabatic flame temperature was calculated based on equilibrium chemistry. While some previous research has focused on the effects of flame temperature (through dilution) on smoke points, the measurements reported here were made to investigate the effects of pressure, different diluents, and varying dilution rates on sooting tendency. The main findings of these experiments were: increasing the amount of diluent to a pure fuel increases the smoke point, the smoke point is a function of the air to fuel velocity ratio, smoke point is strongly dependent on the inverse of pressure, and residence time decreases with increases in pressure. Measurement of Smoke Point in Laminar Jet Diffusion Flames at Atmospheric and Elevated Pressures by Tiffany Leigh Berry A thesis submitted in partial fulfillment of the requirements for the degree of Master of Science Aerospace Engineering North Carolina State University 2005 Approved by: _____________________________ Dr. William L. Roberts Chair of Supervisory Committee _____________________________ Dr. Toafang Zeng Co-Chair of Supervisory Committee _____________________________ Dr. Robert T. Nagel Member of Supervisory Committee ii Biography The author was born Tiffany Leigh Berry on December 31, 1980 in Raleigh, NC, daughter of Billy and Dorothy Berry and younger sister of Adrienne Lynn Berry Bauer. She graduated from Cary High School in 1999, and chose to attend North Carolina State University to pursue a degree in Aerospace Engineering. Upon completion of her undergraduate degree in May 2003, Tiffany decided to continue her education at North Carolina State University in pursuit of a Master of Science degree in Aerospace Engineering. At the conclusion of the first year of her graduate program she received the General Electric Faculty of the Future Program Fellowship for the following academic year, and had the opportunity to aid Dr. Tarek Echekki in preparing and giving lectures for graduate level courses. These experiences further emphasized her desires to seek her doctorate degree in Mechanical Engineering in order to pursue a career in academia. Tiffany has been accepted and will attend North Carolina State University for this degree, continuing her work with Dr. William Roberts. iii