The Effects of Initial Diameter on Sooting and Burning Behavior of Isolated Droplets under Microgravity Conditions

• Published in: Combustion science and technology 1998-02, Vol.132 (1-6), p.139-156
• Main Authors: LEE, KYEONG-OOK, MANZELLO, SAMUEL L., CHOI, MUN YOUNG
• Format: Article
• Language: English
• Subjects: Applied sciences; Combustion of liquid fuels; Combustion. Flame; droplet combustion; Energy; Energy. Thermal use of fuels; Exact sciences and technology; Microgravity combustion; soot volume fraction; Theoretical studies. Data and constants. Metering
• ISSN: 0010-2202; 1563-521X
• DOI: 10.1080/00102209808952013

The influence of initial droplet diameter on the sooting and burning behavior of isolated droplets under microgravity conditions was investigated by measuring soot volume fraction, ƒ v , soot mass, m s, soot and burning rate. Theƒ v , and m s, soot were measured using a full-field light extinction and tomographic inversion technique. The experiments were conducted at the NASA-Lewis 2·2 second droptower in Cleveland, OH. The ƒ v , and m s, soot measurements represent the first quantitative assessment of the influence of initial diameter on the sooting behavior in microgravity conditions. Results indicate that ƒ v (which provides information regarding the local magnitude of sooting) and m s, soot (which is related to overall sooting magnitude) are sensitive to the initial droplet size. It is believed that the spatial extent of the flame which is proportional to the droplet size, influences the residence time for fuel vapor transport. Thus, larger droplets will provide longer residence time for fuel pyrolysis, soot precursor formation and carbonization. The increase in the sooting behavior and enhanced radiation heat losses for larger droplets indicate that the initial diameter can influence the droplet burning behavior.