Diffusion-flame extinction of liquid fuel at elevated pressures

✍ Scribed by Takashi Niioka; Susumu Hasegawa; Tatsuro Tsukamoto; Jun'ichi Sato

• Publisher: Elsevier Science
• Year: 1991
• Tongue: English
• Weight: 662 KB
• Volume: 86
• Category: Article
• ISSN: 0010-2180
• DOI: 10.1016/0010-2180(91)90064-i

✦ Synopsis

The objective of this study is to determine the effect of pressure on droplet size at extinction of the diffusion flame around the droplet. An analogy between the diffusion flame in a stagnation-point flow on a liquid fuel and that of a droplet is given, and an analytical equation is obtained for the relationship between both diffusion flame extinctions. This equation makes it possible to calculate droplet diameter (de) at extinction without any chemical parameters. In order to obtain extinction velocities, experiments are conducted for the diffusion flame in a stagnation-point flow at elevated pressures. The extinction velocity increases with pressure, but it becomes almost constant at pressures from about 0.3 to 1 MPa. From these data, it is found that the droplet diameter at extinction decreases sharply with pressure: d c = 150/zm at 0.1 MPa, 46/~m at 0.3 MPa, and 17/~m at 0.8 MPa for heptane in an air environment.

NOMENCLATURE

tion-point flow 1 -exp{-(M/r) a stretch rate or velocity gradient (C/Cg)(~kg/X)} in droplet combustion c specific heat at constant pressure ~l(2aPeCe] /YPg (2apc/X)Yl/2 d droplet diameter D diffusion coefficient ~g ~ ~ ] Jo P dy H distance between nozzle outlet and fuel sur-0