Tentative session assignment is listed below:
ID#: 39
Abstract Title: Triple Flames Around Two Droplets in Flows with Fuel Vapor
Session Title: Poster Session I
Session Date: 7/31/01
Session Start Time: 2:50 PM
Contributing Author: Chen, W.
Organization: Foo Yin Institute of Technology
Country: Taiwan R.O.C
Authors: Wei-Hsin Chen
Short Abstract: Flame structures around two equal-sized and interactive fuel droplets in high-temperature flows are examined by means of a numerical method in which a body-fitted technique in association with non-orthogonal curvilinear coordinate is employed. For the two-droplet system, the leading droplet versus the trailing one intrinsically acts as a fuel vapor source. Therefore, when the fuel is vaporized from the leading droplet and then brought to where near the trailing one, a situation of non-uniform mixture is exhibited. Under such a situation, when the gas-phase combustion is excited, while the flame is stabilized between the two droplets as a consequence of another role played by the bluff body of the leading droplet, an anchor-shape flame structure, i.e. the triple flame, is observed. In this flame, three different combustion modes including fuel-lean, fuel-rich, and stoichiometric burnings are simultaneously observed. When far-field temperature or ambient equivalence ratio is increased, because flame speed is enhanced, the flame propagates upstream and the fuel-lean premixed flame withers. However, if the ambient equivalence ratio is as high as 0.2, it is obvious to find that two wings of the triple flame, viz. the fuel-lean and the fuel-rich premixed flames, extend outward from the stoichiometric point. Once the flame encloses the leading droplet, the triple flame evolves into a double-flame consisting of a fuel-lean premixed flame and a diffusion flame. Accordingly, the obtained results elucidate that both upstream temperature and fuel vapor concentration play a vital role on the two dropletsí vaporization rate and flame structure.