Influence of Drop Spacing on Burning of an Emulsified-Drop Stream

• Main Authors: Yu-YuLin, 林郁妤
• Other Authors: Ta-Hui Lin
• Format: Others
• Language: en_US
• Published: 2013
• Online Access: http://ndltd.ncl.edu.tw/handle/94059079787166721725

碩士 === 國立成功大學 === 機械工程學系碩博士班 === 101 === Combustion characteristics of water-in-dodecane emulsion drops with various initial spacings were studied experimentally by using a free-falling drop burning apparatus. The initial drop spacing (Si) of the drop string was 2.5, 5, 10, 40, 70, or 100. Si (s/di) was defined as the ratio of the drop center-to-center distance (s) to the initial drop diameter (di). The oxygen concentration (ΩO2) was fixed at 21%, while two drop sizes, 550 μm and 450 μm, and three water contents (β), 5 vol. %, 20 vol. %, and 30 vol. %, were compared. These results showed that the transition of the drop flame occurred for all cases in the experiment. For Si 〉 10 along the flow direction, the flame around the drops would change from a blue spherical flame to a yellow flame and a wake flame, and the drop flame extinguished later in the downstream region. Soot particles was generated and drop collision and merging occurred to form a flame tube for Si = 2.5 in all cases. Besides, drop expansion was also observed in all cases, while micro-explosion only occurred in the far downstream region for the case of Si = 40, di = 450 μm, β = 5 % and 20 %. It was also shown that the emulsion drop evaporation rate was not a constant, and the trend of the drop evaporation rate was strongly influenced by the initial drop size and the water content.