The study of droplet ignition in hot convective environment

• Main Authors: Chir-Shyong Lin, 林琦雄
• Other Authors: J. M. Char 、S. M. Liang
• Format: Others
• Language: zh-TW
• Published: 1993
• Online Access: http://ndltd.ncl.edu.tw/handle/41253607093844099092

碩士 === 國立成功大學 === 航空太空工程學系 === 81 === The fuel droplets spout from injector nozzle contains several different sizes of diamete, and the life time of these droplets is an important factor in combustion chamber and sprayer design . Therefore , it is an important study to understand the vaporization / combustion situation of a single fuel droplet in a high temperature and oxidizing environment with external flow. Especially , the study of droplet ignition plays an important role to understand the droplet combustion phenomena. In a real fuel spray combustor , the combustion of fuel droplets occure in a convective , high temperature , oxidizing environment and the relative motion of neighboring air turns the problems into two dimensional or more . Due to the complex chemical reaction and fluid interaction with combustion , the droplet combustion becomes an extremely difficult phenomenon to solve . This research of simple ignition model is to understand the effects of the fuel droplets and of the external environment on the ignition delay . Threeply - period concept is introduced to interpret the dominant factors that govern the ignition process . Numerical technique is applied to get an insight of transient behavior of a fuel droplet to ignition . A special hybird numerical scheme ICED-ALE is used to circumvent the difficulties arising from the rapid transition of ignition and regression offuel droplet . The results indicated the droplet in smaller dimension is easier to be be ignited in most cases . But in higher temperature enviroment , the dimension of fuel droplet affects the delay times less .At enviroment temperature of 1050 k , the ignition delay time difference between large and small fuel droplet is 7.7% . Basically , it saves 34.6% time for fuel droplet ignition in convective enviroment than one in stagnant which coincides the real physical situation .