中文摘要：

以小尺度陶瓷管为燃烧器喷管,与陶瓷管同轴的石英玻璃管构造受限空间,采用实验研究与数值模拟相结合的方法分析液体乙醇微小射流火焰特性。实验选择燃料流量为0-2.1 m L/h,采用的陶瓷管包括内径为1.0 mm和0.6 mm两种。结合火焰燃烧过程所涉及的特征参数,包括液滴高温蒸发率、无量纲热损失、熄火直径等,分析了不同燃料流量、燃烧器喷管内径等对微火焰稳定性、温度、形态等的影响。液体乙醇流量从零开始增加,整个变化过程会经历5个阶段,同时微火焰温度升高。而燃烧器喷管内径减小时,火焰逐渐变小。研究结果表明在稳定燃烧阶段,随着乙醇燃料流量的增加,燃料整体高温蒸发量增大,微火焰温度升高、火焰高度增大;随着燃烧器喷管内径减小,无量纲热损失增大,微火焰温度降低、火焰高度减小。适当调整燃料流量和燃烧器喷管内径有利于增强火焰稳定性。

英文摘要：

A small scale ceramic tube was used as a combustor nozzle, and a coaxial jet ethanol flame was established in the confined space between the ceramic tube and the quartz glass tube. The fuel flow rates were 0 - 2.1 mL/h, and the ceramic tubes with inner diameters of 1.0 mm and 0.6 mm. The small jet flame characteristics were analyzed, while some relevant characteristic parameters were discussed. Some important parameters were selected, including high temperature droplet evaporation rate, normalized heat loss, and quenching diameter. Based on these, the effects of the fuel flow rate and the nozzle inner diameter on flame characteristics, including stabilities, flame temperature and flame shape, in the confined space were investigated experimentally and numerically. When the liquid ethanol flow increased from zero, the change process went through five stages and the flame temperature increased. When the burner nozzle diameter was reduced, the flame became smaller. The results showed that fuel flow and nozzle diameter played an important role in fuel evaporation and combustion process. In the stable combustion stage, overall fuel evaporation, flame temperature and height all increase with the increasing of the fuel flow rate, resulting in flame ignition difficulty in low flow rate and flame oscillation in high flow rate. Normalized heat loss increases, flame temperature and height both decrease due to the diminishment of the nozzle diameter and it would affect the flame stability. Properly adjusting the fuel flow rate and the burner nozzle diameter is helpful to enhance the flame stability.