【作者】 宋晓丹；

【导师】 孙宝芝；

【作者基本信息】 哈尔滨工程大学 ， 热能工程， 2009， 硕士

【摘要】 增压燃烧技术是船用大型蒸汽动力装置的关键技术之一,本文研究对象是某增压燃烧试验平台的增压锅炉,其炉膛内的燃烧过程是锅炉设计运行中的重要环节。本文根据试验台锅炉设计图纸建立了三维实体几何模型,应用FLUENT软件,采用realizablek-ε湍流模型、“简单化学反应系统”模型、简化的PDF模型和DO辐射模型对多个稳态工况下的炉内燃烧流场进行了数值模拟。通过数值模拟,得出了流场主要参数的分布情况,指出增压锅炉炉内空气动力特性,燃油喷雾流场的分布特性,并提出了利用当量混合分数的分布来考核火焰长度的方法。当燃烧器对冲布置时,炉内的混合气体分布更均匀,火焰充满度好,有利于强化燃烧。数值模拟结果说明：随着稳焰器到调风器出口距离的增大,回流区尺寸逐渐减小,而调风负荷对其影响并不大。在喷油压力较低时,雾化液滴的索特平均直径随喷油压力的增大而变大,当达到一定压力时,索特平均直径随着压力的增大而逐渐变小；同时提高炉膛工作压力对降低液滴粒径有明显的促进作用。当过量空气系数为1.15时,高温区最大,火焰最长；过量空气系数为1.3时,由于氧气量大,火焰最短,高温区最小。炉膛内部的增压燃烧流场、冷态流场及喷雾流场的数值模拟结果对试验方案选取和试验结果预测具有一定指导意义。更多还原

【Abstract】 Pressurized combustion technology is one of the key technology for steam power plant. The subject is the supercharged boiler on a pressurized combustion test platform. The furnace combustion process is the important aspect in the design and operation of boiler.A three-dimensional geometric model entitiy was set up based on test-bed boiler design drawings. Combustion flow fields of test boiler were simulated for several steady states with FLUENT software, the realizablek-εturbulence model, a single chemistry reaction system, simplified PDF model and DO thermal radiation model.By numerical simulation, the distribution of main parameters for flow field were gained, the pressurized air power characteristics of boiler and fuel spray distribution characteristics were pointed out, and the method of using equivalent mixture fraction to assesslame length was proposed. The burner opposing arrangements was helpful for enhancing combustion, because gas mixture distributed more evenly in the furnace and the fullness of flame was good.The result of numerical simulation showed that, recirculation zone size decreased gradually with increase of the distance from the steady flame device to register, while the register load did not affect it so much. At a lower injection pressure, the SMD of atomized droplets increased with increase of the injection pressure. When a certain pressure was reached, the SMD decreased with increase of the injection pressure. At the same time, improving the working pressure in the chamber could promote reducing droplet size. When the excess air coefficient was 1.15, the high temperature zone was the largest and flame was the longest. When excess air coefficient was 1.3, due to the large quantity of oxygen, the flame was the shortest and high temperature district was the smallest. The results of numerical simulation for supercharged combustion, cold flow field and the spray flow field in the furnace had guiding significance on the selection of test schemes and prediction of test results.更多还原