旋流燃烧特性的数值计算与分析

发布时间：2018-06-24 15:33

本文选题：旋流燃烧 + 油雾燃烧　；参考：《清华大学》2015年硕士论文

【摘要】：在能源动力系统中,旋流燃烧有着广泛的应用。旋流能稳定火焰,促进燃料和空气混合,达到提高燃烧效率、减少污染排放的目的。因此,研究旋流燃烧的燃烧特性无论对基础研究还是技术开发都具有重要意义。本文以车载加热器和燃气轮机燃烧室为研究对象,以数值计算为主,结合实验,研究了旋流燃烧时旋流特征参数和旋流喷嘴结构对流场结构、液滴蒸发和燃烧特性的影响。以车载燃烧器为研究对象,首先利用实验研究了雾化压力对于雾化稳定性、液滴尺寸、雾化角、燃料流量的影响,在实验基础上选择合适的雾化压力进行了冷态和热态的实验研究,观察液滴的运动掺混和火焰的形态特征。接着在实验工况下,对油雾旋流燃烧的过程进行了数值计算,并与实验结果对照讨论。结果表明:旋流流场的结构主要可以分为中心回流区和两层螺旋涡结构,随着旋流数的增加,内层涡旋的强度增加,外层涡旋的强度降低。旋流数的增加还能促进液滴的扩散、蒸发以及液滴和空气掺混,使得燃烧室上游燃料浓度增加,燃烧效率提高。随着雷诺数的增加,中心回流区增加,火焰长度变短。以燃气轮机燃烧室为研究对象,首先归纳整理了IGCC燃烧室的试运数据和实际参数,在此基础上对IGCC燃烧室进行了建模,并针对合成气的旋流燃烧做了数值计算,研究当量比、叶片旋向、开孔数目等条件和旋流喷嘴参数对燃烧特性、污染排放的影响。结果表明:随着燃料当量比的增加,燃烧室出口温度增加,中心回流区向下游移动;当旋流叶片异向布置时,中心回流区减小,但气流的剪切力增强;孔的布置使得合成气和燃料提前混合,火焰长度变短,但可能会导致喷嘴烧蚀;二次风的稀释能有效降低燃烧室出口温度,降低NOx的排放。本文工作为进一步研究旋流对于燃油、燃气燃烧的影响,优化旋流燃烧器结构,提高其燃烧效率和减少排放提供了支持。
[Abstract]:Swirl combustion is widely used in energy power system. Swirl can stabilize flame, promote fuel and air mixing, improve combustion efficiency and reduce pollution emission. Therefore, it is of great significance to study the combustion characteristics of swirl combustion for both basic research and technology development. In this paper, taking the on-board heater and gas turbine combustor as the object of study, the effects of swirl characteristic parameters on swirl combustion and the structure of swirl nozzle, droplet evaporation and combustion characteristics are studied in combination with numerical calculation. Firstly, the influence of atomization pressure on atomization stability, droplet size, atomization angle and fuel flow rate was studied by experiments. On the basis of the experiments, the cold and hot states of the droplets were studied by choosing the proper atomization pressure, and the motion and mixing of the droplets and the morphology of the flame were observed. Then, the process of swirl combustion of oil mist is numerically calculated under the experimental conditions, and the results are compared with the experimental results. The results show that the structure of the swirl flow field can be divided into the central reflux region and the two-layer spiral vortex structure. With the increase of the swirl number, the intensity of the inner vortex increases, and the intensity of the outer vortex decreases. The increase of swirl number can also promote the diffusion, evaporation and mixing of droplets and air, thus increasing the fuel concentration and combustion efficiency in the upstream of the combustor. With the increase of Reynolds number, the central reflux region increases and the flame length becomes shorter. Taking the gas turbine combustor as the research object, the trial operation data and actual parameters of the IGCC combustor are summarized and collated at first. On the basis of this, the IGCC combustion chamber is modeled, and the swirl combustion of syngas is numerically calculated, and the equivalent ratio is studied. Effects of blade rotation, number of holes and swirl nozzle parameters on combustion characteristics and pollution discharge. The results show that with the increase of the fuel equivalent ratio, the outlet temperature of the combustion chamber increases, the central reflux zone moves downstream, and when the swirl blade is arranged in the opposite direction, the central return zone decreases, but the shear force of the gas flow increases. Because of the early mixing of syngas and fuel, the flame length becomes shorter, but it may lead to nozzle ablation. The dilution of secondary air can effectively reduce the outlet temperature of combustion chamber and the emission of no _ x. This work provides support for further research on the effect of swirl on fuel and gas combustion, optimization of swirl burner structure, improvement of combustion efficiency and reduction of emissions.
【学位授予单位】：清华大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TK16

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