【作者】 李强；

【导师】 付忠广；

【作者基本信息】 华北电力大学(北京) ， 热能工程， 2017， 硕士

【摘要】 近些年来,燃气—蒸汽联合循环技术以及燃气轮机技术的快速发展对燃气轮机技术的要求越来越高,而燃烧室是燃气轮机中一个不可缺少的核心部件,因此对它的研究也越来越紧迫。燃烧室内部的工作过程相对于其他的部件要复杂得多,它会涉及到气体的传热、传质、流动以及化学反应等一系列复杂的过程。长期以来主要是通过试验得出的大量数据来归纳总结燃烧室设计方法的经验公式,研发的成本很高。随着计算燃烧学以及计算流体力学的快速发展以及商业模拟软件的广泛应用,利用计算机来数值模拟研究燃烧室的设计方法成为一种趋势。本文就是基于一个燃气轮机高压燃烧室,先利用Gambit软件构建了燃烧室的模型并将其网格化,之后再利用计算流体力学软件Fluent进行模拟计算。燃烧室设计的燃烧组织方式为天然气/空气旋流预混燃烧。由于天然气掺混CO₂燃烧能够很好降低燃烧的温度,甚至影响其他的燃烧特性,因此本文选取了二氧化碳掺混率为0、0.2、0.4以及0.6四种天然气和CO₂的混合物燃料,然后分别在常压、1MPa、2MPa以及4 MPa四种压力下进行模拟计算,研究分析得到了燃烧温度场的变化特性、污染物NO_x排放规律以及天然气的燃烧情况,总结如下:温度场变化特性:在压力相同时,天然气掺混CO₂燃烧的1500K高温区段的长度L1500K是随着二氧化碳掺混率YCO₂的增加而逐渐减小的,当CO₂的掺混率相同时,1500K的高温区段长度L1500K以及最大宽度W1500K,MAX随着压力的增大而增大;且在各个压力下,燃烧室出口的温度分布系数是随着二氧化碳掺混率的增大先减小而后增大的,特别是掺混率达到0.4之后,出口温度分布系数急剧增加。污染物NO_x排放规律:在同一掺混率时,天然气掺混二氧化碳燃烧产生的氮氧化物的量是随着压力的增大而增大的,同一压力下,燃烧产生氮氧化物的量是随着掺混率的增大先减小后增大的,且当压力越大时,产生氮氧化物量的变化幅度也越大。天然气的燃烧情况:当压力为常压时,甲烷燃尽处的高度（甲烷摩尔浓度为0.001kmol/m3处对应燃烧室的高度）是随着CO₂掺混率的增大先增大而减小的,而压力在1MPa、2 MPa、4 MPa时,甲烷燃尽处的高度都是随着CO₂掺混率的升高而降低的,几乎呈现线性关系;在CO₂掺混率相同时,压力越高,相同质量流量的甲烷燃尽处的高度也越高。更多还原

【Abstract】 In recent years,with the rapid development of Gas-Steam Combined Cycle Technology and Gas Turbine Technology,the requirements of gas turbine technology is getting higher and higher.The combustion chamber is an indispensable core component of the gas turbine,so its research is more and more urgent.The working process inside the combustion chamber is much more complex than that of the other components,it will involve the gas heat transfer,mass transfer,flow and chemical reactions and a series of complex process.For a long time,the empirical formula of the combustion chamber design method has been summed up and deduced from the large amount of experimental data.The cost of research and development is very high.However,with the rapid development of computational combustion and computational fluid dynamics and the wide use of commercial simulation software,it is a trend to use computer numerical simulation to research combustion chamber design method.The research in this paper based on a bench of high-pressure gas turbine combustion chamber.The model of the combustion chamber was built and meshed by Gambit software,and then use the CFD software Fluent to simulate the numerical simulation.The combustor is designed for the natural gas / air cyclone premixed combustion.Due to natural gas blending CO₂ combustion can be a good way to reduce the combustion temperature,and even affect the other combustion characteristics,four kinds of blended fuel of natural gas and CO₂ with blending ratio of 0,0.2,0.4 and 0.6 are simulated under normal pressure,1MPa,2MPa and 4MPa respectively in this paper.The combustion temperature field variation characteristics,the pollutant NO_x emission rule and the natural gas combustion condition were obtained,which are summarized as follows:The combustion temperature field variation characteristics: When the pressure is the same,the length of 1500 K high-temperature section of natural gas mixed with CO₂ combustion decreases gradually with the increase of blending rate.When the CO₂ blending rate is the same,the length and maximum width of 1500 K high temperature section increase with the pressure increasing.The outlet temperature distribution coefficient of the combustion chamber decreases and then increases with the increase of the mixing ratio,especially after the blending ratio reaches 0.4,the outlet temperature distribution coefficient increases sharply.The pollutant NO_x emission rule: At the same mixing ratio,the amount of nitrogen oxides produced by combustion of natural gas blended with carbon dioxide increases with the increase of pressure.At the same pressure,the amount of nitrogen oxides produced by combustion increases first and then decreases with the increase of mixing ratio,and the greater the pressure,the greater change in the amount of nitrogen oxides produced.The natural gas combustion condition: When the pressure is atmospheric,the height of methane burn-out is first increased and then decreased with the increase of CO₂ blending ratio,while the pressure is at 1 MPa,2 MPa and 4 MPa,the height of methane burn-out decreases with the increase of CO₂ blending rate,which shows a linear relationship.When the CO₂ mixing rate is the same,the higher the pressure,the higher the height of methane burnout at the same mass flow rate.更多还原