【作者】 武辉；

【导师】 肖云汉； 王岳；

【作者基本信息】 中国科学院研究生院（工程热物理研究所） ， 工程热物理， 2009， 博士

【摘要】 IGCC与CO₂零排放技术的发展提出了在燃气轮机燃烧室中采用纯氢或富氢合成气为燃料的要求。目前工业燃机中普遍采用以天然气为燃料的旋流稳焰燃烧器，由于氢气的燃烧特性与天然气相比有很大差异，在传统旋流燃烧器中燃用富氢燃料时会出现火焰不稳定、局部高温、NO_x排放高等问题。因此需要针对富氢燃料的特点，研发与之相适应的新型燃烧技术与燃烧室。驻涡燃烧技术源自航空发动机加力燃烧室，由于其特殊的结构与卓越的性能，被认为是最具潜力的新一代富氢燃料燃烧窜技术。但对于这一方向的研究目前才刚刚开始，其可行性还有待进一步验证。在此背景下，本文建立了用于实现富氢燃料预混燃烧的凹腔驻涡模型燃烧室实验台，并构建了相应的数值计算模型，对纯氢与富氢合成气在模型燃烧室中的燃烧特性进行了实验与数值研究。首先研究了模型燃烧器中凹腔长度与前后壁面高度比例、腔内燃料与空气的入射位置、以及主流入射角度等结构参数对腔内流场变化、驻涡形成、以及燃烧器压损等方面性能的影响。在此基础上，提出了模型燃烧器设计时应遵循的原则，并根据实验要求选取了合理的模型实验装置结构参数。随后研究了模型实验装置中的流场特性、火焰形态、以及凹腔区域火焰中OH基的瞬时分布。结果表明，模型实验装置在很宽的流动范围内，实现了驻涡燃烧技术，并且在合适的流量下，能够实现腔内双驻涡结构。在模型实验装置中，通过贫燃吹熄实验、动态压力监测、火焰中OH基的脉动图像分析及信号强度的概率密度统计等手段，对驻涡燃烧器的火焰稳定性进行了研究。结果表明：模型燃烧器燃氢时火焰稳定性要好于合成气；腔内反应物采用扩散或是预混燃烧方式，对燃烧稳定性的影响不大；燃烧室热负荷增加或总当量比降低时，燃烧稳定性变差；模型燃烧器稳定性较好时对应的特征操作参数为：燃料分配系数S_f=0．4。对两种燃料在模型燃烧器中燃烧时污染物生成与排放的研究表明：燃氢时，实验范围内NO_x排放在3～10ppmvd（15％O₂）之间；腔内预混燃烧方式下，NO_x排放比扩散方式下降低了3～5ppmvd；燃合成气时，实验范围内相同工况下NO_x排放比燃氢时低3ppmvd左右；燃烧室总当量比降低或热负荷增加时，NO_x排放降低；模型燃烧器污染物排放较低时对应的特征操作参数为：一次当量比φ_p=0．4。将燃烧器按不同反应区域进行建模的数值研究结果表明，由于合成气与氢气的化学反应尺度不同，因此从降低污染物排放的角度考虑，两种燃料在各燃烧区域适合的停留时间有所差异。对于氢气，反应物在凹腔与掺混区内停留时间越长越有利于燃烧器出口NOx的降低，而对于合成气，情况正好相反。反应物在主燃烧区的停留时间越短，对于NOx减排越有利，但对于合成气，这一时间不能短于CO燃尽的需要。通过本文的研究，了解了氢气与富氢合成气在凹腔驻涡模型燃烧器中的燃烧特点，验证了驻涡燃烧技术燃用富氢燃料的初步可行性，提出了模型燃烧器中燃烧稳定性较好与污染物排放较低时各自对应的特征操作参数，为进一步研究和技术的发展提供了理论依据和基础数据。更多还原

【Abstract】 The development of IGCC and CO₂ Zero Emission technology has brought forward ademand of using hydrogen or hydrogen rich syngas as fuel in gas turbine combustionchambers. Presently, combustors in industrial gas turbines mostly are swirl burners whichtake natural gas as fuel. Due to the big difference between the chemical characteristics ofhydrogen and natural gas, there might be many problems for a traditional swirl burner touse hydrogen rich fuel, such as flame instability, local high-temperature, and high NO_xemissions. Therefore, a novel combustion technology and a new type of combustor forhydrogen rich fuel use must be developed.Trapped vortex combustion technology, which was firstly developed from theaero-engine after burner, is considered the most potential candidate among the newgeneration of hydrogen rich fuel combustion technologies. However, research works aboutthis subject have just been started, and the feasibility of the technology has not beenconfirmed yet. Therefore, in this paper, an experimental trapped vortex combustor wasmanufactured, and a numerical simulation model was fabricated for realizing premixedcombustion of hydrogen rich fuel in a trapped vortex combustor. Experimental andnumerical studies were carried out focusing on combustion characteristics of purehydrogen and hydrogen rich syngas in the model combustion chamber.First of all, some structure parameters, such as the dimension scale of cavity walls, thelocation of primary flow injection holes, the entrance angle of main flow, and so on, havebeen studied, focusing on their influence to the cavity flow field, the forming of vortexes,and the pressure drop in the combustor. Based on the studing results, principles for a modelTVC design have been put forward, and appropriate structure parameters for theexperimental combustor have been chosen.Then the characteristics of flow field, the shape of the flames, and the instantaneousOH images have been studied. Results showed that a trapped vortex is realized in themodel combustor, and a two-vortex structure could be achieved in the cavity zone whenunder suitable flow conditions.Flame stability performances in the experimental trapped vortex combustor were carried out by doing the lean-blow-out experiments, monitoring the dynamic pressue,analysing the root mean square images of OH, and PDF statistic of OH signal intensity.Results showed that, flame stability of the model combustor is better when burninghydrogen than burning syngas, the combustion mode in the cavity zone has few influencetowards flame stability, flame stability performance turns worse when increasing the heatloading of the combutor or decreasing the overall equivalent ratio. The characteristicoperating parameter when flame stability is relatively better is S_f=0.4.Pollutants emission was tested in the experiments for both fuels. Results showed thatNOx emission for hydrogen was in the range of 3～10ppmvd （15%O₂）. When the primaryflow is in a premixed mode, NOx emission for hydrogen was 3～5ppmvd lower than that ofin non-premixed mode. When taking syngas as fuel, NOx emission was about 3ppmvdlower than taking hydrogen as fuel, at the same operating condition. NOx emission of thecombutor was reduced when the overall equivalence ratio decreased or when the heat dutyincreased. The characteristic operating parameter for a relatively lower pollutants emissionin the model combustor isΦ_p=0.4.A numerical research, in which the combustor was divided into three reaction zones,showed that, for pollutants deduction, the residence time needed by hydrogen and syngasin each reaction zone is different. For hydrogen, NO_x emission would decrease as theresidence time of reactants in the cavity and mixing zone increases, whereas, the situationof syngas is just on the opposite. Shortening the residence time of both fuels in the maincombustion zone is good for NO_x deduction, but for syngas, the residence time can’t be tooshort to complete the combustion of CO.Through the research work of this paper, a general view of hydrogen rich fuelcombustion characterisitcs in a trapped vortex combustor has been portrayed, and thefeasibility of trapped vortex technology as a potential hydrogen rich fuel combustiontechnology has been preliminarily confirmed. Corresponding characteristic operatingparameters for relatively high flame stability performance and relatively low pollutantsemission have been put forward seperately. In general, the work of this paper has provideda data basis for further research of adopting trapped vortex combustion technology intohydrogen rich fuel combustion chambers and IGCC gas turbine systems.更多还原