摘要
宽燃料适应性是先进燃气轮机的重要设计要求之一,燃用来源广泛的富氢燃料气是燃气轮机未来发展的重要方向,因此富氢燃料气的湍流火焰熄火特性应成为燃气轮机燃烧室设计过程中重点关注的问题。该文通过使用优化的对冲火焰实验方法和数值模拟计算方法,比较了2种典型的富氢燃料气在层流和湍流燃烧状态下的熄灭拉伸率,并分析了贫燃侧2种燃料预混火焰熄灭拉伸率差异的主要原因。结果表明:在该文研究的工况范围内,采用数值模拟方法可较好地预测层流和湍流火焰的熄灭拉伸率。在层流燃烧状态下,火焰锋面内活性自由基H、O和OH的物质的量浓度相对更高的富氢燃料气,其火焰锋面内部的关键化学反应速率和释放热量的速度更高,因此能抵抗更高程度的火焰拉伸形变。湍流作用加快了火焰锋面内部的反应速率,但同时会使热量更快地从火焰锋面内部向外输运,相比于层流火焰,湍流火焰熄灭拉伸率降低。
[Objective]Adaptability of fuel is an essential design requirement of advanced gas turbines.Hydrogen-rich fuel gas can be obtained from a variety of sources,and its use will be an important part of the future development of gas turbines.When using gas turbine combustion technology to burn hydrogen-rich fuel,if the flame goes out,it will lead to unsafe equipment.As a result,the extinction of turbulent hydrogen-rich fuel flame is the key problem when we design gas turbine combustors.[Methods]In this study,the optimized experimental approach and numerical simulation method of counterflow flame are used to compare the extinction strain rate of two typical hydrogen-rich fuel gases under laminar and turbulent combustion conditions,and the main reasons for the difference were examined.Two typical hydrogen-rich fuel gases used in this study are called FA and FB in this paper.As far as FA is concerned,the CO component ratio of fuel is higher,the dilution ratio is lower,and the calorific value is significantly higher.FA can be considered as the typical hydrogen-rich synthetic gas obtained from entrained flow coal gasification,and FB can be regarded as the typical hydrogen-rich synthetic gas obtained from fluidized bed coal gasification,both of which have certain representative significance.The upper nozzle of the counterflow flame produces nitrogen,while the lower nozzle produces premixed fuel with varying equivalence ratios.The equivalence ratio covers a range of 0.4-1.0.The gas temperature at the nozzle outlet is 300 K.The particle image velocimetry(PIV)system is used to obtain the velocity information of the flow field at the nozzle outlet.The turbulent transport model is added to the OPPDIF code for numerical simulation.[Results]The results demonstrated that,within the range of working conditions studied,the numerical simulation method used in this paper could well predict the extinction strain rate of laminar and turbulent flames.The difference between experimental and simulation results was less than±10%for a laminar counterflow flame and±40%for a turbulent counterflow flame.Due to the instability of the turbulent flow field,the measurement of the extinction strain rate fluctuated greatly during the turbulent combustion experiment,and the error bar was greater than that of the laminar combustion experiment.[Conclusions]Under laminar combustion conditions,hydrogen-rich fuel gas with a higher mole fraction of active radicals such as H,O,and OH in the flame front has a higher reaction rate and heat release rate of key chemical reactions,so it can resist higher flame stretching deformation.With the increase of the equivalence ratio,the extinction strain rate indicates an upward trend.Turbulence not only improves the mixing of active groups and reactants,thereby improving the reaction,which increases the rate of key chemical reactions and heat release in the reaction area,but it also improves heat transfer of the flame from inside to outside,resulting in a lower internal temperature of the flame.
作者
邹俊
李昭兴
张海
吕俊复
张扬
ZOU Jun;LI Zhaoxing;ZHANG Hai;LüJunfu;ZHANG Yang(Key Laboratory for Thermal Science and Power Engineering of Ministry of Education,Department of Energy and Power Engineering,Tsinghua University,Beijing 100084,China)
出处
《清华大学学报（自然科学版）》
EI
CAS
CSCD
北大核心
2023年第4期585-593,共9页
Journal of Tsinghua University(Science and Technology)
基金
国家科技重大专项项目(2019-III-0018-0062)
国家自然科学基金项目(52176116)。
关键词
富氢燃烧
预混火焰
对冲火焰
熄灭拉伸率
hydrogen-rich combustion
premixed flame
counterflow flame
extinction strain rate
