旋风炉内气相燃烧及两相流动的数值模拟

在有反应两相流动及煤粉燃烧的全双流体模型（ＰＴＦ模型,ｐｕｒｅ ｔｗｏ－ｆｌｕｉｄ ｍｏｄｅｌ）基础上,采用修正的ｋ－ε－ｋｐ两相湍流模型,对旋风炉内的湍流气相燃烧（甲烷和一氧化碳的燃烧）及在气相燃烧条件下的两相流动进行了数值模拟研究,模拟结果表明,在有燃烧的情况下,在旋风炉的底部存在近壁回流区,该回流区有利于火焰稳定,气粒两相切向速度分布具有类似的Ｒａｎｋｉｎｅ涡结构,该研究为煤粉燃烧的数值模拟     

天然气柔和燃烧锅炉结构参数影响模拟研究

在天然气锅炉中引入柔和燃烧技术将大大降低NOx排放,高速未燃气卷吸高温烟气回流并与之快速掺混再燃烧是柔和燃烧的重要特征,因此,开展天然气锅炉关键结构参数优化设计以组织流场形成柔和燃烧所需的高温低氧反应气氛非常必要。基于天然气锅炉的工况特征,设计了热负荷15kW的模型燃烧室,采用数值模拟手段详细研究了燃烧室高度、喷嘴孔径、喷嘴相对位置及烟气出口尺寸对燃烧室流场、组分场及关键参数——烟气回流比的影响规律,并最终确定了燃烧室结构优选方案,对天然气锅炉柔和燃烧机设计提供理论基础数据。     

燃气轮机燃油燃烧室改用双燃料流场数值分析

针对燃气轮机燃油燃烧室改成双燃料燃烧室对燃料喷嘴进行一体化概念设计,并采用CFD技术对其双燃料燃烧流场进行数值模拟。针对燃烧室燃用C7H16和裂解气燃料的不同情况,采用标准κ-ε湍流模型、化学平衡条件下的快速化学反应系统和简单概率密度函数（PDF）燃烧模型、液体燃料的喷雾模型以及SIMPLE算法。模拟并对比分析了两种燃料燃烧时的燃烧效率、出口温度均匀性、壁面最高温度以及速度分布等参数随工况变化的趋势,并得出结论：1）不同燃料燃烧时的流场特征基本保持一致;2）裂解气燃料燃烧时,其燃烧效率较高,但出口温度均匀性较差;3）在加入相同焓值的燃料进入燃烧室时,裂解气燃料燃烧得到的出口温度低于燃油的燃烧状态。     

高速热气流试验系统燃烧室温度性能数值仿真

给出了燃油在高速热气流试验系统燃烧的分布式数学模型,在GAMBIT软件中建立了系统燃烧室的几何模型,并进行了网格划分。为了了解燃油在燃烧室燃烧的性能以及系统燃烧室的出口温度分布,利用计算流体力学仿真软件FLUENT模拟了燃油在燃烧室中的燃烧,分别研究了不同油气比对燃烧室出口温度的影响和不同喷射角度对燃烧室出口温度的影响。仿真结果表明,油气比为理论油气比,喷射角度为30°左右时,燃烧室出口温度最均匀。     

The effects and characteristics of hydrogen in SNG on gas turbine combustion using a diffusion type combustor

Converting coal to natural gas may be one of the alternative solutions for satisfying the demand for natural gas. However, synthetic natural gas (SNG) has not been proven effective in natural gas-fired power plants. In this research, several combustion tests using a diffusion type combustor were conducted to determine the effect of hydrogen content in SNG on gas turbine combustion. Three kinds of SNG with different H₂ content up to 3%vol were used for the combustion tests. Even a small amount of hydrogen in SNG affects the flame structure: it shortened the flame length and enlarged the flame angle slightly. However, hydrogen content up to 3% in SNG did not affect the gas turbine combustion characteristics, which are emission performance and combustion efficiency. Due to a similarity with real gas turbine combustor conditions for power generation, a high pressure combustion test helped us verify the ambient pressure combustion tests conducted to determine the effect of hydrogen in SNG. In the high pressure combustion test, the pattern factors were identical even though the hydrogen content was varied from 0% to 3%.     

Design and numerical analysis of a 3 kWe flameless microturbine combustor for hydrogen fuel

In this work, a new 3 kWe flameless combustor for hydrogen fuel is designed and analyzed using CFD simulation. The strategy of the design is to provide a large volumetric combustion for hydrogen fuel without significant rise of the temperature. The combustor initial dimensions and specification were obtained from practical design procedures, and then optimized using CFD simulations. A three-dimensional model for the designed combustor is constructed to further analysis of flameless hydrogen combustion and consideration that leads to disappearance of flame-front and flameless combustion. The key design parameters including aerodynamic, temperature at walls and flame, NO_X, pressure drop, combustion efficiency for the hydrogen flame is analyzed in the designed combustor. To well demonstrate the combustor, the NO_X and entropy destruction and finally energy conversion efficiency, and overall operability in the microturbine cycle of hydrogen flameless combustor is compared with a 3 kWe design counterpart for natural gas. The findings demonstrate that hydrogen flameless combustion is superior to derive the microturbines with significantly lower NO_X, and improvements in energy efficiency, and cycle overall efficiency with low wall temperatures guaranteeing the long-term operation of combustor and microturbine parts.     

预混天然气小尺度燃烧特性的CFD研究

运用计算流体力学（CFD）二维模型研究预混天然气在小尺度空间内燃烧及墙壁的导热系数、外部的热损对燃烧特性的影响。研究表明，墙壁的导热系数和外壁面的热损直接影响着火焰的点燃、稳定及氮氧化物的生成。对于预混气体。仅存在一个很小的流速区间能维持通道内的燃烧。最后分析了轴向及径向的温度梯度对燃烧器的影响，找到了在模拟条件下最佳的热力条件，并以此达到优化小尺寸燃烧器的目的。     

氢混天然气燃气轮机加湿低氮燃烧性能研究

为了解贫预混燃烧室天然气掺氢加湿燃烧时的性能变化和容许加湿范围,解决氢混燃气轮机NO_x排放超标问题,以某燃气轮机燃烧室为研究对象,数值研究了掺氢比和加湿比对燃烧性能及污染物排放特性的影响。结果表明：燃料无加湿条件下,燃烧室出口CO和CO₂排放值随着掺氢比的增加而减小,较高燃烧温度将导致热力型NO_x排放值增加,掺氢比达到0.2以上时,NO_x排放已超出环保限值;燃料加湿条件下,随着加湿程度增加,燃气出口平均流速及水蒸气组分含量均增加,燃烧筒内全局温度、CO₂和NO_x排放值均降低,CO排放值先降低后增加;掺氢天然气加湿可实现低氮燃烧,考虑到低掺氢工况燃气轮机功率输出效能和高掺氢工况燃烧性能恶化问题,水蒸气加湿量不宜过多,当掺氢比为0.3时,推荐燃料加湿比为0.463。     

燃气轮机双燃料燃烧室温度场优化研究

为了优化双燃料燃烧室温度场分布,针对某型逆流环管双燃料燃烧室,设计了3种不同的火焰筒配气结构。利用ANSYS FLUENT软件,选用Realizable k-epsilon湍流模型及Finate Rate Chemistry and Eddy-disspation燃烧模型对燃烧室额定工况下的温度场及速度场进行了数值模拟。研究表明:对比液体燃料,由于气体燃料扩散较快,燃烧室在使用气体燃料时高温区分布周向收缩并沿火焰筒轴向后移。对于本型燃烧室,适当增大主燃孔孔径并在火焰筒轴向方向偏后布置,可以有效解决双燃料燃烧室使用气体燃料时高温区后移的问题,对气/液两种燃料条件下的温度场组织更为有利。     

多流体模型在燃气轮机燃烧室三维反应流中的应用

对一种模型燃气轮机燃烧室中的三维反应流进行了数值模拟，模型燃烧室的燃料是CH4，燃烧类型是预混燃烧，在数值模拟过程中，采用了Spalding于1995年提出来的多流体模型来对燃烧室中的湍流预混燃烧进行了数值模拟，在数值模拟过程中考虑了辐射问题，采用了六通量辐射模型。通过数值模拟给出了速度，压力，湍流脉动动能，湍流动能耗散率，焓值，湍流粘度，温度，密度，燃烧产物质量分数，氧的质量分数，燃料/空气混合比，燃料质量分数，空间三个方向的辐射热通量以及各种流体的质量分数等变量的分布情况，此外，还采用传统的旋涡破碎模型对此燃烧室进行了数值模拟，并对两种方法的结果进行了分析比较，由分析可以看出多流体模型的结果接近于实际情况，对模型燃烧室进行三维反应流数值模拟的工作为今后对实际燃烧室反应流的数值模拟打下了一定的基础。     

Modelling of combustion performances and emission characteristics of coal gases in a model gas turbine combustor

In recent years, gas mixtures are being used as alternative fuels in combustors. These gas mixtures are obtained by different methods. For instance, coal gasification and carbonization as coal have the largest reserves among fossil fuels. Gas mixtures obtained via coal gasification and carbonization are called water gas, generator gas, town gas and coke oven gas. These fuels contain various gases. As a result of this, heating values of fuels are also different. Therefore, combustion performances and emission characteristics of these fuels need to be investigated. In this study, combustion performances and emissions including CO, CO₂ and NO_X of water gas, generator gas, town gases, coke oven gas and methane were numerically investigated in a model gas turbine combustor. The numerical modelling of turbulent nonpremixed diffusion flames has been performed in this combustor. Mathematical models used in this study involved the k–ε model of turbulent flow, the PDF/mixture fraction model of nonpremixed combustion and P‐1 radiation model. A CFD code ANSYS Fluent was used for all numerical investigations. Temperature distributions of axial and radial directions were determined. A NO_X post‐processor was used for the prediction of NO_X emissions from the gas turbine combustor. Modelling was performed for 60 kW thermal power and different equivalance ratios (i.e. Ф = 0.91, Ф = 0.77 and Ф = 0.67). The studied type 1 model gas turbine combustor was modelled for Ф = 0.91 equivalance ratio. Then, Other equivalance ratios were analysed for type 2 model gas turbine combustor. The effect of dilution air on combustion performances and emission characteristics was also investigated. It is concluded that the coke oven gas, the town gas I, town gas II and the water gas are appropriate for usage as alternative fuel, whereas the generator gas is not suitable for gas turbine combustors. Copyright © 2013 John Wiley & Sons, Ltd.     

Numerical study of an annular gas turbine combustor with dump diffuser

INTRODUCTIONThemainfunctionofagasturbinediffusersystemistoreduceinletvelocityoftheflametubeandtoachieveminimaltotalpressurelossforimprovedcombustionprocesses.Inmoderngasturbinecombustors,thedumpdiffuserhasbeenwidelyused,becausethesuddenexpansionatpre...     

进气温度对微型燃机燃烧室污染物排放性能的影响

燃烧室是微型燃气轮机的四大部件之一,其性能优劣直接影响微型燃气轮机的整体性能。以一微型燃气轮机燃烧室模型为研究对象进行热态实验,研究不同进气温度对污染物（UHC、CO、NOx）排放性能的影响。实验结果表明,进气温度升高,使燃烧反应速度加快,有利于天然气更快更完全的燃烧,从而减少未燃尽碳氢化合物UHC,抑制CO的生成,并降低NOx的排放浓度。     

燃气轮机环形燃烧室内燃烧流动的数值模拟

对一个复杂的GE—F101型工业燃气轮机环形燃烧室，采用Reynolds应力湍流模型(RSM)、EBU—Arrhenius湍流燃烧模型和六通量热辐射模型描述其燃烧流动，应用FLUENT软件进行了三维化学反应流场的数值模拟研究。研究结果表明：旋流和燃料进口射流对燃烧室流内温度和流场分布有着重要的影响；利用数值手段得到燃烧室出口的温度分布以判断其能否满足透平叶片进口温度的要求是可行的；燃烧室工作压强对出口的NO分布有着重要影响。在燃用气体燃料时，燃气轮机的NO排放主要来自于热NO，瞬时NO只占很小一部分。图11参6     

3D numerical modelling of turbulent biogas combustion in a newly generated 10 KW burner

This study concentrates on the 3D numerical modelling of combustion of different biogases in a generated burner and combustor. The main goal of this study is to investigate the combustion characteristics (such as temperature and emissions) of biogases through a combustor due to depletion of natural gas. Moreover, the effect of the preheated air on flame temperatures of biogases have been studied in the present study. Finally, the effect of H₂S amount in biogas on SO₂ emissions has been investigated within these predictions. The numerical modelling of turbulent diffusion flames has been performed by using the standard k–ε model of turbulent flow, the PDF/Mixture Fraction combustion model and P-1 radiation model in the combustor. A CFD code has been used for all predictions. Temperature gradients have been determined on axial and radial directions for better understanding combustion characteristics of biogases. Modelling has been studied for thermal power of 10 kW and excess air ratio of λ = 1.2 for each biogas combustion. The first finding is that combustion of biogases is possible via the newly generated burner. Moreover, the results show that the one of biogas is very close to methane in terms of temperature distributions in the combustor due to including high amount of methane compared to other biogases. It is also concluded that the flame temperatures of biogases increase with preheating the combustion air as expected. It is finally revealed that SO₂ emissions increase as amount of H₂S in biogas is increased through the combustor.     

Numerical simulation of a hydrogen fuelled gas turbine combustor

The interest for hydrogen-fuelled combustors is recently growing thanks to the development of gas turbines fed by high content hydrogen syngas. The diffusion flame combustion is a well-known and consolidated technology in the field of industrial gas turbine applications. However, few CFD analyses on commercial medium size heavy duty gas turbine fuelled with pure hydrogen are available in the literature. This paper presents a CFD simulation of the air-hydrogen reacting flow inside a diffusion flame combustor of a single shaft gas turbine. The 3D geometrical model extends from the compressor discharge to the gas turbine inlet (both liner and air plenum are included). A coarse grid and a very simplified reaction scheme are adopted to evaluate the capability of a rather basic model to predict the temperature field inside the combustor. The interest is focused on the liner wall temperatures and the turbine inlet temperature profile since they could affect the reliability of components designed for natural gas operation. Data of a full-scale experimental test are employed to validate the numerical results. The calculated thermal field is useful to explain the non-uniform distribution of the temperature measured at the turbine inlet.     

空气分级比对同轴分级燃烧室性能参数的影响

为掌握同轴分级燃烧室性能参数随空气分级比(主燃级空气流量的比值)的变化规律,以某同轴分级燃烧室为研究对象,数值分析了空气分级比对燃烧室的燃烧效率、总压损失、出口温度分布、污染物排放和绝热壁面最高温度的影响。结果表明：空气分级比主要会改变角涡位置的燃烧温度和高温烟气的停留时间;随着空气分级比的升高,燃烧室总压损失、出口温度分布系数、NO_x排放、绝热壁面最高温度逐渐升高,但燃烧效率、CO污染物排放、径向温度分布系数对空气分级比不敏感;在同轴分级燃烧室设计中,在保证燃烧稳定的前提下可采用较小的空气分级比以实现燃烧室高效、低阻、低污染燃烧。     

水煤气作为原油输运加热炉替代燃料初探

从燃气的互换性以及燃烧特性参数等方面对水煤气作为原油输运加热炉替代燃料进行了可行性分析。计算结果表明：在不改变燃烧器结构的情况下，水煤气与天然气是不能直接互换的；但若选用煤气燃烧器，以水煤气替代天然气不仅能达到原油输运加热炉热负荷要求而且具有良好的经济效益。     

Experimental analysis of the effects of hydrogen addition on methane combustion

This paper presents gas emissions from turbulent chemical flow inside a model combustor, for different blending ratios of hydrogen–methane composite fuels. Gas emissions such as CO and O₂ from the combustion reaction were obtained using a gas analyzer. NOx emissions were measured with a NOx analyzer. The previously obtained flame temperature distributions were also presented. As the amount of hydrogen in the mixture increases, more hydrogen is involved in the combustion reaction, and more heat is released, and the higher temperature levels are resulted. The results have shown that the combustion efficiency increases and CO emission decreases when the hydrogen content is increased in blending fuel. It is also shown that the hydrogen–methane blending fuels are efficiently used without any important modification in the natural gas burner. Copyright © 2011 John Wiley & Sons, Ltd.     

某型燃气轮机燃烧室燃烧流场数值研究

燃气轮机燃烧室的燃烧特性受到旋流强度、雾化特性等因素的强烈影响,旋流强度和雾化特性分析对燃烧室的设计和优化具有非常重要的作用。对燃气轮机燃烧室的燃烧流场,应用商用程序FLUENT进行了数值模拟,并分析了空气过量系数α和燃油雾化粒径对燃烧室内燃烧特性的影响。模拟结果表明,控制空气过量系数和燃油雾化粒径对提高燃烧室工作性能和降低污染物排放具有重要意义。