高温升燃烧室主燃区流场和燃烧性能

常温常压下,采用PIV技术研究了方案A(双旋流器/双油路离心喷嘴头部)和方案B(三旋流器/单油路气动雾化喷嘴头部)对高温升燃烧室主燃区流场的影响.在单头部矩形燃烧室上进行了慢车状态贫油熄火试验,在三头部燃烧室上进行了大状态下出口温度分布试验.试验结果表明,方案B的出口温度分布系数比方案A小41%,贫油熄火性能比方案A小了13.5%.用主燃区PIV流场结果分析了燃烧性能存在差别的原因.     

燃烧流场测量的PIV应用初步研究

使用丹麦Dantec公司生产的二维PIV(Particle Image Velocimetry)系统对甲烷/空气的扩散燃烧热态速度场进行了测量，得到了燃烧状态下的速度场信息，解决了利用PIV进行热态测量的问题。     

三级旋流杯燃烧室流场测量与数值模拟

为满足高温升高热负荷燃烧室头部设计要求,参照旋流器设计准则,设计4种不同三级旋流杯燃烧室,采用数值模拟和PIV试验相结合方法对其冷态流场进行初步研究。研究结果表明:第3级旋流器叶片安装角增加,火焰筒头部旋流特性更显著,回流区直径增大,有利于火焰稳定;同时主燃孔射流深度增加,有利于截断火焰。第3级旋流器叶片数增加,主流速度衰减加快,气动损失增大,使火焰筒头部进气量减少,同时削弱三级旋流杯出口气流旋转强度,火焰筒头部回流区直径减小,不利于燃烧。     

燃气轮机燃烧室流场数值计算研究及分析

对燃气轮机逆流式环形燃烧室,热态三维流场的数值模拟问题进行了研究,建立了三维计算模型,生成了数值计算网格。数值模拟研究表明,改变燃烧室的几个结构参数,可以得到更加合理的流场。通过对关键截面的流动分析,可以判断燃烧室设计的合理性,为进一步优化燃烧室结构设计、改善流场奠定了基础。     

辅助动力装置全环形燃烧室燃烧性能试验研究

针对某型辅助动力装置全环形燃烧室开展了整机燃烧性能试验研究。采用温度耙测量全环形燃烧室出口温度分布,研究不同进口温度和油气比条件下辅助动力装置燃烧室整机燃烧性能。试验结果表明:随着进口温度和油气比的增加,燃烧室出口温度相应增加,但温度分布规律基本保持不变,出口温度分布系数(OTDF)小于0.2,径向温度分布系数(RTDF)基本小于0.1,而燃烧效率和燃烧室进出口压力损失系数增加;随着进口总温的增加,燃烧室贫油熄火油气比逐渐减少(余气系数增加),但燃烧室的贫油熄火余气系数均大于13。     

湍流燃烧模型对某燃气轮机燃烧室性能计算的影响

针对某型燃气轮机环形燃烧室,通过数值模拟,对比分析了Standardk—ε、RNGk-ε、Realizable k-ε、Standard k-ω、雷诺应力五种湍流模型以及简单概率密度模型（PDF）、有限速率模型、涡耗散模型（ED）、涡耗散概念模型（EDC）四种燃烧模型对环形燃烧室性能计算的影响。结果表明：Realizable k-ε模型模拟的冷态流场与PIV试验测量结果最符合;EDC模型最能合理的模拟燃烧效果,但在预测NOx排放时不如有限速率模型精确。以上结论为后续该型号燃气轮机环形燃烧室的数值计算和设计提供了参考。     

燃烧室压力对燃油喷雾和燃烧的影响研究

采用CHAMKIN模拟分析燃烧过程,基于自行设计的可视化定压燃烧系统试验研究燃烧室压力对燃油喷雾和燃烧的影响。结果表明:随着压力的升高雾化效果逐渐变差;进气旋流可以改善雾化效果;如果进气旋流是高温气体,则改善情况更明显。压力的增加仅加快了反应速率,缩短了着火延迟时间,并没有引起着火过程中温度的很大变化。随着燃烧压力的增加,火焰逐步向燃油喷嘴处移动,可通过提高烟气卷吸率增强气旋效果,使火焰更长,燃烧更均匀,避免烧坏油头及燃烧室内部分温度过高等不良后果。     

汽油机燃烧室催化燃烧试验研究

本文阐述了利用分子束和电子能谱技术对催化材料进行筛选后，选用Ｃｕ２Ｏ作催化剂，涂在汽油机燃烧室表面，进行的性能对比试验及试验结果分析。     

燃烧室形状对燃烧过程的影响研究

针对燃烧室形状对燃烧过程的影响进行了研究,得到了喉口直径对喷雾贯穿距离、索特平均直径(SMD)、湍动能、涡流强度、缸内压力、放热规律以及NO-SOOT的影响规律,并通过三维对比分析了燃烧反应率场、温度场、浓度场以及速度场的变化趋势.分析表明:在本次研究中燃烧室喉口直径的合理范围是100～120 mm.     

旋流角度和压降对分级燃烧室流场和雾化的影响研究

为了得到不同结构参数及气动参数下的油气掺混特性,采用粒子图像测速与平面激光散射方法研究副模旋流器旋流角度、旋流器压降对中心分级燃烧室头部流场与燃油分布的影响。结果表明：在常温常压状态,随着副模旋流角度的增大,副模燃油喷雾锥角增加,台阶回流区减小,中心回流区增大,主副模射流在喷嘴下游轴向位置更近处发生融合;随着旋流器压降的增加,主副模射流增强,中心回流区最大宽度增大,副模燃油喷雾锥角微弱减小,但主模燃油的分散特性得到明显改善;副模与主模燃油在场内浓度峰值位置受耦合影响较小,主模射流轨迹附近的破碎状态在主副模燃油单开的叠加场中与耦合场中的结果差别较大。     

燃气轮机燃烧室三维冷态流场数值模拟

本文针对某燃气轮机环管型燃烧室三维冷态流场的数值模拟问题进行了研究。根据该型燃气轮机燃烧室的设计图纸建立真实的三维计算几何模型;在计算中采用SIMPLE算法,k-ε双方程湍流模型,对其进行了冷态空气流场的数值模拟;通过对各处流场分布的分析,特别是对主要区域各关键截面的流动分析,可以判断出燃烧室设计的合理性,为进一步优化燃烧室的结构设计、改善流场结构,并为开展燃烧室热态流场的数值模拟奠定了基础。     

Experimental study on oxy-fuel combustion of heavy oil

Oxy-fuel combustion of heavy oil can be applied to oil field steam injection boilers, allowing the utilization of both heavy oil and CO₂ resources. The present study investigated the oxy-fuel combustion characteristics of heavy oil under different conditions, including the flame, temperature, and pollutant emission characteristics. The results showed that heavy oil combustion was stable at O₂ concentrations of 29%, as the O₂ concentration was increased, the flame began to brighten gradually, becoming shorter and thicker, while the temperature gradient became higher and the high temperature zone moved closer to the burner exit. The overall temperature and the combustion rates in O₂/CO₂ atmospheres were below those seen in O₂/N₂ atmospheres. The volume of NO emitted in the flue gas was almost unaffected by the change in O₂ concentrations in atmospheres containing high concentrations of CO₂, but it increased rapidly with increasing O₂ concentration in O₂/N₂ atmospheres.     

Numerical investigation of the flow inside the combustion chamber of a plant oil stove

Recently a low cost cooking device for developing and emerging countries was developed at KIT in cooperation with the company Bosch und Siemens Hausger te GmbH.After constructing an innovative basic design further development was required.Numerical investigations were conducted in order to investigate the flow inside the combustion chamber of the stove under variation of different geometrical parameters.Beyond the performance improvement a further reason of the investigations was to rate the effects of manufacturing tolerance problems.In this paper the numerical investigation of a plant oil stove by means of RANS simulation will be presented.In order to reduce the computational costs different model reduction steps were necessary.The simulation results of the basic configuration compare very well with experimental measurements and problematic behaviors of the actual stove design could be explained by the investigation.     

Experimental study of humid air reverse diffusion combustion in a turbulent flow field

Experiments were performed to investigate the differences between the propane/air turbulent diffusion reactive flows past bluff-body and the propane/humid air turbulent diffusion reactive flows in the same conditions. The velocity distributions of the non-humid reactive flow fields and the humid reactive flow fields were measured by particle image velocimetry (PIV) techniques. The temperature fields were measured by high temperature thermocouples, and NO_x distributions were obtained by using gas detection instruments. The results show that although humid air reactive flow fields are similar to non-humid flow fields in general, there are some differences in the humid air combustion flow field comparing with the non-humid combustion flow field: the center of the reversed-flow region goes forward; the dimension of the reversed-flow region is smaller; the peak temperature and NO_x formation are reduced. It is suggested that humid air combustion is helpful to shorten the axial length of combustors, and reduce the formation of pollutants. __________ Translated from Journal of Shanghai Jiaotong University, 2006, 40(8): 1 287–1 292 [译自: 上海交通大学学报]     

Experimental study on the flame propagation characteristics of heavy oil oxy-fuel combustion

This paper studied the flame propagation characteristics of heavy oil oxy-fuel combustion in ignition and stable combustion. The results showed that the ignition process could be divided into three stages: the pro-ignition, mid-ignition and end-ignition. The pro-ignition, the fire core generated and evolved into spherical; the mid-ignition, the spherical fire core gradually turn into tapered structure; the end-ignition, the flame tapered structure disappeared and turn into a relative stable columnar structure. By calculating the flame propagation velocities, we found that in the same combustion atmosphere, the flame propagation velocity in 29% O2 was higher than that in 21% O2; in the same O₂ concentration, the flame propagation velocity in O₂/N₂ atmosphere was higher than that in O₂/CO₂. During the stable combustion, we observed the local flame structure extinguished, distorted and grew.     

Effect of flow field for colorless distributed combustion (CDC) for gas turbine combustion

Colorless distributed combustion (CDC) investigated here is focused on gas turbine combustion applications due to its significant benefits for, much reduced NOx emissions and noise reduction, and significantly improved pattern factor. CDC is characterized by distributed reaction zone of combustion which leads to uniform thermal field and avoidance of hot spot regions to provide significant improvement in pattern factor, lower sound levels and reduced NOx emission. Mixing between the combustion air and product gases to form hot and diluted oxidant prior to its mixing with the fuel is critical so that one must determine the most suitable mixing conditions to minimize the ignition delay. Spontaneous ignition of the fuel occurs to provide distributed reaction combustion conditions. The above requirements can be met with different configuration of fuel and air injections with carefully characterized flow field distribution within the combustion zone. This study examines four different sample configurations to achieve colorless distributed combustion conditions that reveal no visible color of the flame. They include a baseline diffusion flame configuration and three other configurations that provide conditions close to distributed combustion conditions. For all four modes same fuel and air injection diameters are used to examine the effect of flow field configuration on combustion characteristics. The results are compared from the four different configurations on flow field and fuel/air mixing using numerical simulations and with experiments using global flame signatures, exhaust emissions, acoustic signatures, and thermal field. Both numerical simulations and experiments are performed at a constant heat load of 25 kW, using methane as the fuel at atmospheric pressure using normal temperature air and fuel. Lower NOx and CO emissions, better thermal field uniformity, and lower acoustic levels have been observed when the flame approached CDC mode as compared to the baseline case of a diffusion flame. The reaction zone is observed to be uniformly distributed over the entire combustor volume when the visible flame signatures approached CDC mode.     

中速磨煤机构件对气相场影响的数值模拟

中速磨煤机内部气相场研究对于燃煤电厂节能减排降碳具有重要意义。然而,中速磨煤机内部构件复杂且存在旋转部件,已有研究往往对磨煤机结构及运行进行简化处理,这势必影响气相场模拟的准确性。采用Realizable k-ε湍流模型,对7种不同结构及运行工况下磨煤机内部气相场开展数值模拟,进行网格无关性验证,并评价磨辊、磨碗与风环、分离器的简化处理对气相场数值模拟结果的影响。结果表明,忽略磨辊对研磨区气相场影响明显,而磨辊转速由28.62r·min^-1变化为57.24 r·min^-1时,典型截面气相速度和磨煤机压力损失几乎不变;忽略磨碗与风环的转动,风环上方平均风速将被低估14.97%,磨煤机压力损失将被低估5.02%;忽略分离器部分对研磨区气相场影响很小,而对研磨区上方内锥体区域气相场影响显著,并使得典型截面气相速度误差高达4.80 m·s^-1。研究结果可为磨煤机内部流场准确、高效的数值模拟提供方法指导。     

分隔室压燃式天然气发动机燃烧过程变参数多维模拟计算

利用详细的化学动力学机理与CFD多维数值模拟计算软件,对分隔室压燃式天然气发动机的着火及燃烧过程进行了变参数模拟研究。研究的参数包括：喷气时刻、进气终了温度、天然气成分。模拟内容有：着火时刻、缸内平均压力、NO质量分数。结果表明,喷气提前使最高温度压力增加,NO排放增加;提高进气终了温度可以改善着火性能;天然气中乙烷含量增加可以改善着火性能,同时使最高温度压力增加,NO排放增加。     

Experimental study of industrial gas turbine flames including quantification of pressure influence on flow field,fuel/air premixing and flame shape

A commercial swirl burner for industrial gas turbine combustors was equipped with an optically accessible combustion chamber and installed in a high-pressure test-rig. Several premixed natural gas/air flames at pressures between 3 and 6 bar and thermal powers of up to 1 MW were studied by using a variety of measurement techniques. These include particle image velocimetry (PIV) for the investigation of the flow field, one-dimensional laser Raman scattering for the determination of the joint probability density functions of major species concentrations, mixture fraction and temperature, planar laser induced fluorescence (PLIF) of OH for the visualization of the flame front, chemiluminescence measurements of OH^* for determining the lift-off height and size of the flame and acoustic recordings. The results give insights into important flame properties like the flow field structure, the premixing quality and the turbulence–flame interaction as well as their dependency on operating parameters like pressure, inflow velocity and equivalence ratio. The 1D Raman measurements yielded information about the gradients and variation of the mixture fraction and the quality of the fuel/air mixing, as well as the reaction progress. The OH PLIF images showed that the flame was located between the inflow of fresh gas and the recirculated combustion products. The flame front structures varied significantly with Reynolds number from wrinkled flame fronts to fragmented and strongly corrugated flame fronts. All results are combined in one database that can be used for the validation of numerical simulations.     

生物质气对内燃机发电机组特性影响的实验研究

文章以30 kW生物质气内燃机发电机组为研究对象,通过改变CO,H_2,CH_4,CO_2等组分的比例配制气体,来模拟不同生物质气,并分析生物质气组分和热值对内燃机发电机组启动特性和发电特性的影响。分析结果表明:CO_2的阻燃效果显著,CO_2的比例升高会阻碍内燃机的点火启动,导致内燃机组无法正常工作;H2的助燃效果显著,提高H2的比例可以改善内燃机组的启动特性和发电特性;内燃机组的最大输出功率随着生物质气热值的增加而上升,当生物质气的热值大于6.75 MJ/m3时,内燃机组可以达到额定输出功率(30 kW);当生物质气热值相同时,降低CO_2比例或提高H_2比例,内燃机组的做功能力将会增强;内燃机组的发电效率随着输出功率的增加而升高,燃气消耗率随着输出功率的增加而降低。