喷嘴结构参数对喷雾和燃烧特性的影响

为探究高喷射压力条件下小孔径喷嘴内部结构对燃油喷雾和燃烧特性的影响,采用相位多普勒粒子分析系统(PDPA)和高温定容燃烧弹系统试验研究了采用挤研技术处理的喷嘴与簇孔喷嘴的喷雾与燃烧特性。试验结果表明:相同喷射条件下挤研无助于改善燃油喷雾的索特平均直径(SMD),随着喷孔挤研量的增大,喷雾SMD持续增大,燃烧生成的碳烟量不断增多;随着簇孔间距增大,喷雾SMD先增大后减小,而碳烟生成量表现出相同的变化趋势,簇孔间距为0.4 mm时,燃烧峰值放热率最高,单孔与0.2 mm间距簇孔的峰值放热率差别不大。     

柴油机燃烧过程中基本碳粒子的生成历程

基于电控燃油喷射柴油机全气缸取样试验平台,利用场发射透射电子显微镜和图像处理技术,对柴油机燃烧过程中基本碳粒子的生成及演变历程进行了研究.结果表明,基本碳粒子的结构在柴油机燃烧过程中逐渐向石墨化过渡.燃烧初期生成的碳粒子很小,没有明显的分层;随着燃烧进程的发展,基本碳粒子逐渐长大,开始出现分层,最终形成洋葱状的微品碳结构,且微晶结构层与层之间的距离逐渐减小.     

装有金属陶瓷雾化片的重油喷嘴的试验

机械加工和冲压制造的重油喷嘴,其材料即使采用特种钢,甚至采用ШХ-15或ХВТ钢,但在运行过程中由于重油中的矿物质硬粒子的作用,很快遭到磨损。因此雾化片的特性也就改变,从而影响了锅炉的燃烧工况。重油中矿物质粒子的基本成分是赤铁矿(75%)和石英岩(25%)。赤铁矿的硬度为     

柴油机中碳微粒氧化率的测量

本文研究了轿车用非直喷式柴油机气缸内燃烧产生的碳烟微粒的形成和氧化。利用全气缸取样系统使气缸内工质迅速排出和稀释,并采集在取样袋中,随后用悬浮粒子电子分析仪进行分析,测定出在膨胀行程中燃烧室内碳烟微粒的质量浓度和表面积浓度随曲轴转角的变化历程。用麻省理工学院发展的随机模型模拟了实测的碳烟微粒曲线。利用Lee 和Beer的动力学公式可以模拟观测到碳烟微粒氧化率。碳烟微粒氧化率对用在模拟模型中设定的碳粒子直径值是非常敏感的。     

双层交错布置多孔喷嘴燃烧排放性能试验研究

在某单缸柴油机上搭建高压共轨系统整机试验台架,研究双层交错布置多孔喷嘴结构对柴油机燃烧和排放性能的影响规律。试验结果表明:相同几何流通面积的双层交错布置多孔喷嘴相比于传统单层喷嘴经济性提高,NOx排放和碳烟排放改善;孔径较小的双层交错布置多孔喷嘴方案燃油消耗率较高,NOx排放较低,碳烟排放较高;下层喷孔喷射夹角小的双层交错布置多孔喷嘴方案缸内平均压力和温度高,油耗和排温降低,NOx排放较多,碳烟排放较少。     

射流喷嘴旋流强度对燃烧室回流和燃烧特性的影响研究

随着燃气轮机参数的提高和稳定低排放运行工况的拓宽,对燃烧的要求也越来越高。柔和燃烧作为一种有潜力的燃烧技术,具有温度均匀、燃烧稳定和污染物排放低等优点,而如何在燃烧室内组织流动是实现柔和燃烧的关键。采用高速射流引射掺混的方式可以较好的满足柔和燃烧产生所需的条件。预混射流喷嘴结构和布置对流场和燃烧特性有重要影响,如何选择射流喷嘴结构值得进一步研究。本文通过实验和数值模拟相结合的方式,研究了柔和燃烧器中预混射流喷嘴的旋流强度对燃烧器流动结构和燃烧排放的影响。结果表明,旋流能增强燃料/空气的掺混,低旋流作用下能使喷嘴出口掺混不均匀度ISMD下降0. 15左右;但是喷嘴旋流对燃烧室的烟气回流有减弱的作用,使回流区向喷嘴和中轴线靠近;同时,旋流会造成温度场和火焰面不均匀分布,略微拓宽燃烧工况范围并略微增加火焰的稳定性。实验结果表明喷嘴旋流进气角从0°变化到45°时,NOx排放随旋流角的增大而增加。     

燃油锅炉机械未完全燃烧损失q_4的确定

在以往通常的过量空气系数α~"_n.n=1.15条件下运行时,焦炭——烟炱粒子在火焰中心业已燃尽。被烟气携带出来的残余未燃尽碳,实际上可以略而不计。通过锅炉各部烟气通道的烟色是透明的。随着过量空气系数的降低,燃烧过程拖长,焦炭——烟炱粒子被带入温度相对为较冷的区域,该处的温度水平已不足以保证碳粒的完全燃尽。因此,部分未燃尽碳被排烟带走,从而产生了机械未完全燃烧损失。在苏联,首次对燃油炉的机械未完全燃烧损失进行测定是由BTN(全苏热工研究所)作出的。按参考资料,在所研究的过量空气系数范围内(1.02及以上)。q_4<0.01%。按照较近的数据,机械未完全燃烧损失当α>1.03时等于零;当α<1.03时建议采用q_4=0.15。资料[2]中给出了更为详细的q_3、q_4与α关系     

重型燃气轮机高炉煤气稳定燃烧特性试验研究

针对高炉煤气燃烧稳定性差、易熄火以及热值波动大等特点,基于某重型燃气轮机的燃烧器,采用全温全尺寸燃烧试验,分析不同的旋流强度和喷嘴长度对超低热值燃烧器的熄火性能、稳定运行区间的影响。研究表明,旋流强度和喷嘴长度对低热值燃烧的稳定性影响较大,且在一定范围内存在最优的组合设计,可以显著拓宽超低热值燃烧熄火边界,使机组的稳定运行区间更宽广。     

进气预混乙醇对柴油机碳烟与NOx排放的影响参数研究

在一台自然吸气式直喷柴油机上，按照组合燃烧的要求．全面、系统地研究了不同喷嘴孔径、不同供油定时、不同喷醇的始点对发动机碳烟、NOx排放以及经济性的影响．研究结果表明，为了获得更低的碳烟和NOx排放以及优越的能量经济性，与燃用纯柴油的发动机相比，采用进气预混乙醇的组合燃烧发动机的柴油供油定时可以稍迟或保持不变，燃油喷嘴的孔径应适当减小，预混乙醇的发动机负荷起点应适中．     

低排放燃烧室值班喷嘴改进设计研究

贫燃预混燃烧是目前实现干式低排放的主要技术措施之一,然而该燃烧技术在机组运行中,总会出现低工况下燃烧室贫燃熄火和回火等问题,为了改善低排放燃烧室的贫燃熄火特性,需要对低排放喷嘴进行结构设计改进。本文针对某型低排放燃烧室,以提高燃烧室贫燃熄火过量空气系数为目标,对低排放喷嘴的值班路进行设计改进。结果表明:(1)旋流缩放组合式值班喷嘴可以形成稳定的值班火焰;(2)旋流缩放组合式值班喷嘴可以引燃主喷嘴;(3)采用旋流缩放式值班喷嘴后,燃烧室的贫燃熄火过量空气系数提高了23%。     

燃气轮机振荡燃烧主动控制方法

振荡燃烧是贫燃预混燃烧室普遍面临的不稳定燃烧现象，该现象会导致发动机振动，污染物排放加剧，喷嘴烧蚀等，因此需要对这种现象进行控制，以减小压力脉动。本文针对某型低排放燃烧室，以对值班燃料供给控制为核心，设计了一套振荡燃烧主动控制系统，并进行了试验研究。分析了燃烧室内压力脉动控制的影响因素和变化规律，试验研究表明：（1）该系统有效地抑制了燃烧室的压力脉动。（2）控制系统投入工作的相位不同时，抑制效果明显变化。（3）该系统对由贫燃燃烧不稳定引起的压力脉动有明显抑制效果，对其他原因引起的脉动无明显抑制效果。     

某型低排放燃烧室喷嘴结构优化研究

为提高干低排放燃烧室火焰稳定性,对某燃气轮机干低排放燃烧室喷嘴进行了结构优化,增加了中心预混值班喷嘴,同时对燃料分配进行调整,分析了值班火焰对燃烧室的火焰稳定性和污染物排放的影响。计算结果表明：值班路过量空气系数为1.5,两级旋流过量空气系数相同时,可有效拓宽燃烧室贫燃熄火边界,同时保持较低的污染物排放。最后通过试验测试了燃烧室的贫燃熄火特性和压力脉动特性,初步验证了值班喷嘴结构对稳定燃烧的作用。     

Study of flow and combustion characteristics of optimized low swirl premixed nozzle for micro gas turbine

With the micro gas turbine is used more and more widely, the operating conditions become complex and fluctuating which impacts the environmental friendliness of combustor. In this work, a low swirl premixed nozzle (LSPN) is designed based on the original premixed nozzle (OPN) of a 60 kW micro gas turbine, in order to adapt the flexibility of load and operating environment by improving the mixing performance of fuel and air. The flow and combustion characteristics of LSPN and OPN fed by natural gas is numerically studied using the standard k-ε model and the combined Finite Rate Chemistry/Eddy Dissipation Model (FRC/EDM) under various operating conditions. The results show that the mixing performance of air and fuel in LSPN has been improved. The flow unmixedness in LSPN is always smaller than OPN, and it is 41.74% lower at the outlet of the nozzle. While the equivalence ratio decreases, the mean temperature in the combustor decline. Furthermore, under the majority of operating conditions, the emission performance of LSPN is better than OPN.     

喷嘴与安装孔之间的缝隙对微型燃气轮机燃烧室影响的数值分析

为了探究喷嘴与燃烧室壁面安装孔间的缝隙对微型燃气轮机燃烧室流动及燃烧特性的影响,运用三维数值计算软件,对30 kW微型燃气轮机燃烧室在不同面积缝隙下的燃烧过程进行了数值计算,得到了燃烧室内的流场及温度场,并对比分析了燃烧室各处的气体流量分配、燃烧室内部温度分布以及污染物排放量。计算结果表明:缝隙面积的变化对燃烧室内气量分配的影响是全局性的,随着缝隙面积的增大,缝隙内的气体流量增加,燃烧室其它各处的流量则相应减小。在贫燃的条件下,这一过程使得燃烧室内部的整体温度逐渐减低,随之C0的排放量小幅增大。此外,一定范围内的缝隙能够在降低燃烧室整体温度的同时维持火焰形态,有效降低NOx的排放量。     

Numerical prediction of operating characteristics of micro-gas turbine combustor with on-board reformed EGR system using co-simulation model and 1D reduced model

In this study, an on-board reforming gas turbine system was proposed to expend the combustion stability and operating points of as gas turbine combustor aiming for fuel lean condition. On-board reforming does not store the syngas unlike the existing conventional reforming device, but formed syngas as the operating load changes and participates in combustion. In previous research conducted for this study, a concept single nozzle combustor was designed that satisfies the thermal output of 150 kW and the turbine inlet temperature of 1200 K. In addition, by designing a non-catalytic partial oxidation-based concept reformer, syngas formation was confirmed in various operation points. In previous research, closed-loop analysis was performed to analyze the independent effects of combustor and reformer. However, in this study, open-loop analysis that simulates the combustor and reformer simultaneously was performed to analyze the effect of the combined system at various operating points. As a result, improved combustion was confirmed by the generation of OH radicals when the oxidizing agent was diluted with increasing hydrogen content. This is similar to the lean OH radical distribution in a low-oxidizing environment, which is the basic characteristics of moderate or intense low-oxygen dilution combustion. The reformer analyzed the reaction by changing the reformate fuel inlet velocity. Through this, it was confirmed that the mixedness inside the reformer improved as the reformate fuel inlet velocity. Finally, to calculate the efficiency of the hydrogen addition operating points under various conditions, suitable operating points were derived by comparison with conventional partial oxidation reforming. The operating range of moderate or intense low oxygen dilution combustion in an on-board reforming gas turbine system was numerically predicted. This is expected to greatly contribute to the study to improve the stability of moderate or intensive low oxygen dilution combustion in the future.     

微型燃气轮机低热值燃料燃烧室喷嘴流动实验研究

为适应生物质气低热值、组分变化大的特点,达到燃烧室燃烧稳定、低排放要求,在某60 kW级微型燃气轮机环形燃烧室结构的基础上,新设计了一种具有不同预混孔结构的新喷嘴,并在上海交通大学微型燃气轮机单喷嘴燃烧室实验台上对原喷嘴及新设计喷嘴进行冷态流动实验,对比分析不同稀释孔直径及工质参数条件下原喷嘴及新喷嘴对燃烧室空气流量分配比及过量空气系数的影响。研究表明:燃料流量、空气流量变化会影响燃烧室空气流量分配,空气温度变化对燃烧室空气流量分配无影响;燃料热值降低会导致燃烧室过量空气系数增大,需要匹配直径更大的燃烧室稀释孔;相比于原喷嘴新喷嘴的流量分配比较大,为使其适应低热值燃料,需要匹配的燃烧室稀释孔直径为11.0 mm,该条件下新喷嘴可适应CH_4摩尔分数为50%~90%的燃料。     

燃气轮机燃油喷嘴性能试验研究

建立了燃气轮机检修时燃油喷嘴的试验检测台架,并利用此台架对某型燃气轮机燃油喷嘴的流量、喷嘴锥角、喷射质量等参数进行了检测,按标准对喷嘴进行了更换,保证了燃气轮机修后的安全性和可靠性。     

An overview on dry low NOx micromix combustor development for hydrogen-rich gas turbine applications

The paper presents a survey of the interactive optimization cycle at Aachen University of Applied Sciences, used for the development of a new low emission Micromix combustor module for application in hydrogen fueled industrial gas turbines. During the development process, experimental and numerical methods are applied to optimize a given baseline combustor with 0.3 mm nozzles with respect to combustion efficiency, combustion stability, higher thermal power output per nozzle and reduced manufacturing complexity.Within the described research cycle combustion and flow simulations are used in the context of parametric studies for generating optimized burner geometries and the phenomenological interpretation of the experimental results. Experimental tests, carried out on an atmospheric combustion chamber test stand provide the basis for validation of simulation results and proof of the predicted combustion characteristics under scaled down gas turbine conditions.In the presented studies, an integration-optimized Micromix combustor with a nozzle diameter of 0.84 mm is tested at atmospheric pressure over a range of gas turbine operating conditions with hydrogen fuel. The combustor module offers an increase in the thermal power output per nozzle by approx. 390% at a significant reduced number of injectors when compared to the baseline design. This greatly benefits manufacturing complexity and the robustness of the combustion process against fuel contamination by particles.During atmospheric testing, the optimized combustor module shows satisfactory operating behavior, combustion efficiency and pollutant emission level. Within the evaluated operating range, which correlates to gas turbine part-, full- and overload conditions, the investigated combustor module exceeds 99% combustion efficiency. The Micromix combustor achieves NO_x emissions less than 2.5 ppm corrected to 15 Vol% O₂ at the design point.Based on numerical analyses and experimental low pressure testing, a full-scale gas turbine combustion chamber is derived. High pressure testing in the auxiliary power unit Honeywell/Garrett GTCP 36–300 shows stable operation during acceleration of the engine, during IDLE and during load variations between IDLE and Main Engine Start (MES) mode. Throughout the investigated operating range, the combustion chamber generates low NO_x emissions under full-scale gas turbine conditions.     

尾气颗粒对可变混流涡轮增压器喷嘴环冲蚀磨损特性的数值模拟

可变涡轮增压器在运行过程中其涡轮喷嘴环会受到尾气颗粒的冲蚀磨损,造成喷嘴环叶片失效和涡轮运行效果下降。借助CFD软件对可变混流涡轮内部的气固两相流进行数值模拟计算,分析喷嘴环开度的变化和颗粒粒径对喷嘴环磨损规律的影响。结果表明：喷嘴环处于不同开度下时,磨损率和磨损区域均有所不同,磨损区域主要集中在喷嘴环压力面的中后段区域,随着开度的增大,磨损率和磨损区域均减小,压力面的磨损程度明显大于吸力面;尾气中的小颗粒因惯性较小对气流的跟随性较好,主要撞击喷嘴环前缘,且开度对喷嘴环前缘的磨损影响较小;尾气中大颗粒的运动轨迹趋于直线,主要撞击喷嘴环压力面的中后段区域;由于涡轮进气涡壳结构的周向不对称性,使得涡轮内部流场沿周向分布不均匀,导致不同周向位置的喷嘴环磨损率和磨损区域有所不同,且随着开度的增大,各喷嘴环之间的磨损差异也增大。