某柴油机怠速燃烧噪声的试验研究

针对某柴油机怠速工况的燃烧噪声进行了试验研究,通过调整轨压、喷射模式、提前角、预喷量和预喷间隔等5个影响燃烧的标定参量,测试了不同状态的燃烧压力和排放烟度,通过缸压数据计算得到燃烧噪声,分析了各标定参量对燃烧噪声的影响,同时考虑排放烟度,给出了怠速燃烧噪声最优的标定参量组合,确定了对燃烧噪声影响较大的标定参量,为后期全MAP优化燃烧噪声提供方向和参考。     

内燃机燃烧模拟现状及应用的研究

传统的内燃机燃烧过程的探索主要通过燃烧实验,但受实验条件、检测条件等多方面限制,燃烧过程很难被控制,研究针对内燃机燃烧模拟方向进行现状分析及应用探讨,减少了燃烧实验难度,内燃机的燃烧决定了内燃机的动力效果与经济价值,对内燃机的排放与环境影响程度也有着重要影响作用。     

汽油机燃烧噪声的多元回归分析

为了更合理地评估发动机燃烧噪声,将燃烧噪声按传递路径不同分为直接燃烧噪声和间接燃烧噪声。基于两种燃烧噪声的传递函数不随发动机工况变化而变化,在每个频率下建立缸压、缸压引起的转矩力与燃烧噪声之间多元回归模型并求解回归系数,得到相应频率下的直接燃烧噪声和间接燃烧的传递系数。对25 Hz~20 000 Hz频率范围内两种燃烧噪声传递函数进行了计算和分析,结果表明:在各个中心频率下的多元回归模型拟合度较高,说明应用此方法获取的直接和间接燃烧噪声传递系数比较准确;直接燃烧噪声和间接燃烧噪声的传递函数在2 000 Hz左右频率段均存在峰值;该汽油机在25 Hz~1 250 Hz频率范围内,间接燃烧噪声高于直接燃烧噪声,在1 250 Hz~20 000 Hz频率范围内,直接燃烧噪声高于间接燃烧噪声。     

帮助燃烧控制的在线分析仪

燃烧控制专家们在确立燃烧调节控制对策耐,早就认识到测量过剩氧的重要意义。而近几年来,开发了一些也能监测一氧化碳和未燃烧烃类的燃烧分析仪器。这样,使燃烧控制专家们能更深入地了解到燃烧过程中另外一些产物的影响。本文着重分析CO/O_2分析器在燃烧控制中的作用。     

烟草燃烧行为的研究进展

烟草的燃烧过程复杂,学者们利用热裂解-气相色谱-质谱联用技术（PY-GC-MS）、热重分析仪（TG）和热重-红外-气质（TG-IR-GC-MS）联用等热分析技术,从不同方面对烟草的燃烧行为进行研究。本文综述了国内外有关烟草燃烧行为的研究进展,分别从燃烧机理、燃烧行为学、热分析计算模型以及研究烟草燃烧所采用的热分析技术这四个方面进行了概述。并对研究烟草燃烧行为方面进行了总结和展望。     

多孔介质式发动机燃烧系统的分析

本文在分析了多孔介质燃烧技术基础上,又对该技术在发动机上的应用进行了详细的分析。将多孔介质燃烧技术运用到发动机上可以降低排放、提高循环热效率、使燃烧温度稳定和燃烧温度均衡。多孔介质燃烧技术的应用能够解决自由火焰固有的问题,实现混合气与多孔介质之间以及燃烧产物与多孔介质之间的快速换热。     

涡流强度对增压柴油机燃烧和排放特性影响的仿真研究

文章首先建立了16V132增压柴油机的燃烧系统仿真模型,之后进行了不同涡流强度方案下的整机燃烧过程CFD仿真计算,分析了涡流强度对发动机发电工况下的燃烧特性和排放特性影响规律,最终确定了合适的燃烧过程涡流比,为16V132增压柴油机燃烧系统的匹配设计提供理论指导。     

生物质成型颗粒燃料气化锅炉的设计研究

根据生物质成型颗粒燃料特性及燃烧规律,通过详细的热工计算设计了生物质成型颗粒燃料气化锅炉。锅炉采用往复炉排,增强了炉膛燃烧强度,高的炉膛高度使得锅炉气化燃烧的程度增加,从而提高了锅炉的燃烧效率和热效率。     

基于EGR的柴油机燃烧过程研究

目前柴油机研究的热点方向之一是如何改善燃烧过程,保证柴油机排放能够满足日趋严格的法规要求。要想达到清洁高效燃烧,这对燃烧过程进行控制必须有非常高的要求。研究了传统燃烧理论与新型低温燃烧理论,并对基于EGR不同策略如何实现柴油机低温燃烧进行分析研究,通过数据对比与图文解释重点阐述,另外对EGR如何改变燃油喷射参数、燃烧相位、含氧燃料等进行探讨,为保障清洁高效的低温燃烧提供较好的参考依据。     

内燃机燃烧研究及面临的挑战

内燃机的燃烧是一个化学反应和能量转换的过程,它涉及到许多学科,内燃机的燃烧过程还没有被人研究透彻,比如燃烧过程中碳粒的生成。严格的排放法规和油耗指标将会推动内燃机的进一步发展,另外,一些新的概念也会推进内燃机燃烧方面的研究。燃烧的优化和燃烧后的处理技术是实现低污染和零排放的重要途径。本文分析了内燃机燃烧研究和今后面临的各种挑战。     

内燃机工作过程模拟分析与研究

采用FIRE软件进行了内燃机工作过程的数值模拟分析,得到与排气噪声影响因素有关的燃烧气体的温度、压力参数,同时还得到了在这些工况下NOx的排放情况,为发动机的燃烧、排放以及燃烧室的优化设计等的研究提供了基础,同时还为进一步设计发动机消声器提供了信息。     

内燃机工作过程模拟分析与研究

采用FIRE软件进行了内燃机工作过程的数值模拟分析,得到与排气噪声影响因素有关的燃烧气体的温度、压力参数,同时还得到了在这些工况下NOx的排放情况,为发动机的燃烧、排放以及燃烧室的优化设计等的研究提供了基础,同时还为进一步设计发动机消声器提供了信息。     

Characteristics of self-excited combustion oscillation and combustion control by forced pulsating mixture supply

Characteristics of self-excited combustion oscillation are experimentally studied using confined premixed flames stabilized by a rearward-facing step. A new idea to suppress combustion oscillation was applied to the flames. The characteristics of unsteady combustion were examined, which is driven by forced pulsating mixture supply that can modulate its amplitude and frequency. The self-excited combustion oscillation having weaker flow velocity fluctuation intensity than that of the forced pulsating supply can be suppressed by the method. The effects of the forced pulsation amplitude and frequency on controlling self-excited combustion oscillations were also investigated comparing with the steady mixture supply. The unsteady combustion used in this experiment plays an important role in controlling self-excited combustion oscillations, and it also exhibits desirable performances, from a practical point of view, such as high combustion load and reduced pollutant emissions of nitric oxide.     

Combustion and heat transfer characteristics inside the combustion chamber of a wood pellet boiler

A grate-firing boiler was developed for wood pellet fuel, and then its combustion characteristics were tested. The flame was stretched to the exit of the combustion chamber, implying insufficient space for complete combustion. As a first step to resolve this problem, a numerical simulation was conducted for the combustion chamber. Turbulent and chemically reacting flow was considered by implementing a homogeneous reaction model. Flow field from the simulation showed strong recirculation flow at the upstream corner of the chamber, along which the flame was stretched to the exit. Based on these results, we suggest possible modification of the combustion chamber to improve combustion characteristics, such as relocating its exit or installing internals like guide vanes.     

浅析流化床锅炉特点、现状及发展前景

流化床技术是一种具有煤种适应性广、高效、清洁的燃烧技术，近年来发展很快。常压流化床(AFBC)已由第一代鼓泡流化床发展到第二代循环流化床(CFBC)，旋涡流化床、增压流化床(PFBC)已进入商业运行阶段，流化床燃烧技术的应用亦由工业锅炉发展到电站锅炉。本文简要介绍流化锅炉的特点、现状及发展前景。     

A study on the characteristics of combustion variations of compression ignition engine

This paper describes the results of a study of the variation of combustion characteristics in a precombusion chamber type water-cooled diesel engine. Statiscal analysis on cycle-by-cycle variation of combustion characteristics such as rate of pressure rise, heat release rate, and mass burning rate from combustion pressure-crank angle data of one thousand cycles were made under several operating conditions. The influence of engine speed and coolant temperature upon maximum frequency of combustion characteristics are discussed also.     

Combustion instability mechanism of a lean premixed gas turbine combustor

Lean premixed combustion has been considered as one of the promising solutions for the reduction of NOx emissions from gas turbines. However, unstable combustion of lean premixed flow becomes a real challenge on the way to design a reliable, highly efficient dry low NOx gas turbine combustor. Contrary to a conventional diffusion type combustion system, characteristics of premixed combustion significantly depend on a premixing degree of combusting flow. Combustion behavior in terms of stability has been studied in a model gas turbine combustor burning natural gas and air. Incompleteness of premixing is identified as significant perturbation source for inducing unstable combustion. Application of a simple convection time lag theory can only predict instability modes but cannot determine whether instability occurs or not. Low frequency perturbations are observed at the onset of instability and believed to initiate the coupling between heat release rate and pressure fluctuations.     

基于图像卷积变分自编码的电站锅炉 燃烧稳定性评价方法

为实现基于电站锅炉火焰图像的燃烧稳定性定量表征,并克服不稳定燃烧样本不足的训练难题,提出一种基于卷积变分自编码模型的燃烧稳定性实时、定量表征方法。首先使用稳定燃烧工况下的火焰图像进行模型训练,利用卷积变分自编码器得到稳定燃烧图像的高维潜在概率分布。记录该模型对应的隐变量分布特征,计算该分布与标准正态分布之间的KL散度值,利用该KL散度实现燃烧稳定性的定量表征。在仿真验证中,通过对比说明引入变分推断理论可提高模型对于燃烧图像的重构质量,图片重构前后均方根误差为0.005 48;通过磨煤机给煤量调整实验,人为制造不同稳定度的燃烧器燃烧工况,验证了该评价方法的准确性和有效性,评价准确率高达92.1%;通过与煤火检评价结果的比较,表明该方法具备煤火检系统对于火焰的定量判断功能,且感知能力更加灵敏,能在燃烧器灭火前167 s给出燃烧不稳定的预警,具有一定的工程应用价值。     

Symptoms of self-excited combustion oscillation and their detection

Monitoring of OH chemiluminescence through an optical fiber was demonstrated to be a useful method in detecting self-excited combustion oscillations. OH chemiluminescence intensity detected by the optical fiber showed mostly excellent agreement with those obtained by high speed CCD camera measurements when combustion oscillations were strong. Symptoms of self-excited combustion oscillation were also studied in order to predict the onset of combustion oscillation before it proceeded to a catastrophic failure. For the purpose, we have found and proposed unique measures to tell the onset of self-excited combustion oscillations based on the careful statistics of fluctuating properties in flames, such as pressure or emission of OH radicals.