利用同步辐射研究正庚烷火焰燃烧特性

利用同步辐射单光子电离和分子束取样技术并结合飞行时间质谱仪,在低压、预混、燃油当量比为1.0情况下研究正庚烷层流火焰的燃烧特性.共检测出24种中间产物,并计算出其摩尔分数.在燃烧反应前期,主要中间产物是酮、醚类物质.在燃烧反应后期,主要中间产物是碳氢化合物,燃烧反应前期的中间产物在燃烧反应后期继续氧化.乙烯在所有中间产物中摩尔分数最大的.另外,火焰中丙炔与苯有极大的相关性.     

同步辐射单光子电离技术研究乙醚富燃火焰

本文利用同步辐射单光子电离和分子束质谱技术研究了乙醚在富燃条件下的低压预混火焰.通过测量光电离质谱和扫描光电离效率谱,我们鉴别了该火焰中大部分的燃烧中间体及产物.此外,通过改变燃烧炉的位置测量光电离质谱,得到了各燃烧中间体及产物的摩尔分数曲线.实验结果为深入研究乙醚燃烧动力学并揭示含氧有机化合物在火焰中的反应机理提供了依据.     

Photoionization and Dissociative Photoionization Study of Cholesterol by IR Laser Desorption/Tunable Synchrotron VUV Photoionization Mass Spectrometr

介绍了一种将红外激光解吸/真空紫外光电离质谱技术应用于分析胆固醇的新方法. 由于近阈值单光子电离作用,可以在低能量下只产生纯净的胆固醇分子离子峰;增加光子能量则可以使碎片离子峰大量出现. 为了验证碎片离子的归属,利用商用高分辨电子轰击电离-飞行时间质谱仪分析并指认了胆固醇主要的碎片峰. 此外,采用量子化学从头算的方法研究了胆固醇母体离子和碎片构型,并讨论了部分主要的光解离机理     

355 nm激光作用下苯甲醚的多光子电离质谱研究

在355 nm激光作用下,利用多光子电离技术结合飞行时间质谱(TOF-MS)对苯甲醚分子进行了研究。实验结果表明苯甲醚分子的多光子电离机制属于母体分子电离-解离模型。通过对主要碎片离子的可能形成过程的讨论,得出该波长下母体分子离子解离的主要有两种通道,但是随激光能量的增强,甲基移除通道逐步占据优势成为主要通道。应用高斯软件采用HF/6-31G(d) 方法对苯甲醚分子和苯甲醚阳离子基态的几何构型进行优化得到其稳定构型,并计算了苯甲醚分子离子及其初级解离产物的能量。比较两条通道的碎片离子能量的变化,理论验证了实验中苯甲醚分子主要解离通道的合理性。     

CH3I分子在440—510nm激光作用下多光子电离

利用飞行时间质谱仪研究了CH₃I分子在440—510nm波段的多光子电离(MPI)机理.在该波段，CH₃I分子吸收三光子激光能量与(5pπ,6p)里德伯态高频端发生共振，然后继续吸收光子电离解离成最终产物离子. 关键词：     

异辛烷/正庚烷混合燃料燃烧中间产物的浓度分布特性

用同步辐射单光子电离和分子束取样技术结合飞行时间质谱仪,在低压预混层流火焰中测量异辛烷/正庚烷混合燃料(体积比9:1)在当量比为1.0时燃烧的主要中间产物.检测出24种主要中间产物,计算各种物质的摩尔分数,对其空间浓度分布进行比较分析,得出不同温度下的物质生成历程.添加金属矿物质可以明显改变热解过程中燃料氮向N2的转化特性.     

同步辐射研究汽油火焰中的成分

利用同步辐射和分子束取样技术研究了汽油与氧气低压预混火焰的燃烧产物,得到汽油燃烧火焰中部的光电离飞行时间质谱图以及一些成分的电离能.与文献中的电离能比较后可以确定火焰中产物的具体结构.通过空间分布曲线着重分析了五种有害物质的反应过程,为建立燃烧反应动力学模型奠定了基础.     

1,2-环氧辛烷的同步辐射光电离解离研究

利用同步辐射产生的真空紫外光和反射式飞行时间质谱仪,在超声冷却条件下测量了1,2-环氧辛烷在光子能量9.8~16.6 eV能区的光电离解离过程,获得了不同能量光子作用下的电离解离产物。通过测量各离子的光电离效率曲线,得到了主要碎片离子的出现势。结合G3理论计算得到了母体离子、中性碎片及离子碎片的结构与能量,通过对比实验测量值与理论值给出了1,2-环氧辛烷的光电离解离通道.     

二甲醚/氧气/氩气低压层流预混燃烧研究

利用同步辐射真空紫外单光子电离结合分子束质谱技术,对当量比φ=1.5的低压预混层流二甲醚火焰进行了实验研究。通过测量光电离质谱和光电离效率曲线,探测到了二甲醚/氧气/氩气的燃烧产物和火焰中间物,包括不稳定的分子和自由基。通过测量离子信号的空间分布曲线,计算了二甲醚/氧气/氩气火焰的主要物种C_2H_6O、O_2、Ar、H_2、H_2O、CO和CO_2的摩尔分数曲线,以及主要中间物种如CH_2O、C_2H_2、C_2H_4、CH_3OH、C_2H_2O、C_2H_4O、CH_3、CH_4、HCO、C_3H_3和C_3H_4的摩尔分数曲线,并分析了主要中间物种的产生和消耗过程。     

在超声分子束下气相四甲基硅分子的多光子解离与电离

采用超声分子束技术，以飞行时间质谱仪，在４１０～３７１ｎｍ内着重检测了不同波长、不同能量的激光对气相Ｓｉ（ＣＨ３）４分子多光子电离（ＭＰＩ）飞行时间（ＴＯＦ）质谱产物分布的影响。根据实验结果，对Ｓｉ（ＣＨ３）４分子多光子解离电离可能经历的通道和反应机理进行了讨论。     

Analysis of Aluminum Dust Cloud Combustion Using Flame Emission SpectroscopySCIEI北大核心CSCD

In this study, aluminum flame analysis was researched in order to develop a measurement method for high-energy-density metal aluminum dust cloud combustion, and the flame temperature and UV-VIS-IR emission spectra were precisely measured using a spectrometer. Because the micron-sized aluminum flame temperature was higher than 2 400 K, Flame temperature was measured by a non-contact optical technique, namely, a modified two-color method using 520 and 640 nm light, as well as by a polychromatic fitting method. These methods were applied experimentally after accurate calibration. The flame temperature was identified to be higher than 2 400 K using both methods. By analyzing the emission spectra, we could identify AlO radicals, which occur dominantly in aluminum combustion. This study paves the way for realization of a measurement technique for aluminum dust cloud combustion flames, and it will be applied in the aluminum combustors that are in development for military purposes.     

Analysis of Aluminum Dust Cloud Combustion Using Flame Emission Spectroscopy

In this study, aluminum flame analysis was researched in order to develop a measurement method for high-energy-density metal aluminum dust cloud combustion, and the flame temperature and UV-VIS-IR emission spectra were precisely measured using a spectrometer. Because the micron-sized aluminum flame temperature was higher than 2 400 K, Flame temperature was measured by a non-contact optical technique, namely, a modified two-color method using 520 and 640 nm light, as well as by a polychromatic fitting method. These methods were applied experimentally after accurate calibration. The flame temperature was identified to be higher than 2 400 K using both methods. By analyzing the emission spectra, we could identify AlO radicals, which occur dominantly in aluminum combustion. This study paves the way for realization of a measurement technique for aluminum dust cloud combustion flames, and it will be applied in the aluminum combustors that are in development for military purposes.     

图象处理技术用于发光火焰温度分布测量的研究

一、前言 火焰温度的测量是一个难题,发光火焰温度分布的测量则更加困难。现有的各种测温方法都难以直接用来测量发光火焰的温度分布,故本文提出采用图象处理法测定发光火焰,特别是煤粉火焰的温度分布。火焰图象是工业燃烧宏观、整体过程的充分反映,也是控制燃烧的直接观察对象。通过对发光火焰图象信息的分析、处理和计算可获取其温度和温度分布,进而可求得反映燃烧状态的其他特征。     

应用预蒸发技术燃烧液体燃料

本文介绍了一种燃烧液体燃料的新技术－预蒸发燃烧技术：通过分离液体燃料的蒸发过程和燃烧过程,实现液体燃料的“气体化”燃烧;重点介绍利用液体燃料着火前存在的冷焰燃烧现象实现燃料预蒸发的技术原理。与传统的燃烧技术相比,液体燃料的预蒸发燃烧具有高效率、低噪音、低有害污染物特别是ＮＯｘ排放、和易调节等优点。     

Flame stabilization with a tubular flame

A new technique to stabilize a flame in a high-velocity stream with use of a tubular flame has been proposed. To elucidate the validity of this technique, an experiment has been conducted by mounting a tubular flame burner on the nozzle. Flame stability limits and temperature distributions around the burner port have been determined, and experiments have been extended to the ducted combustion to measure pressure fluctuations and to analyze the burned gases. Results show that the tubular flame can successfully stabilize the main flame up to 130 m/s, which is the upper limit of the present supply facility. The main flame is well anchored at the exit of the nozzle, and the tubular flame efficiently supplies heat and radicals to the main flame. In the ducted combustion, the pressure fluctuations are reduced significantly. The exhaust gas analyses, however, indicate that an almost chemical equilibrium condition can be achieved at 50 m/s, but not at 90 and 130 m/s. Since the energy input relative to the main flame is just 6.1% at 130 m/s, the present tubular burner is not enough to burn all the unburned gas completely at high velocities, although the main flame can be anchored. The slit length and/or the slit width of the tubular flame burner should be larger to overcome this shortage. From the above results, it is concluded that the tubular flame has a potential for stabilizing a flame in a high-speed stream.     

Further investigation on the enhancement of flame speed in vortex ring combustion

Enhancement of flame speed in vortex ring combustion has been investigated experimentally. The flame speed and the maximum tangential velocity for each vortex ring were simultaneously measured with a PIV system and a high speed camera. To vary the extent of the enhancement, methane/hydrogen mixtures were used. Furthermore, rich mixtures were used as a source of vortex ring so that the situation of the experiment and the results could be applied more directly to practical use. Results have confirmed that enhancement of flame speed does occur in vortex ring combustion of rich methane/hydrogen mixtures in air. The extent of the enhancement becomes larger as the hydrogen content is increased. The flame speed reaches about twice as high as the maximum tangential velocity for pure hydrogen. Based on momentum conservation across the flame, a simple equation on the ratio of the flame speed to the maximum tangential velocity has been obtained, which has shown that the flame speed enhancement can be explained successfully by considering the spherically expanding type premixed combustion behind the flame. The pressure rise of a spherically expanding type premixed flame can explain the flame speed enhancement observed in the present rich methane/hydrogen vortex ring combustion.     

Combustion at the focus: laser diagnostics and control

Fifty years after the foundation of the Combustion Institute and almost 150 years after Michael Faraday’s famous lectures on the combustion of a candle, combustion diagnostics have come a long way from visual inspection of a flame to detailed analysis of a combustion process with a multitude of sophisticated techniques, often using lasers. The extended knowledge on combustion phenomena gained by application of these diagnostic techniques, combined with equally advanced numerical simulation of the process, has been instrumental in designing modern combustion devices with efficient performance and reduced pollutant emission. Also, similar diagnostic techniques are now employed to develop sensors for process control in combustion. This article intends to give a perspective on the potential of combustion diagnostics by highlighting selected application examples and by guiding the reader to recent literature. In particular, techniques are emphasized, which permit measurement of important features of the chemical composition, sometimes in conjunction with flow field parameters. Although a complete image of present research and applications in combustion diagnostics and control is beyond the scope of this article, this overview may be a starting place where ideas may be found to solve specific combustion problems with the aid of diagnostics.     

Imaging and diagnostics of turbulent methane-air premixed flames by acetone-OH simultaneous PLIF

A strategy of diagnostics of ultra-lean combustion based on acetone-OH simultaneous PLIF is presented. Acetone seeded in the fuel flow and combustion-generated OH work for a marker of \ldunburned\rd and \ldburnt\rd zones, respectively. Since acetone and OH does not coexist when the proper combustion takes place, the signal \ldvalley\rd (dark zone) between acetone and OH fluorescence can be detected, which corresponds to flame zone; representative of the combustion status. System required for current imaging technique is one-laser and one-detector combination with \ldturned\rd band-pass filter. Transmittance characteristics of the filter and acetone-seeding rate are key issues to attain clear imaging, and we found that there is proper combination of them for that purpose. Imaging demonstration for the turbulent premixed flames shows the usefulness and applicability of this scheme on complex flame diagnostics: unique flame broken flame structure (\ldunburned\rd or \ldburnt\rd islands exist separately) are clearly obtained by this approach.     

Large Eddy Simulation of a turbulent lifted flame using multi-modal manifold-based models: Feasibility and interpretability

A general model for multi-modal turbulent combustion is achievable with two-dimensional manifold equations that use the mixture fraction and a generalized progress variable as coordinates. Information about the underlying mode of combustion is encoded in three scalar dissipation rates that appear as parameters in the two-dimensional equations. In this work, Large Eddy Simulation (LES) of a multi-modal turbulent lifted hydrogen jet flame in a vitiated coflow is performed using this new turbulent combustion model, leveraging both convolution-on-the-fly and In-Situ Adaptive Tabulation for computational tractability. The simulation predicts a lifted flame consistent with observations from past experiments. The feasibility of such a model implemented in LES is examined, and the cost per timestep is found to be comparable to conventional one-dimensional manifold-based models describing one asymptotic mode of combustion. Additionally, the model provides clear interpretability, allowing for combustion mode analysis to be performed with ease by evaluating the scalar dissipation rates and generalized progress variable source term. This analysis is used to show that the flame is stabilized by autoignition and has a trailing nonpremixed flame. Furthermore, transport of progress variable from the most reactive mixture fraction towards richer mixtures at the centerline is found to be important.     

Continuous 100 Hz planar laser-induced fluorescence applied to the study of combustion processes

In this paper, a 100?Hz planar laser-induced fluorescence system based on the off-shelf commercial laser and self-made intensified camera is presented, which is low cost and maintainable to be applied in practical combustion research. By using this device, 100?Hz continuously planar laser-induces fluorescence laser combustion diagnostics was conducted. To evaluate this device, both laboratorial combustors and a scramjet combustor were studied. In these experiments, the structure of flame and expansion and the oscillation process of combustion can be resolved.