推进剂燃烧火焰温度CARS测试技术问题的探讨

论述了推进剂燃烧CARS(Coherent Anti-Srokes Raman Scattering)测温中烟尘及其产生的碎片C2基和激光强度对测温的影响,探讨了时间分辨率和空间分辨率对推进剂燃烧测温的重要性,表明研究推进剂火焰烟尘对CARS测温精确度影响的必要性,实现高时空分辨率的重要性。     

双基推进剂燃烧火焰温度CARS测定技术

得到了双基推进剂燃烧火焰CARS实验谱图及相应的温度拟合值。实测结果表明，燃烧火焰平衡区的CARS实验拟合温度数值与相应的热力学计算温度值基本吻合，连续采集的CARS谱显现的温度梯度说明CARS技术可以应用于推进剂燃烧火焰温度的实时诊断。     

Al粉含量对CMDB推进剂特征信号的影响

采用烟雾透射计、红外热像仪、FTIR光谱仪和高速摄像仪等测试仪器研究了Al粉含量对CMDB推进剂可见光、红外和激光透过率、红外辐射温度和红外辐射强度等特征信号的影响规律.结果表明,随Al粉含量增大,CMDB推进剂燃气尾焰的可见光、红外和激光透过率显著降低,红外辐射温度、强度、火焰长度和宽度明显增大.Al粉含量对推进剂燃烧产物的种类影响不大.     

NEPE推进剂燃烧机理研究

应用微热电偶测温和燃烧火焰单幅照相技术测得 NEPE推进剂在稳态燃烧条件下的燃烧波温度分布及火焰结构 ,研究了该推进剂中主要组分对燃烧性能的影响 ,同时利用扫描电镜 -能谱仪观测了熄火表面形貌和元素分布规律。经过综合分析 ,提出了 NEPE推进剂的燃烧过程 ,为该类推进剂燃烧物理模型的建立奠定了基础     

宽带CARS在诊断固体推进剂燃烧场中的应用

为了测量固体推进剂燃烧场温度和氮气组分的浓度,建立了10 Hz重复频率运转的宽带CARS实验系统.结果表明,氮气CARS谱测量温度的相对不确定度优于4%;在较低浓度范围内,测量组分浓度的相对不确定度优于5%.采用宽带CARS技术测量了常压和2 MPa背景压力下固体推进剂燃烧场,获得了较高信噪比的单次脉冲氮气CARS实验谱,用CARS理论计算软件拟合CARS实验谱给出了固体推进剂瞬态燃烧场温度和氮气浓度随高度的分布.     

DNTF-CMDB推进剂的燃烧机理（英文）

采用燃烧火焰单幅照相技术、微热电偶测温和扫描电镜-能谱仪研究了DNTF-CMDB推进剂的火焰结构、燃烧波温度分布、熄火表面形貌及元素分布。结果表明,含10%DNTF改性双基推进剂的火焰结构为预混火焰,其燃烧波结构与双基推进剂类似。含50%DNTF改性双基推进剂的火焰结构为扩散火焰,其燃烧波结构与AP-HTPB复合推进剂类似。燃烧表面炭物质的减少是推进剂压强指数升高的主要原因。     

红外辐射吸收法测量火焰温度

简述了几种温度测量的方法，介绍了红外辐射吸收法测温原理及实验装置，并对稳定的煤气火焰进行温度测量，试图在此基础上测量固体推进剂火焰的温度。     

含TKX-50推进剂能量性能及特征信号研究

为考察含TKX—50(1,1′—二羟基—5,5′—联四唑二羟胺盐)推进剂能量性能及特征信号,理论计算不同含量TKX—50分别取代硝胺炸药、AP(高氯酸铵)、Al时推进剂能量变化,通过理论及试验研究含TKX—50推进剂燃烧产物烟雾状况。结果表明:TKX—50取代硝胺炸药时,随TKX—50含量增加,推进剂密度及比冲均呈上升趋势;取代AP时,随TKX—50含量增加,推进剂密度呈下降趋势,比冲先上升后下降;取代Al时,随TKX—50含量增加,推进剂密度及比冲均呈下降趋势;随TKX—50含量增加,AP、Al含量降低,推进剂可见光透过率、红外光透过率、激光透过率均呈上升趋势,从而在保证能量的同时可降低推进剂特征信号。     

含AP包覆硼的富燃推进剂燃烧机理研究

通过微热电偶测温和火焰单幅照相技术测试了含硼富燃料推进剂燃烧波温度分布及燃烧火焰结构;用扫描电镜对熄火表面形貌进行了观察,并通过能谱仪进行局部元素分析;对DSC曲线进行积分,得到推进剂的凝相放热量;测量推进剂燃烧的爆热和低压燃速,获得了其低压燃烧特性和一次燃烧放热情况。结果表明,含AP包覆硼的推进剂燃烧更剧烈,推进剂的绝热火焰温度更高,AP包覆硼提高了含硼富燃料推进剂的凝相放热、爆热和低压燃速。初步确定了该类推进剂的燃烧过程,为建立含硼富燃料推进剂燃烧物理模型提供了依据。     

基于图像传感器的推进剂发烟量测试方法

提出了一种基于图像传感器的推进剂发烟量测试方法。用平行光管代替传统测试装置中的卤素钨灯,用图像传感器代替传统测试装置中的光电二极管或光敏电阻,设计了一种表面有镂空条纹的遮光罩对光源信号进行调制,采取图像数据处理方法消除环境噪声对测试结果的影响。测量了SQ2推进剂、Al-CMDB推进剂和NEPE推进剂燃烧烟雾的发烟量。结果表明,SQ2推进剂和Al-CMDB推进剂的烟雾透过率曲线在点火后50s左右基本稳定;NEPE推进剂燃烧的烟雾光透过率曲线在点火50s后稳定,但有缓慢上升趋势;3种推进剂烟雾光透过率分别为84.1%、65.9%、22.3%,与传统测试方法一致。     

钾盐对发射药静态燃烧烟焰性能的影响

为研究钾盐对发射药静态燃烧烟焰性能的影响,以含钾盐的发射药样品为对象,采用单幅放大彩色摄影法、微热电偶测温法以及双光路透射率系统,研究了硫酸钾(K2SO4)、硝酸钾(KNO3)、新型有机钾盐(DK、HK、LK、JK和PK)等对发射药燃烧时的火焰形貌、火焰峰温、烟雾可见光透光率的影响。结果表明,无机钾盐K2SO4对发射药静态燃烧火焰大小和峰温的抑制效果最好,但会使发射药静态燃烧时的烟雾可见光透过率大大降低;高氧含量的新型有机钾盐DK、HK及LK对发射药静态燃烧火焰大小和峰温有较好的抑制效果,并且含新型有机钾盐的发射药静态燃烧时的烟雾可见光透过率较高,3种含高氧含量钾盐(LK、DK和HK)的发射药的烟雾可见光透过率均大于50%;钾盐的粒径从104μm减小到5μm时,消焰效果得到提高,但烟雾可见光透过率的变化规律并不一致。     

Sooting and non-sooting propylene diffusion flames with irradiation of laser light

The structural change in co-flow propylene diffusion flames by irradiation of laser light is experimentally investigated to examine the effect of soot radiation at a certain position. The soot volume fraction and the flame/soot temperatures are measured by laser extinction and two-color-ratio pyrometry techniques. Transitions from a non-sooting to a sooting flame and vice versa are observed to depend on the irradiated positions of laser light. The structural change could be attributed to the following processes. When laser light is irradiated at the soot-formation region (lower part in the flame), the temperature of soot particles is increased by absorption of laser energy; the raised temperature enhances soot formation and increases the local volume fraction of soot. The increased amount of soot enhances the radiation loss and eventually lowers the flame temperature at the downstream direction. As a result, the soot-oxidation process is suppressed, and finally a non-sooting flame transforms to a sooting flame. The laser light irradiated at the competing section of soot formation and oxidation or at the oxidation section (upper part of the flame) also increases the temperature of soot particles, however, the increased soot temperature mostly enhances soot oxidation in these regions. Therefore, a decreased amount of soot lowers the radiation loss from the flame and maintains the flame temperature relatively high, compared with that without irradiation of laser light. As a result, the soot-oxidation process is more enhanced, and finally the transition from a sooting flame to a non-sooting flame occurs. __________ Translated from Fizika Goreniya i Vzryva, Vol. 42, No. 6, pp. 74–81, November–December, 2006.     

利用简化的化学反应动力学模型耦合CFD代码模拟气体燃烧器中的烟黑生成(英文)

A computational study of soot formation in ethylene/air coflow jet diffusion flame at atmospheric pressure was conducted using a reduced mechanism and soot formation model. A 20-step mechanism was derived from the full mechanism using sensitivity analysis, reaction path analysis and quasi steady state (QSS) approximation. The model in premixed flame was validated and with computing savings in diffusion flame was applied by incorporating into a CFD code. Simulations were performed to explore the effect of coflow air on flame structure and soot formation. Thermal radiation was calculated by a discrete-ordinates method, and soot formation was predicted by a simple two-equation soot model. Model results are in good agreement with those from experiment data and detailed mechanism at atmospheric conditions. The soot nucleation, growth, and oxidation by OH are all enhanced by decrease in coflow air velocity. The peak soot volume fraction region appears in the lower annular region between the peak flame temperature and peak acetylene concentration locations, and the high soot oxidation rate due to the OH attack occurs in the middle annular region because of high temperature.     

Collection and Characterization of Soot from an Optical Fiber Preform Torch

To follow the development of particle morphology, silica soot is extracted from four axial positions in the flame of a torch used to manufacture optical fiber preforms by the vaporphase axial deposition method. The soot, collected by three extraction techniques, is analyzed by transmission electron microscopy and gas adsorption to identify which characteristics of the soot morphology are dependent on the sampling technique and which upon the position in the flame. Comparison is also made to other work in which silica soot was extracted from a nondiffusion flame.     

Evolution of structure and charge of soot aggregates during and after formation in a propane/air diffusion flame

Evolution of soot aggregate morphology, size and concentration is investigated during and after formation of soot in propane/air diffusion flame. Monitoring of gaseous intermediates in the flame is done by gas chromatography. Soot aggregate size and morphology are analyzed by a transmission electron microscope; soot number concentration is determined by an automated diffusion battery. Aggregate–aggregate collisions and aggregate structural transformations are observed in real time using a video system. It is determined that soot aggregates formed in flame are charged. The electric charge per aggregate is determined by video observation of aggregate movement in electric field. Both positively and negatively charged aggregates are formed. Typical net charge per aggregate is a few elementary units. An effect of soot aggregate restructuring from chain-like to compact structures is observed. It is determined that the driving force for this restructuring is Coulomb interactions between different parts of the aggregate. It is demonstrated that Coulomb interactions between aggregates can affect considerably coagulation process and the final aggregate shape.     

炭黑对一氧化氮的吸附反应性

在管式炉石英固定床反应器上研究了程序升温条件下炭黑与NO反应的规律,主要研究了不同NO浓度、温度条件下不同炭黑、反应气中存在CO₂、O₂及其浓度改变时炭黑对NO的还原规律等.实验材料为在扩散火炬中取样得到的天然气炭黑、蜡烛炭黑、丁烷火焰炭黑,同时还选用了一种烟煤焦炭.实验结果表明：各炭黑试样与NO的反应有明确的起始反应温度和较好的反应规律;天然气炭黑比其他炭黑具有更高的脱除率、最低的起始反应温度;炭黑的起始反应温度随着NO反应气浓度增大而升高;反应气中氧存在可以降低炭黑-NO起始反应温度和反应程度最大点温度;反应气中CO₂存在对天然气炭黑反应无影响,可以降低蜡烛炭黑和焦炭与NO起始反应温度,使反应分成两个阶段.     

Combustion synthesis of fullerenes and fullerenic nanostructures

Samples of condensable material collected from low-pressure premixed and diffusion benzene/oxygen/argon flames were analyzed chemically to determine fullerene yield and by high-resolution transmission electron microscopy to characterize the fullerenic material on and within the soot particles. Results show that fullerene formation is sensitive to changes in operating conditions, such as fuel/oxygen ratio, chamber pressure, and inert gas dilution, and that the formation of amorphous and fullerenic carbon occurs early in the flame, with the structures becoming more curved with greater residence time. All flames exhibit a fullerene maximum with the premixed flame showing two distinct regions of formation. Additionally, the fullerene maximum in the diffusion flames is always just above the stoichiometric flame surface and a maximum is observed with increasing dilution due to competing dilution effects. Image analysis data show that the curvatures and diameters of the structures are consistent with the chemical analysis and that nanostructures, found at greater residence times than fullerenes, are formed directly from curved structures in the soot. These data complement previous fullerene studies and shed light on several proposed mechanisms for fullerene formation in combustion.     

Catalytic oxidation kinetics of iron-containing carbon particles generated by spraying ferrocene-mixed with diesel fuel into a hydrogen-air diffusion flame

Kinetic measurements of the catalytic oxidation of iron-containing soot particles were made for a better understanding of the role of catalytic particles in the initiation of soot oxidation. Carbon-based iron-containing soot particles were generated by spraying ferrocene-mixed with diesel fuel into an oxy-hydrogen flame. A commercial carbon black was used as a standard. Their oxidative kinetics and physico-chemical characteristics were measured by thermogravimetric analysis, secondary ion mass spectrometry, X-ray diffraction, gas-cell Fourier-transform infrared spectroscopy, induced coupled plasma-atomic emission spectroscopy, and high-resolution transmission electron microscopy. It was found that a tiny amount of ferrocene led to a significant reduction in both the on-set temperature and the activation energy of soot oxidation. Catalytic oxidation occurred in two consecutive steps, as temperature increased. The initiation of oxidation, even with an addition of ferrocene, was controlled mainly by surface oxygen complexes and partly by the long-range crystalline order of the carbon graphene layer. However, once catalytic oxidation began, the progress of the reaction was mainly determined by the amount of ferrocene that was added.