一种热气机用盘式旋流气体燃烧器的试验研究

为满足小型热气机常温常压条件下燃烧的需要,在数值模拟的基础上设计了一种盘式旋流气体燃烧器,并试验研究了不同开孔方式、负荷条件和过量空气系数下燃烧室内的温度分布和火焰形状,结果表明:燃气孔为内孔,空气旋转流动,同时燃烧器外径减小到原来的2/5左右的情况下,燃气-空气混合均匀,燃烧稳定,火焰透明、脱壁且不直接灼烧加热器头部,高温区分布合适,满足热气机燃烧要求。     

在小型燃烧室内压力雾化旋流燃烧过程的数值模拟

利用概率密度函数模型(PDF),针对不同供油压力和喷雾锥角下压力旋流雾化喷嘴出口下游液滴群在小型燃烧室内的燃烧过程进行数值模拟研究。研究表明:随着喷雾锥角的增加,火焰张角有所增大,火焰中心及火焰区域外的燃烧室空间温度逐渐上升。燃烧室单侧出口导致了火焰偏斜,且随喷雾锥角增加而越发明显,适当增加喷嘴供油压力可改善远出口端的温度分布。本文研究的压力雾化喷嘴,在小型燃烧室内喷雾锥角=60～80°、供油压力=0.9 MPa～1.2 MPa时可以取得较好的燃烧效果。     

某100,kW微燃机燃烧室结构优化及数值模拟

为解决某微型燃气轮机燃烧室的燃料由燃油改为燃气时出现的火焰偏长、出口温度均匀性差的问题,对此燃烧室的头部和掺混孔的结构进行了优化设计,并利用计算流体力学方法研究了燃烧室头部结构和各区段空气量分配比例对燃烧室内燃烧过程的影响.研究结果表明,采用带有旋流器的多孔喷头能够促进燃烧室内燃气与空气的混合,有效解决燃烧室内火焰偏长的问题.采用多孔、多段的掺混孔能够避免掺混空气在燃烧室出口集中送入,更利于燃烧室出口温度的均匀分布.     

等离子助燃高炉煤气燃烧室模拟研究

利用数值模拟手段探究高炉煤气燃烧室热态场分布规律,并探究了等离子中活性粒子氧原子对高炉煤气燃烧室的热态场影响规律。结果表明:燃烧室内高炉煤气燃料浓度呈U字形分布。在燃烧室的头部燃料喷嘴附近形成高温区,在主燃孔后有少部分的高温区;随着活性粒子的加入,高炉煤气燃烧室头部高温区范围增大,火焰筒内的回流区速度更加均匀,燃烧效率提高,由97.38%增加到99.65%。活性粒子浓度越高,等离子助燃高炉煤气燃料燃烧强化效果会逐渐减弱。     

过量空气系数及旋流数对天然气燃烧特性的影响研究

针对天然气在O2/N2氛围下扩散燃烧时,过量空气系数和旋流数对WNS型燃气锅炉燃烧室内的温度分布、速度分布及NOx生成的影响,利用CFD软件,采用标准k-ε湍流模型、P-1辐射模型和涡耗散模型进行数值模拟。基于旋流对流动特性的影响,采用旋流数S来表示入口空气的旋流强度。结果表明：在过量空气系数α从1.0增大到1.3的过程中,火焰直径逐渐变小,排烟温度降低,燃烧室出口处NOx的质量分数逐渐减小;在空气旋流数从0提高到0.8的过程中,燃烧室内形成了中心回流区,火焰的径向流动分布逐渐改善,燃烧室内的温度分布更加均匀;旋流燃烧的火焰中心轴线温度分布高于直流射流燃烧,提高空气旋流数可以有效降低NOx的质量分数。     

进气参数对LPP燃烧室振荡燃烧特性和火焰结构的影响

为研究贫预混预蒸发(LPP)燃烧室振荡燃烧规律和LPP火焰结构,利用动态压力传感器测量了LPP燃烧室内不同进气参数下时域及频域上的压力脉动;利用激光诱导荧光(PLIF)测量系统研究了不同进气参数下的LPP火焰结构变化规律。结果表明:随着燃烧室入口流速的增加,激励出的振荡燃烧的当量比区域会减小;在一定的入口流速下,所激励的振荡燃烧主频会随着当量比的增加而增加;随着燃烧室入口空气温度的提高,激励出振荡燃烧的区域会减小,激励出的振荡燃烧的强度会下降,但振荡燃烧的主频均会增加;稳定燃烧时,LPP火焰为V型火焰;振荡燃烧则会将LPP火焰转化为平整型火焰。     

某型航空发动机燃烧室等离子体助燃的数值研究

为开展等离子体助燃技术在航空发动机燃烧室中的应用研究,利用Fluent软件对某型航空发动机环形燃烧室进行了等离子体助燃的数值计算,设计了等离子体助燃的数值计算方案,对比分析了正常燃烧状态条件和等离子体助燃条件下的数值计算结果.结果表明:从主燃孔实施助燃后火焰筒内的高温区向主燃区移动,煤油在主燃区燃烧得更充分,燃烧室出口截面的平均温升增高约57.97 K,燃烧效率提高约2.42%;出口处温度分布均匀性有所改善,燃烧室出口处截面温度的分布不均匀系数下降达21.82%;提高了燃料燃烧完全程度,燃烧尾气中CO的体积分数下降约13.58%,极大改善了燃烧室的性能.     

微通道壁面加热对甲烷空气预混火焰传播特性的影响

对于甲烷和空气预混合气在矩形微燃烧室内的燃烧过程,采用加热片加热,对比分析了在外部加热时,有无隔板对燃烧稳定性的影响,并分析了不同加热温度下隔板式燃烧室内火焰传播特性。实验结果表示,随着加热温度的提升,隔板型燃烧室稳定燃烧区域不断增大；加热温度高于600K,隔板型燃烧室的火焰吹熄极限有明显改善；高温加热利于提高隔板型燃烧室在较大流量情况下燃烧的稳定性。相较于单通道燃烧室,外部加热对隔板型燃烧室燃烧稳定性的改善更加明显。     

当量比变化对合成气双旋流喷嘴燃烧火焰特征的影响

采用平面激光诱导荧光（PLIF）、高温热电偶及红外气体分析仪,对不同当量比下的合成气在双旋流模型燃烧室内的火焰特征进行了试验研究.结果表明：当量比为0.2时,合成气火焰的反应区呈月牙形,随着当量比的增大,合成气火焰根部逐渐出现M型分布特征,火焰锋面的内、外侧张角均单调减小,火焰推举高度与穿透深度增大,同时,燃烧室中下游出现大量的反应区,火焰根部受到压缩,燃烧室排气温度升高,CO排放量迅速降低.     

燃气轮机低热值合成气燃烧室内三维湍流流动的数值模拟研究

对GE-F101型工业燃气轮机环形燃烧室燃用甲烷和低热值合成气的燃烧性能进行了数值研究,采用标准κ-ε湍流模型和涡耗散湍流燃烧模型对燃烧室在不同燃料条件下的流场特性进行了数值模拟,并对燃烧室内的流场结构、温度分布、火焰结构及NOx分布进行了分析与比较;在此基础上对原燃烧室进行了一些改造.结果表明:随着燃料热值的降低,燃料射流速度增大,燃料和空气的混合程度减弱,燃烧稳定性降低,燃烧室内最高温度降低,NOx排放量减少;通过增大燃料喷嘴口径和增加旋流器的旋流数,可在一定程度上改善燃烧室内流动结构,增强燃料和空气的混合程度,因而提高了燃烧稳定性.     

小型锅炉烟尘测试时锅炉出力的计算

锅炉烟尘测试时,必须对锅炉出力进行测试。但监测中,许多小型锅炉往往不具备相关的计量装置和仪表,为解决这一问题,文章提出了用烟气量和空气过剩系数来计算锅炉的出力的公式,在实际使用中,该方法简单易行,其结果和实测值具有很好的一致怀。     

Unerroric of control of mutual compliance of the efficiency of hydrogen engines of unmanned vehicles in the conditions of mass production

The issues related to the reliability of hydrogen engines of unmanned vehicles and increasing the efficiency of using hydrogen as fuel when using the method of its production during the decomposition of hydrogen-containing molecules of liquid-phase organic compounds in a plasma discharge under the action of intense ultrasonic exposure are considered. Experiments have shown that as a result of decomposition in the acoustoplasma discharge of liquid hydrocarbons, solid-phase carbon-containing products are formed, chemical transformations occur in the liquid phase and hydrogen-containing combustible gas is formed. Hydrogen-containing gas can be used as fuel immediately after synthesis, i.e. it does not require separation, since in addition to hydrogen it contains only impurities of CO₂ and water vapor. The purpose of the study is to formalize the basic conditions for tightening the control of mutual compliance with the efficiency of hydrogen engines of the same series in the conditions of their mass production. Methods of mathematical statistics and hardware-software modeling were used in the study. The term “unerroric of quality mutual compliance control” is introduced to describe a set of hardware and software tools for such control. The principle of in-depth testing of the technical condition of such engines of one series is described in a multidimensional formulation of the quality control problem for three of their operating parameters at once. The conditions for increasing the mutual correspondence of the measured values of such parameters in the conditions of serial production of hydrogen engines are formalized.     

中国煤炭地下气化技术的发展

本文综述了煤炭地下汽化技术的国内外发展现状,对我国“长通道、大断面”煤炭地下气化新工艺给予了技术经济评述,并提出了发展煤炭地下汽化技术的政策建议。     

Review of theory of distortion and disintegration of liquid streams

Linear and nonlinear analyses of the instabilities and distortion of liquid streams injected into a gaseous media are discussed. The various fundamental mechanisms and the predictive capabilities for the distortions are emphasized. Round jets, planar sheets, annular sheets, and conical sheets are discussed in detail. The balance between capillary and inertial forces is primarily examined. The method for simplifying the analyses in the case of thin liquid sheets is discussed. The capabilities for representing the droplet size distribution that follows the stream disintegration are outlined.     

MgO膨胀剂细度对MgO水化和水泥浆体膨胀的影响

基于《水工混凝土掺用氧化镁技术规范》中的Ⅰ型氧化镁（MgO）,研究了该型MgO膨胀剂（MEA）细度对掺粉煤灰水泥浆体膨胀性能的影响。即采用X射线衍射分析(XRD)及同步热分析（TG DSC）分析了掺MEA水泥浆体中MgO的水化性。结果表明,养护温度相同时,MEA的细度对水泥浆体内MEA中MgO的水化和水泥浆体的膨胀无显著影响,产生的膨胀均能补偿水泥浆体的收缩;MEA的细度可从试验设计采用的45 μm筛筛余15%左右增加到30%左右,这将有利于MEA生产企业的节能降耗。     

机车车轮多轴疲劳强度安全评定的研究

使用ANSYS8.0软件对高速列车车轮进行了三维有限元分析,计算出车轮在直线、曲线和道岔条件下牵引、制动共6种工况时孔边薄弱部位的应力,分别通过Mises等效平均应力方法、Sines平均主应力方法和应力分量中考虑平均应力方法计算出应力在极值位置时的等效应力幅、等效平均应力,从而进一步算出车轮的安全系数,对其疲劳强度进行评定,并对3种方法进行了比较研究。     

Constructal optimization of the geometry of an array of micro-channels

This paper documents the geometric optimization of an array of circular and non-circular ducts. The optimization was carried out numerically using finite volume method. As optimal dimensions were independent of the array configuration, the numerical simulation was performed on a unit cell. Numerical optimization for circular, square and isosceles right triangle cross-sections of channels was performed. Based on the results of this investigation, some correlations were proposed to predict the optimal hydraulic diameter and dimensionless heat transfer per unit volume. In addition to examining the effect of pressure drop on these parameters, it was showed that among the different geometries of this study, square cross-section has the most efficiency for a given volume. The numerical results of the present study were compared with approximate results reported in the literature which a good agreement was observed.     

固体热辐射Yong性能分析

本文对漫灰均温物体在常物性条件下对外辐射传热的Ｙｏｎｇ值计算建立了数学模型。通过与物体内能Ｙｏｎｇ公式的数值计算比较,得出了辐射能量的Ｙｏｎｇ值不大于内能Ｙｏｎｇ值的结论。从初步的热射Ｙｏｎｇ值计算公式发现。Ｙｏｎｇ与物体表面辐射率有关。     

Measurements of concentration distribution of hydrogen jet using deflection of center of the laser spot

The main purpose of this work is to propose a new method to evaluate the concentration distribution of the hydrogen jet by using a He–Ne laser through the jet. This research attempts to apply the expression of concentration Gaussian distribution, the refraction formula of inhomogeneous refractive index medium, and the concentration inversion function to disclose the displacement of the center of the laser spot at different heights in the gas jet. The spot images of the laser beam passing through the gas jet at three vertical heights z = 10d, 20d, 30d, and different radial positions are obtained. The radial spatial asymmetry of the gas jet is also found in the experiment. Finally, the calculated concentration distribution curve and the fluent simulation curve, it is found that the two results are very similar. Our findings show that the error between the concentration distribution of this method and the simulated concentration distribution reaches 2.43%.     

Heat of vaporization of mixtures

General expressions for the heat of vaporization of mixtures at constant pressure; at constant temperature; and at constant pressure, temperature, and composition are proposed. The last one is related to the liquid-vapor interface where steady vaporization or condensation is taking place. Numerical examples by the proposed expressions are shown for binary mixtures of HCFC22(R22) and (HCFC123(R123) © 1997 Scripta Technica, Inc. Heat Trans Jpn Res, 25(1): 12–24, 1996