空气夹层在间歇式窑炉窑墙中的作用研究

本文从空气夹层的位置，窑炉的升温时间等方面研究了空气夹层在间歇式窑炉窑墙中的作用。     

窑炉夹壁墙及双层拱顶在稳定传热中的作用

一、引言所谓夹壁墙,就是窑墙中设置空气夹层,有一定厚度。当此空气夹层封闭时即为封闭夹壁墙;当此空气夹层中空气强制流动时则为通风夹壁墙。所谓双层拱顶,就是窑顶由二层拱构成,其间有一定空隙,形成空气夹层。双层拱顶也区分为封闭的以及通风     

飞机环控导管包覆绝热套管的质量控制研究

描述了飞机环控系统绝热套管采用包覆空气夹层绝热套管的新工艺方法,通过对包覆空气夹层绝热套管新方法特点进行分析,结合导管与复合材料胶接成型特点,重点对如何控制该方法带来的质量问题进行了研究,探索和总结了其规律和特点,并对各项质量问题做了改进措施,为进一步深入研究和推广应用包覆空气夹层绝热套管新技术打下良好的基础。     

带芯管的管式反应器中流体力学的实验研究

本文以电石法聚氯乙烯生产流程中的转化器为背景,提出在转化器列管内加入芯管的改进方案,改变管内物料的流动状态及温度分布,以提高反应器的生产能力。通过实验测量反应器入口与各出口流速及压差,计算出空气在其中流动时夹层及开孔处的阻力系数。实验表明在相同的入口流量下,空气进入夹层,分别从芯管和夹层同时流出时,芯管开孔直径越大,芯管与夹层的出口流量比增大;在相同的孔径的条件下,随着入口流量的增加,夹层和芯管的出口流量差值减小。并根据实验数据拟合了空气流经开孔的阻力系数公式。     

空气夹层隔热作用的讨论——带有空气夹层的一维复合平壁传热计算机分析

本工作利用电子计算机对带有空气夹层的一维复合乎壁中的传热过程进行了分析。所得的结果清楚地表明:在高温热工设备的围护结构或隧道窑窑车衬砌中,不论在稳态或非稳态情况下,空气夹层的隔热作用都是微乎其微的,对节约能源不会有实际效果。同时对传热过程中的各种影响因素进行了讨论,指出只有在常温或低温设备围护结构中采用带空气夹层的结构隔热才有效,在高温热工设备中则应改向采取其它技术措施。文中给出了非稳态传热的典型计算示例。所附为国产DJS—130电子计算机用扩展BASIC语言编制的源程序尚可供工程设计计算时应用。     

NACA构型泡沫夹层复合材料空气风门的结构强度分析

泡沫夹层复合材料具有比强度、比刚度大,保温隔热性能优异等优点,广泛应用于航空航天等诸多领域,在飞机上则应用于一些载荷不大而厚度较小的部件或结构。研究的NACA构型泡沫夹层复合材料空气风门以其材料的特殊性,在组合工况下受力情况复杂,目前对其在多工况下进行强度分析的相关研究较少。以NACA构型的泡沫夹层碳纤维复合材料空气风门为研究对象,建立了有限元模型。通过重点对多工况下风门壳体的等效应力分布情况进行对比和分析,并对夹层结构各层的应力危险区域进行强度校核,得到了各工况下复合材料面板层和泡沫芯材层的应力敏感区域和失效情况,以及载荷对模型应力影响的规律。     

航空用复合材料异形导管技术研究

复合材料空气导管组件为碳纤维/蜂窝芯夹层结构,外形为闭环、变截面、双曲度的腔体式,其零件结构复杂、成型工艺难度大。本文从结构设计、模具加工和成型工艺等方面对复合材料空气导管进行了系统的研究,可为航空复杂结构整体成型技术提供参考。     

保温瓶

为了抽去双层瓶胆夹层内的空气 一般都在抽真空前,于外瓶底部熔接一根排气管,抽完真空后再将排气管口封闭。由于排气管突出在瓶胆的外部,既容易碰坏、又给安装外壳带来了麻烦。本发明的方法是:在双层瓶胆的外瓶底中间打一小孔,用真空泵将夹层内的空气抽去,达到规定的真空度后,用激光照射小孔的四周,使小孔逐渐熔封。这样制成的真空双层瓶胆消除了上述的排气管突出的缺陷,便于瓶胆的搬运和装配。 (虞若桦)     

塑料房屋

塑料房屋荷兰贝亨奥普佐姆市建成一幢试验性的塑料房屋。这座建筑物从墙壁到卫生设备均采用了各种聚合物材料。尤为引人注目的是透明的“气候调节墙”，该墙由两层坚固的聚碳酸酯薄板构成，夹层间有空气循环，冬天可隔绝户外冷空气，夏天可使室内凉爽。经由阳光加热到８５...     

夹层复合材料的工艺与应用

本项研究探讨了结构用夹层复合材料的工艺技术，并讨论了其工艺步骤、技术特点以及作为结构用各类夹层复合材料的某些具体应用。研究中强调了通用型工艺技术的经济性，同时讨论了几种普通工艺方案。研究中有两个主要成果：第一，对特殊应用领域的可行性分析，提出了与现有工艺技术相对照的方法；第二，为进一步研究和发展夹层复合材料工艺提供了基础资料。本项研究还讨论了有关夹层复合材料及其工艺技术路线的近期与未来的发展趋势。夹层结构应用领域很为广泛，如汽车、冷藏车车厢、船舶、贮罐、飞机、建筑业用板材等。面板材料通常采用金属…     

A mathematical model to study the effect of the air jet in the film blowing process

The aerodynamic effect of the air jet that supports the polymeric films produced in the film blowing process is studied theoretically. The nonlinear coupling between the air and the polymer is examined by assuming steady, axisymmetric, and isothermal flow for both phases. The governing equations for the polymer are simplified by following the thin‐film approximation and the corresponding ones for the air are derived by applying a boundary‐layer type analysis. The latter are solved analytically by first applying the Mangler transformation that reduces the boundary layer equations for the axisymmetric case to those for a plane boundary layer. Then a similarity solution is obtained, allowing the shear stress and the pressure on the outer polymer/air interface to be evaluated in terms of the film shape only. The final set of ordinary differential equations for the film is solved numerically using finite differences. The results show that the force caused by the airflow has a significant effect on the film shape and the characteristics of the final product. POLYM. ENG. SCI., 2011. © 2011 Society of Plastics Engineers     

Experimental study on the effect of lateral concentrated smoke extraction on smoke stratification in the longitudinal ventilated tunnel

Smoke is the main cause of death in tunnel fires. It is one of the important measures to maintain smoke stratification in the early stage of tunnel fire. This article focused on experimentally studying the combined effect of lateral concentrated smoke extraction and longitudinal ventilation on the smoke stratification, which never be revealed before. The velocity of the smoke layer and air layer, vertical temperature distribution, and the flow patterns of the smoke were measured. It was found that the longitudinal ventilation and lateral concentrated smoke extraction would affect the flow of the smoke and change the shear velocity between the smoke layer and air layer, then, the patterns of the smoke layer will be affected. And the flow patterns with Froude (Fr) number can be classified into three categories: (a)Fr < 0.6 , with stable smoke stratification; (b) 0.6 < Fr < 0.85 , with a stable smoke stratification but the blurring interface; and (c) Fr > 0.85 , the smoke layer is completely unstable. The result can provide a reference for ventilation design of immersed tube tunnels.     

气体辅助挤出的实验研究

对一种新型挤出技术-气辅挤出进行了实验研究,建立了气辅挤出实验装置并进行了实验研究,实验中在口模内壁和聚合物熔体之间建立了稳定的气垫膜层。研究了气体压力、气体温度和实验过程对气辅挤出中气垫膜层的影响。形成稳定的气垫膜层,应使气体压力低于熔体压力,但在0.2MPa以上,气体温度控制在与口模温度接近,实验时应先打开压力控制阀再进行挤出,并分析了气辅挤出对口模压降、挤出机产量及挤出胀大的影响。     

Development and evaluation of multilayer air filter media

Three types of multilayer air filter media were developed and evaluated. Two other existing filters were also used for comparison of filter performance. The pressure drop, the collection efficiency, and the dust-holding capacity of the tested filters were measured, and the internal structure of the filter media was analyzed by using a scanning electron microscope. The multilayer filters tested in this study are composed of pre-surface layer, surface layer, and substrate layer. Among those layers, the surface layer is mainly responsible for particle collection. As a test result, it was found that the thickness of a surface layer has the greatest effect on filtration performance of a multilayer air filter. Additionally, filtration velocity and electrostatic forces should be considered together as important parameters for multilayer air filter design.     

直接空冷凝汽器翅片管污垢层清洗的数值研究

直接空冷凝汽器翅片管作为空冷单元的重要换热组件,翅片管的清洁程度直接影响空冷单元的高效换热能力。目前对如何提高直接空冷凝汽器翅片管换热能力的研究较多,但是对于直接空冷凝汽器翅片管粘有污垢层后的清洗状况鲜见报道。对此,本文对直接空冷凝汽器蛇形翅片管污垢层清洗进行了数值模拟,分析了翅片管表面具有不同厚度的垢层时,在清洗过程中所受到的压力和剪切应力随时间的变化规律。结果表明：清洗带有不同厚度垢层的翅片管,翅片管表面垢层越薄,就越容易清洗,所需清洗时间越短;翅片管表面垢层受到的压力和剪切应力随垢层厚度的减小而减小,随清洗时间的增加而减小;经计算得出,清洗喷嘴的移动速度为1.1～1.5m/min时可更好的清洗翅片管表面的污垢。     

Study on the heat exhaust coefficient and smoke flow characteristics under lateral smoke exhaust in tunnel fires

The heat exhaust coefficient and smoke flow characteristics under lateral smoke exhaust in tunnel fires were studied in this paper. Through the dimensional analysis, the dimensionless relationship between the heat exhaust coefficient, heat release rate, exhaust vent size, and exhaust velocity was obtained. In addition, this paper also studied the effect of the lateral exhaust vent on the smoke flow field. Results showed that the lateral smoke exhaust caused strong air entrainment on the downstream of the exhaust vent and boundary layer separation on the upstream of the exhaust vent. As the exhaust velocity increased, the degree of air entrainment gradually increased, and the smoke layer near the exhaust vent gradually became thinning and plug‐holing phenomenon occurred; meanwhile, the boundary layer separation would be suppressed or disappear, but the increase of the heat release rate would enhance the boundary layer separation. As the exhaust vent got narrower, the air entrainment downstream of the exhaust vent was reduced, and the boundary layer separation also got weaker.     

Experimental Study of the Temperature Rise in the Frontal Layer of a Structured Porous Metal Catalyst in Air Conversion of Methane

Heat-resistant Ni/MgO block catalysts have been developed on porous nickel carriers for the air conversion of natural gas to synthesis gas. The catalysts were tested under normal pressure, which allowed one to select of a number of samples that demonstrate relatively the low temperature of the frontal layer of the catalytic block of 880–940°C at the inlet temperature of the mixture of 20°C and excess air factor of 0.3. The composition of the mixture at the outlet remained close to thermodynamic equilibrium at a volumetric flow rate of up to 49 000 h^–1. It was experimentally established that the temperature of the frontal layer decreases with increasing pressure (2–6 atm), an increase in the frontal layer temperature with an increasing coefficient of excess air (0.31–0.42) and the rate of the inlet mixture (0.30–0.74 m/s). This made it possible to obtain approximate estimates of the areas of exothermic and endothermic reaction stages taking into account external diffusion inhibition based on the analysis of the heat balance equation for the frontal layer of the catalyst.     

AERMOD模式系统理论

作为新一代法规性质的稳态大气扩散模式,AERMOD将最新的大气边界层和大气扩散理论应用到空气污染扩散模式中。AERMOD具有下述特点:(1)按空气湍流结构和尺度的概念,湍流扩散由参数化方程给出,稳定度用连续参数表示;(2)中等浮力通量对流条件采用非正态的PDF模式;(3)考虑了对流条件下浮力烟羽和混合层顶的相互作用;(4)AERMOD模式系统可以处理:地面源和高架源、平坦和复杂地形和城市边界层;(5)AERMAP提出了一个有效高度对流场的影响。示踪试验表明,AERMOD模拟的结果比较理想。     

Rising behavior of air bubbles in superposed liquid layers

An air bubble that passes through a horizontal interface from a lower layer of Freon-113 to an upper layer of aqueous glycerol forms a two-phase bubble in the upper layer as a result of entrainment of a certain volume of Freon-113 from the lower layer. The volume of entrained Freon-113 and the rise velocity of such a two-phase bubble have been measured. The former increases with an increase of the bubble size irrespective of the viscosity of the upper liquid. The latter is somewhat lower than that of a normal air bubble of the same size.