液体火箭冷氦增压系统低温试验研究

为研究液体火箭低温氦增压系统中电磁阀与孔板组合方式的增压性能和优化孔板的设计,开展了使用液氢温区的氦气作为增压介质的冷氦增压系统试验,并通过排放液氧模拟火箭贮箱内液氧的消耗.通过分析试验过程中增压氦气流量和贮箱压力的情况,获得了该增压方式对贮箱的增压性能.试验结果表明电磁阀与孔板组合能将贮箱压力维持在设计范围内,是一种简单、可行的液体火箭液氧贮箱增压方案.     

冷氦直接增压排放推进剂试验系统的研制及性能调试

针对在液氧贮箱内贮存冷氦气并用于增压煤油贮箱排放的技术方案,研制了一套以液氮为冷源,借助换热器冷却常温氦气获得冷氦,继而送入煤油贮箱进行挤压排放的地面模拟试验系统。对该试验系统的主要功能进行了调试,包括流量调控测试,以及最大排液流量、制冷能力和贮箱内部温度分布测量等。结果表明,该试验系统能够安全可靠地模拟箭上冷氦增压系统的工作过程,可用于相关原理性验证试验和机理研究。     

冷氦增压系统的研制

冷氦增压在我国是首次研制，并成功地应用于长征三号甲型号。冷氦增压是长征三号甲研制中的关键技术之一。介绍了冷氦增压系统方案，冷氦增压方案的优点，箭上冷氦增压系统几个部件的主要设计技术要求，冷氦增压系统地面设备及主要技术要点、箭上冷氦增压系统安全措施，冷氦增压系统的试验及主要结果，冷氦增压计算，长征三号甲火箭冷氦增压试验结果以及国外冷氦增压技术等。     

含二氧化碳和水蒸气的氮气增压输送液氮模拟试验

进行了低温液体火箭推进系统的液氧箱自生增压输送过程的模拟试验，专门设计加工了液氮箱增压输送模拟试验台，试验得出了液氮增压输送过程中温度、压力、流量的变化规律以及含饱和CO2、H2O的氮气通过过滤器时，对系统的流量和压降的影响。指出为保证低温流量计测量准确，必须重视在避免管路中出现两相流方面采取措施。试验结果表明，本试验装置能有效地进行含CO2、H2O(气)的氮气增压输送试验，保证了试验的圆满成功。     

冷氦增压系统换热器换热性能研究

为研究各种流量工况下冷氦增压系统中换热器的换热性能和压力损失,开展了冷氦增压系统搭载发动机试验和数值仿真研究,研究结果表明通过换热器的冷氦气体流量增大,换热器的出口温度降低且对换热器压力损失增加,数值仿真结果与试验结果吻合较好,换热器性能试验研究为提升冷氦增压系统工作性能打下基础。     

基于AMESim的贮箱增压过程仿真

某挤压式液体火箭发动机推进剂供应系统采取共底贮箱,增压过程中要求严格控制氧化剂箱和燃料贮箱的压差,防止贮箱中隔板破裂发生危险。利用AMESim软件,对该推进剂供应系统增压过程进行动态仿真,并进行系统地面增压试验,仿真结果与试验情况基本吻合。结果表明,在系统增压过程中,隔板压差在设计范围之内,能够保证贮箱安全、可靠工作。     

低温推进剂贮箱增压过程的传热传质数学模拟

针对火箭发动机地面试验中低温液氧贮箱的预增压和增压过程建立了气相空间的传热、传质数学模型.运用实际气体的状态方程、连续性方程、能量守恒方程以及推进剂与气相空间的传热、传质方程等组成了关于气相空间参数的微分方程组,并运用四阶Runge-Kutta算法对其进行求解.获得了气相空间的压力、温度、增压气体流量、液氧挥发速率以及贮箱壁温等参数的变化规律.结果表明,在发动机启动前的预增压过程中,气相空间的温度和压力急剧增加,液氧的挥发速率也增加很快;发动机启动后的保持增压阶段,由于气相空间的体积不断发生变化,气相空间参数的变化趋于平缓,液氧表面向气相空间的传质速率也趋于稳定.     

冷氦压力调节器的研制

长三甲火箭在国内率先采用了冷氦增压系统，冷氦压力调节器是冷氦增压系统中的最关键阀门之一。本文介绍冷氦压力调节器的方案，原理及形成过程。叙述了研制中解决的几个关键技术问题。整理出恒压加载式压调器的设计步骤，推导了设计计算公式。     

高压低温换热贮罐换热性能仿真计算

设计了一种高压低温换热贮罐,配合斯特林制冷机可用于获取和贮存20 K@35 MPa冷氦气,在无液氢的情况下具备液氢温区试验能力,以满足液体火箭冷氦增压系统实验的气源要求。对该贮罐进行了漏热分析,得到贮罐漏热量。采用Solidworks和Matlab对预冷过程和换热过程进行仿真计算与分析,得到预冷时间和换热时间分别为3小时和47小时。     

带搅拌器ZBO低温贮箱长期在轨存储非稳态分析

针对带搅拌器ZBO低温贮箱在轨工作过程,采用计算流体动力学软件FLUENT对液氢贮箱进行非稳态模拟分析,获得了贮箱内流体的两相流特性以及压力变化规律。低温贮箱的物理模型为贮箱顶部和底部为椭球形,中间为柱段,贮箱顶部换热器连接低温热管,底部采用喷射泵装置。计算结果表明,随着贮箱外部热量的不断导入,贮箱底部和顶部都出现了气泡,并且逐渐增大,流体最高温度和压力不断上升,增压运行至设定值(运行约80 h)后开启喷射泵和低温制冷机,气泡体积均缩小,流体最高温度和压力明显降低(运行约20 min)。     

The Research of Anti-Wear Properties of Organomolybdenum Compounds in the Engine Oils

A four-ball tester was used to evaluate the anti-wear performance of three kinds of organomolybdemun compounds in the engine oils, i. e., molybdenum dialkyldithiophosphate (MoDDP), molybdenum dialkyldithiocarbamate ( MoDTC), and sulphur and phosphorus freeorganomolybdeum (Molybdate). The results indicate that a low concentration of MoDDP doesn' t improve the anti-wear properties of the commercial engine oils, but a high concentration of MoDDP can obviously improve the anti-wear properties and the load-carrying capacity of the engine oils. MoDTC doesn' t improve the antiwear properties of the engine oils, but worsens the anti-wear properties of the oils. Signifi can timprove ment of frictional and wear characteristics is obtained with Molybdate added in the commercial engine oils and the formulated oils.     

Certification Becomes Important for the I Quality; and Safety Supervision of the Chinese Liquor Sector

The end of 2007, over 200 unit products of more than 80 Chinese firms have passed the quality grade certification for liquor products. These products involve distilled spirits, beer, wine, yellow wine, fruit syrup wine and others, and cover over 80% of the national top-branded liquor products.……     

Deposition and Coating Properties on CVD Tungsten

Surface characterization and microstructure studies are performed on chemical vapor deposited (CVD) tungsten coating. There is about 2 μm thickness diffusion layer of tungsten in the molybdenum substrate. The thermal shock test shows tungsten coating has good adhesion with molybdenum substrate, but the elements of oxygen and carbon in the tungsten coating have the bad affection to the adhesion. The result of high-temperature diffusion experiment is the diffusion rate from molybdenum substrate to tungsten coating is faster.     

Analysis of marine hydrobiont lipid extracts as possible cryoprotective agents

We studied a combined effect of the cryoprotectants both of lipid and carbohydrate origin at the presence of DMSO or without it on cell viability and the RNA synthesis in the embryonic mollusc and echinoderm cell cultures obtained at different developmental stages. Cryoprotective properties of exogenous lipids correlated with their thermotropic behavior. Lipid extracts from marine hydrobiontes, which thermal transitions are characterized by relatively small part of calorimetric thermogram area lying at temperatures above 0 °C (6–18%), were found to possess a considerable cryoprotective activity. The results are discussed in relation to the prediction of the cryoprotective activity of lipid extracts for marine animal cells. In addition, it was found that marine invertebrate cells can be cryopreserved without DMSO at the presence of trehalose and lipid extracts of some marine hydrobiontes.     

Low-Temperature Properties of Silver

Pure silver is used extensively in the preparation of high-temperature superconductor wires, tapes, films, and other configurations in which the silver not only shields the superconducting material from the surrounding materials, but also provides a degree of flexibility and strain relief, as well as stabilization and low-resistance electrical contact. Silver is relatively expensive, but at this stage of superconductor development, its unique combination of properties seems to offer the only reasonable means of achieving usable lengths of conductor. In this role, the low-temperature physical (electrical, thermal, magnetic, optical) and mechanical properties of the silver all become important. Here we present a collection of properties data extracted from the cryogenic literature and, to the extent possible, selected for reliability.     

Early ironwork in Biscay: Survey,excavation, experimentation and materials characterization. An integral study of the mountainside ironworks (ferrerías de monte or “haizeolak”)

ABSTRACT

The production of iron in Biscay (Basque Country, Spain) has been a hallmark of this territory of the North of the Iberian Peninsula throughout its history. The Archaeology team of the Basque Country Mining Museum has spent 13 years, so far, studying the origins of this activity through the evidences left at the old pre-hydraulic iron production workshops known as mountainside ironworks (ferrerías de monte) or haizeolak. It has catalogued 170 archaeometallurgical sites of this type in Biscay, and the archeological excavation of some of them has led to the knowledge of the different stages of the production process that took place in these workshops. The team has also experimentally reproduced the work carried out in a mountainside ironworks from the High Middle Ages, and it has currently started the characterization process of this type of activity through the study of the collected materials.     

Mechanism Study on the Wear of CrAlTiN Coated High-Speed Steel Twist Drills Under Dry Cutting Conditions

As demands about environment protection are growing up, dry cutting technology is getting more and more concerns from all over the world. Main works performed here are study on dry cutting performances and wear mechanisms of M2high-speed steel (HSS) twist drills with CrAlTiN multicomponent coatings, which was deposited using magnetron sputter ion plating system, in drilling 45 and 30CrMnSiA steel, and their comparisons to those in drilling the same steel but using monolayer CrN and commercial TiN coated drills. Drilling performances of drills are evaluated mainly through the measurements of width on outer corner flank land and the cutting forces. Results show that performances of CrAlTiN coated drills are better than those of monolayer CrN and TiN coated drills. In drilling 45 and 30CrMnSiA steel, the average tool life of the CrAlTiN coated drills are 17.2 and 11.8 times higher than those of the uncoated drills. Observing wear of the drill with scanning electronic microscope, results show that there is no crack or spallation of the CrAlTiN coatings in wear zones. Main mechanism of the wear here is adhesion.     

Study on Bond Ability of Arc-Spraying Coatings with Different Surface Pretreatment on Cast-Iron

Arc spraying coatings are widely used in various applications, but uncommon in cast iron substrate. Different surface pretreatment technology is tested on substrates of gray cast iron. Surface roughness and residual stress were measured by TR200 and X-ray diffraction analyzer. Influence of different surface pretreatment methods ( dry blasting and fusebond) on roughness and residual stress was analyzed. The arc-sprayed coatings of wire 3Cr13 (φ2mm) on gray cast iron substrate is studied. The microstructure and interface of bonding layer were observed by SEM. The bond strength was taken by tensile test. Results show that bond strength with grit blasting is higher than fuse-bond; it is feasible to make wire 3Cr13 coating with arc spraying on cast iron substrate roughened by grit blasting.     

Structural Characteristics of TiO2 Ceramic Coating by Micro-Plasma Oxidation

TiO2 ceramic coatings with thickness of 20 μm were formed on the surface of pure titanium by micro-plasma oxidation. Their micro-structures were investigated by by using X-ray diffraction and their surface images were detected by using scan electronic microscope. There were three kinds of TiO2 coatings, pure anatase type TiO2 phase, mixed phases consisted of rutile type TiO2 phase and anatase type TiO2 phase, pure rutile type TiO2 phase. The coating surface with the pure anatase type TiO2 phase is rough, while the coating surface with the pure rutile type TiO2phase is smooth. The upper coating surface with the mixed type TiO2 phases is anatase type TiO2 structure and the subsurface of the TiO2 coating is rutile type TiO2structure.     

Evaluation of fatigue life of steel using steel grain size

The insightful discussion of the relationship between the construction of metallographic and fatigue life and proposition of mathematical relationships describing this relationship was conducted in the paper. This paper presents a method for estimating the fatigue life, based on the construction of the microstructural material taking into account the grain size and the participation of ferrite and pearlite phase.