冷氦换热器低温换热试验研究

为验证采用液氧对冷氦加温的可行性,研究光管、整体翅片管两种形式的换热器在不同流量、压力下的换热性能,开展了冷氦换热器的原理性试验和数值仿真研究.研究结果表明:相同工况下,整体翅片管换热效果比光管好很多,整体翅片管对强化换热效果明显,数值仿真结果与试验结果吻合较好.     

冷氦换热器数值建模及性能仿真研究

采用基于集总参数法的AMESim仿真软件对某型号运载火箭冷氦换热器进行建模,模型考虑了管外的高温燃气凝结换热、管内的强制对流换热及换热管沿轴向、径向的导热。在此基础上,开展了冷氦换热器的单元无关性分析、换热器性能仿真及参数影响性分析。仿真模型有效性通过搭载发动机地面试车试验数据进行验证。计算结果表明:仿真模型能较好地模拟冷氦换热器的性能,且随着冷氦进口温度升高,出口温度也基本线性递增;随着冷氦流量增大,出口温度逐渐降低,而工作压力对换热器性能影响较小。     

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.     

液氢温区冷氦增压系统试验研究

针对某型号火箭冷氦增压系统,建设了液氢温区冷氦增压系统试验平台,通过试验得到了冷氦气源压力和温度、冷氦加热器性能、模拟贮箱压力和温度的变化规律.结果表明:低温制冷机组配合高压低温换热贮罐可以真实模拟箭上的冷氦气源;根据对增压过程中贮箱压力的分析表明排气方式可以真实模拟箭上推进剂消耗过程中贮箱压力的变化情况;另外,试验中压力信号器、电磁阀和贮箱工作正常,验证了火箭冷氦增压系统的可靠性.     

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。     

超临界氦增压与排放过程的压力温度特性

为了探讨超临界氦增压技术在中国运载火箭和航天器上实现的可行性,进行了超临界氦增压排放实验研究。分析了低温杜瓦内的超临界氦的热分层稳定性;讨论了温度计引线两端大温差引起热声振荡和漏热现象;此外,由于节流微分效应和换热器管壁轴向导热,换热器出口温度在排放过程出现大幅温度波动。实验结果证明超临界氦增压过程中增压压力平稳、可靠,压力容易控制。但后续改进实验中应消除换热器节流微分效应导致的出口温度波动,并且减小杜瓦以及支撑结构的漏热。     

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。     

超临界氦增压系统及试验研究

为了对超临界氦增压技术在运载火箭中的应用可行性进行验证,研究超临界氦增压系统设计参数的匹配特性,本文对比分析了不同增压方式的效率,开展了超临界氦增压系统试验.在试验中通过分析比对超临界氦增压系统的各项参数,获得了超临界氦增压系统的增压性能,同时验证了超临界氦的置换、预冷、加注等流程.试验表明,在适当的参数匹配条件下,超临界氦增压系统增压性能稳定,是一种具有较高效率和可靠性的液体火箭的增压方案.     

大型超流氦低温系统中冷压缩机叶轮的设计和优化

随着超导加速器建设规模的扩大,为其提供低温环境的超流氦系统得到了广泛应用。国际上各大加速器实验室的大型超流氦系统大都使用冷压缩机作为负压低温氦气的增压设备,叶轮是冷压缩机的关键部件。采用CFturbo软件对叶轮进行设计计算,得到了冷压缩机叶轮的参数和三维模型。采用CFD软件对设计的叶轮性能进行模拟仿真,分析模拟结果及流场分布规律,探究叶轮性能随结构参数的变化关系,从而对叶轮进行优化。优化得到的叶轮模型仿真结果较好,叶轮性能满足设计要求。     

Insertion of triangulated surfaces into a meccano tetrahedral discretization by means of mesh refinement and optimization procedures

In this paper, we present a new method for inserting several triangulated surfaces into an existing tetrahedral mesh generated by the meccano method. The result is a conformal mesh where each inserted surface is approximated by a set of faces of the final tetrahedral mesh. First, the tetrahedral mesh is refined around the inserted surfaces to capture their geometric features. Second, each immersed surface is approximated by a set of faces from the tetrahedral mesh. Third, following a novel approach, the nodes of the approximated surfaces are mapped to the corresponding immersed surface. Fourth, we untangle and smooth the mesh by optimizing a regularized shape distortion measure for tetrahedral elements in which we move all the nodes of the mesh, restricting the movement of the edge and surface nodes along the corresponding entity they belong to. The refining process allows approximating the immersed surface for any initial meccano tetrahedral mesh. Moreover, the proposed projection method avoids computational expensive geometric projections. Finally, the applied simultaneous untangling and smoothing process delivers a high‐quality mesh and ensures that the immersed surfaces are interpolated. Several examples are presented to assess the properties of the proposed method.     

Certification Institutions Expected to Update and Transfer Information on Present Standards

Standards are the basis for production enterprises to organize production, ex-factory inspection, trade (delivery) and technical exchanges, product certification, quality arbitration and supervision.……     

Flow calorimeter for enthalpy increment measurements on condensed gases

A flow calorimeter for enthalpy increment measurements on condensed gases is presented. A better knowledge of the properties of the liquefied natural gas is needed, and therefore a liquid loop has been designed for our flow calorimeter. The fluid loop in the calorimeter is designed in order to avoid the two-phase region, since two phases would give compositional disturbances in the measurements. The avoidance of the two-phase region is made possible by increasing the pressure of the test fluid after the measurement section, then heating the fluid at super-critical pressure past the critical point. Finally, the fluid is throttled to the low-pressure gas state at the inlet condition of the compressor that circulates the fluid. To perform the pressure increase, a new cryogenic pump has been designed. To evaluate the new equipment, measurements were taken on liquid ethane over the temperature range 146–256 K at pressure between 0.9 and 5.1 MPa.     

From Industry 4.0 to Research 4.0. Development of High Performance Fibers in the Light of Digitization

We associate a variety of innovations with the term ＂Industry 4.0＂. The pioneer of many 4.0 modifications forms the basisfor the trend towards the integrated di...     

Refrigerators Enter a New Era of Health Preservation Frestech initiates the establishment of China's first standard for household sterilization refrigerators

On November 30, 2007, the China Association for Standardization (CAS) held a press conference at Beijing Diaoyutai State Guest House. Leaders from the China Household Electric Appliance Research Institute, the China Household Electric Appliance Association, and the China Consumers' Association attended and made speeches.……     

Optimum-Simulation von Ernteprozessen

Zusammenfassung Bei der Gestaltung von Ernteprozessen — beispielsweise des Prozesses Mähdrusch, Körnertransport und -abnahme — als transportverbundene Fließarbeitsverfahren mit mindestens zwei verschiedenen Arbeitsmitteln gibt es einen großen Optimierungsspielraum. Solche Prozesse sind mehrstufige Bedienungsprozesse mit gemischter Anordnung der Bedienungseinrichtungen. Außerdem besitzen sie stark ausgeprägte räumliche Aspekte. Es wird vor allem gezeigt, welche Merkmale solcher Prozesse in Simulationsmodellen abgebildet sein müssen, welche Zielgrößen in Abhängigkeit von welchen Einflußgrößen unter Berücksichtigung welcher Prozeßbedingungen ermittelt werden sollten und wie der Bewertungsprozeß zur Ermittlung der gewünschten Informationen gestaltet werden muß.     

Roman iron and steel: A review

ABSTRACT

The production of ferrous metal increased during the Roman Late Republican period, Principate and Empire. The direct bloomery process was used to extract the metal from its ores using slag-tapping and slag-pit furnaces. The fuel was charcoal and an air blast was introduced by bellows-operated tuyères. Iron formed as a bloom, often as a spongy mass of metal, which contained impurities from the smelting process, including unreacted ore, fuel, slag and fragments from the furnace walls, while the metal was often inhomogeneous with varied carbon contents. Blooms were either smithed directly into bars or ingots or they were broken up, which also allowed the removal of gross impurities and a selection of pieces with similar properties to be made. These could then be forge-welded together and formed into characteristically shaped ingots. Making steel in the furnace seems to have been achieved: it depended on the ore and the furnace and conditions within it. Surface carburization was also carried out. Iron and steel were used extensively in construction and for tools and weapons. Fire welding was often used to add pieces of steel to make the edges of tools and weapons, which could be heat-treated by quenching to harden them.     

A study of centrifugal cast high boron high speed steel

In the present study a high‐boron high speed steel (HSS) roll material was designed. Many expensive alloy elements have been substituted by cheap boron alloy, and high‐boron high speed steel roll has been manufactured by centrifugal casting method. The microstructures, mechanical properties and wear resistance of centrifugal casting high‐boron high speed steel roll have been investigated by optical microscopy (OM), scanning electron microscopy (SEM), and X‐ray diffraction (XRD) analysis, hardness test, impact test and wear test. The results indicated that the solidification microstructures of high‐boron high speed steel roll consisted of M₂(B,C), (W,Mo)₂(B,C), M₃(B,C), M₂₃(B,C)₆ type borocarbides and martensite, a small amount of retained austenite. Borocarbides were continuously distributed over the grain boundary. After quenching from 1050 °C, local broken network appeared in partial borocarbides, and fine secondary borocarbide precipitated from the matrix. After tempering from 525 °C, the amount of precipitated borocarbide increased significantly. After heat treatment, the hardness of high‐boron high speed steel roll excelled 60 HRC, and its impact toughness excelled 8.0 J/cm². The single groove steel rolling amount of high‐boron high speed steel rolls increases by 500% than that of bainite cast iron roll, when the rolls are used in K₁ mill housing of bar mill.     

Brainstorming for ISO Strategy 2016-2020

正Responding to ISO’s appeal for survey for the to-be-developed ISO Strategy Plan for 2016-2020,SAC hosted a special workshop over the needs and comments of various fi elds on June 8 in Beijing.The workshop was attended by ISO President-elect and Ansteel General Manager Zhang Xiaogang,SAC Vice-Administrator Yu Xinli,and 30 experts from