加装红外抑制器的直升机红外辐射的计算及测量

计算了光谱在3～5 μm及8～12 μm范围内,加装与机身结构一体化红外抑制器的某型直升机排气系统的红外辐射特性.计算中考虑了排气系统部分蒙皮的红外辐射、双喷管发动机喷气流的红外辐射、背景辐射及大气的吸收衰减对直升机排气系统红外辐射信号的影响.实验发现,一架加装与机身结构一体化红外抑制器的直升机排气系统红外辐射特性的计算结果,与实测结果基本一致.     

宽高比对矩形喷管外尾焰红外辐射的影响

建立了三种不同宽高比矩形喷管的物理模型,采用Fluent6.3软件对三种矩形尾喷管外的三维流场进行了数值模拟,得到尾焰流场的温度、压强和密度等数据,并根据矩形尾喷管外尾焰的特点确立三种矩形尾喷管外尾焰的红外辐射核心计算区域.利用基于洛伦兹线型的统计窄带模型,求出尾焰在窄带l的平均吸收系数;然后采用有限体积法(FVM)求解气体介质中辐射传输方程,最后得到了尾焰的红外辐射的光谱特性与三种矩形喷管尾焰在3～5 μm波段的总强度分布.结果表明:尾焰辐射在2.7 μm和4.3 μm处出现两个辐射峰,并且随着矩形喷管宽高比的增加,尾焰的红外辐射强度大大降低.     

降低发射率对发动机喷管红外隐身效果的影响

以某型发动机为原型,将该原型发动机简化成一个由涡轮出口、中心锥、火焰稳定器、引射出口和发动机腔体喷管组成的轴对称模型。利用该模型计算在发射率为0.9、反射率为0.1时的喷管红外辐射强度,采用降低腔体发射率的方法,计算发射率为0.2、反射率为0.1时的喷管红外辐射强度。通过对比分析两种模拟计算结果,评估降低腔体发射率对发动机喷管红外隐身效果的影响。     

热喷流红外辐射特性的实验测试

本文对热喷流的红外辐射特征进行了实验研究,着重介绍了以通用仪器组成的红外探测系统,对热喷流的红外辐射能的空间分布和红外光谱特征进行测试的测试方法和实测结果。实验表明,探测系统和测试方法是有效的,实测结果是可信的。因此本文为热喷流及其它红外辐射目标的红外特性的测试与研究,提供了一种可供借鉴的探测系统和测试技术。     

贴附射流与辐射板复合空调系统优化

利用Fluent软件对贴附射流与辐射板复合空调系统进行模拟计算,分析其舒适性,并根据壁面温度计算其辐射不对称性。结合模型设置和模拟结果提出3种改善其辐射不对称性的方案并进行模拟计算。结果表明,侧壁辐射板布置于正对送风口方向以及与送风口所在壁面相邻壁面的下部空间,辐射不对称性可降低1.5~2.0℃,且不会有结露的风险,温度均匀性优于原方案。     

卫星轨控推进器尾焰红外辐射的数值模拟

为全面了解卫星的红外辐射特性,需掌握卫星轨控推进器尾焰的红外辐射特性.按照先计算尾焰的流场、再计算尾焰的吸收系数、最后用有限体积法求解尾焰红外辐射亮度的先后顺序,较完整地建立了卫星轨控推进器尾焰红外辐射的求解模型.根据该模型计算得到的尾焰辐射亮度,进一步求解获得了1 000～4 500 cm-1 内的光谱和波段辐射强度.通过分析,光谱辐射强度在1 525 cm-1、1 700 cm-1、2 155 cm-1、2 175 cm-1、2 350 cm-1 和3 750 cm-1附近的数值较大;到喷管出口截面的垂直距离不同,最大的波段辐射强度可能对应不同的方位角.在波数2 350cm-1和3 750 cm-1 附近,光谱辐射强度与同类文献中的计算结果能够相互吻合.此结果表明,该模型具有较高的可行性和精确性.     

氧化膜对耐热不锈钢试验喷管传热特性的影响

建立了耐热不锈钢试验喷管轴对称非稳态传热数值计算模型以及不锈钢在高水蒸气含量燃气中的氧 化动力学模型,研究了氧化膜对喷管传热特性的影响.考虑了燃气时壁面的辐射换热及材料热物性参数随温度的变化,分别计算了结构材料无氧化膜、氧化膜表面光滑、氧化膜表面粗糙情况下的内喷管温度分布,通过理论计算值验证了数值计算模型的合理性与可靠性.结果表明,耐热不锈钢表面氧化膜的低导热系数使喷管热阻增大,但较大的氧化膜表面粗糙度强化了传热,2种因素综合作用决定了氧化膜对喷管传热特性的影响,氧化膜起到了隔热作用,计算结果可为表面热应力腐蚀数值模拟提供数据支持.     

飞行器表面温度和发射率分布对红外辐射特征的影响

为了考察飞行器表面8～14μm波段内红外辐射特征的控制规律,建立了包括蒙皮外气动热与蒙皮内部传热的数学物理模型,分别采用有限体积法求解蒙皮温度分布和反向蒙特卡罗法计算飞行器表面8～14μm波段内红外辐射特征.通过数值模拟,计算分析了在水平方向上飞行器各主要部件对红外辐射强度的贡献.最后,改变飞行器各主要部件的表面温度和发射率,获得了对飞行器水平方向上总的红外辐射特征的影响和控制规律.     

换热管间距对冷辐射板换热性能的影响

冷辐射空调以较好的热舒适性和较大的节能潜力越来越受到人们重视，但其表面易结露及单位面积制冷能力偏低影响了其工程应用。本文通过建立金属辐射板传热过程模型，分析了辐射板换热管间距排列对换热性能的影响。结果表明：对常规等管间距排列铜管辐射换热表面，在供水温度及流速分别为17℃和0.3 m/s时，对某1.2 m×0.4 m辐射板，当管间距由100 mm降至68 mm时，辐射板表面平均温度和最高温度分别下降0.58、0.76℃,温度不均匀系数分别降低3.56%、9.41%。在此基础上，设计了4排、5排、6排三类共9种变管间距排列辐射板，分别与相应等管间距排列辐射板对比，表面平均温度最高分别下降0.37、0.56、0.36℃,温度不均匀系数最高分别下降19.3%、23.5%、30.3%,换热管变管距排列表面温度更均匀。     

基于涂层性能退化的卫星红外辐射灵敏度分析

由于卫星表面热控涂层在空间恶劣环境下发生性能退化,导致实际参数与设计参数发生偏差,而重复计算卫星温度场和红外辐射耗时非常大.本文首先根据地面模拟实验数据建立了热控涂层性能退化模型,然后在卫星温度场和表面红外辐射计算模型的基础上,推导了卫星表面节点温度灵敏度和红外辐射灵敏度的计算公式.结合具体的卫星模型和轨道参数,求解了卫星表面节点温度灵敏度和红外辐射灵敏度.结果表明,热控涂层性能退化造成的卫星红外辐射特性变化,可直接利用卫星红外辐射灵敏度来分析,避免了卫星温度场和空间红外辐射的重复计算.     

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.     

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.     

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     

CNAS Passes APLAC's PTP Review

正The review group of Asia Pacific Laboratory Accreditation Cooperation(APLAC)carried out a 4-day peer review of the proficiency testing provider(PTP)for China National Accreditation Service for Conformity Assessment(CNAS)from July 28 to 31,2014.CNAS passed the PTP review with excellent performance.Two senior peer reviewers of APLAC made a comprehensive,rigorous and detailed review of CNAS’s PTP accreditation activities,and made the on-spot inspection of the review groups in Shanghai and Shenzhen respectively.     

新闻(英文)

正China and Greece Sign the Standardization Cooperation Agreement Witnessed by Chinese Premier Li Keqiang and Greek Prime Minister Antonis Samaras,AQSIQ Minister Zhi Shuping and ELOT Chairman and Executive Director Angelos Tolkas signed the SAC-ELOT Standardization Cooperation Agreement.The Agreement is one of the critical cooperation documents signed during Li Keqiang’s visit in Greece,encouraging China and Greece to