共查询到20条相似文献,搜索用时 47 毫秒
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辐照碳化硅测温晶体是航空发动机研制过程中热端旋转部件温度测量的重要方法,其测量精度依赖于对其温度-缺陷浓度响应关系的精准标定,标定过程可分为温度标定试验、晶体缺陷表征测量、标定曲线建立3个阶段。温度标定试验中,温度场的波动、测温晶体与测温热电偶感温偏差以及非理想因素导致的传热是辐照晶体技术测量误差的重要来源。利用实验和数值方法,研究了辐照测温晶体在温度标定试验过程中不同阶段下主导的传热传质过程,分析了支杆材料的热物理参数、温度过冲以及准热平衡状态下的温度扰动对于测温晶体感温的影响,结果发现测量误差主要由辐射场在轴向方向的不均匀分布所导致,最后对支杆的材料和结构设计提出了相应的改进方案。 相似文献
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一种利用激光及热电器件的实时测温系统的测温精度 总被引:1,自引:1,他引:1
基于Kirchhoff定律,利用半导体激光器及钽酸锂热释电探测器设计了一种实用化的实时测温系统。从反射辐射对该测温系统测温精度的影响出发,讨论了水冷遮蔽板的相对尺寸(即H/R之值)与测温不确定度的关系,并确定了H/R之值;从波长对该测温系统测温精度的影响出发,并结合系统的测温灵敏度、探测器的温度分辨率及大气的透射窗口和温度的标准差等的研究结果,确定了系统的工作波长;总结了影响该实时测温系统测温不确定度的5种原因,结合光路中的外界干扰对该测温系统测温精度的影响,对该测温系统的测温精度及系统的测温不确定度进行了简要的分析。实验表明,在400-1200℃测温范围内,系统的测温不确定度优于0.3%。 相似文献
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超声测温技术在模拟航空发动机燃烧室温度测量中的应用 总被引:1,自引:0,他引:1
温度的测试对航空发动机的发展具有重要的意义,燃烧室出口温度是航空发动机的一个重要参数.超声测温技术具有测温范围广、响应快、精度高等优点,近年来被广泛应用于高温测量领域.设计了一套应用于模拟航空发动机燃烧室的超声测温系统.介绍了超声测温的基本原理,设计了基于铱铑合金的超声测温传感器,并在1 600℃高温炉内进行温度与声速的标定实验,最后将铱铑合金超声测温系统应用于模拟航空发动机燃烧室出口气流温度的测量试验中,获得温度-时间曲线,同时将测量结果与热电偶测量数据进行对比分析.结果表明,铱铑超声温度传感器的测量准确度可以达到97%. 相似文献
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使用RTU和RBC两种精密仪器对中国计量科学研究院中温基准实验室的F900高精密测温电桥进行了标定和评估,分析了不同工作频率、不同输出电流在长杆标准铂电阻温度计测温范围内对测量精度的影响。结果表明:电桥在不同的工作频率下精度的差异比较明显。工作频率为25 Hz时,使用RTU和RBC进行标定的最大测量偏差分别约为0.01 mK和0.06 mK;工作频率为75 Hz时,使用RTU和RBC进行标定的最大测量偏差约为0.08 mK和0.2 mK,且相比出厂时有了较大的漂移。电桥在不同的输出电流下精度的差异非常小,在15 μK以内。采用RTU及RBC对F900测温电桥评价的结果之间相互印证,该结果对中温固定点基准复现过程的不确定度评定提供了数据支撑。 相似文献
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发动机燃烧室出口温度分布测试的新型传感器 总被引:2,自引:0,他引:2
发动机燃烧室出口的温度分布对于推进技术的发展具有重要意义,而现阶段发动机内部温度已达1 800℃以上,主要测温手段辐射测温和热电偶受限于限于精度和材料,对这种高温氧化环境无法测试。该文依据超声测温原理,设计了一套可以在超高温氧化环境下用一根蓝宝石光纤测量多点温度的温度分布测试系统,并且在20~1 800℃范围内进行标定并多次校准。实验结果表明该系统测量精确、重复性良好,在1 600℃时灵敏度为0.004μs/℃,重复性达98.4%。在加装滞止罩后将感温元件封装于发动机燃烧室出口处,经过多此实验,测得了该燃烧室运行时出口处径向温度分布。 相似文献
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《纳米技术与精密工程》2016,(4)
为了实现超精密车削温度的在线测量,本文研究了一种基于薄膜热电偶的测量瞬态切削温度的方法.以切削刀具的刀尖作为镀制薄膜的基底,通过磁控溅射方法制备了Si O2绝缘薄膜和Ni Cr/Ni Si薄膜电极,制成了带有测温传感器并且可以进行超精密车削加工的PCBN刀具.文中对该薄膜热电偶温度传感器进行了标定,得到其塞贝克系数并采用该刀具对PMMA材料进行了超精密车削加工实验,实验结果表明该方法能够有效地测量出加工过程中的瞬态切削温度. 相似文献
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《International journal for numerical methods in engineering》2018,113(9):1488-1506
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. 相似文献
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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. 相似文献
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Standards are the basis for production enterprises to organize production ex-factory inspection trade 《中国标准化(英文版)》2008,25(1):24-25
Standards are the basis for production enterprises to organize production, ex-factory inspection, trade (delivery) and technical exchanges, product certification, quality arbitration and supervision.…… 相似文献
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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. 相似文献
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The end of over unit products of more than Chinese firms have passed the quality grade certification for liquor products. These products involve distilled spirits beer wine yellow wine fruit syrup wine others cover over % of the national top-branded liquor products.…… 《中国标准化(英文版)》2008,25(1):30
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.…… 相似文献
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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. 相似文献
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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.…… 相似文献
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N.A. Odintsova N.V. Ageenko K.V. Kiselev N.M. Sanina E.Y. Kostetsky 《International Journal of Refrigeration》2006,29(3):387
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. 相似文献
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David R. Smith F. R. Fickett 《Journal of research of the National Institute of Standards and Technology》1995,100(2):119-171
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. 相似文献