过冷态超流氦恒温器的热力学分析

对过冷态超流氦恒温器的热力学过程进行分析,考察了不同的设计温度和J-T换热器热效率下恒温器的制冷性能,得到了理论制冷量的变化曲线.结果表明,理论制冷量与设计温度和J-T换热器的热效率密切相关.计算发现,160 L液氦在2W制冷量下从4.2K降至1.8K大约需要24 h.     

液氢温区单级高频多路旁通型脉冲管制冷机

为了既能降到液氢温区又能确保制冷机的温度稳定性,开展了仅采用长颈管,不使用双向进气进行调相的单级高频多路旁通型脉冲管制冷机的实验研究。首先用数值计算的方法获得了多路旁通开度是否最佳的判据。研制出的制冷机在充气压力1.73MPa,输入电功220W时,无负荷最低制冷温度能够降到23.6K,为目前所报道的在没有双向进气时单级高频脉冲管制冷机获得的最低温度。在达到稳定状态后,制冷机性能稳定,温度波动幅值小于0.1K。在220W输入电功下,能够在29.2K获得0.516W,34.3K获得1.0W的制冷量。     

大功率单级脉管制冷机回热器性能模拟与实验

为了提高单级脉管制冷机在20 K-40 K温区的制冷量,对自行设计制作的1台单级G-M型脉管制冷机采用REGEN3.3进行了计算模拟,获得了铅丸直径选择、不同温区回热器材料最佳组合等结果。在此基础上,对该台单级脉管制冷机进行了试验,实验结果表明该脉管制冷机在20.6K和29.9 K可分别获得20 W和40 W的制冷量,输入功率为7.5 kW。     

大冷量单级G-M型制冷机的研制

对50 W/30 K单级G-M制冷机实验室研制工作进行了总结,给出了理论分析、结构设计以及实验结果.在常规形式狭缝式换热器的样机的基础上进行实验,得到17 K的最低温度,在30K的情况下获得了27 W的制冷量.     

电阻阵列冷却用脉管制冷机研制

为解决以电阻阵列器件为基础的动态红外景像产生器中的冷却问题,设计并研制了一台采用线性压缩机驱动的在223 K工作的脉管制冷机。实验结果表明:在500 W的电输入功下,制冷机的最低无负荷制冷温度为99.7 K,在232.8 K获得了181.3 W的制冷量,与理论预测制冷量189.4 W吻合良好,相对卡诺效率达到10.4%,工作对脉管制冷机在普冷温区的应用是一次有益的探索。     

铑铁电阻温度计简单分度特性研究

收集18支英国Tinsley和10支中国云南制作的低温标准铑铁电阻温度计在0.5 K至27.1 K温区的分度数据,以2.1768K为参考温度点,定义电阻比值为W(T)=R(T)/R(2.1768K),再用最小二乘法以切比雪夫多项式拟合计算这些分度数据.采取参考函数加偏差修正的方式,用2.1768 K、13.8033 K和24.5561 K做单点、两点和三点简单分度,求出简单分度表对常规多点拟合分度表的偏差.选取W(24.5561 K)值相近的温度计做配对计算,可以进一步降低简单分度的最大内插偏差.其中有二对云南制温度计在1 K至25 K温区用两点简单分度算法获得了最大内插偏差小于0.5 mK的良好结果.     

2 W@80 K星载斯特林制冷机丝网的优化选型设计

介绍了丝网的种类,考虑丝网质量对回热器性能的影响,给出了优质丝网的判据.详细分析了丝网目数对空隙率、比传热面积和当量直径的影响,以回热器回热损失与压降损失之和最小,尽可能减小回热器空容积为原则进行计算分析,得出2 W@80 K制冷机回热器的最佳填料为丝径0.036 mm、276目×276目的平纹方孔网.试验结果表明选用该规格丝网的制冷机在制冷温度80 K、压缩机输入功率46.2 W时,获得的制冷量为2 W.     

120 K～150 K温区混合工质内复叠节流制冷机的实验研究

混合工质节流制冷机在许多方面获得越来越广泛的应用,本文提出了利用内复叠节流制冷系统获得120K－150K温区的制冷方安分析了它的应用前景,建立了相应的单级油润滑制冷压缩驱动的实验系统。无热负荷时最低温度达到112K,在130K时获得了60W的制冷量,135K时获得了74W的制冷量。     

利用稳态法测量聚合物薄膜纵向热导系数

在一维稳态热传导模型的基础上,设计了一套用于测量聚合物薄膜纵向热导系数的实验装置,并利用Comsol软件对该测量装置进行数值模拟并优化设计。同时利用本文设计的实验装置,测量得到了不同温度下聚酰亚胺(PI)膜、聚四氟乙烯(PTFE)膜以及混合纤维素酯(MCE)膜的热导系数。在35℃~60℃的温度范围内热导系数测量值分别维持在0.21 W/(m.K),0.26 W/(m.K),0.13 W/(m.K)左右,标准不确定度在9.5%以下。测量结果与参考值相符,验证了实验装置的测试精度。     

一种气动弹簧内置结构的斯特林制冷机设计

设计了一台100 W/77 K的分置式大冷量斯特林制冷机,其中气动弹簧组内置于空心排出器中,缩小了膨胀机的轴向尺寸。热端膨胀腔与压缩腔之间通过辐射状分布的分离式"明渠"结构通气槽连通,降低了加工难度。压缩机为对置式双气浮活塞结构,最大输入功率2 kW。介绍了该制冷机的热力设计和动力设计,给出了参数设计结果,最后分析了压缩机各类损失对制冷效率的影响。模拟结果表明,在1 064 W的PV功下,制冷机77 K可以获得104 W制冷量,当压缩机效率大于85%,热端温度20℃时,电功消耗小于1 252 W,比卡诺效率大于23%。     

Stress analysis of a strip with a step and a crack

Stress analysis for a strip of which widths are different at the right and left handsides is carried out for before and after occurrence of a crack at a corner of a step. The strip is analyzed as a thin plate bending problem subject to transverse bending and torsion, and as a plane eleastic problem subject to bending in the plane and uniaxial tension. The rational mapping function of a sum of fractional expressions and complex variable method are used. Stress distribution and stress intensity factors are obtained.     

Interaction between a liquid and a cylindrical body touching a wall

An exact solution is obtained for the problem of interaction between the ideal liquid homogeneously moving at infinity and streamlining a round cylinder touching a solid wall.     

Calculation of a transient in a two-pole network with a thermistor

An analytical expression is derived which describes the variation of the thermistor temperature during a relay-effect transient process following an instantaneous change in the supply voltage in an R — R_T two-pole network.Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 38, No. 3, pp. 465–472, March, 1980.     

Imaging a point to a line with a single spherical mirror

Methods for imaging a single point source to a line image are discussed, and a design study of single spherical mirror systems that form aberration-free line images is presented. An expression forthe ray density along the line image is derived for such systems in the cases of (i) uniform beam profiles and (ii) Gaussian beam profiles. The resulting ray density profiles are illustrated for single spherical mirror systems over a wide range of design parameters.     

Influence lines for bending under a ring load of a free shell,a shell embedded in a soft medium and a shell containing a soft core

Summary Theoretical expressions for stresses and displacements have been derived for bending under a ring load of a free shell, a shell embedded in a soft medium, and a shell containing a soft core. Numerical work has been done for typical cases with anElliot 803 Digital Computer and influence lines are drawn therefrom.

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Einflußlinien für die Biegung einer freien Schale, einer Schale in einer weichen Bettung und einer Schale mit weichem Kern

Zusammenfassung Für die Biegung einer freien Schale, einer weich gebetteten Schale und einer Schale mit weichem Kern unter einer Ringlast werden Ausdrücke für die Spannungen und Verschiebungen hergeleitet. Die Ergebnisse wurden für einige typische Fälle mit einem DigitalrechnerElliot 803 numerisch ausgewertet. Die sich ergebenden Einflußlinien wurden graphisch dargestellt.

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Nomenclature A (),B () Functions of - a, t Mean radius and thickness of the shell - E _S , _S Young's modulus andPoisson's ratio of the shell - G _c , _c Shear modulus andPoisson's ratio of the casting or core - I ₀ (r),I ₁ (r) ModifiedBessel functions of the first kind and order zero and one respectively - K ₀ (r),K ₁ (r) ModifiedBessel functions of the second kind and order zero and one respectively - p Ring load, lb/in - U, W Displacement components in the casing or core in thez andr direction - u, w Displacement components of a middle surface point in the shell - _r , _rz Radial and shearing stress components - Independent variable of infinite integrals - k [3(1–S ²)a ²/t ²]^1/4 With 13 Figures     

Analysis of a Premature Failure of a Hub from a Diesel Generator of a High-Speed Motor Ship

Failure analysis is carried out on a fractured hub obtained from a diesel generator of a high-speed motor ship. Macrofractography, microfractography, standard optical metallography, material characterization techniques, and numerical modeling were used to verify the findings of the current investigation. Cracking initiation is attributed to fretting fatigue caused by a modification performed in the vicinity of the fractured hub. Operational vibrations contributed to the propagation of the cracks as typical fatigue cracks until final fracture.     

Piercing a metallic barrier with a jet of a dilute polymer solution

Results are shown pertaining to the action of jets of dilute polymer solutions on solid barriers. The piercing of a barrier is explained by the viscoelastic properties of aggregates which, during an impact, behave like solid particles.Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 25, No. 6, pp. 1090–1094, December, 1973.     

Linear heat transfer in a flow around a cylinder or a sphere

It is shown that the relation between the Nusselt and Reynolds numbers determined by the Reynolds analogy is linear with self-similarity of the hydrodynamic resistance coefficient.Special Design and Technology Office Element, Odessa, Ukraine. translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 68, No. 3, May–June, pp. 395–396, 1995.