Thermoelastic State of a Semiinfinite Body with Plane Surface Crack under the Action of Heat Sources

We study the influence of stationary heat sources on the stressed state of a semiinfinite body with a surface crack (in the form of a circular segment) perpendicular to its boundary by the method of boundary integral equations. The load-free boundary is maintained at zero temperature; the crack is not loaded and is either thermoisolated or maintained at a certain specified temperature. The dependences of the stress intensity factor on the angular coordinate of a point on the contour of the crack are constructed for various distances of a heat source from the boundary of the half-space and depths of the crack.     

含内热源大型不规则腔体高精度水循环控温方法研究

将用于测量辐射信号的球形实验装置置于直径为43 m、高为44 m的圆柱形实验厅内,球体外侧安装信号接收光电倍增管球壳层(PMTs),其运行会产生200 kW的高热。为维持球体表面水体温度稳定在(21±1)℃高精度恒温环境下,本文采用计算流体力学(CFD)技术,将球体浸没在循环水中并配合上下两段式布水方式进行精准控温。结果表明:上下两段布水方式可实现大型水体空间局部精确控温。考虑到不规则腔体流道限制,设计调整水循环布水角度,上布水口低温面积最大增幅达20%;提出增大上下布水器水量比以控制水体垂直温差,上下布水器水量之比为2.5∶1时控温能力最强,且降温最有效的区域是多孔介质PMT层与外水层;为得到不同热量下温度分布的统一规律,增大热源发热量,内水层上下布水口低温面积变化幅度有差异,上布水口低温面积缩小41%,下布水口缩小62%,但下布水口低温面积始终大于上布水口。     

Phase State of a Steel Plate Caused by the Action of Distributed Heat Sources

We propose a procedure for the numerical analysis of the structural state of steel plates caused by the action of moving distributed heat sources. With the help of an additional source whose intensity is five times lower than the intensity of the main source, one can halve the maximum content of martensite and, thus, significantly weaken the undesirable consequences of local heating. The results of the proposed investigation can be used in the development of the optimal technological procedures aimed at the minimization of residual welding stresses.     

Structural State of Steel Plates under the Action of Moving Heat Sources

We develop a procedure for the analysis of the phase composition of thin steel plates subjected to the action of distributed moving heat sources with several centers of localization. It is shown that the proper choice of the intensity and location of the centers of heating makes it possible to halve the maximum content of martensite and substantially decrease the nonuniformity of its space distribution in the zone of thermal influence.     

恒温槽温度补偿的晶体振荡器研制

本文主要介绍简易恒温晶体振荡器。由于加入了热敏电阻补偿网络，当温度从－１０℃－＋４５℃变化时，振荡器的频率稳定度得到了很大改进。     

Temperature Field of a Turbulent Flow in a Well with Allowance for the Temperature Dependence of Heat Capacity

The article discusses a method to solve a field-matching problem that describes a nonstationary heat exchange between an upward flow of fluid in a pipe and an ambient medium with allowance for the variability of the coefficients due to the turbulence of a multiphase flow and the nonlinear dependence of the oil heat capacity on temperature and precipitation of paraffins. The method combines asymptotic methods of small and formal parameters. Analysis of the experimental data on the dependence of heat capacity on the temperature makes it possible to approximate it by a linear function that contains a small parameter in the form of the first terms of the Taylor series. Expansion of the problem by the small parameter in the zeroth approximation leads to a linear problem that is solved by the asymptotic method for a formal parameter for uncoupling of the first coefficient of the expansion. Expressions determining the temperature field in the well and surrounding rocks that take into account the orthotropy of the thermophysical properties of the media are obtained.     

基于有限元思想的无限微热源冶炼炉温度机理研究

对无限微热源法制备β-SiC粉体的冶炼炉进行温度机理研究,根据传热形式、传热模型推导出无限微热源冶炼炉的导热微分方程,采用Galerkin法对方程进行变分并得出平面非稳态导热温度场分布方程,利用有限元思想对方程进行推导,再采用有限差分方法求解温度矩阵以得到炉内各个时刻温度的变化情况.     

A Generalized Thermoelasticity Problem for a Half-Space with Heat Sources and Body Forces

In this work, a two-dimensional problem of distribution of thermal stresses and temperature in a linear theory of a generalized thermoelastic half-space under the action of a body force and subjected to a thermal shock on the bounding plane is considered. Heat sources permeate the medium. The problem is in the context of the theory of generalized thermoelasticity with one relaxation time. Laplace and exponential Fourier transform techniques are used. The solution in the transformed domain is obtained by a direct approach. The inverse double transform is evaluated numerically. Numerical results are obtained and represented graphically.     

双冷源热回收调温型冷却除湿系统设计及实验研究

针对温湿度独立控制空调系统中,新风采用冷却除湿方式存在能耗较高、送风温度低、相对湿度大容易产生湿冷感的问题,本文提出一种双冷源热回收调温型冷却除湿系统方案。通过对其进行理论分析及实验验证,确定不同因素,如压缩机频率、预冷器水流量、新风量,对送风状态点的影响情况,研究其变化规律,形成送风状态点控制策略,确认了系统调节能力可满足送风舒适的要求,在标准工况下,送风温度最高可调至25.0 ℃。与普通除湿系统相比,双冷源热回收调温型冷却除湿系统能效提升幅度最高可达93.6%。     

Pyroelectric Transducers for the Measurement of Heat Transfer under Conditions of Hypersonic Flow

Pyroelectric detectors have been fabricated from polycrystalline samples of barium titanate. These detectors were mounted in a model for tests in a hypersonic wind tunnel and calibrated. The method of calibration is discussed and tables of calibration data are included. Thermocouples were mounted in the model to evaluate the detectors. The detectors were tested and results of the tests are discussed. Advantages of pyroelectric detectors are presented and typical output traces from both the pyroelectric detectors and the thermocouples are shown.     

Numerical Simulation of Thermocapillary Convection in a Shallow Rectangular Cavity Under the Action of Combining Horizontal Temperature Gradient with Vertical Heat Flux

In order to understand the influence of the vertical heat flux on thermocapillary convection, we conducted a series of unsteady two-dimensional numerical simulations of thermocapillary convection in a differently heated shallow rectangular cavity with vertical heat flux on the bottom by means of the finite volume method. The cavity was filled with the 1cSt silicone oil (Prandtl number Pr = 13.9) and aspect ratio is 30. It is found that a small vertical heat flux has slightly influence on the flow pattern of stable or unstable thermocapillary convection. However, the critical Marangoni number increases first, and then decreases with the increase of the heat flux. And the flow pattern of the oscillatory thermocapillary convection transits from a series of the rolls rotating clockwise and moving from the cold wall to the hot wall to the single roll near the hot wall and a series of rolls near the cold wall, further, two series of rolls moving from the hot wall and cold wall towards the hot spot with the maximum temperature. With the increase of the Marangoni number, the period and the wavelength of the oscillatory thermocapillary convection increase, but the wave speed decreases.     

蒸馏水恒温控制智能装置的研制

本文采用AT89C51作为整个系统的MCU,利用LM35温度传感器、OP07电压放大器和ADC0804组成的温度采集电路以实现蒸馏水温度的采集,并将其与标准温度进行比较;使蒸馏水温度恒温于此标准温度.该系统由硬件电路和软件编程两部分构成,实现蒸馏水的恒温控制.此系统LCD显示清晰,恒温控制精确到1℃.     

计量检定恒温室设计

本文详细介绍了一种能独立控温,节能、环保、经济型计量检定恒温室的设计.温度控制采用温度补偿方式进行,即运用PID温度控制系统原理进行恒温室内工作区温度的高精度控制.温场控制根据空气动力学原理,采用等距离上送风方式,正向风压气流循环系统来完成温场控制,使恒温室温度控制达到计量检定标准恒温室的要求.     

恒温槽温度均匀性测量值的不确定度评定

本文介绍恒温槽温度均匀性测量值的不确定度评定方法。     

在福州地区以天然能源为热泵冷热源的应用前景

以夏热冬暖地区城市-福州的气候、水文条件为基础，结合一住宅全年空调负荷的DOE-2．1模拟结果，分析在福州采用天然能源作为热泵的冷热源的应用前景，结果表明：（1）全年绝大部分时间内适合利用空气作为冷、热源；（2）闽江、内河周边的用户适合采用水源热泵；（3）温泉聚集地区不适合采用地下水和岩土作为冷源；（4）夏季适合联合使用岩土和辅助散热装置作冷源，冬季只使用岩土作热源。