月基望远镜热设计及热分析

为了利用月球观测地球等离子体层的优势,开展了月基望远镜的研究,并对其进行了热设计和热分析.分析了月基望远镜所处的空间环境.对望远镜各个部分进行了热设计;采用被动热控措施控制望远镜的温度水平,降低空间环境的影响;采用热疏导的方式对探测器进行散热.根据月基望远镜的空间环境、结构特点,以及采取的热控措施,在I-DEAS/TM...     

空间相机热光学分析与试验验证

为了对空间高分辨率相机热设计提出准确的技术要求,基于光学波像差的基本理论,对某高分辨率空间相机的温度场进行热光学分析.在此基础上确定了热控指标,并在真空罐中进行热真空成像试验,验证了热光学分析的正确性和热控指标的合理性.结果表明:最佳焦面位置与相机温度水平的关系近似成线性关系,最佳焦面位置变化量约0.08～0.1mm.℃-1;当温度水平在(20±1)℃之间变化时,像面处在系统焦深范围内,系统传递函数变化量在0.02左右;当径向温差和轴向温差会大于2℃引起最佳焦面位置发生移动,若不调焦,传函会明显下降.     

空间相机热光学分析与试验验证

为了对空间高分辨率相机热设计提出准确的技术要求,基于光学波像差的基本理论,对某高分辨率空间相机的温度场进行热光学分析.在此基础上确定了热控指标,并在真空罐中进行热真空成像试验,验证了热光学分析的正确性和热控指标的合理性.结果表明:最佳焦面位置与相机温度水平的关系近似成线性关系,最佳焦面位置变化量约0.08～0.1 mm·℃-1|当温度水平在(20±1 )℃之间变化时,像面处在系统焦深范围内,系统传递函数变化量在0.02左右|当径向温差和轴向温差会大于2 ℃引起最佳焦面位置发生移动,若不调焦,传函会明显下降.     

高分辨率空间相机精密热控设计及验证

基于波像差分配理论,提出了某高分辨率空间相机的热控指标.在分析相机空间外热流环境的基础上,进行了热控方案设计,并利用热分析软件进行了高低温工况下的瞬态热分析.结合热平衡试验验证了热设计的有效性和正确性.     

热致梯度折射率对非球面光学系统成像质量的影响

机载相机在上升过程中,由于温度降低和镜头各部分材料的导热率大小不同,镜头部分会产生温度梯度,从而导致非球面光学系统产生梯度折射率.利用有限元分析软件对镜头部分进行瞬态热分析以模拟机载相机上升过程中温度的变化情况,将有限元分析不同时间节点温度分布结果导入编写的折射率梯度系数拟合程序,将所求解的梯度折射率系数通过镜面类型接口在光学软件中建立光学系统模型,利用点列图的弥散斑半径评价不同时间节点梯度折射率对成像质量的影响.结果表明,机载相机刚升入工作高度时温度梯度最大,对成像质量影响也最严重,梯度折射率系数随着温度梯度系数的降低而降低,同时成像质量提高,该结果对光学系统的设计具有指导意义.     

空间光学遥感器热设计

为了保证空间光学遥感器所需温度条件,本着被动热控为主、主动热控为辅的原则对其进行了热设计.首先,分析了遥感器在轨工作模式,建立了遥感器外热流计算模型,根据遥感器各面外热流变化,确定了3个极端工况.然后,以对日低温工况热设计为主对遥感器进行了热设计.最后,对热设计进行了热仿真分析和热试验验证.结果表明:镜组温度水平可控制...     

大口径望远镜结构热分析

为了评估温度对望远镜的影响,针对某地基光电望远镜,建立了包括光学组件,跟踪架结构以及电控设备等在内的有限元热模型.在传导、对流、辐射以及热流等不同热环境下进行热分析,计算了望远镜光机结构的时间和空间温度分布.根据温度分布进行了热-弹性分析,得出了望远镜结构的热变形.分析表明:温度变化对望远镜跟踪架以及主光学系统的影响很大,对主次镜造成的相对位移达到毫米级,必须进行严格控制.最后从防护圆顶、跟踪架以及主镜等方面入手给出了热控设计方案.     

高分辨率高空相机光机系统的热设计

在极端低温情况下,为保证高空相机镜头光学系统温度满足设计要求,结合被动热控和主动热控进行相机光机系统的热设计.以聚酰亚胺为隔热材料进行被动热控,增大相机内部与外界的热阻,减弱外界低温环境对镜头温度的影响.采用电加热膜加热对相机镜头进行主动热控,在WorkBench有限元软件中建立镜头和窗口组件的传热模型,分析载荷构成,加载加热功率载荷、热对流载荷和热辐射载荷,进行稳态热分析.结果表明,在六个加热区,当加热功率分别为12、17、22、17、10、13 W时,相机光学系统的温度控制在18℃~22℃范围内,满足热控设计要求.     

热致变色可变发射率材料的制备与辐射特性研究

采用固相反应法制备了钙钛矿型锰氧化物热致变色材料,机械加工制得了薄层样品,测量了样品的晶体结构、居里温度以及辐射特性,分析了材料组分对样品居里温度和辐射特性的影响.试验结果表明,热致变色材料的发射率在相转变温度点附近会随温度的变化而突变.     

太阳同步圆轨道空间相机瞬态外热流计算

为了使空间相机热设计、热分析、热试验具备准确、可靠的热边界条件,对太阳同步圆轨道空间相机的瞬态外热流进行了计算。总结了卫星空间定位的6个轨道根数之间的关系,给出了太阳同步圆轨道空间定位的必要参数。针对某给定太阳同步圆轨道,采用STK软件进行了轨道面与太阳光矢量相对位置关系（β角）的计算,确定了该轨道的高、低温工况位置。归纳了空间外热流的理论计算方法,以外接于卫星平台的空间相机为例,建立了外热流计算模型,采用IDEAS/TMG模块对给定太阳同步圆轨道的高、低温工况轨道周期内瞬态外热流变化进行了分析计算,得出了太阳辐射热流、地球太阳反照热流、地球红外辐射热流在轨道周期内的详细变化曲线,得到的结果可以作为空间相机热设计、热分析及地面热试验外热流模拟的输入条件。     

Measurement of thermal parameters of a heat insulating material using infrared thermography

The article presents results of research developing methods for determining thermal parameters of a thermal insulating material. This method applies periodic heating as an excitation and an infrared camera is used to measure the temperature distribution on the surface of the tested material. The usefulness of known analytical solution of the inverse problem was examined in simulation study, using a three-dimensional model of the heat diffusion phenomenon in the sample of the material under test. To solve the coefficient inverse problem an approach using an artificial neural network is proposed. The measurements were performed on an experimental setup equipped with a ThermaCAM PM 595 infrared camera and a frame grabber. The experiment allowed verification of the chosen 3-D model of the heat diffusion phenomenon and proved suitability of the proposed test method.     

Sectoral thermal emitter for testing of modern IR systems

The paper presents multi-sector stable IR grey body radiation source, that can be used for testing of MRT. Its main element is monolithic metal plate with a test pattern, made of material with high thermal conductivity. On the surface of the test plate the sectors of different emissivity are created during manufacturing process. As a result when viewed by a thermal camera those sectors exhibit thermal contrast depending mainly on the radiative properties of each sector. The value of thermal contrast between particular sectors can be adjusted by changing the temperature of a test plate with respect to ambient. The emissivity values of particular sectors have been calculated and the procedure of adjusting the thermal contrast has been described, as well as the technology used to create the test plate. The model of described emitter has been tested and the results of temperature values obtained from thermal camera were compared with theoretical, calculated figures. The proposed emitter is dedicated for testing and calibrating of modern observations IR systems.     

Application of the nitroanisole as an infrared detector used in middle infrared interferometer

We propose the application of nitroanisole as a detector for middle infrared (mid-IR) interferometry or holography. The present experiment utilizes the liquid form of nitroanisole, which has a thermal lens effect, i.e. a temperature dependent refractive index. Since the nitroanisole absorbs IR radiation as heat, it is possible to estimate the IR intensity distribution on the nitroanisole from the diffraction pattern made by visible laser light that is transmitted through the nitroanisole. In this study, the time resolution and the diffraction efficiency of the nitroanisole was measured under various conditions. The experimental results show that the nitroanisole has a time resolution as high as that of a standard video camera, as well as a high diffraction efficiency and the spatial resolution equivalent to that of a conventional IR camera. Furthermore, we confirmed that the phase shift in mid-IR region can be estimated by analyzing the change in the visible diffraction pattern.     

基于显热回收的分离式热管传热特性的实验研究

针对新风空调机组,采用倾角为15°的分离式热管用于显热回收.研究充液率,迎面风速及空气进口温度对显热效率的影响,分析了其影响规律.研究表明,采用热管空调机组设计风速范围内,充液率介于66％～75％时,其换热效率最高.迎面风速较低时,空气进口温度介于34℃～36℃,其显热效率较高.因此,采用分离式热管机组适合用于高热地区...     

基于EPICS的颗粒传热实验测控系统应用研究

颗粒传热实验测控系统是为颗粒换热平台设计的测控系统。该系统基于分布式系统EPICS架构设计,通过对NI硬件平台、红外热像仪设备以及Oracle数据库进行集成,实现了颗粒换热平台实验的在线采集、监测、控制与实时存储。由于红外热像仪具有灵敏度高、测温范围广、非接触测温等优点,因此在该测控系统中用于测量颗粒在换热器出口处的温度。本文使用SDK将其集成到EPICS系统中,利用红外图像更加直观地呈现出颗粒的实时温度分布,并提取红外图像中的数据,与热电偶的测量数据对比,进一步检测利用红外热像仪作为一种颗粒实时温度测量设备的可行性。实验结果表明,集成后的红外热像仪操作软件能够实时提取并存储红外图像中的温度数值,并且采用EPICS架构设计、开发的颗粒传热实验测控系统完全可以满足颗粒换热平台的数据采集与存储需求。     

高分辨率空间相机精密热控设计及验证

基于波像差分配理论,提出了某高分辨率空间相机的热控指标.在分析相机空间外热流环境的基础上,进行了热控方案设计,并利用热分析软件进行了高低温工况下的瞬态热分析.结合热平衡试验验证了热设计的有效性和正确性.     

Analysis of thermal and electrical properties of ZnO arrester block

Voltage–current characteristics of ZnO surge arresters are highly dependent on temperature in the low-conduction region. ZnO surge arresters experience thermal runaway when the temperature exceeds the acceptable limit. This phenomenon is associated with the increase of resistive leakage current due to degradation. This paper presents the thermal and electrical characteristics of ZnO arrester blocks under the power frequency AC operating voltages. The leakage currents of ZnO arrester blocks were measured over a period of the time. The temperature profiles of ZnO arrester blocks were observed by the infrared camera. The degradation and the thermal runaway of the ZnO arrester blocks are closely related to the temperature limit which determines the heat generation and dissipation. As the leakage current was 0.5 mA, the amount of heat generation is lower than that of heat dissipation. So temperature of the ZnO arrester blocks was rarely changed. On the other hand, as the leakage current was 0.7 and 1 mA, the amount of heat generation was greater than that of the heat dissipation. The temperature of ZnO arrester blocks gradually increases and the test specimen experiences thermal runaway. At that time the temperature located at the center of ZnO arrester blocks string was higher compared to that of ZnO block at both edges.     

航天相机主动热控测试系统设计

为了检测航天相机主动热控系统的功能、性能及可靠性,设计了主动热控仿真测试系统。依据传热学基本定律、航天器轨道理论和热控策略,给出了计算航天相机温度场的热网络数学模型,使主动热控系统能在模拟的空间热环境中连续工作,实现了对主动热控系统的闭环仿真测试。采用两个数字电位器相串联的方法模拟温度传感器的走势,得到的最大阻值为100 kΩ,精度达到10Ω,符合设计中对总电阻和电阻变化率的需求,实现了对主动热控系统的功能、性能以及可靠性的仿真测试。     

Direct and absolute temperature mapping and heat transfer measurements in diode-end-pumped Yb:YAG

We report on direct and absolute temperature measurements in a diode-end-pumped Yb:YAG crystal, using a calibrated infrared camera, with a 60 m spatial resolution. The heat transfer coefficient has been measured, for the first time to our knowledge, with four different types of thermal contact (H=0.25, 0.28, 0.9, and 2.0 for bare contact, graphite layer, indium foil, and heat sink grease respectively). The dynamics of thermal effects are also presented. PACS 42.55.Xi     

环路热管式空调机组传热特性的实验研究

采用环路热管式空调机组用于新风的预冷及再热,减少了表冷器的冷量及降低再热设备的能耗。文中研究了充液率、倾角对热管蒸发段和冷凝段温差及显热效率的影响。研究表明,环路热管式空调机组,充液率介于55%～75%时,热管蒸发段和冷凝段温差较大;随着倾角的增加,热管蒸发段和冷凝段温差也逐渐增大,显热效率也随之较高。因此,采用环路热管式空调机组可降低能耗,提高人体的热舒适性,可用于热带及亚热带地区,最大限度回收热量。