高功耗抗恶劣环境计算机散热研究

以某高功耗军用加固计算机热设计为实例,介绍了热设计过程中,加固计算机主板芯片到风道这一传导路径热阻计算的具体方法,对比了军用加固计算机采用单、双风道各自的传导热阻.并用IcePak热分析软件对采用单、双风道的加固计算机主板温度分布进行了仿真计算,通过实践证明了双风道散热形式在高功耗加固计算机中的可实施性和优越性.     

PCB板卡在加固计算机中的刚性设计

为了提高PCB板卡适应恶劣环境的能力,文中针对某机载加固计算机内主板的抗恶劣环境设计,研制了主板的刚性加固结构,给出了主板固有频率的计算方法。利用ANSYS Workbench仿真软件,对主板模块和整机结构进行了模态分析,得出了主板和主板模块的固有频率和振动薄弱点。通过对振动薄弱点采取刚性加固改进措施,有效提高了主板和主板模块的固有频率。对改进后的整机结构进行了随机振动仿真分析,并对比了主板在仿真分析中的响应位移与主板单振幅理论限额。结果表明,主板模块的刚性设计满足设备抗恶劣环境指标要求,从而实现了PCB板卡在加固计算机中的刚性设计。     

强迫风冷军用加固计算机声学噪声的实验研究

针对某强迫风冷军用加固计算机声学噪声源、噪声特性及影响噪声的主要因素进行了实验研究。研究结果表明:影响强迫风冷军用加固计算机声学噪声特性的因素主要包括风机、机箱风道,同时也排除了风机罩对计算机声学噪声特性的影响,同时也提出了各主要影响因素对整机声学噪声贡献的占比,为将来进一步控制强迫风冷军用加固计算机声学噪声指明了方向。     

舰载军用加固计算机的可靠性设计

为了提高舰载军用加固计算机的可靠性,针对该设备在恶劣环境条件下工作的现实,从电磁兼容、热设计等方面阐述了提高加固计算机可靠性设计思想,并根据设备工作的热环境和电磁环境,从计算机主机功能模块、主机箱体、系统I/O接口设计等方面详细地描述了提高其散热能力和电磁兼容能力的具体设计方法.经过试验证明,该方法能够有效地防止恶劣环境条件对计算机的干扰,提高其可靠性,保证计算机正常工作,对舰载电子设备的可靠性设计有普遍的意义.     

军用计算机的结构加固技术及其质量控制

本文是根据笔者赴美国考察军用计算机加固技术的汇报材料编写的。回顾了国内外军用计算机结构加固设计思想的形成过程,描述了军用计算机的整机结构,分析其结构加固设计的方法和特点,并讨论其环境适应性、可靠性及可维性。     

某功放模块的强迫风冷散热设计

介绍了某功放模块的强迫风冷设计方案,并通过CFD热仿真软件对温度场和风速场进行了计算分析.讨论了建模过程中常见的一些问题（如材质的选择、接触热阻的计算、风机的建模等）,并对该系统的风道阻力特性进行了分析,提出通过降低风道阻力,合理调整风机的工作点,或改变散热器的结构形式,对原有的设计方案进行了优化.     

地埋管热响应测试及数据分析方法

对上海某商务楼垂直地埋管换热器进行热响应测试,该商务楼占地面积大,在相隔300m两个地块分别钻三口测试井.本测试的特点是:地埋管换热器有效换热深度大,测试内容包括单U型及双U型地埋管,根据测试要求设定不同的循环流速.采用一维线热源模型对测试数据进行科学严谨的分析,本文将给出计算土壤导热系数、垂直地埋管换热器传热热阻及确定单位井深换热量方法.试验数据具有很强的对比性并能验证测试准确度.测试结果表明,该测试点的土壤导热系数为1.84～1.94 W/(m·K);相同埋管形式与管径地埋管换热器,传热热阻相同.本测试中双U型φ32埋管热阻大于双U型φ25热阻,单U型φ32型埋管热阻最大.应用线热源模整理出计算给定进水温度下的单位井深换热量公式,并计算出不同埋管形式及循环水流量下的单位井深换热量.     

抗恶劣环境计算机的热加固技术

本文主要论述军用计算机的热加同技术,包括冷却方案的确定,热设计基本原则,热设计技术以及热评定方法等。良好的热设计,可以改善军用计算机的环境条件,提高设备的热可靠性。论文中提出的热设计技术,可供军用计算机热设计与热分析参考。     

某机载雷达的结构及散热设计

文中针对机载电子设备的环境特点,开展了密闭式机箱的热设计工作,重点在于降低插件导冷板的板内横向传导热阻和机箱侧壁风道的对流热阻.仿真分析和试验测试均证实,热设计能够保证机箱内电子设备在高温工况下正常工作.在密闭式机箱散热过程中,冷却空气与电子器件不直接接触,因而在解决散热问题的同时,也提高了机箱的环境适应性,尤其适用于机载电子设备.而人工石墨贴片则适用于以导热为主要散热措施的场合,用于解决集中热源的散热问题.     

基于TRIZ理论的军用加固计算机散热问题探讨

TRIZ理论为创造性地发现问题和解决问题提供了系统的理论和方法。针对传统海军军用加固计算机在正常使用过程中,散热量以及噪声大在一定程度上影响舰员正常操作使用的情况,介绍应用TRIZ创新理论对加固计算机散热机构的优化设计进行探讨研究,为今后新型海军军用加固计算机散热设计提供了新思路和新方向。     

A general computer solution for radial and mixed flow turbomachine performance prediction

A general one dimensional performance prediction procedure applicable to both radial inflow turbines and centrifugal compressors is presented. By separating the fundamental one dimensional gas dynamic theory from the empiricism needed to extend the one dimensional analysis to a prediction procedure for a flow which is full three-dimensional, a single equation is developed to represent the flow in all types of ducts encountered in radial turbomachines. This separation of the fundamental gas dynamics from the application of empirical parameters gives the user a clear insight into the assumptions involved, and leads to a computer procedure which is constructed of a series of subroutines representing the empiricism needed for each duct. Consequently it is a relatively simple matter for the user to modify or replace any loss correlation in light of his own experience, and therefore, develop a computer prediction procedure which closely meets his own specific requirements.     

Resistance Characteristics of Hydraulic Oil through Isodiametric T-type Duct with Sharp Corners

Rational determination and reduction of local energy loss of oil flow at pipe junctions are of important significance to improve hydraulic pipeline's work efficiency, especially for complex hydraulic pipeline connected by isodiametric T-type ducts with sharp comers to get combined and divided flow. From this point of view, the formulae of resistance loss for combined flow and divided flow through isodiametric T-type duct with sharp comers as well as the correlations of resistance loss coefficients in the branches of the duct are derived using energy method. On this basis, resistance characteristics of hydraulic oil in the duct are obtained by numerical simulation of different flow modes, which are commonly applied in hydraulic pipelines, using computational fluid dynamics (CFD) method, and the reasons for the resistance loss are analyzed based on the pressure change mechanism in the flow field. A part of simulation results was validated with the reference data. The research shows that for combined flows the resistance loss of symmetrical is lower than that of tmsymmetrical to obtain low speed in common branch, but to gain high speed is quite the contrary, for divided flows, the symmetrical is always a reasonable choice to reduce resistance loss. These conclusions can be applied to optimize the design of hydraulic pipeline.     

Three-dimensional fine structure of the biliary tract: Scanning electron microscopy of biliary casts

The three-dimensional structure of the biliary tract was studied by scanning electron microscopy (SEM) of biliary casts. The replica of the biliary tract was successfully prepared by retrograde injection of low viscosity resin into the common bile duct. Bile canaliculi are intricate networks in which hexagonal and pentagonal meshworks are interconnected. Each hexagonal or pentagonal meshwork is on a plane, but adjoining meshworks are on different planes. Bile canalicular networks connect with bile ductules at the periphery of the portal tract. The intrahepatic bile duct showed considerable interspecies variation. The human bile duct has plexiform side branches and periductal sacculi, which are most numerous near the liver hilum and fewest in the smaller portal tracts. The hilar plexus and sacculi are present on opposite sides of the bile duct. The plexus formed at the bifurcation of the bile ducts exhibits a plane. Periductal sacculi were also observed in the monkey and pig bile ducts, particularly the latter, while rat bile ducts possess a peculiar portal bile ductular plexus situated between the portal tract and the surrounding liver parenchyma. No such structures were observed in either the dog or rabbit bile ducts. SEM of the biliary casts showed that the biliary tract was not a simple draining tube but had additional structures, such as periductal sacculi and plexiform side branches. These structures, together with the peribiliary vascular plexus, may be implicated in the modification of bile.     

Acoustic intensity measurement in a narrow duct by a two-sensor method

The use of two pressure sensors [Fusco et al., J. Acoust. Soc. Am. 91, 2229 (1992)] makes it possible to determine the acoustic intensity of a gas column in a duct, but the application of this method was limited to wide ducts. In this letter, the formulation of the method is modified to include narrow ducts where the duct radius is as small as the viscous boundary layer thickness of the gas. The validity of this method is shown by comparison with the direct measurements of the pressure and velocity.     

Algebraic model of turbulent flow in ducts of rectangular cross-section with rounded corners

Of increasing importance are nowadays ducts of rectangular cross-section with large-radius rounded corners. They are used for large air flow rates at low pressure levels — typically for air flow distribution in buildings ventilation and heating systems. Paper develops an analytic model of turbulent flows in these ducts. It makes possible in particular evaluation of velocity profiles – and volume flow rates as a function of duct cross-section shapes. The model was validated by comparing the solutions with full-scale duct laboratory measurements.     

Ontogeny of the testicular excurrent duct system of male Japanese quail (Coturnix japonica): A histological,ultrastructural, and histometric study

The testicular excurrent duct system undergoes several physiological and morphological changes during the reproductive stage or breeding season in mammals, birds, and reptiles. Studies on normal age-related histomorphological changes in the excurrent duct system of Japanese quails (Coturnix japonica) remain unreported, despite the extensive use of this bird as an avian model in research studies. The current study investigated the histological, ultrastructural, and histometric changes in the testicular excurrent duct system of the Japanese quail during three reproductive stages, namely prepubertal, pubertal, and adult. Simple squamous to low cuboidal cells formed the epithelia of the rete testis in prepubertal and pubertal birds, while in adult birds the lining was low cuboidal to cuboidal. In pubertal and adult birds, the nonciliated Type I epithelial cells of the proximal efferent duct displayed a subapical endocytotic apparatus comprising coated pits, coated apical tubules, and endosomes. There was a significant increase (p ≤ .001) in epithelial heights of all ducts of the excurrent duct system in the mature, sexually active, adult birds when compared to the other age groups. The luminal and tubular diameters, and the cross-sectional areas of efferent ducts and the epididymal duct unit increased significantly (p ≤ .001) with age. It is concluded that the morphology and morphometry of the excurrent ducts of the testis of the Japanese quail change as birds mature.     

Morphology of the intralobular duct of the submandibular gland in rats in case of experimental diabetes mellitus

The objective of study is to study the peculiarities of morphological changes in different subdivisions of the intralobular duct of the submandibular gland (SMG) in rats in case of experimental diabetes mellitus (DM). The study included sexually mature male Wistar rats. Experimental DM was induced by streptozotocin. Electron microscopic study of subdivisions of the intralobular duct of the SMG was carried out on the 14th, 28th, 42nd, 56th, and 70th days of the experiment. In early stages of experimental DM the intercalated ducts are characterized by a relatively unchanged structure, and in late stages vacuolization of the cytoplasm of their epithelial cells is observed. Since the 14th day vacuolization of mitochondria is observed in epithelial cells of the granular ducts being the most pronounced on the 28th day and not apparent over the subsequent periods. The degree of filling with granules reduces till 56th day, however, it increases sligthly on the last day of the experiment. On the 28th–70th days vacuolization of the cytoplasm is observed in epithelial cells of the striated ducts. In addition, on the 14th day the mitochondrial matrix of these cells condenses; over the next periods it becomes enlightened and mitochondrial cristae are clearly visualized and disorganized. Conclusion: In the intralobular duct of the SMG in experimental DM dystrophic changes of different intensity occur in the granular and striated ducts on the 14th day and in the intercalated ducts only since the 42nd day of the experiment.     

Supersonic flow of hydrogen and air in a duct with variable area

A chemically nonequilibrium supersonic flow of hydrogen and air has been investigated in a duct with conically divergent or convergent walls. Elementary reaction schemes of radicals involved in reaction of hydrogen-air have been considered and solved through the CHEMKIN code. The aim was to promote an understanding of characteristics of chemically nonequilibrium supersonic flow by introducing a simple mathematical formulation. The temperature, pressure, and density all were found to decrease for divergent ducts as the flow was accelerated, whereas they increased for a slightly convergent duct or a constant cross-sectional area duct. For the divergent nozzle with a greater degree the flow became chemically frozen. But it was quite necessary to take account of the effect of chemical nonequilibrium in a moderately expanded or all convergent conical ducts. As was expected, it was found that the temperature, pressure and Mach number were reduced for a fuel-lean mixture.     

双螺杆泵同步双圆弧齿轮传动热网络分析

综合传热学、摩擦学和齿轮啮合原理等,建立了双螺杆泵同步双圆弧齿轮箱热网络模型和热平衡方程组,确定了热源、热阻、对流换热系数等参数的计算模型,计算了该部件在润滑油润滑条件下的边界温度,为双圆弧齿轮传动热分析提供了理论基础.