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本文建立了小型平板CPL蒸发器毛细多孔芯内汽液两相流动与传热的模型以及金属外壁和工质区的导热模型,并进行耦合求解.分析了金属侧壁效应对蒸发器性能的影响,提出小型平板CPL存在着侧壁效应传热极限.数值结果表明,工质蒸发发生在多孔芯加热表面附近,蒸发器采用单一金属外壁时由于侧壁效应导致系统传热极限低,而上壁采用导热系数大,侧壁及下壁采用导热系数小的新型结构能够明显的提高系统的传热能力,同时使加热表面的温度维持在较低的水平. 相似文献
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探路者号火星探测器气动热和传热耦合分析 总被引:1,自引:0,他引:1
本文建立高超声速气动热和结构传热的松耦合计算方法,以探路者号火星探测器为研究对象,开展了探测器高超声速气动热和结构传热的耦合计算研究,分析了探测器进入条件下某轨道点上气动加热和结构传热机理。耦合计算表明,随着时间的推进,表面结构温度逐渐升高,壁面热流相对降低,表面趋向辐射平衡温度。因热防护系统结构传热时间尺度长于飞行器进入过程总时间,探测器进入的真实过程滞后于辐射平衡过程。耦合研究表明,使用耦合计算方法能较好地再现真实的气动加热和结构传热过程。 相似文献
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实验测定了水平和垂直放置状态下,铜-水交叉齿内螺纹重力热管的传热特性,并与普通铜-水重力热管进行了比较,得出了交叉齿内螺纹对重力热管传热性能的影响.水平放置状态下,交叉齿内螺纹重力热管具有较低的蒸发段温度、轴向温差和热阻,相比普通重力热管其传热极限也有极大的提升.垂直放置状态下,在40 W低加热功率时,交叉齿内螺纹重力热管传热性能低于普通重力热管,随着加热功率的增加,其传热性能实现反超。 相似文献
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冲击加热半无限体热应力问题理论分析 总被引:3,自引:0,他引:3
本文以快速瞬态导热微分方程式(双曲线型)为基础,对在自然状态下冲击加热半无限体产生的动态热应力问题进行了理论求解并对热冲击期间温度和应力的变化规律做了较深入的分析和讨论.所得结论对热冲击问题的理论研究及实际问题中热冲击损伤机理的研究都具有一定的价值. 相似文献
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由热应力决定的高功率连续Nd:YAG激光器的最大泵浦功率 总被引:1,自引:0,他引:1
本文报导了一台累积寿命为50小时的高功率连续激光器(更换一次氪灯)。其最大输出功率为366W,并研究了该激光器的输出特性和稳定性.此外,从实验上测量了激光棒内部耗散的功率,分析了Nd:YAG晶体棒中的温度和热应力,指出了高泵浦功率下热应力的存在是棒发生炸裂的主要原因,并确定每根棒的最大泵浦功率. 相似文献
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针对高超声速飞行器工作时前缘恶劣的气动加热环境, 为了保证飞行器前缘的尖锐外形, 提出内嵌高温热管前缘结构. 针对热管内部复杂流动与换热情况, 对内嵌高温热管前缘结构进行一体化建模, 将模型的核心部件液态金属热管工作状况的计算与实验进行对比以验证模型的可靠性. 本文还分析了给定工况下内嵌高温热管前缘结构的热防护效果, 其中壁面最高温度下降了11.6%, 最低温度上升了8%, 高温区和低温区均被封闭在前缘外层区域, 内层温度更加均匀, 实现了热流由高温区向低温区的转移, 削弱了高温区的热负荷. 本文还分析了接触热阻对热管冷却前缘结构效果的影响.
关键词:
热管
前缘
疏导式热防护
气动热 相似文献
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在5 GPa压力下对铝青铜进行750℃、保温15 min的高压热处理,对高压热处理前后铝青铜的电导率以及25~600℃温度范围内的热扩散系数、热容和热导率进行测试,结合显微组织的观察结果,探讨了高压热处理对铝青铜热物理性能的影响。研究表明:高压热处理能增大铝青铜的热扩散系数,减小热容;对热导率而言,温度低于400℃时高压热处理能增大铝青铜的热导率,而温度高于400℃时高压热处理能减小铝青铜的热导率。分析认为,产生变化的主要原因是高压热处理使铝青铜的微观组织发生了变化。 相似文献
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M.M. Mostafa 《Czechoslovak Journal of Physics》2001,51(3):223-228
Stress-strain curves of slowly cooled and quenched Sn-33wt. alloy were studied in the temperature range from 353 to 433 K. The coefficient of logarithmic work/hardening, the fracture time, the yield stress and the fracture stress of annealed and quenched samples decreased with increasinig deformation temperature and exhibited a minimum at 393 K. The activation energy of the fracture mechanism is found to be 5.4 and 12.8 KJ/mol characterizing a dislocation mechanism for annealed and quenched samples. The X-ray analysis of the slowly cooled and quenched samples showed that the residual internal strains increase in the low temperature relaxation stage and decrease in the second stage. 相似文献
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A hot aluminum alloy AA6082 and nickel disc of 560°C and 850°C was cooled by water spray of various spray flux under different condition of experiment. Temperature history was recorded with use of an infrared camera. During the quenching process, it was observed that the area with no apparent boiling and the outer annular region with vigorous liquid boiling have formed the boiling region. The width of the boiling region is essential as the maximum heat flux point is within the boiling region. Boiling width increases with initial temperature but decreases with water subcooling, spray flux and salinity. 相似文献
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The transient analytical solutions of temperature distribution, stress, strain and optical path difference in convectional cooled end-pumped laser rod are derived. The results are compared with other works and good agreements are found. The effects of increasing the edge cooling and face cooling are studied. It is found that an increase in the edge cooling has significant effect on reducing the maximum temperature that can be reached in the laser rod but it has no effect on the value of optical path difference. It is also found that increasing this type of cooling significantly reduces the time required to reach the thermal equilibrium with a slight increase in the max. tensile hoop stress that can be reached as the cooling increases. On the other hand, increase in face cooling reduces the response time, optical path difference and the maximum temperature that can be reached in the laser rod but a significant increase in the max. tensile hoop stress is observed. A matching between the advantages of these two type of cooling may be useful for a designer. 相似文献
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E. HajjariM. Divandari S.H. RazaviS.M. Emami S. Kamado 《Applied Surface Science》2011,257(11):5077-5082
Interfacial heat flux (IHF) between solid pure aluminum/magnesium melt and solid 413 aluminum alloy/magnesium melt couples was evaluated using lumped capacitance method, and the interface microstructures were assessed by scanning electronic microscope. The variation of maximum IHF with surface roughness for these two couples also was evaluated. The results showed that, for both solid aluminum/magnesium melt couples, with increasing the surface roughness, the maximum IHF increases at first and then starts to decrease after reaching a maximum value. In addition the measured maximum IHF for solid 413 aluminum alloy/magnesium melt couples was found to be higher than those measured for solid pure aluminum/magnesium melt couples. That seems to be because of the better wettability of 413 aluminum alloy than pure aluminum, by magnesium melt. 相似文献
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针对飞行器高超声速飞行时严重的气动加热环境, 提出内嵌定向高导热层的疏导式热防护系统. 运用数值方法分析了特定条件下内嵌定向高导热层的疏导式系统的防热效果, 外壁面最高温度下降了9.1%, 内壁面最高温度下降了31.5%, 高温区和低温区都被封闭在外层区域, 内层温度更加均匀, 实现了热流由高温区向低温区的转移, 削弱了高温区的热载荷, 强化了整体结构的热防护能力. 研究表明, 随着气动热流密度比与辐射散热面积比的增大, 疏导结构的冷却效果增强. 本文还对疏导防热系统的结构参数和材料参数对冷却效果的影响进行了分析, 为结构的设计和材料的选取提供一定的依据. 相似文献
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为了研究毫秒脉冲激光辐照硅基PIN多层结构产生的温度场和应力场的特点,本文基于热传导理论和弹塑性力学理论,利用等效比热容法处理相变潜热,考虑多个热源,尤其是底层铝电极反射的影响,并考虑硅基PIN探测器每层材料参数的非线性影响,采用有限元模拟软件COMSOL Multiphysics,对毫秒脉冲激光辐照硅基PIN多层结构的过程进行了二维数值模拟,得到了材料表层及内部各层的瞬态温度场与应力场的时空分布和变化规律.结果表明,底层铝电极对激光的反射,使得在底层铝电极处及附近硅层的温度都略有升高.在此基础上,分析了毫秒脉冲激光辐照硅基PIN的硬破坏机理,即熔融前力学损伤导致硅基PIN探测器的功能失常. 相似文献
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用高温应变计和热偶计等诊断技术,研究连续波氧碘化学激光(CW/COIL)与铝合金板作用产生的激光热应力。当照射靶面激光强度约1 000 W/cm2时,激光热应力随靶厚的增加而快速减小。当激光辐照靶材厚度h=1.00 mm、激光强度I=640~980 W/cm2时,激光热应力随辐照靶面激光强度的增加而增大。两者的激光热应力-时间曲线随靶厚的减薄或随辐照靶面激光强度的增加而变得越来越复杂。当靶厚h≤2.50 mm,辐照靶面激光强度I≥800 W/cm2时,激光热应力强度超过激光辐照区材料断裂强度,萌生许多孔洞裂纹,引起材料断裂破坏。 相似文献