共查询到19条相似文献,搜索用时 234 毫秒
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实心圆锥喷嘴喷雾单相区冷却性能模拟研究 总被引:1,自引:0,他引:1
喷雾冷却可获得高效散热效果,本文以深入分析喷雾冷却性能影响因素为目标,对不同实心喷嘴在多种运行工况下的喷雾过程进行了模拟,并分析了喷雾冷却单相区的换热性能.CFD模拟与部分文献试验结果比较验证分析,表明模拟结果可作为深入分析压力旋流喷嘴喷射过程,以及优化其设计和运行的参考. 相似文献
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论述低温气体雾化射流冷却原理及特点,以池内膜态沸腾为基础,将喷雾颗粒的冲击作为一种扰动,建立雾滴射流进入切削区冷却高温壁面的模型,讨论雾滴冷却高温壁面的换热系数,着重探讨工艺参数水流密度对喷雾冷却换热系数的影响.进行了不同水剂量的低温气体雾化射流冷却钛合金高温壁面的瞬态实验,获得了钛合金试件表面温度分别为100℃、150℃、200℃和250℃时,低温气体雾化射流冷却达到最佳冷却效果时水剂量,分析了水剂量对冷却效果的理论依据,结果证实该模型对实际应用具有一定的指导作用. 相似文献
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《流体机械》2021,49(6)
电子产品的发展趋势是运行速度快、发热功率大、体积小,散热能力对其性能影响很大。冲击射流因其冷却效果好被广泛用于冷却电子产品。基于冲击射流冷却技术,设计搭建了一个空气冲击射流冷却试验装置,通过试验研究了加热功率、射流温度、喷嘴与壁面间距离和喷嘴直径对空气冲击射流换热的影响:加热功率在15.7~49.0 W范围内,沿径向壁面温度均先降后升、换热系数先增后减;随着加热功率增大,壁面径向温度分布越不均匀、平均温度升高,对换热系数没有影响;射流温度一定,沿径向壁面温度先降后升、局部换热系数先增后减;随着射流温度升高,壁面平均温度小幅升高、径向温度分布越均匀,空气物性发生变化,换热系数略有提高,但换热系数的最大值位置不变。 相似文献
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采用低熔点液态金属工质散热的热沉传热数值模拟 总被引:2,自引:0,他引:2
为研究低熔点液态金属散热工质的强化散热机理,针对芯片散热,对热沉内低熔点液态金属镓以及水分别作为散热工质时的层流传热性能分别进行数值模拟,比较分析热沉流道长度、直径、Re数及工质导热系数对热沉散热性能的影响.结果表明,以镓为工质时,芯片温度受流道长度变化的影响较小,随流道直径、Re数的增加而降低:仅在流道长度小于临界长度的较短范围内具有比水更好的冷却效果,且临界长度随Re数的增加而增大;工质导热系数越大,芯片温度降低的程度越来越小.研究结果为合理设计液态金属散热系统提供理论基础. 相似文献
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Cong Mao Hongfu Zou Yong Huang Yafei Li Zhixiong Zhou 《The International Journal of Advanced Manufacturing Technology》2013,66(1-4):363-370
The surface heat transfer exhibits highly nonlinear characteristic during minimum quantity lubrication (MQL) grinding owing to the high grinding surface temperature gradient, the complicated movement characteristic of the spray and the random droplet size. Based on the atomization mechanism, the influencing factors about the velocity and the diameter of the droplet were analyzed. The grinding zone was divided into four different regions according to the heat transfer mechanism of the droplet at different surface temperatures, namely non-boiling heat transfer region, nucleate boiling heat transfer region, transitional boiling heat transfer region and stable film boiling heat transfer region. Furthermore, the related mathematical models of heat transfer in the grinding zone were established. The surface grinding experiment is carried out; a good agreement is found between the simulative result and experimental measuring result of the surface temperature during MQL grinding, which shows that the theory of surface heat transfer coefficient during MQL grinding is creditable. 相似文献
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Several important parameters, such as liquid mass flux, droplet size distribution, droplet velocity, and heating target conditions
(roughness and surface temperature) are involved in the industrial spray cooling heat transfer process. In this study, we
investigated the effect of liquid mass flux, heating target roughness, and the droplet size on the droplet wall direct contact
heat transfer in spray cooling phenomena. Three different conditions of surface roughness were investigated. The measurement
of test surface temperature was performed using a non-intrusive method, i. e., using an infrared thermometer. The droplet
size distribution of water spray was measured with Malvern 2600. The results indicated that the most influential parameters
were the liquid mass flux and the surface roughness. The droplet size and the velocity played a less important role in the
direct contact heat transfer because the interactions between droplets were very strong in a dense spray. The smooth surface
showed the highest heat transfer among the surfaces tested. At high air pressure ([7] kPa), however, the degree of roughness
did not affect much the heat transfer rate. 相似文献
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功放芯片是现代雷达和电子战设备最重要的发热器件,其中Ga N芯片在T/R组件中得到了越来越广泛的应用。文中针对Ga N芯片热耗大、热流密度高等特点,探讨了从两相流冷却技术角度解决散热问题的工程可行性。分析了两相流冷却原理,提出了用菱形肋微通道冷板来强化对流沸腾换热的方法,并搭建了试验系统对散热性能进行了测试。试验结果证明了两相流冷却技术应用于高热流密度功放芯片散热的有效性和可行性,为未来高热流密度功放芯片的散热提供了可行的解决方案。 相似文献
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Micro-texture at the tool face is a state-of-the-art technique to improve cutting performance. In this paper, five types of micro-texture were fabricated at the flank face to improve the cooling performance under the condition of high pressure jet coolant assistance. By using micro-textures consisted of pin fins, plate fins and pits fabricated 0.3 mm away from the cutting edge, heat transfer from the tool face to coolant was enhanced. The conditions of tool wear, adhesion and chip formation were compared between the micro-textured and non-patterned tools in the longitudinal turning of the nickel-based superalloy Inconel 718. As a result, micro-textured tools always exhibited the reduced flank and crater wear compared with the non-patterned tool, and the rate of tool wear was influenced by the array and height of fin. The energy dispersive spectroscopy analysis of worn flank faces and the electromotive forces obtained from the tool-work thermocouple supported better cooling performances of micro-textured tools. In addition, coolant deposition at flank face evidenced that heat transfer could be promoted by micro-texture near the border of the contact area between the flank wear land and machined surface. Finally, the changes of flow patterns with pit depth are analyzed for pit type tools by computational fluid dynamics. This investigation clearly showed the function of micro-textures for increasing the turbulent kinetic energy and cooling the textured tool face. 相似文献
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基于超声雾化理论和超声聚焦理论,提出了一种应用于精密磨削加工中的球面聚焦超声汽雾冷却系统,在使用超声雾化作为冷却方式的同时,利用聚焦超声将汽雾汇聚到指定的换热位置,以提高汽雾的利用率。利用Fluent软件数值模拟和平面热源条件下稳态换热试验分析了聚焦汽雾和聚焦超声对聚焦超声汽雾冷却系统换热特性的影响。结果表明,当试件位于汽雾焦区时,聚焦汽雾的换热性能最佳,试件表面温度最低;同时,聚焦超声有助于强化中心区汽雾换热,进一步提高聚焦超声汽雾冷却系统的换热能力。 相似文献
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磨削接触区材料去除厚度是不一致的,同时,在微量润滑过程中,雾滴之间的运动特征存在差异且易受其他因素的影响,致使整个接触区的磨削温度分布呈现出非线性,换热机理也异常复杂。从雾化机理出发,对影响换热效果的两个关键因素--雾滴直径和雾滴速度进行了分析。依据雾滴在不同壁温处表现出的不同换热特性,将磨削区划分为无沸腾换热、核态沸腾换热、过渡沸腾换热和稳定膜态沸腾换热四个不同的换热区域,建立了微量润滑磨削区的换热系数数学模型。在此基础上,运用有限元技术对微量润滑磨削表面的温度场进行了仿真分析,采用单级热电偶技术测量了磨削温度,发现磨削区仿真温度值与实验测量值吻合较好,表明通过该理论获得的微量润滑磨削表面换热系数是可信的。 相似文献