【作者】 刘博；

【导师】 刘伟；

【作者基本信息】 华中科技大学 ， 工程热物理， 2009， 硕士

【摘要】 航天技术是二十一世纪最热门,也是发展最迅速的一门科学。由于大功率和高热流密度的电子设备的广泛应用以及航天器上空间的限制,传统的热控装置已经很难满足要求。近年来一种结构更加紧凑,稳定性能更好,传热能力更强的热控技术—毛细抽吸两相环路(Capillary Pumped Loop)备受关注,它是靠毛细芯结构的毛细抽力为系统提供驱动力,靠工质的相变散热。正因为CPL的高功率和远距离输送的特点,所以更适合应用于航天飞行器的热控系统中。本文系统地介绍了内国外CPL的发展现状,阐述了CPL的运行机理和传热特点。本文改进了原有的CPL实验系统,通过翻转蒸发器和在插入蒸发器的液体管路上开十字形的槽道,消除了不凝性气体对CPL系统的影响,并针对不凝性气体对系统的影响做了定性分析,指出不凝性气体的存在会阻塞液体管路导致系统的崩溃。对改进后的系统进行了有重力倾角下和无重力辅助下的启动实验和变工况实验。实验结果表明:有重力辅助情况下,系统可以在加热功率100W～800W(热流密度达到2.05W/cm~2)下顺利启动;无重力辅助情况下,系统可以在加热功率100W～500W(热流密度达到1.28W/cm~2)下顺利启动。通过对系统的变工况实验,结果表明系统有良好的适应变热负荷能力。本文建立了CPL蒸发器典型单元的三维模型,利用FLUENT软件中的多相流模型模拟了蒸发器不同热流密度下的运行情况,以及改变了蒸发器中蒸汽槽道的尺寸和形状后,槽道中的流动和换热情况。通过对蒸发器的数值模拟希望能够对蒸发器的优化设计指明方向。更多还原

【Abstract】 Space technology is one of the most popular and the fastest growing science in twenty-first century. Because of high-power and high heat flux electronic equipments widely used and space limitation on spacecrafts, traditional thermal control devices have been difficult to meet the requirements. In recent years, a sort of thermal control device (Capillary Pumped Loop) has been concerned, which has more compact structure and more stable performance and higher heat transfer capability. It depends on capillary force driving CPL system from porous media and working fluid phase changing. Therefore, CPL is more suitable for spacecraft thermal control systems due to the characteristics of high power and long-distance transmission.This thesis introduces development of CPL from homeland and abroad and expounds operation principles and heat transfer characteristics. This thesis improves former CPL system. By turning the evaporator over and splitting a cross channel on liquid pipeline to evaporator, the new structure eliminates influence of non-condensated gas to CPL system. And the influence of non-condensated gas is carried into qualitative analysis. Non-condensated gas will block liquid pipeline, which leads to dry-out phenomena.A series of startup and operation capability experiments are carried out under the conditions of gravity assisted and non gravity assisted. The experiment results show: under the gravity assisted condition, CPL could start up smoothly when heat load is 100W to 800W (heat flux up to 2.05W/ cm~2); under the non gravity assisted condition, CPL could start up smoothly when heat load is 100W to 500W (heat flux up to 1.28W/ cm~2). Through operation capability experiments, the results show that the CPL system has the capability of well bearing mutative heat load.This thesis establishes a three-dimensional model of evaporator of CPL system. And heat transfer and fluid flow characteristics under different heat flux densities are numerically simulated using mixture model of FLUENT software. Moreover, flow and heat transfer conditions in evaporator are simulated by changing size and transforming figure of vapor channel. After a series of numerical simulation, the thesis hopes to offer suggestions for optimal design of evaporator.更多还原