论文标题
在微重力条件下大直径脉动热管的实验分析和瞬态数值模拟
Experimental analysis and transient numerical simulation of a large diameter pulsating heat pipe in microgravity conditions
论文作者
论文摘要
比较了针对国际空间站（ISS）的未来实验设计的大直径脉动热管（PHP）的启动的多参数瞬态数值模拟，并与欧洲航天机构支持的抛物线飞行运动中获得的结果进行了比较。由于通道直径大于正常重力中的毛细管极限，因此这种设备在地面上表现为循环热诗和在失重条件下的PHP。因此，对于脉动模式，微重力环境是必须的。由于抛物线飞行过程中的微重力持续时间很短，因此数据仅涉及设备的瞬态启动行为。文献中最全面的模型之一，即内部1-D瞬态代码CASCO（法语代码的avanc {é} de simulation de caloduc振荡剂：英语中的高级PHP模拟代码），已通过几何学，拓扑，材料，材料属性和热量界面的临时范围进行了相比。参数：管壁温度，压力以及液体塞的速度，其长度和温度分布。模拟结果与不同输入功率的实验一致。预测温度的最大偏差为7％。压力变化趋势是定性捕获的，以及液体塞速度，长度和温度分布。该模型还显示了在提供热负载后流体压力开始振荡时捕获瞬间的能力，这是将在ISS上测试的工程模型正确设计的基本信息。 我们还揭示了在实验和模拟的液体塞末端附近的液体温度梯度的存在。最后，给出了微重力直径PHP稳定功能的理论预测。结果表明，所提供的具有185W的输入功率的系统应能够在1分钟后达到稳态，并从那时开始保持稳定的操作。
A multi-parametric transient numerical simulation of the start-up of a large diameter Pulsating Heat Pipe (PHP) specially designed for future experiments on the International Space Station (ISS) are compared to the results obtained during a parabolic flight campaign supported by the European Space Agency. Since the channel diameter is larger than the capillary limit in normal gravity, such a device behaves as a loop thermosyphon on ground and as a PHP in weightless conditions; therefore, the microgravity environment is mandatory for pulsating mode. Because of a short duration of microgravity during a parabolic flight, the data concerns only the transient start-up behavior of the device. One of the most comprehensive models in the literature, namely the in-house 1-D transient code CASCO (French acronym for Code Avanc{é} de Simulation du Caloduc Oscillant: Advanced PHP Simulation Code in English), has been configured in terms of geometry, topology, material properties and thermal boundary conditions to model the experimental device.The comparison between numerical and experimental results is performed simultaneously on the temporal evolution of multiple parameters: tube wall temperature, pressure and, wherever possible, velocity of liquid plugs, their length and temperature distribution within them. The simulation results agree with the experiment for different input powers. Temperatures are predicted with a maximum deviation of 7%. Pressure variation trend is qualitatively captured as well as the liquid plug velocity, length and temperature distribution. The model also shows the ability of capturing the instant when the fluid pressure begins to oscillate after the heat load is supplied, which is a fundamental information for the correct design of the engineering model that will be tested on the ISS. We also reveal the existence of strong liquid temperature gradients near the ends of liquid plugs both experimentally and by simulation. Finally, a theoretical prediction of the stable functioning of a large diameter PHP in microgravity is given. Results show that the system provided with an input power of 185W should be able to reach the steady state after 1min and maintain a stable operation from then on.
