Contact Angle Measurement of Liquid Hydrogen (LH2) in Stainless Steel and Aluminum Cells
Contact Angle Measurement of Liquid Hydrogen (LH2) in Stainless Steel and Aluminum Cells
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不锈钢和铝电池中液氢 (LH2) 的接触角测量
DOI：
10.1115/1.4032232
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发表时间：
2016
期刊：
影响因子：
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通讯作者：
A. Tamilarasan
中科院分区：
文献类型：
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作者：
K. Bellur;V. Konduru;M. Kulshrestha;D. Tyrewala;E. Médici;J. Allen;C. Choi;D. Hussey;D. Jacobson;J. Leão;J. McQuillen;J. Hermanson;A. Tamilarasan
长期空间飞行任务的关键限制之一是避免推进剂在微重力空间环境中蒸发。即使使用推进剂的主动和被动控制，蒸发也是不可避免的。推进剂行为的长期CFD模拟取决于蒸发/冷凝系数（称为调节系数），而蒸发/冷凝系数又取决于润湿特性。在美国国家标准与技术研究所（NIST）的BT-2中子成像装置上，将H2蒸气注入放置在70 mm“橙子”低温恒温器中的10 mm Al 6061和SS 316 L测试池中，进行了相变实验。冷凝是通过将低温恒温器的温度降低到饱和点以下来实现的，反之亦然。与蒸汽和测试单元材料相比，液体H2的高中子横截面允许观察不同的液体-蒸汽界面。多个图像被堆叠以增加信噪比，并且通过检测在液体弯月面处具有最大强度梯度的像素来获得弯月面边缘。接触角是通过将杨氏-拉普拉斯方程曲线拟合到检测到的弯月面而获得的。发现Al 6061和SS 316的接触角在0°和4°之间。不确定性来自中子成像装置的边缘检测、放大率和分辨率限制。测试在21 K（1.215巴）的饱和温度下进行。中子实验的结果将与有限元热模型和动力学相变模型结合使用，以提取适应系数。
One of the key limitations to long-term space missions is to avoid propellant boil-off in a microgravity space environment. Even with the use of active and passive controls of propellants, boil off is inevitable. Long-term CFD simulations on propellant behaviors depend on evaporation/condensation coefficients (known as accommodation coefficients) which are in turn dependent upon the wetting characteristics. Phase change experiments were conducted in the BT-2 neutron imaging facility at the National Institute of Standards and Technology (NIST) by introducing vapor H2in 10 mm Al6061 and SS316L test cells placed inside the 70mm ‘orange’ cryostat. Condensation is achieved by lowering the cryostat temperature below the saturation point and vice versa for evaporation. The high neutron cross-section of liquid H2in comparison to both the vapor and the test cell materials allows for visualization of a distinct liquid-vapor interface. Multiple images are stacked to increase the signal-to-noise ratio and the meniscus edge is obtained by detecting the pixels with largest gradients in intensities at the liquid meniscus. The contact angle is obtained by curve fitting of the Young-Laplace equation to the detected meniscus. The contact angle for Al6061 and SS316 is found to be between 0° and 4°. The uncertainty arises from edge detection, magnification, and resolution limits of the neutron imaging setup. The test was conducted at a saturation temperature of 21K (1.215 bar). The results from the neutron experiments will be then used in conjunction with FEA thermal models and kinetic phase change models to extract accommodation coefficients.