Heat transfer during bubble shrinking in saturated He II under microgravity condition

Cryogenic Engineering Conference 2015

材料科学;物理学

Takada, S.^1 ; Kimura, N.^2 ; Murakami, M.^3 ; Okamura, T.^2

National Institute for Fusion Science, Oroshi-cho, Toki, Gifu

509-5292, Japan^1

High Energy Accelerator Research, 1-1Oho, Tsukuba, Ibaraki

305-0801, Japan^2

3 University of Tsukuba, 1-1 Tennodai, Tsukuba, Ibaraki

305-8573, Japan^3

关键词: Liquid-vapor interface;    Microgravity conditions;    Microgravity environments;    Microgravity experiments;    Pressure differences;    Spherical bubbles;    Time duration;    Time variations;   

Others  :  https://iopscience.iop.org/article/10.1088/1757-899X/101/1/012163/pdf
DOI  :  10.1088/1757-899X/101/1/012163

学科分类：材料科学（综合）

来源: IOP

【 摘 要 】

Microgravity experiments of He II boiling were carried out using a drop tower. The process of bubble shrinking in He II in microgravity was observed by a high speed camera. The time duration of the microgravity environment less than 1 m-g was about 1.3 sec. First, a large spherical bubble of about 10 mm in diameter was created by a short wire heater (Diameter 0.05 x Length 2.82 mm) for a heating time of 0.4 sec. The subsequent bubble shrinking was visualized after the heater was switched off. The time variation of the volume of bubble was estimated by image analysis. The shrinking speed of bubble was calculated from these time variation data. The shrinking speed depends on the heat flux across the liquid-vapor interface. It is found that the heat flux across the interface in microgravity can be explained by the kinetic theory with a pressure difference due to surface tension.