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Three dimensional heat transfer characteristics of superfluid helium and its mechanism

超流氦三维传热特性及其机理

基本信息

批准号：
12450086
负责人：
SHIOTSU Masahiro
金额：
$ 3.46万
依托单位：
KYOTO UNIVERSITY
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (B)
财政年份：
2000
资助国家：
日本
起止时间：
2000 至 2001
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/en/grant/KAKENHI-PROJECT-12450086/
关键词：
Superfluid Helium 3-dimensional Heat Transfer Steady-state Critical Heat Flux Transient Heat Transfer Experiments ＆ Numerical Analysis 定常臨界熱流束定常熱伝達

项目摘要

Major Results of this study are as follows.1) Steady-state heat transfer and its critical heat flux on a flat plate of various dimensions in He II were measured under wide ranges of experimental conditions. Effect of the test plate dimension was clarified and an equation which can describe the experimental data was presented.2) To investigate the mechanismof heat transfer in case of expanding or shrinkingheat flow from a heated surface in He II, measurements of heat transfer were made for the following cases : (1) the heat flow expands from a test plate located at one end of a rectangular ductcontaining He II with the cross sectional area larger than the surface area of the test plate to the other open end of the duct, (2) for a duct with a sudden increase in its cross sectional area, (3) for a duct with an orifice.3) Moreover, the measurements were made for a duct with the heated surface located on the wall at the middle of the duct and heat flowed turning to both open ends of the duc … More t. Effect of the gap length from the test heater to the opposite wall was clarified. Equations that can express the experimental data of 2) and 3) were given.4) Transient heat transfer from a test plate produced by a step heat input with the height higher than the steady-state critical heat flux was measured for the above mentioned cases of (2), (3) and (4). The transient heat transfer for a stepwise heat input is such that the quasi-steady state exists with a certain lifetime on the extrapolationof steady-stateKapitza conductance curve and then jumps to film boiling regime. Effects of expansion or sublimation of heat flow on the relation of the lifetime and step height was clarified.5) The computer code of two-dimensional heat and fluid flow in He II named SUPER-2D was developed based on the two-fluid model for He II in turbulent flow condition. The numerical solutions of the steady-state critical heat flux and transient heat transfer produced by a step heat input are in good agreement with the experimental data for the corresponding conditions. It was confirmed that the numerical code can describe the steady-state and transient heat transfer phenomena in He II. Mechanism of two-dimensional heat transfer in He II was clarified through the calculation Less

主要研究结果如下：1）在较宽的实验条件下，测量了不同尺寸平板在He Ⅱ中的稳态传热及其临界热流密度。2）为了研究He Ⅱ中受热面热流膨胀或收缩时的传热机理，对以下几种情况进行了实验测量：（一）热流从位于截面积大于测试板表面积的装有He II的矩形管道一端的测试板膨胀到另一开口，此外，还对受热面位于中部壁面上，热流转向导管两端开口的导管进行了测量。 ...更多信息 t.阐明了试验加热器与对置壁面之间的差距长度的影响。4）对上述（2）、（3）和（4）三种情况下，在高于稳态临界热流密度的高度上，对阶梯状热输入下的平板瞬态传热进行了测量。对于阶梯式热输入的瞬态传热，在稳态Kapitza导热曲线外推的过程中，存在一个具有一定寿命的准稳态，然后跃变到膜态沸腾。5）基于湍流条件下He Ⅱ的双流体模型，开发了He Ⅱ二维热流计算程序SUPER-2D。在相应的条件下，数值解的稳态临界热流密度和阶跃热输入产生的瞬态传热与实验数据吻合良好。结果表明，该数值计算程序可以描述氦Ⅱ稳态和瞬态传热现象。通过计算阐明了He II的二维传热机理。