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RESEACH ON THE GENERATION MECHANISM OF BURNOUTNEAR THE FLOW OBSTRACTION IN BOILING TWO-PHASE FLOW WITHIN ANANNULAR CHANNEL

环形通道内沸腾两相流流动阻碍附近烧坏产生机理的研究

基本信息

批准号：
14350094
负责人：
FUKANO Tohru
金额：
$ 9.34万
依托单位：
KYUSHU UNIVERSITY
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (B)
财政年份：
2002
资助国家：
日本
起止时间：
2002 至 2003
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/en/grant/KAKENHI-PROJECT-14350094/
关键词：
Boiling two-phase flow Dry-out Burnout Flow obstruction Critical heat flux 限界熱流速混相流

项目摘要

In order to clarify the mechanism of burnout occurrence near the obstacle, which simulate spacers of BWR, flow phenomena was carefully observed' by using a high-speed video and time varying wall temperatures were measured at many axially different locations. The results are summarized as follows.1.In relation to the occurrence of burnout, we carefully observed two-phase flow phenomena. The generation of dry-out of liquid film, which acts as a trigger of generation of burnout, is caused by the dry-out of base film between two disturbance waves at the location upstream of the spacer. On the other hand burnout is scarcely generated downstream of the spacer because wall temperature is always low and liquid film is easy to formed even if dry-out is occurred. This result means the importance of the behavior of disturbance wave.2.Based on the above mentioned results we detected the passing of the disturbance waves by the differential pressure fluctuation. It is again confirmed the close relation between the passing of disturbance wave and the generation of dry-out as well as the generation of burnout are. It is also noticed that in order to explain the frequent generation and disappearance of the dry patch we never forget the unsteadiness of the vapor-liquid two-phase flow. The spacer has important influence on the fluid and thermodynamic phenomena downstream of the spacer.3.We put two spacers at axially different locations and it was clarified that the shorter the spacer distance, the higher the critical heat flux. Because the large amplitude of film thickness due to disturbance waves was flattened by the spacer, time averaged film thickness became thick. And therefore dry-out generation rate became low.4.We proposed a theoretical flow model to explain the dry-out as well as the burnout occurrence. It is based on the disturbance wave flow and time fluctuate phenomena is taken into consideration.

为了阐明模拟沸水堆隔板的障碍物附近发生烧毁的机制，通过使用高速视频仔细观察流动现象，并在许多轴向不同位置测量随时间变化的壁温。主要研究结果如下： 1.针对烧毁的发生，我们仔细观察了两相流现象。作为产生烧坏的触发因素的液膜干涸的产生是由间隔件上游位置处的两个扰动波之间的基膜干涸引起的。另一方面，由于壁温始终较低且即使发生干涸也容易形成液膜，因此隔离件下游几乎不会发生烧毁。这一结果意味着扰动波行为的重要性。2.基于上述结果我们通过压差波动检测扰动波的通过。再次证实了扰动波的通过与干烧、烧坏的发生之间的密切关系。还值得注意的是，为了解释干斑的频繁产生和消失，我们永远不会忘记汽液两相流的不稳定性。隔板对隔板下游的流体和热力学现象具有重要影响。3.将两个隔板放置在轴向不同的位置，发现隔板距离越短，临界热流密度越高。由于干扰波引起的膜厚的大幅值被隔离物平坦化，因此时间平均膜厚变厚。因此干烧的发生率变低。4.我们提出了一个理论流动模型来解释干烧和烧毁的发生。它基于扰动波流并考虑了时间波动现象。