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Gas Entrainment Inception from a Free Surface of Fast Breeder Reactor

快速增殖反应堆自由表面的气体夹带起始

基本信息

批准号：
63460232
负责人：
MADARAME Haruki
金额：
$ 2.05万
依托单位：
THE UNIVERSITY OF TOKYO
依托单位国家：
日本
项目类别：
Grant-in-Aid for General Scientific Research (B)
财政年份：
1988
资助国家：
日本
起止时间：
1988 至 1989
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/en/grant/KAKENHI-PROJECT-63460232/
关键词：
Fast Breeder Reactor bubble entrainment bubble Formation Free Surface Turbulent Flow Analysis 乱流解析コード

项目摘要

A rapid liquid flow into a tank may impinge on the free surface making it swell partially. The returning flow branches off from the free surface and re-submerges at the border of the swollen surface. When the flow velocity along the swollen surface is high enough, gas bubbles are formed at the border and entrained by the liquid flow. If a significant concentration of gas is entrained by the sodium flow in a plenum of a fast breeder reactor, bursts of gas bubbles may pass through the reactor core, causing a change in reactivity. Gas entrainment must be carefully prevented in fast breeder reactor design. The conditions necessary for gas entrainment in a simple system were examined experimentally, using water and air as working fluids.The simulated coolant flowed in through a hole on one side of the rectangular test section, and out through many holes in the bottom plate.The height of the free surface, the width of the section and the inlet hole size were parametrically varied to investigate the scale effect. The effect of surface tension was examined by adding a surface active agent to the water. The results showed that the gas entrainment inception is determined by the width of the test section and the product of the Froude and Weber numbers based on the local velocity at the bubble formation point. A computer code for analyzing the two-dimensional turbulent flow with free surfaces was developed, thus the local velocity and the free surface configuration can be calculated by the code.

快速流入罐中的液体可能会冲击自由表面，使其部分膨胀。回流从自由表面分叉，并在膨胀表面的边界处重新淹没。当沿着溶胀表面的流速足够高时，气泡在边界处形成并被液体流夹带。如果在快中子增殖反应堆的增压室中的钠流夹带显著浓度的气体，则气泡的爆发可能穿过反应堆堆芯，导致反应性的变化。在快中子增殖反应堆设计中，必须小心防止气体夹带。以水和空气为工质，通过改变自由液面高度、截面宽度和入口孔尺寸，对一个简单的系统进行了实验研究，模拟的冷却剂从矩形试验段一侧的一个孔流入，从底板上的许多孔流出。通过向水中添加表面活性剂来检查表面张力的影响。结果表明，气体夹带起始由测试段的宽度以及基于气泡形成点的局部速度的弗劳德数和韦伯数的乘积决定。开发了二维自由表面湍流计算程序，可计算局部速度和自由表面形状。