A study on rollover of two density-stratified layrs of liquids

两层密度分层液体的翻转研究

基本信息

批准号：
04452145
负责人：
TANASAWA Ichiro
金额：
$ 3.14万
依托单位：
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：
1992
资助国家：
日本
起止时间：
1992 至 1993
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/en/grant/KAKENHI-PROJECT-04452145/
关键词：
Rollover Buoyancy convection Density-stratified liquid layr Natural convection Heat and mass transfer Flow visualization Numerical simulation Shadowgraph technique 伝熱密閉容器貫入シャドウグラフ

项目摘要

The rollover referred to in this report is a rapid mixing of two layrs of liquids which initially were stratified stably in a vessel due to a density difference. Heat invasion through the vessel wall into the liquid layrs induces buoyancy convection in both of the liquid layrs. Subsequent heat and mass transfer inside each of the liquid layrs and between the two layrs, and evaporation at the free upper surface gradually reduces the density difference between the two liquids. Finally the stability of the two layrs is lost, leading to a rapid mixing of the both liquids.The sequential processes from the start of buoyancy convection to the onset of rollover were studied experimentally and numerically. In the experiment, the profile and movement of the interface between the two liquid layrs and the flow patterns were visualized with the shadowgraph technique. The timewise changes in the distributions of temperature and density were measured at the same time. The distribution of flow velocity near the vertical wall of the vessel was obtained by measuring the displacement of tracer particles illuminated with a laser light. The results of experiment elucidated the process leading to the complete mixing of the two liquids. When the density difference became small, the boundary layr flow in the lower liquid rising along the wall penetrated deep into the upper layr and finally reached the free surface. From this moment on the rapid mixing of the entire fluid took place. The boundary between the two liquids descended as the mixing proceeded, became fuzzy, and vanished in the end.Numerical simulation using a large-scale computer has shown quite the same results.

本报告中提到的转盘是两种液体的快速混合，由于密度差，最初在容器中稳定地分层。通过血管壁进入液体液体的热侵袭均在两个液体层中引起浮力对流。随后在每个液体内部和两个线路之间进行热量和传质，并且在自由上表面的蒸发逐渐降低了两种液体之间的密度差。最后，对两个液体的稳定性丢失，导致两种液体的快速混合。从浮力对流开始到滚动开始的顺序过程，通过实验和数值进行了研究。在实验中，用阴影图技术可视化了两个液体外线和流动模式之间界面的轮廓和运动。同时测量了温度和密度分布的时间变化。通过测量用激光光照射的示踪剂颗粒的位移来获得血管垂直壁附近的流速分布。实验结果阐明了这两种液体的完整混合过程。当密度差异很小时，下部液体中的边界线沿壁沿着深处渗透到上层，最后到达自由表面。从这一刻开始，整个液体的快速混合。随着混合的进行，两种液体之间的界限，最终变得模糊并消失了。使用大型计算机的数量模拟显示出相同的结果。