摘要
气泡行为对两相流动与换热特性有重要影响。为了研究花瓣形棒束通道内气泡的动力学特性,采用流体体积法(VOF)模拟了静水中气泡在棒束通道内的气泡行为,获得了不同初始尺寸气泡的运动轨迹、形状和上升速度。结果表明,气泡在上升过程中存在横向移动现象。气泡初始尺寸越小,横向位移幅度越大,在上升过程中越容易碰触到花瓣形螺旋棒。随着气泡尺寸的增大,气泡稳定速度增大,稳定速度维持在0.2 m/s左右。气泡上升运动行为研究可以明晰花瓣形棒束通道内的气泡行为机理,为揭示两相流流动与换热机理奠定基础。
Bubble behavior has a significant impact on the characteristics of two-phase flow and heat transfer.To investigate the dynamics of bubbles in a petal-shaped rod bundle channel,the behavior of bubbles in static water in the rod bundle channel was simulated using the volume of fluid method(VOF)and compared with the behavior of moving bubbles in a circular rod bundle channel.The trajectory,shape,and rise velocity of bubbles with different initial sizes were obtained and analyzed to understand the mechanism of bubble behavior through the flow and pressure fields around the bubbles.The results show that bubbles exhibit lateral movement during the ascent process.The smaller the bubble size,the more pronounced the lateral movement,making it more likely for the bubble to touch the wall surface.After touching the wall surface,the bubble slides along the wall surface.Bubbles that do not touch the wall move towards the center of the flow channel and finally rise steadily along the center.The calculated size range produces spherical and ellipsoidal bubble shapes.Before the bubble touches the wall,the bubble deformation increases and the aspect ratio decreases as the bubble gradually rises,reaching stability after a period of time.While after the bubble touches the wall,the bubble adheres to the wall and its shape changes to semi-circular and its aspect ratio decreases rapidly.The stabilization rate of bubble increases as the size of the bubble increases.In the first stage,the bubble velocity rises rapidly from zero and the wake begins to form.In the second stage,the bubble velocity rises slowly and the wake changes asymmetrically at both ends of the bubble.In the third stage,the bubble velocity decreases rapidly if it touches the wall,and the shape of the wake changes near the wall.If the bubble does not touch the wall,the bubble velocity will fluctuate around the stable velocity and the flow field will stabilize,and the wake will be generated and shed in a continuous cycle.The direction of bubble movement can be determined
作者
张文超
李嘉元
杨光
孙建闯
金光远
蔡伟华
ZHANG Wenchao;LI Jiayuan;YANG Guang;SUN Jianchuang;JIN Guangyuan;CAI Weihua(Laboratory of Thermo-fluid Science and Nuclear Engineering,Northeast Electric Power University,Jilin 132012,China;Key Laboratory of Advanced Reactor Engineering and Safety,Ministry of Education,Tsinghua University,Beijing 100084,China)
出处
《原子能科学技术》
EI
CAS
CSCD
北大核心
2023年第10期1899-1909,共11页
Atomic Energy Science and Technology
基金
国家自然科学基金(52206233)
清华大学先进反应堆工程与安全教育部重点实验室开放基金(ARES-2022-08)。
关键词
花瓣形棒束通道
气泡轨迹
气泡形状
气泡上升速度
数值模拟
petal-shaped rod bundle channel
bubble trajectory
bubble shape
bubble rising speed
numerical simulation
