1. 浙江大学 海洋学院, 浙江 舟山 316000； 2. 国家海洋局第二海洋研究所, 杭州 310012； 3. 伍兹霍尔海洋研究所, 美国 伍兹霍尔 02543
出版日期:2019-04-28发布日期:2019-04-28通讯作者:贺治国，男，教授，博士生导师，E-mail: hezhiguo@zju.edu.cn.作者简介:赵亮（1993-），男，湖北省襄阳市人，博士生，从事环境流体力学方面研究.基金资助:国家自然科学基金（11672267），浙江省自然科学基金（LR16E090001），深圳市科技研发资金（JCYJ20160425164642646）The Process of Mass Transport for a Buoyant Plume in Linearly Stratified Environment
ZHAO Liang1,ZHANG Wei1,HE Zhiguo1,2,TAN Liming1,JIANG Houshuo31. Ocean College, Zhejiang University, Zhoushan 316000, Zhejiang, China; 2. Second Institute of Oceanography, State Oceanic Administration, Hangzhou 310012, China; 3. Woods Hole Oceanographic Institution, Woods Hole, MA 02543, USA
Online:2019-04-28Published:2019-04-28摘要/Abstract
摘要： 在线性层结盐水中进行18组浮力羽流实验，采用粒子图像测速(PIV)技术获取羽流的时空高分辨率流场，提出浮力羽流最大输移质量计算公式，并定量分析羽流卷吸及质量输移过程.实验结果表明：卷吸系数从喷口处开始沿着射流方向逐渐增加，并在最大穿透距离 0.3～0.5 倍时，于数值 0.11 左右波动，之后逐渐减小为负值.浮力羽流在羽干处卷吸入周围环境流体后，沿射流方向被输移到最大穿透距离处，并在其约 0.65 倍处垂向质量通量达到最大值；混合后的羽流最终在中性浮力层向四周扩散；最大输移质量由浮力通量、浮力频率和与喷口处于相同高度的周围环境密度共同决定.层结环境折射率变化引起的伪湍动进而导致最大输移质量计算误差约为3%，因此折射率变化的影响可以忽略.
关键词: 浮力羽流, 线性层结, 粒子图像测速法, 最大输移质量, 伪湍动
Abstract: Eighteen experimental cases for the buoyant plume were conducted in linearly stratified saltwater. The particle image velocimetry (PIV) technique was used to acquire flow fields of plumes in high spatial and temporal resolutions. A new formula for maximum transported mass of buoyant plumes in stratified fluids was proposed. The process for entrainment and mass transport of plumes were analyzed quantitatively. Results show that the entrainment coefficient αe increases gradually along the jetting direction from the source, fluctuates at 0.11 from 0.3Zmax to 0.5Zmax (Zmax is the maximum penetration distance) and then decreases gradually to negative. The buoyant plume which entrains ambient fluids from the plume stem is transported to －Zmax along the jetting direction and its vertical mass flux reaches the maximum at about －0.65Zmax. The mixed plume finally spreads to surroundings at the neutral buoyancy layer. The maximum transported mass is determined by the buoyancy flux, the buoyancy frequency and the environment density at the same level. The calculation error due to pseudo turbulence caused by variations of the refractive index within the stratified fluid is about 3%, so the influence of refractive index is negligible.
Key words: buoyant plume, linear stratification, particle image velocimetry (PIV), maximum transported mass, pseudo turbulence
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