汇流旋涡临界贯穿条件与Ekman抽吸演化机理（英文）  

Critical penetration condition and Ekman suction-extraction mechanism of a sink vortex

作　　者：Da-peng TAN Lin LI Yin-long ZHU Shuai ZHENG Zi-chao YIN Dai-feng LI 

机构地区：[1]College of Mechanical Engineering, Zhejiang University of Technology

出　　处：《Journal of Zhejiang University-Science A(Applied Physics & Engineering)》2019年第1期61-72,共12页浙江大学学报（英文版）A辑（应用物理与工程）

基　　金：Project supported by the National Natural Science Foundation of China(No.51775501);the Zhejiang Provincial Natural Science Foundation of China(No.LR16E050001)

摘　　要：目的:提出一种自由汇流旋涡形成过程建模求解方法,得到其临界贯穿条件,并揭示其Ekman边界层抽吸演化机理。创新点:1.基于二维Rankine位势涡理论,建立自由汇流旋涡动力学模型,得到其压力、速度分布;2.提出一种基于Helmholtz方程的汇流旋涡贯穿临界条件求解方法;3.成功搭建一种基于双目内窥技术的汇流旋涡观测实验平台,可实现对旋涡贯穿及Ekman抽吸过程的精确观测。方法:1.将汇流旋涡定义为涡核与核外流两部分,并基于Bernoulli方程与Lamb-ΓΡΟΜΕΚΟ方程得到汇流旋涡界面形状及压力、速度分布;2.基于上述动力学模型,结合Helmholtz涡量动力学方程,利用分离变量积分方法,得到旋涡形成轴向速度与深度的解析关系表达式;3.基于粒子图像测速(PIV)方法,结合双目内窥技术,实现对汇流旋涡临界贯穿与边界层抽吸的流动细节特征的实时追踪。结论:1.汇流旋涡临界贯穿条件是一个解集,这是由不同的流场初始扰动条件造成的;2.旋涡抽吸孔最低点的高度由容器的几何参数决定,与初始扰动速度无关;3.若初始扰动增强,旋涡深度与Ekman层厚度增加,但在抽吸过程中的边界层涡量强度有减弱趋势;4.PIV实验验证了上述理论结果的正确性,并观测到旋涡半径边界与涡量集聚现象。The critical penetration condition is an essential component of studies on the mechanism of sink vortex formation. However, the condition and its transition process are unknown. To address this issue, we constructed a Rankine-vortex-based fluid mechanic model, and proposed a Helmholtz-equation-based solution method to acquire the critical penetration condition. The two-phase mass suction-extraction mechanism of the Ekman boundary layer was discussed. Numerical results show that the critical penetration condition is dependent on the initial velocity components;if the initial disturbances are enhanced, the suction-extraction height and Ekman layer thickness increase. A particle image velocimetry(PIV)-based observation experimental platform was developed, and the effectiveness of the proposed method was verified. The vortex core boundary was observed first, so the radius of the vortex core could be acquired precisely.

关 键 词：汇流旋涡 临界贯穿条件 Ekman边界层 抽吸演化机理 

分 类 号：O35[理学—流体力学]