摘要：为明确电场对汽─液两相系统的效应，进一步研究EHD作用下的两相系统中汽泡的行为，揭示EHD强化沸腾换热机理，本文对电场作用下汽泡的行为进行了理论研究。从汽泡周围电场分布特性及其受力角度，对不同电场作用下的乙醚工质的沸腾换热进行理论研究。为了探明外加电场对于汽泡的作用,如形状发生变化、脱离半径变小、脱离频率加快等。本课题针对均匀电场下汽泡周围电场分布状况进行研究，选用乙醚工质、平行平板电极，其中铜板作为零势面，铜网施加0-20kV的直流高压电场，加热方式为电加热方式。采用Ansys计算软件，编程求解出不同电场作用下汽泡周围场强分布特性，对单个气泡附壁、脱离及多个汽泡生成并部分脱离时电场分布特性进行了数值模拟。 结果表明：汽泡周围电场分布不再均匀，其两侧的场强有所增加，靠近汽泡顶部以及底部附近，场强降低,沿球面顶部外法线方向，场强梯度达到最大。随着汽泡数量的增多，电场对汽泡的作用也相应变弱。电场使汽泡周围电场特性发生改变，导致EHD强化效果增强。57967

毕业论文关键词： EHD强化传热；汽泡；数值模拟；电场特性

The Effect of The Electric Field on The Bubble under The Action of Ether

Abstract: To clarify the effect of electric field on gas-liquid two-phase system, the EHD effects of bubble behavior, and the mechanism of EHD enhanced heat transfer in the electric field is carried out in this paper. Based on the characteristic of electric field around a bubble and forces on a bubble, the boiling heat transfer enhancement in different electric field using the working fluid ether were studied theoretically.In order to clarify the effects imposed on the bubbles by of electric field, such as the change of shape, the shrinking of departure radius and the increase of the departure frequency etc，this research focuses on the numerical simulation of the electric field distribution around the bubble that is under the uniform electric field. The working fluid used in simulation is ether and the electric field is produced by the parallel plate electrode, in which the copperplate is grounded to the earth, and voltage is performed from 0kV to 20kV. The heating method involved in the research is electric heating. Ansys is used to simulate the  

electric field distribution of the bubble under different uniform electric field. Also, the simulations is carried out when a bubble attaches, departs or when the formation with partial departure of several bubbles. The results indicate that the electric field distribution around the bubble is no longer uniform, and the electric fields of the two sides are enhanced while near the top and bottom areas the electric fields decrease. Along the outer normal, the gradient of the electric field reaches the maximum. As the numbers of bubbles become more, the effect of electric field on bubbles becomes weaker. So the conclusion is reached that the electric field distribution around the bubbles will be changed by the electric field and thus will enhance the effect of EHD.

KeyWords: EHD(electrohydrodynamics)；bubbles；numerical simulations；electric characteristics

目录

1 绪论 1

1.1 课题的目的和意义 1

1.2 国内外研究历程 2

1.3 国内外研究现状与发展趋势 3

2 汽泡对EHD强化沸腾换热的影响 4

2.1 电场作用下汽泡行为的变化 4

2.1.1 汽泡的大小和形状 6

2.1.2 汽泡的接触角和表面张力 6

2.1.3 汽泡的碰撞和破碎