Numerical Simulation And Experimental Research On The Cold Air Bubbles Behavior By Electrohydrodynamics Effect

Electrohydrodynamics（short for EHD) is a kind of active heattransfer enhancement method and technology，which has good effect ofthe characteristics and small power consumption, so it has promisingapplication foreground. Electric field can change the bubble behaviorcharacteristics and movement, to change the structure of flow field canachieve heat transfer strengthening, so the bubble plays a core link duringthe heat transfer process. The content about the bubble behavior and themotion law become difficulties and key point in the EHD heat transferenhancement.Firstly, to discuss the effects of electrohydrodynamics nucleateboiling heat transfer. The bubble behavioral characteristics were analyzedby numerical simulation and experimental research in this paper, Bubblebehavior mainly including the bubble deformation, the departure period,and size under electric field effect. In this paper, under the condition ofthe grid of electrodes forming by the uniform electric field, establishingthe reasonable bubbles model, the single bubble rising shape, thedeparture period and the bubble behavior affecting the distribution of theelectric field around the bubble were researched when the bubble attachedon the coins wall. The bubble behavior was experimental researchedthrough the influence factors the electric field strength and the gas holediameter, the experimental results and numerical results are compared tovalidate the numerical results.As follows，the results of the bubble behavior was numericalsimulated under the effect of the electric field.1、 The departure period decreased while the bubble elongated alongthe direction of the electric field under the electric field.2、 Square pool model form the uniform electric field under the nobubble existence condition, but for the formation of air bubbles, whichderanged the uniform electric field, and forming uneven electric field in the square pool model.3、 The electric-field strength in the bubble is the largest of all and inthe top center outside the bubbles, the electric field strength minimum inthe square pool model, along the ball toward the surface bubbles in thebottom and top, field strength gradually decreased, so the gradient of theelectric field is largest at the top of the spherical bubbles.Secondly, the bubble behavior was researched under the electricfield; experimental investigation shows that as follows.1、 The departure shape is as well as the ellipse, the shape of thedeparting bubble formed the cylindrical shape more obvious along withthe increase of the voltage.2、 The bubble elongated along the direction of the electric field, withincreasing electric field strength, the bubble’s aspect ratio at the departureincreased while the departure volume and period decreased.3、 The electric stresses on the actual bubble surface were calculated,which indicated that the electric stress exerted on the bubble tip pulled thebubble while that exerted on the bubble sides pressed the bubble, causingthe bubble elongation deformation along the electric field direction. Thebigger the diameter of the gas hole is, the larger stress will exerted on thebubble...