Visualization Study Of The Bubble Behavior

The problem of heat transfer has widely existed in the process ofindustrial production, such as in the petrochemical industry. With the outbreakof the global energy crisis, people pay more and more attention on how toimprove the efficiency of heat transfer. Among them, the EHD boiling heattransfer is one of the methods to improve the efficiency of heat transfer. Butthe basis of researching the EHD boiling heat transfer is to study thegeneration, the growth, the detachment and the rising of the bubbles, and themovement of the bubbles in the fluid. If we can find out the factors to affectthe generation, the growth, the detachment and the rising of the bubbles, andgive an accurate description of the factors, it will be of great significance inthe research of the EHD boiling heat transfer and the efficiency of heattransfer.This article analyzes how the surrounding environment of bubblesaffects the generation and the rising process of the bubbles by bubble visibleexperimental apparatus, and analyzes when a single isolated bubble comes outduring the boiling heat transfer process by numerical simulation analysis. Itsmain tasks are as follows:（1）To establish the model of the heating boiling water tank by meshing,defining the boundary conditions, and selecting the appropriate governingequations. And to analyze when the bubble comes out during the boiling heattransfer process by combining the velocity distribution diagram, theproportion of steam volume diagram, the pressure distribution diagram andthe temperature distribution diagram, which makes it easier to study on asingle isolated bubble.（2）Design and install a bubble visible of experimental apparatus. Toanalyze how the pillar height, the pore size and the voltage affect thelength-diameter ratio, the separation volume, the separation frequency and rising speed of the bubble by observing the formative stages and the risingphase of the bubble through a high-speed camera. When the pillar height of acertain value, the higher the voltage increases, the higher the length-diameterratio and the separation frequency are, but the smaller the size of the bubbleseparates. When the voltage is the same, the smaller the pore sizes of injectedbubbles, the greater the length-diameter ratio and the departure frequency ofbubbles. When the voltage is the same, the higher the pillar height is, thebubble departure size and departure frequency will be larger, while the bubbleaspect ratio becomes smaller. In the upward phase of the bubble, the bubblevolume change is not the law; this article only studied the rise velocity ofbubbles’ rising phase. During the upward phase of the bubble, when thevoltage U increases, the bubble rising speed is also increased accordingly.