Experimental Study On The Formation And Movement Of Bubbles In Water

Taking advantage of high-speed photography, the characteristics of how the air bubbles form in the liquid and their ascending motion are studied. Under the different inside diameters of the pore and different gas-flow rates, this thesis investigates the impact that two kinds of air inlet mode-plane hole and internal-extension hole have on the formation of air bubbles in the water. The separated size and the time that is taken to form the bubbles are tested. It studies the impact that the height of internal-extension hole and water temperature have on the formation of air bubbles and also studies the movements of air bubbles in alcohol flow field and ethanediol flow field. The bubble motion velocity and trajectory under different test conditions are obtained.The results show that under the same experiment condition, the size of formed air bubbles are larger when the inside diameter of the pore and gas-flow rate increase.Internal-extension hole forms air bubbles with small size and takes less time for formation, which is also related with the height of internal-extension hole. Air bubble gets formed with small size and takes less time in the high-temperature water. The final rising speed of air bubbles is not changeless but waving around some speed up and down. With the increase of the bubble volume, the trajectory of the bubble is gradually changed from the "Z" shape to an irregular curve. Besides, the viscosity of external fluids and surface tension have great influence on the formation and movement of air bubbles.With the increase of liquid viscosity, the rising velocity of bubbles decreases, and the moving trajectory is more close to the straight line.With the increase of liquid surface tension, the volume of bubble formation and bubble departure time increase.