Experimenting And Researching The Effect Of Different Sizes Of Aeration Bubbles On Cavitation Bubbles Properties

With the development of hydropower and hydraulic, the issues of cavitation in high-velocity flow become universal concern. In order to solve the problem of cavitation damage because of high-velocity flow, an aerator is usually used to aerate air in the low-pressure region or upper region that cavitation damage occurs. But since more than half a centuries, the research on aeration cavitation-alleviation for spillway dam is commonly thorough. But there is little research on the corresponding relations of aeration bubble sizes, aeration bubble concentration and velocity of flow which needs a breakthrough about theoretical research.In this article, the interaction of bubbles and aeration bubble in cavitation region were observed in details by using three-dimensional Particle Image Velocimetry, high speed photography, and the pressure data acquisition system of Sinocera-Ye6263in the Hydraulics Laboratory at Zhe Jiang University of Technology. Variations of pressure and cavitation number within cavitation zone behind semi-cylindrical irregularities and cylindrical protrusions with different sizes of aeration bubble, gas concentrations, velocity of flow were measured. Cavitation characteristics, the sport evolution with the flow and the collapse of cavitation bubble were observed. The effect of different sizes of aeration bubble on cavitation bubble generation and collapse was revealed. Analyzed the effect of different sizes of aeration bubble on vertical velocity and longitudinal velocity on cavitation. Under the conditions of the gas concentrations was on the interval which could reduce the cavitation. The experimental results showed that:for10mm high semi-cylindrical irregularity with6mm in diameter of bottom cavitation number of2mm aeration hole could reach the maximum; For5mm high cylindrical protrusions with6mm in diameter of bottom at10mm aeration holes cavitation could be more relief.