Research On Dynamics Of The Cylindrical Cavitation Bubble Near A Right-Angle Wall With Bulge Based On Kelvin Impulse And High-Speed Photography

When cavitation occurs near a hydraulic mechanical wall,jet impact caused by cavitation bubble collapse will cause serious damage to the wall.When cavitation bubbles are generated in microscale environment,they often show cylindrical characteristics.In order to investigate the dynamic behavior of cylindrical cavitation bubble,based on Kelvin impulse theory and high-speed photography experiments,the dynamic behavior of cylindrical cavitation bubble in symmetric and asymmetric positions near a right-angle wall with bulge is researched theoretically and experimentally.Firstly,based on the Kelvin impulse expression of cylindrical cavitation bubble,the cylindrical cavitation bubble point source near a right-angle wall with 1/4 cylindrical bulge is treated by conformal transformation and mirror image method,and the exact formula for calculating the Kelvin impulse of cylindrical cavitation bubble is derived.Then,the theoretical properties of Bjerknes force,bubble wall velocity,Kelvin impulse strength and direction are discussed parameterically.And the dynamic behavior of cylindrical cavitation bubble near a right-angle wall with bulge was verified and further analyzed by high-speed photography experiment.The results show that:(1)When the cylindrical cavitation bubble is located in the symmetrical position,the bubble sag points to the origin of the wall,and the bubble splits into two equal parts at the end of collapse.The degree of non-spherical deformation,the centroid displacement and the Kelvin impulse intensity of bubble in the collapse stage all increase gradually with the decrease of dimensionless distance or the increase of dimensionless bulge radius.(2)When the cylindrical cavitation bubble is located in the asymmetric position,with the cavitation bubble gradually deviates from the symmetric position,the volume of the part near the flat wall at the end of collapse gradually increases,the velocity distribution of the bubble wall loses symmetry,the intensity of Kelvin impulse gradually increases,the Kelvin impulse angle and the centroid displacement angle decrease and are more inclined to the near flat wall.(3)By comparing the theoretical and experimental results,it is found that the theoretical model of the cylindrical cavitation bubble near a right-angle wall with bulge has a good agreement with the experimental results.