The Influence Of Rising Bubbles On The Stability Of Floating Body

In recent years,with the rapid development of activities such as lake and reservoir projects,river undercutting projects,underwater pipeline transportation projects and the development of Marine seabed resources,the active exhaust and passive leakage of underwater engineering and the gas emission after the decomposition of underwater organic matter existing in nature also increase.In this process,there is a potential danger that has not attracted wide attention,that is,when the underwater gas is discharged close to the water surface,if there is a floating body on the water surface in the bubble emergence area,the floating body may be unstable or overturn under the influence of a large number of rising bubbles.In this context,this study studied the mechanism of the influence of rising bubbles on the stability of floating body on the water surface through theoretical analysis,physical model test and other methods,so as to provide some basic data support for the risk assessment and prevention of such problems in the future.Firstly,the theoretical basis of bubble generation and floating movement in water is studied in this paper.According to the bubble volume,the force balance of the bubble is analyzed,and several forces on the bubble generation at the orifice are analyzed.In the process of bubble formation,the main factors that affect the diameter of bubbles are orifice diameter,gas flow rate and the physical properties of liquid,etc.Secondly,this paper carried out an experimental study on the movement law of rising bubbles under water.The results showed that when the gas flow rate was constant,the diameter of the air bubble cavity would increase with the increase of the inner diameter by changing the inner diameter of the air hole.When the gas flow rate is constant,the diameter of bubble exit hole increases with the increase of gas flow rate,and the bubble exit time decreases with the increase of gas flow rate.When the gas flow rate is constant,the bubble exit diameter decreases with the increase of water temperature,and the bubble exit time decreases with the increase of water temperature.Bubble in the process of floating,only just off the moment of rapid acceleration,and then do approximately uniform motion,and the bubble floating speed is related to its diameter;The software extracts the coordinates of thebubble at different moments in its upward movement,and makes the trajectory diagram of the bubble,and finds that it rises in a "spiral" shape.Finally,this paper carried out an experimental study on the influence of rising bubbles on the stability of floating body.It was concluded from the test that the introduction of gas into liquid to form bubbles would lead to the decrease of the average density of gas-liquid mixture,and the main factor affecting the average density of gas-liquid mixture was gas flow rate.For the cube floating body with the same density,the smaller the volume is,the greater the instability Angle is,and the more violent the shaking will be.For a cube floating body of the same size,the smaller the density is,the greater the instability Angle is,and the more violent the shaking will be.However,the greater the density is,the greater the relative change of draft depth will be.For the same cube floating body,the greater the gas flow is,the greater the unstable inclination of the floating body is,the more violent the shaking will be,and the greater the relative change of draft depth will be.For the same cube floating body,when the gas flow is constant,the larger the bubble diameter is,the greater the instability inclination of the floating body is,and the more violent the shaking will be.Therefore,it can be seen that the main factors affecting the stability of the floating body are the gas flow,the size of bubbles,the volume of the floating body and the density of the floating body.