The effect of bubble size in descaling process of bubble flow pipes based on leaky ultrasonic guided waves

Crystal scaling in gas-liquid two phase flow pipes is a common issue in many fields, such as chemical engineering, water industries, and energy industries, posing a great threat to the production process and the environment. The characters of air bubbles in the bubble flow have a serious impact on the ultrasonic guided wave descaling inside a pipe. The interaction mechanism between the air bubbles with various sizes and the cavitation bubbles are studied in this paper by combined the finite element method and the bubble dynamics equation, qualitatively analyzing the impact of the air bubble size and the acoustic pressure in the fluid field on the leaky ultrasonic guided waves descaling. The numerical and experiment results show that the maximum expansion radius ratio of cavitation bubble is suppressed from 2.4 to 1.3 when the radius of air bubble grows from 0.5 mm to 4.5 mm. The Ca content removal ratio at 35.5 cm was 81 %, 66 % and 28 %, while the Ca content removal ratio at 60 cm was 76 %, 56 % and 16 % when the gas outlet orifice is 100 μm, 200 μm and 300 μm respectively in the experiment. The results indicate that large bubbles in two phase flow inhibit the cavitation effect of cavitation bubbles and reduce the effectiveness of descaling.