Visualization of Acoustic Waves and Cavitation in Ultrasonic Water Flow

Abstract

Visualization experiments were performed to examine whether acoustic bubbles play a role in ultrasonic water flow cleaning, as in convention cleaning with ultrasonic baths. Schlieren visualization confirmed the standing-wave-like acoustic field in ultrasonic water flow that collides with a glass surface. Backlight visualization showed that cavitation bubbles appear in the water flow spreading over the glass surface. These bubbles are found to oscillate in volume and move inside film flow and thus expected to play a role as active cleaning agents.

Chemically controlled megasonic cleaning of patterned structures using solutions with dissolved gas and surfactant

“…Similarly, when bubbles are larger than the resonance size, they move from the acoustic antinode to the acoustic node [6] , resulting in a standing wave-like acoustic field inside the acrylic bath. Similar observations were made by Ando and co-authors [37] , [38] . To gain insight into the coalescence and agglomeration behavior of bubbles, we recorded the input power and corresponding output power while bubbles were streaming in the ultrasonic standing wave field.…”

Optimal Injection Distance in Ultrasonic Water Flow Cleaning

“…To avoid cavitation erosion on the sensor part of the hydrophone, we use the lower input power, while that at 20 W was used for the cleaning tests. The acoustic pressure at 10 W is approximately 0.4 MPa, implying that the larger acoustic pressure at 20 W will produce cavitation inside the water jet and film flow as visualized in our previous reports [2,3].…”

“…In this technique, ultrasound-superposed water jets are set into collision against cleaning targets and the hydrodynamic force acting on attached particles is expected to contribute to particle removal [1]. From visualization of 0.43 MHz or 0.95 MHz ultrasound superposed water jets and the subsequent film flow spreading over glass surfaces [2,3], cavitation bubbles are found to play a key role in particle removal as in the conventional method with ultrasound cleaning baths [4,5,6]. To be specific, motion of near-wall cavitation bubbles can produce strong wall shear stress [7] and thus augment the cleaning performance.…”

Experimental Analysis of Water-1MHz-gasified with O2, and Simulation Analysis of Physicals Parameters Effect of Solvents in Megasonic Cleaning

“…Typical resonance frequencies of the transducer are of the order of 1MHz. A hydrophone with broadband between 0.2 and 10 MHz, used to capture the signal of the transition from stable to transient cavitation for all liquids (IPA, Water, NMP, DMSO) [3], [18], [19]. The intensity of the sound is proportional to the square of the maximum pressure amplitude in the cleaning chemicals and calculated by this equation (1):…”