OBRABOTKAMETALLOV technology Vol. 27 No. 2 2025 Results and discussion Comparison of CET and CAT surface mechanisms Fig. 5 shows a film diagram of the CET process. Fig. 5. CET process cinematography (frame rate: 5,339 fps) At the moment ultrasound is activated, the liquid is subjected to varying compressive and tensile forces corresponding to the oscillation phases of the radiator end. As a result of breaks in liquid continuity, cavitation bubbles are formed. These bubbles oscillate, collapse, combine, and move within the treated volume under the influence of acoustic streams. The most favorable locations for bubble formation and accumulation are various surface irregularities, such as protrusions and depressions of the microrelief. The first frame shows the formation of cavitation bubbles on the treated surface. This process begins even before the bubbles formed under the radiator are transferred to the surface by the acoustic stream. Over time, the number of bubbles increases, and they combine near the largest surface irregularity, forming a cavitation cluster. Similarly, other clusters form on the surface at different times. The frames illustrate the formation and a portion of the life cycle of two cavitation clusters, which pulsate, absorb cavitation bubbles carried by the acoustic stream, collapse and reform. The frame corresponding to 168 ms of the treatment process shows the collapse of cluster 2. In the next frame (187 ms), it begins to reform in the same location and reaches its maximum size by 261.8 ms. At 280.5 ms, the two clusters begin to merge. The combined cluster then partially collapses, and the remaining part of the bubbles splits into two (317.9 ms), which return to their previous locations and begin to grow again (336.6–355.3 ms).
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