Observation of multibubble phenomena in an ultrasonic reactor

A cylindrical ultrasonic reactor radiated by a BLT (bolted Langevin transducer) with a large horn operated at 27.3 kHz was employed to investigate the behaviors of bubbles in the present research. The characteristics of this reactor were analyzed using experimental methods. It was found that traveling transient bubbles can eliminate the effect of standing wave on cleaning efficiency. Fresh tap water and degassed water were employed as test liquids. In tap water, a conical cavitation structure was observed as the input voltage of transducer was increased over 100 V. The detail of the conical cavitation structure was anatomized and its shape varied with the change of input voltage. In degassed water, ultrasonic fireworks were observed and special attention was paid to their subsequences, snowflake bubble clouds and water jet.