Refined Active Control of Sloshing by Intermittent Air-Bubble Injection

Abstract

We present in this paper a rule-based control system which effectively suppresses liquid sloshing by injecting air bubbles into the sloshing liquid. We show that the most important control parameter is air-bubble injection timing, which is determined by the control laws established from the knowledge on characteristics of slosh suppression by air-bubble injection. The control experiments carried out using an 800-mm-long, 500-mm-high, and 150-mm-wide rectangular tank reveal that (1) the control laws that delay the air bubble injection timing with decrease in the sloshing amplitude and adjust the zero-level crossing timing of sloshing can successfully suppress sloshing oscillation, (2) the effectiveness of the control algorithm is experimentally demonstrated for earthquake-induced sloshing, and (3) the visualization of slosh circulation flow reveals a unique flow pattern when the sloshing is effectively suppressed and can offer an insight towards understanding the mechanism of slosh suppression by air-bubble injection.