Interaction dynamics between cavitation bubbles and compressible air bubbles in an infinite domain

Abstract

Air entrainment is of great significance for mitigating cavitation erosion damage, but current numerical studies on cavitation predominantly neglect the influence of air bubbles on cavitation bubble dynamics. This study employs a two-component compressible phase-change model to elucidate three distinct interaction modes between cavitation and air bubbles: upward jetting, splitting, and downward jetting. Notably, the downward jetting mode demonstrates markedly higher velocity compared to other patterns. Crucially, when inter-bubble spacing reduces below a critical dimensionless threshold, the high-pressure pulse from air bubble collapse induces micro-jets exceeding 200 m/s. Through dimensional analysis, we establish a dimensionless parameter correlating air bubble size (η) and separation distance (γ). Theoretical derivation shows the cavitation bubble collapse time exhibits an exponential decay dependence on the parameter (γ/η), while maximum expansion velocity scales with the sixth power of its reciprocal. The theoretical breakthrough lies in demonstrating that regulated air bubble sizing can strategically suppress cavitation erosion: Air bubble collapse not only attenuates cavitation collapse intensity but also redirects destructive energy through micro-jet orientation control. These findings establish fundamental guidelines for cavitation protection in hydraulic structures, providing crucial theoretical references for erosion suppression.