Active flow control on unsteady cloud cavitation: Insights into jet dynamics

Unsteady cloud cavitation significantly impairs the performance of marine systems. Active flow control method has shown promise in effectively reducing cavitation, yet its specific mechanisms of action require elucidation. This study investigates continuous water injection on a NACA66 (MOD) hydrofoil as an active control against unsteady cloud cavitation. Results show notable reductions in cavitation volume: 52.57 % at a cavitation number of 0.83 and 86.24 % at 1.29. Employing the Lagrangian approach, the study tracks ideal particles to explore the jet's behavior and its interaction with cavitation. The interaction between the jet and cavitation is reciprocal: cavitation draws the jet, which in turn alters the cavitation's structure. The jet's movement is synchronized with the evolution process of cavitating flow, effectively limiting the spread of attached cavitation, disrupting cloud integrity, and encircling scattered clouds to prevent their growth. The analysis identifies the jet's streamwise direction as critical in suppressing cavitation, with the normal direction providing supplementary support, and the spanwise direction having minimal impact. Furthermore, the jet promotes a condensation-dominant state in local flow regions, hindering cavitation growth by altering the water-vapor mass transport process.