Dynamic response and acoustic characteristics of composite hydrofoil under cavitation-induced vibration

The non-constant characteristics of cavitation flow can cause adverse effects, including vibration, noise, and cavitation. With the application of composite materials, the vibration and deformation of hydrofoils are becoming increasingly obvious and the fluid-solid coupling problem is becoming very important. Herein, the cavitation flow field of NACA (National Advisory Committee for Aeronautics) 0012 hydrofoil composed of bronze alloy and composite material is numerically investigated. The hydro-elastic response of a hydrofoil is obtained via a fluid-structure coupling method under a tight coupling strategy. The Schnerr-Sauer model is used to describe the cavitation process, and the large eddy simulation method is used to solve the turbulence problem. Additionally, the finite element method is used to determine the structural deformation. Comparison of the numerical calculation results of the fluid-solid acoustic coupling under two operating conditions shows that the composite materials can suppress the sheet cavitation attached to the hydrofoil suction surface and the tip leakage vortex (TLV) cavitation and can decrease the flow field pressure pulsation and increase the lift-to-drag ratio of the hydrofoil. Additionally, the composite material significantly improves the wake field turbulence, reducing the turbulence intensity and integration scale, and nearly eliminates the large scale vortex. Moreover, the composite material changes the vortex structure evolution at the gap flow field, results in smoother TLV development, and enhances the flow field velocity gradient effect. Finally, the monitoring of the flow noise radiation characteristics shows that the composite material effectively reduces the sound pressure level of the self-noise and far-field radiation noise.