Experimental Investigation of fluid-structure interaction of composite hydrofoils in cavitating flow

This paper experimentally studies the cavitating fluid-structure interaction of composite hydrofoils with different ply angles. The synchronous measurement system with high-speed camera and for laser Doppler vibrometer (LDV), the feedback pressure regulation system, and the flow rate control system are established. The experimental results of the cavitation evolution show that, compared with the rigid hydrofoil, the composite hydrofoils with +45° ply angle and 0° ply angle accelerate the cavitation inception, and the composite hydrofoil with −45° ply angle delays the cavitation inception. At the same cavitation number, the cloud cavitation of the +45° laminated hydrofoil is the most severe, followed by that of the 0° laminated hydrofoil, and that of the −45° laminated hydrofoil is relatively weak and close to that of the rigid hydrofoil. The analyses of the structural vibration of the composite hydrofoils in different cavitation stages show that the three composite hydrofoils have no significant vibration at the incipient cavitation and the supercavitation, but relatively significant vibration is observed in the sheet and cloud cavitation. The vibration amplitude of the composite hydrofoil with +45° ply angle is the largest, followed by those of the −45°, 0° laminated hydrofoils. In the sheet cavitation, the dominant frequencies of the structural vibration velocity of the +45° laminated hydrofoil and the −45° laminated hydrofoil are the first and second modal frequencies, but no explicit dominant frequency is observed for the 0° laminated hydrofoil. In the cloud cavitation, the dominant frequencies of the three composite hydrofoils mainly include the first modal frequency, the second modal frequency, and the cavity shedding frequency.