Ply angle effects on cavitating flow induced structural response characteristics of the composite hydrofoils

The objective of this paper is to experimentally investigate the structural response characteristics of composite hydrofoils with different ply angles. A synchronous measurement system composed of the high-speed camera, the laser Doppler vibrometer, the flow rate regulation system and the pressure regulation system is established. The results show that the composite hydrofoil with +45° ply angle promotes the cavitation inception and has the most severe cavitation behavior at the same cavitation number. Relatively significant structural vibration can be observed in the sheet and cloud cavitation regimes. From the incipient cavitation to the supercavitation regimes, the probability density distribution of vibration velocity of the composite hydrofoils gradually deviates from the normal distribution. The structural displacement responses for different hydrofoils have quasi-periodic characteristics. The dominant vibration displacement frequency is consistent with the cavity shedding frequency and cavitating area pulsation frequency. The cavitation number range of frequency lock-in satisfies composite hydrofoil with +45° ply angle > composite hydrofoil with −45° ply angle > composite hydrofoil with 0° ply angle.