Suppression of unsteady cavitation around oscillating hydrofoils using spanwise obstacles near trailing edge

Cavitation can cause flow path blockages in hydraulic machinery, while the formation, growth, evolution, and collapse of unsteady cavitation may lead to pitting or erosion on boundary surfaces, ultimately damaging hydraulic components. Due to the numerous disadvantages that cavitation imposes on the operation of hydraulic machinery, delaying cavitation onset or suppressing cavitation shedding has become a critical and challenging focus in hydraulic machinery research and development. In practical operation, the inflow encountered by hydrofoil sections often varies with time and space, causing changes in the effective angle of attack (AoA) of the hydrofoil. This study investigated a method for suppressing unsteady cavitation on oscillating hydrofoil surfaces by installing spanwise obstacles near the trailing edge. The experiments utilized synchronized multi-physics measurement methods to collect imagery, mechanical, and acoustic data. The findings reveal that, compared to the suppression effect of spanwise obstacles near the trailing edge on unsteady cavitation under static AoA conditions, the suppression effect is more effective during sinusoidal oscillation. Additionally, the presence of spanwise obstacles generates a positive torque on the hydrofoil, reducing the maximum negative torque experienced by the hydrofoil. Meanwhile, wavelet transform analysis comparing moments with and without cavitation during sinusoidal oscillation reveals that the noise generated by unsteady attached cavitation around the hydrofoil is primarily concentrated in the 40–400 Hz frequency range.