The present work is an original study of the flow induced vibration, cavitation structures and cavitation induced pressure pulsation characteristics around a typical hydrofoil named 791, which is widely applied in the axial flow pump.
From the vibration experiment of the hydrofoil at various operating conditions, it is clear that at low frequency band, with Reynolds number increasing, vibration energy first experiences a stable slightly increasing tendency, and then decreases rapidly, finally rises steeply again. Besides, according to the results of several positive incidence angles, it is observed that vibration energy usually achieves a local minimum level at a certain positive incidence angle falling into the range of 2° to 4°.
Based on results obtained from the detached eddy simulation (DES) turbulent model, full developing process of cavitation stages including, incipient cavitation, sheet cavitation and cloud cavitation could be captured and easily identified. It is found that pressure spectra in accordance with different cavitation stages show great discrepancy. In the stage of incipient cavitation and cloud cavitation, predominant components in pressure spectra are caused by the cyclical evolution of the main cavity and the periodic variation of the small vacuoles shedding at the span-wise outer edge of the hydrofoil. However, in sheet cavitation stage, the pronounced excitation frequencies are generated by cyclical evolution of the main cavity and cavity shedding from both sides of the U-shaped cavitation structure. Pressure pulsation amplitude is pretty small at the cavity stable adhesion region. But the amplitude of vacuoles shedding from the hydrofoil is much larger than main cavity adhesion region at these three stages.