Partial cavitation on a hydrofoil over a wide range of size scales

Partial cavitation occurs when a relatively stable pocket of gas forms and closes on a flow boundary. Natural cavities can occur on hydrofoils, propulsor blades, and control surfaces, leading to performance degradation, vibration, and erosion. Monitoring erosion on a full-scale model and relating it to flow structures is not feasible, resulting in the dependence on model-scale experiments. In the present work, we report on a series of experiments in which partial cavitation forming on a two-dimensional hydrofoil is examined at two different size scales (hydrofoil chords of 0.152 m and 2.13 m, a 1:14 range of size scales) over a chord-based Reynolds number range from 1 million to 38 million. Findings from two geometrically similar facilities, the Large Cavitation Channel (LCC) and a 1/14 scale model, the Model Large Cavitation Channel (mLCC), are presented. In addition, X-ray densitometry-based void fraction measurements were performed at a third facility to quantify mixture compressibility effects. It is shown that the cavity topology and dynamics, cavity length, pressure, void fraction, shedding frequency, and hydrodynamic loading are similar between the two scales.