Assessment of cavitation erosion risk indicated by pressure impact exceeding material strength threshold

Abstract

Cavitation erosion can seriously affect the performance of hydraulic machinery. To assess its risk, the cavitation erosion that covered a NACA0015 hydrofoil was investigated using experiment and simulation. In particular, the material strength threshold was considered in the experiment, and soft specimens were employed instead of common painting surfaces. High-speed cameras were utilized to capture cavity morphology, while pressure sensors simultaneously measured the impact intensity of cavitation collapse. Additionally, an erosion assessment method based on pressure impact was used in the numerical simulation. The results indicate that the cavitation erosion risk can be indicated by the intensity of pressure impact, which is caused by the collapse of cavity. The high erosion risk appears near 60% of chord length where shedding cloud collapses. Due to the influence of middle-entrant jet and side-entrant jets, the erosion risks are different at various span-wise locations. Additionally, the response differs for different materials exposed to cavitation. When the material strength threshold is low, the chord-wise difference of cavitation erosion is not significant, because the slight impact can also generate erosion pits. When the threshold is high, the chord-wise difference of erosion becomes larger, and erosion pits are more centralized.