This article studies the effects of air content on propeller cavitation and pressure fluctuations.The cavitation is observed while the pressure fluctuations on the hull are measured.When adjusting the air content,the sheet cavitation range does not change distinctly,but the pressure fluctuations see obvious differences.The amplitudes of the pressure fluctuations increase with the decrease of the air content.The results indicate that the air content has little effect on the sheet cavitation range but has an important effect on the bubble cavitation and the tip vortex cavitation.When the air content decreases,the water tensile force increases,which results in the instability of the bubble cavitation and the tip vortex cavitation and the increase of the pressure fluctuations.To minimize the scale effects,the experiments should be run at a high Reynolds number with a high nuclei content.The high Reynolds number is often realized by increasing the flow velocity and the propeller rotation speed,and the high nuclei content is often made by increasing the dissolved air content.