Investigation on the fluctuation characteristics of slamming pressure during water entry of an open cavity

Compared to sealed cylinders, when an open cavity impacts water, it causes an influx of external liquid into the cavity and an outflow of internal liquid. The additional disturbance from the liquid inside the cavity not only leads to fluctuations in the wall of the water entry cavity but also results in periodic fluctuations in the slamming pressure. This is an issue that has not been thoroughly investigated in the previous studies. In this paper, we numerically and experimentally study the water entry of an open cavity, with a focus on the periodic fluctuations of slamming pressure during the process. First, a numerical model incorporating gas compressibility was established for open cavity water entry based on computational fluid dynamics method, we numerically simulate the water entry of an open cavity under different cases; second, a test system for the open cavity impact the water is constructed. Next, numerical results on the slamming pressure of the open cavity show good agreement with those measurement in the physical experiments. Furthermore, we also study the influence of Froude number on the amplitude, duration, and evolution patterns of pressure fluctuations and reveals the distinctive features of impact pressure between open cylindrical cavities and sealed cylinders.