Sampling rate effect on wedge pressure record in water entry by experiment

Water entry experiment is the most reliable method by which impact pressures on marine structures are measured. Several parameters have to be controlled during the water entry experiments to obtain accurate and reliable results. Sampling rate of data acquisition system is one of the influencing factors. In this paper, the effect of sampling rate on impact pressure on wedge water entry experiments is investigated. A wide range of wedges with deadrise angles of 5-35 are dropped into water at the entry velocity of 3.13 m/s and impact pressures are recorded with different sampling rates. Results are compared to analyze the effect of sampling rate on outcomes. Finally, to mitigate the negative aspects, some thresholds of sampling rate are determined for different wedges. It was found that for wedges with deadrise angles of 25 degrees and higher, a sampling rate of 25 kHz is adequate for this configuration. This sampling rate; however, is not appropriate for deadrise angles lower than 20 degrees where a higher rate is needed. Results indicate that the acceptable sampling rate for a wedge of 5 deadrise angle is 600 kHz at water entry velocity of 3.13 m/s.