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Test-to-test dispersion SMAES facility

Test-to-test dispersion analysis

In order to assess the dispersion of the measurements and the repeatability capabilities, ten repeats of the same test were performed for two different conditions. In both cases thick aluminium plates were used which ensured that the plate deformation remained well within the purely elastic range. The analysis was carried out for U=40 m/s, V=1.5 m/s at pitch angles of 4 and 10 degrees. An excellent overlapping of the data was found in terms of pressures, strains and loads, for the 10 degrees condition. For the tests at 4 degrees pitch angle the entrainment of air bubbles beneath the plate causes a scatter of the pressure records, particularly for probes located at the rear of the plate which are the first to get in contact with the water. In spite of the scatter of the pressure measurements, the data in terms of strains and loads display a very high repeatability. Some of the results are given here below whereas further details can be found in the references provided at the end of the page.

Pressure, 10 deg: Time histories of the pressure measured by one of the probes in the ten repeats.Pressure, 10 deg: Time histories of the pressure measured by one of the probes in the ten repeats.

Strains, 10 deg: Time histories of strain measured by one of the probes in the ten repeats.Strains, 10 deg: Time histories of strain measured by one of the probes in the ten repeats.

Pressure, 4 deg: Time histories of the ten records of the pressure measured by one of the probesPressure, 4 deg: Time histories of the ten records of the pressure measured by one of the probes

Strains, 4 deg: Time histories of strain measured by one of the probes in the ten repeats.Strains, 4 deg: Time histories of strain measured by one of the probes in the ten repeats.
Underwater image, 4 deg: Air bubbles are entrained which are responsible for the large scatter of the pressure.Underwater image, 4 deg: Air bubbles are entrained which are responsible for the large scatter of the pressure.
Loads normal to the plate, 4 degLoads normal to the plate, 4 deg Loads normal to the plate, 10 degLoads normal to the plate, 10 deg

References

A. Iafrati, M. Siemann, L. Benìtez~Montañès, Experimental study of high speed plate ditching, 29th IWWWFB, Osaka (JP), April, 2014

A. Iafrati, S. Grizzi, M. Siemann, L. Benìtez~Montañès Experimental Analysis of the Water Entry of a Plate at High Horizontal Speed, 30th ONR Symp. on Naval Hydrod., Hobart, Tasmania (AU), November 2014.