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Prediction and Verification of Water-entry Traces Size of Small Falling Objects into the Sea
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 Title & Authors
Prediction and Verification of Water-entry Traces Size of Small Falling Objects into the Sea
Min, Anki; Hwang, Tae-Won;
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 Abstract
An unmanned aerial photography method by using an unmanned helicopter is useful method for measuring of the water-entry traces of small falling objects into the sea. Pixel sizes on the aerial photograph may be too large due to a limit of camcorder resolution and a wide shooting area. If the pixel size is too large, identification of water-entry trace is impossible. Thus an accurate prediction of water-entry trace size is required. The traces of water-entry could be classified into three types such as splash, water column, and bubble. Diameters of each trace are predicted by water-entry impact pressure theories, cavity theories, and trial test results. The results are verified by drop tests using an unmanned helicopter at two water-entry speeds. As a result, prediction and test results showed sufficient similarity to evaluate the identifiability of water-entry trace.
 Keywords
Traces of Water-entry;Unmanned Aerial Photography;Small Falling Object;
 Language
Korean
 Cited by
 References
1.
Th. Von Karman, "The Impact on Seaplane Floats during Landing," NACA TN 321, 1929.

2.
H. Wagner, "Landing of Seaplanes," NACA TN 62, 1931.

3.
W. J. C. Boef, "Launch and Impact of Free Fall Lifeboats. Part I. Impact Theory," Ocean Engineering, Vol. 19, No. 2, 1992.

4.
M. Arai, "Water Entry Simulation of Free-fall Lifeboat," Journal of The Society of Naval Architects of Japan, Vol. 178, 1995.

5.
P. R. Payne, "The Vertical Impact of a Wedge on a Fluid," Ocean Engineering, Vol. 8, No. 4, pp. 421-436, 1981. crossref(new window)

6.
Jong-Boong Lee, "A Study on the Impact Pressure of a Falling Body upon a Free Surface Water," J. Korean Society of Industrial Application, Vol. 4, No. 3, pp. 295-304, 2001.

7.
V. Duclaux, F. Caille, C. Duez, C. Ybert, L. Bocquet, C. Clanet, "Dynamics of Transient Cavities," Journal of Fluid Mechanics, Vol. 591, pp. 1-19, 2007.

8.
E. S. Winkel, S. L. Ceccio, D. R. Dowling, M. Perlin, "Bubble-size Distributions Produced by Wall Injection of Air into Flowing Freshwater, Saltwater and Surfactant Solutions," Experiments in Fluids, Vol. 37, pp. 802-810, 2004. crossref(new window)

9.
H. Yan, Y. Liu, J. Kominiarczuk, D. K. P. Yue, "Cavity Dynamics in Water Entry at Low Froude Numbers," Journal of Fluid Mechanics, Vol. 641, pp. 441-461, 2009. crossref(new window)