Browse > Article
http://dx.doi.org/10.3744/SNAK.2015.52.3.236

An Experimental Study on Ventilated Supercavitation of the Disk Cavitator  

Kim, Byeung-Jin (Department of Naval Architecture & Ocean Engineering, Chungnam National University)
Choi, Jung-Kyu (Department of Naval Architecture & Ocean Engineering, Chungnam National University)
Kim, Hyoung-Tae (Department of Naval Architecture & Ocean Engineering, Chungnam National University)
Publication Information
Journal of the Society of Naval Architects of Korea / v.52, no.3, 2015 , pp. 236-247 More about this Journal
Abstract
In this paper, the experimental equipments for ventilated supercavitation in cavitation tunnel is constructed and the basic data of ventilated supercavitation regard to the entrainment coefficient and Froude number is fulfilled. The experiments are conducted for the disk cavitator with injecting air and the pressure inside cavity and the shape of cavity are measured. As the entrainment coefficient increases while the Froude number is kept constant, the ventilated cavitation number decreases to a minimum value which decreases no more even with increasing the air entrainment. The minimum value of ventilated cavitation number, caused by the blockage effect, decreases according to increasing the diameter ratio of test section to cavitator. The cavity length is rapidly enlarged near the minimum cavitation number. In low Froude numbers, the cavity tail is floating up due to buoyancy and the air inside the cavity is evacuated from its rear end with twin-vortex hollow tubes. However, in high Froude numbers, the buoyancy effect is almost negligible and there is no more twin-vortex tubes so that the cavity shape becomes close to axisymmetric. In order to measure the cavity length and width, the two methods, which are to be based on the cavity shapes and the maximum width of cavity, are applied. As the entrainment coefficient increases after the ventilated cavitation number gets down to the minimum cavitation number, the cavity length still increases gradually. These phenomenon can be confirmed by the measurement using the method based on the cavity shapes. On the other hand, when the method based on the maximum width of cavity is used, the length and width of the cavity agree well with a semi-empirical formular of natural cavity. So the method based on the maximum width of cavity can be a valid method for cavitator design.
Keywords
Ventilated cavitation; Supercavitation; Cavitator; Cavitation tunnel;
Citations & Related Records
Times Cited By KSCI : 6  (Citation Analysis)
연도 인용수 순위
1 Self, M.W. & Ripken, H.F., 1955. Steady–State Cavity Studies in a Free-Jet Water Tunnel, Report No. 47. University of Minnesota, USA: St. Anthony Falls Hydraulic Laboratory.
2 Michael, P.K. Jules, W.L. & Robert, F.K., 2009. Air entrainment Mechanisms from Artificial Supercavities: Insight based on numerical simulations. Proceedings of the 7th International Symposium on Cavitation CAV2009. Ann Arbor, Michigan, USA, 17-22 August 2009, pp.1-14.
3 Savchenko, Y.N., 2001. Experimental investigation of supercavitating motion of bodies. RTO AVT Lecture Series on "Supercavitating Flows", VKI in Brussels, Begium, 12-16 Feburary 2001, pp.4-1-4-24.
4 Schauer, T.J., 2003. An Experimental Study of a Ventilated Supercavitating Vehicle. M.S. thesis. Minneapolis, USA: University of Minnesota.
5 Semenenko, V.N. 2001. Artificial supercavitation. physics and calculation. RTO AVT Lecture Series on “Supercavitating Flows”, Brussels, Belgium, 2001, pp.11-1-11-33.
6 Spurk, J.H., 2002. On the gas loss from ventilated supercavities. Acta Mechanica, 155, pp.125-135.   DOI   ScienceOn
7 Kim, H.T. & Lee, H.B., 2014 A Numerical Analysis of Gravity and Free Surface Effects on a Two-Dimensional Supercavitating Flow. Journal of the Society of Naval Architects of Korea, 51(5), pp.435-449.   DOI   ScienceOn
8 Karlikov, V.P. & Sholomovich, G.I., 1966. Method of Approximate Account for the Wall Effect in Cavitation Dlow Around Bodies in Water Tunnels. Izvestiya Akademii Nauk SSSR, Mekhanika Zhidkostii Gaza. Izdatel'stvo Nauka, 1(4), pp.89-93.
9 Kawakami, E.G., 2010. Investiation of the Behavior of Ventilated Supercavities. M.S. thesis. Minneapolis: University of Minnesota.
10 Kim, B.J. Jung, S.W. Ahn, B.K. & Kim. H.T., 2014. An observation of ventilated supercavitation of disk cavitator. The Korean Association of Ocean Science and Technology Societies, Busan, Korea, 22-23 May 2014, pp.1309-1314.
11 Knapp, R.T. Daily, J.W. & Hammit, F.G., 1979. Cavitation. IOWA: Institute of Hydraulic Research.
12 May, A., 1975. Water entry and the cavity-running behavior of missiles, Naval Sea Systems Command, Hydroballistics Advisory Committee Technical Report 75-2. National Technical Information Service U. S. Department of commerce: Hydroballistics Advisory Committee.
13 Kim, J.H. Jang, H.G. Ahm, B.K. & Lee, C.S., 2013. A Numerical Analysis of the Supercavitating Flow around Three-Dimensional Axisymmetric Cavitators. Journal of the Society of Naval Architects of Korea, 50(3), pp.160-166.   DOI   ScienceOn
14 Kim, S.H. & Kim, K.W., 2014. Study on Dynamics modeling and Depth Control for a Supercavitating underwater Vehicle in Transition Phase. Journal of the Society of Naval Architects of Korea, 51(1), pp.88-98.   DOI   ScienceOn
15 Lee, H.B. Choi, J.K. & Kim, H.T., 2013 Numerical Analysis of Supercavitating Flows of Two-Dimensional Simple Bodies. Journal of the Society of Naval Architects of Korea, 50(6), pp.436-449.   DOI   ScienceOn
16 Ahn, B.K. Lee, C.S. & Kim, H.T., 2010. Experimental and Numerical Studies on Super-cavitating Flow of Axisymmetric Cavitator. Interernational Journal of Naval Architecture and Ocean Engineering, 2(1), pp.39-44.   DOI   ScienceOn
17 Ahn, B.K. Lee, T.K. Kim, H.T. & Lee, C.S., 2012. Experimental Investigation of Supercavitating Flows. International Journal of Naval Architecture and Ocean Engineering, 4(2), pp.123-131.   DOI   ScienceOn
18 Brennen, C., 1969. A Numerical Solution of Axisymmetric Cavity Flows. Journal of Fluid Mechanics, 37, pp.671-688.   DOI
19 Epshtein. L.A., 1966. Minimal cavitation number and cavity width in plane and axisymmetric channels. Fluid Dynamics, 1(5), pp. 54-56.   DOI
20 Franc, J.P. & Michel, J.M., 2005. Fundamentals of Cavitation. Kluwer Academic Publishers: Netherlands.
21 Campbell, I.J. & Hilborne, D.V., 1958. Air entrainment behind artificially inflated cavities. Second Symposium on Naval Hydrodynamics, Washington, D.C., U.S.A, 25-29 August 1958, pp.467-481.