Penentuan Added Mass Hycat Akibat Gerakan Couple Heaving Pitching pada Gelombang Reguler
DOI:
https://doi.org/10.5614/jts.2003.10.1.2Keywords:
HYCAT, Added Mass, Heaving, Pitching, Teori Strip.Abstract
Abstrak. Untuk menentukan besarnya added mass pada model HYCAT akibat gerakan couple heaving-pitching telah dilakukan studi eksperimental di Laboraturium Hidrodinamika Indonesia. Penelitian ini dilakukan pada kondisi sarat air 0,278 m, tinggi gelombang 0,1 m, tiga variasi kecepatan model 4,432 m/dt, 4,77 m/dt dan 5,144 m/dt masing-masing dengan rentang periode gelombang 0,8 ~ 1,4 detik. Dari percobaan tersebut di atas diperoleh hasil pada kecepatan 4,432 m/dt untuk heaving rentang added mass berkisar antara 24,67 ~ 46,68 kg, dan untuk pitching rentang added mass 5,98 ~ 20,35 kg, pada kecepatan 4,77 m/dt rentang added mass untuk heaving 18,72 ~ 41,31 kg, dan rentang added mass untuk pitching 4,68 ~ 17,54 kg. Pada kecepatan 5,114 m/dt rentang added mass untuk heaving 15,51 ~ 35,28 kg dan rentang added mass untuk pitching 3,17 ~ 15,72 kg. Keseluruhan hasil percobaan tersebut selanjutnya diverifikasi dengan hasil perhitungan teoritis menggunakan teori strip. Hasil verifikasi menunjukkan bahwa hasil percobaan dan perhitungan teoritis memberikan trend grafik yang sama, yaitu terjadi kenaikan nilai added mass seiring dengan naiknya periode gelombang. Disisi lain dengan naiknya kecepatan model, terjadi penurunan besaran added mass.Abstract. An experimental study has been performed at the Indonesia Hydrodynamics Laboratory to measure the added mass of a HYCAT model due to couple heave-pitch mode of motion. A series of tests were conducted by setting
the model draft at 0,278 m, in the 0,1 m wave height, three different model speed of 4.432 m/sec, 4.77 m/sec, and 5.144 m/sec, with variation in wave period ranging from 0.8 to 1.4 sec, for each model speed. Results of the experiment show that at 4.432 m/sec model speed, the added mass for heave ranges between 24.67 ~ 46.68 kgs and the added mass for pitch ranges between 5.98 ~ 20.35 kgs. At 4.77 m/sec model speed, the added mass for heave ranges between 18.72 ~ 41.31 kgs and the added mass for pitch ranges between 4.68 ~ 17.54 kgs. Whereas at 5.144 m/sec model speed, the added mass for heave ranges between 15.51 ~ 35.28 kgs and the added mass for pitch ranges between 3.17 ~ 15.72 kg. These experimental results were further verified by the data predicted through the application of the Strip theory. Both the experimental and theoretical results show similar trend, in which the added mass is increasing in proportion to the increasing of wave period. In contrast to this, the added mass eventually decreases along with increase in model speed.
References
Arii T., Miyata H., dan Kawaguchi, 1993, "Development of a Foil-Assisted Catamaran Superjet-30" , FAST'93.
Bhattacharyya, R., 1978, "Dynamic of Marine Vehicles" , John Wiley and Sons Inc., New York.
Callisal, S.M. and Sabuncu, T., 1989, "Study of a Heaving Vertical Cylinder in Towing Tank" , Journal of Ship Research, Vol. 33 No. 2.
Chakrabarti, S.K., 1987, "Hydrodynamics of Offshore Structures" , Springer Verlag, Berlin.
Dawson, T.H., 1983, "Offshore Structural Engineering" , Pretince-Hall, Inc., New Jersey.
Faltinsen, O.M., 1990, "Sea loads on Ships and Offshore Structures" , Department of Marine Technology, Cambridge University Press, London.
Le Mehaute, B., 1976, "An Introduction to Hydrodynamics and Water Waves" , Springer-Verlag,New York.
Mc. Cormick, Michael, E., 1989, "Ocean Engineering Wave Mechanic" , John Wiley & Sons, New York.
Mikkelsen, J. and Callisal S.M., 1993, "An Experimental Study of Hydrodynamics of Cylindrical Structures" , Marine Structures Vol. 6, pp. 259-277, Dept. of Mechanical Engineering, Univ. of British Columbia, Vancouver BC.Canada.
Murtedjo, Mas, 1997, "Studi Eksperimental Massa Tambah dan Koefisien Redaman Struktur Silinder Konfigurasi T Akibat Gerakan Heaving" , Jurnal IPTEK-ITS, Vol. 8, No. 3.
Murtedjo, Mas, 2002, "Studi Eksperimental Added Resistance HYCAT Akibat Gerakan Kopel Heaving-Pitching pada Gelombang Regular" , Jurnal IPTEK-ITS, Vol.13, No.1.
