Abstract

Research papers at previous OMAE conferences by Thiagarajan and Troesch 4 5 described forced oscillation model tests using a 0.45-m-dia cylinder and a 0.6-m-disk appended to the cylinder base for drag augmentation. Scaling laws were proposed based on a component scaling concept for extrapolation of full-scale added mass and damping coefficients. The present work further verifies the scaling methodology by presenting and discussing results on smaller models—cylinder and disk of diameters 0.15 m and 0.19 m, respectively. The dimensions of the smaller models are typical of more complex offshore platform models tested in scale 1:50 to 1:75 design sea states. The hydrodynamic coefficients of the cylinder and of the disk are estimated individually, and component-scaling methodology is examined. Physics-based arguments for the differences in force coefficients of the configurations are discussed: flow around the cylinder, flow around the disk, and flow around the composite structure. The analysis results from force measurements and flow visualization conducted during forced oscillation experiments. Further, difficulties in maintaining accuracy with the smaller models are examined. [S0892-7219(00)00202-8]

Issue Section:
Technical Papers
Keywords:
structural engineering, hydrodynamics, scaling phenomena, drag, oceanographic equipment
Topics:
Cylinders, Damping, Disks, Drag (Fluid dynamics), Spar platforms, Tension-leg platforms, Wing spars, Flow (Dynamics), Flow visualization
1.
Pagano, S. S., 1998, “Deep Water Plays: Where the Action Remains,” Sea Technology, Apr.
2.
Fischer, F. J., and Gopalkrishnan, R., 1998, “Some Observations on the Heave Behavior of Spar Platforms,” 17th International Conference on Offshore Mechanics and Arctic Engineering, OMAE98-0603.
3.
Prislin, I., Blevins, R. D., and Halkyard, J. E., 1998, “Viscous Damping and Added Mass of Solid Square Plates,” Proc. Offshore Mechanics and Arctic Engineering Conference, Lisbon, Portugal.
4.
Thiagarajan, K. P., and Troesch, A. W., 1993, “Hydrodynamic Damping Estimation and Scaling for Tension Leg Platforms,” 12th International Conference on Offshore Mechanics and Arctic Engineering, Book No. G00677, pp. 473–479.
5.
Thiagarajan
,
K. P.
, and
Troesch
,
A. W.
,
1998
, “
Effects of Appendages and Small Currents on the Hydrodynamic Heave Damping of TLP Columns
,”
ASME J. Offshore Mech. Arct. Eng.
,
120
, Feb. pp.
37
–
42
.
6.
Chakrabarti
,
S. K.
,
1989
, “
Hydrodynamic Damping Tests for a Vertical TLP Leg Model
,”
Marine Research Newsletter, CBI
,
4
, No.
2
, p.
1
1
.
7.
Keulegan
,
G. H.
, and
Carpenter
,
L. H.
,
1958
, “
Forces on Cylinders and Plates in an Oscillating Fluid
,”
J. Res. Natl. Bur. Stand.
,
60
, No.
5
, pp.
423
–
440
.
8.
Sarpkaya, T., and Isaacson, M., 1981, Mechanics of Wave Forces on Offshore Structures, van Nostrand Reinhold, New York, NY.
9.
Troesch
,
A.
, and
Kim
,
S.
,
1991
, “
Hydrodynamic Forces Acting on Cylinders Oscillating at Small Amplitudes
,”
Journal of Fluids and Structures
,
5
, pp.
189
–
199
.
10.
Thiagarajan, K. P., 1991, “Hydrodynamics of Flows Past Disks and Circular Cylinders,” Ph.D. dissertation, Dept. Naval Arch. and Marine Engin., Univ. of Mich., Ann Arbor, MI.
11.
Huse, E., and Torbjorn, U., 1994, “Springing Damping of Tension Leg Platforms,” Proc. Offshore Technology Conference, Houston, TX, pp. 259–266, OTC7446.
12.
Graham
,
J. M. R.
,
1980
, “
The Forces on Sharp-Edged Cylinders in Oscillatory Flow at Low Keulegan-Carpenter Numbers
,”
J. Fluid Mech.
,
97
, Part 1, pp.
331
–
346
.
13.
De Bernardinis
,
B.
,
Graham
,
J. M. R.
, and
Parker
,
K. H.
,
1981
, “
Oscillatory Flow Around Disks and Through Orifices
,”
J. Fluid Mech.
,
102
, pp.
279
–
299
.
14.
Huse, E., 1990, “Resonant Heave Damping of Tension Leg Platforms,” 22nd Annual OTC, Paper 6317, pp. 431–436.
15.
Chakrabarti, S. K., and Hanna, S. Y., 1990, “Added Mass and Damping of a TLP Column Model,” 22nd Annual OTC, Paper 6406, pp. 559–571.
16.
Chakrabarti
,
S. K.
, and
Hanna
,
S. Y.
,
1991
, “
High Frequency Hydrodynamic Damping of a TLP Leg
,”
Symp. Off. Mech. Arctic Eng.
,
1-A
, pp.
147
–
151
.
17.
Moe, G., and Verley, R. L. P., 1980, “Hydrodynamic Damping of Offshore Structures in Waves and Currents,” Proc. Offshore Technology Conference, Houston, TX, 3, pp. 37–44, OTC3798.
18.
Dalzell, J. F., 1978, “Non-Linear Forces on Oscillating Plates: Review and Analysis of the Literature,” Stevens Institute of Technology, Davidson Laboratory, Hoboken, NJ, Report SIT-DL-78-9-2031.
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