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Title: OTEC cold water pipe design for problems caused by vortex-excited oscillations

Vortex-excited oscillations of marine structures result in reduced fatigue life, large hydrodynamic forces and induced stresses, and sometimes lead to structural damage and to diestructive failures. The cold water pipe of an OTEC plant is nominally a bluff, flexible cylinder with a large aspect ratio (L/D = length/diameter), and is likely to be susceptible to resonant vortex-excited oscillations. The objective of this report is to survey recent results pertaining to the vortex-excited oscillations of structures in general and to consider the application of these findings to the design of the OTEC cold water pipe. Practical design calculations are given as examples throughout the various sections of the report. This report is limited in scope to the problems of vortex shedding from bluff, flexible structures in steady currents and the resulting vortex-excited oscillations. The effects of flow non-uniformities, surface roughness of the cylinder, and inclination to the incident flow are considered in addition to the case of a smooth cyliner in a uniform stream. Emphasis is placed upon design procedures, hydrodynamic coefficients applicable in practice, and the specification of structural response parameters relevant to the OTEC cold water pipe. There are important problems associated with in shedding of vortices from cylindersmore » in waves and from the combined action of waves and currents, but these complex fluid/structure interactions are not considered in this report.« less
Authors:
Publication Date:
OSTI Identifier:
5360514
Report Number(s):
DOE/NOAA/OTEC-28; NRL-MR-4157
DOE Contract Number:
EG-77-A-29-1078
Resource Type:
Technical Report
Research Org:
Naval Research Lab., Washington, DC (USA)
Country of Publication:
United States
Language:
English
Subject:
14 SOLAR ENERGY; OCEAN THERMAL POWER PLANTS; OSCILLATIONS; PIPES; CYLINDERS; DESIGN; FAILURES; FATIGUE; HYDRODYNAMICS; LIQUID FLOW; MECHANICAL VIBRATIONS; OFFSHORE PLATFORMS; RESONANCE; RESPONSE FUNCTIONS; SERVICE LIFE; STRESSES; VORTICES; WATER CURRENTS; WATER WAVES; WAVE FORCES; CURRENTS; FLUID FLOW; FLUID MECHANICS; FUNCTIONS; MECHANICAL PROPERTIES; MECHANICS; POWER PLANTS; SOLAR POWER PLANTS 140800* -- Solar Energy-- Ocean Energy Systems