Accession Number : ADA084555


Title :   OTEC Cold Water Pipe Design for Problems Caused by Vortex-Excited Oscillations.


Descriptive Note : Final rept.,


Corporate Author : NAVAL RESEARCH LAB WASHINGTON DC


Personal Author(s) : Griffin,Owen M.


Report Date : 14 MAR 1980


Pagination or Media Count : 149


Abstract : 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 destructive 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 cylinder 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 the shedding of vortices from cylinders in waves and from the combined action of waves and currents, but these complex fluid/structure interactions are not considered in this report.


Descriptors :   *VORTEX SHEDDING, *MARINE ENGINEERING, *OFFSHORE STRUCTURES, *WATER PIPES, OCEAN CURRENTS, FATIGUE LIFE, DYNAMIC RESPONSE, STRUCTURAL RESPONSE, ENERGY CONVERSION, COEFFICIENTS, DRAG, OSCILLATION, HYDRODYNAMICS, REYNOLDS NUMBER, FLEXIBLE STRUCTURES, CROSS FLOW.


Subject Categories : MARINE ENGINEERING
      PUMPS, FILTERS, PIPES, TUBING, FITTINGS & VLVS
      STRUCTURAL ENGINEERING AND BUILDING TECHNOLOGY
      FLUID MECHANICS


Distribution Statement : APPROVED FOR PUBLIC RELEASE