WIND LOADS ON A 1: 115 MODEL OF A SEMISUBMERSIBLE.

Abstract

To obtain a fuller understanding of the aerodynamics of semi- submersibles, a research project was undertaken in which a 1:115 scale model of a semisubmersible was tested, in the transit and the drilling configurations, in a wind tunnel at the University of Michigan. The work included measuring the model's drag coefficient and centroid of lateral force, determining the wind angle that gave the largest drag force and overturning moment at zero heel , and several other tasks. After discussing the problem and describing the techniques used in this experimental work, the Authors discuss the work and its results under the headings: Reynolds Number Effect; Influence of Boundary-Layer Profile; Drag and Height Coefficients for Zero Heel Angle; Evaluation Angle; Evaluation of Various Test Techniques; Contribution of Various Components to the Total Drag - Calculation and Experiment. Among the conclusions, it is mentioned that the drag and height coefficients at the critical wind direction were somewhat overpredicted by the ABS Rules, and that the results suggest that more research is required before the complex interaction effects of an ocean structure's various components are completely understood.