EXPERIMENTAL INVESTIGATION ON THE HYDRODYNAMIC EFFECT TO THE DRAG COEFFICIENT AND THE INERTIA COEFFICIENT OF AN INCLINED CYLINDER.

EXPERIMENTAL INVESTIGATION ON THE HYDRODYNAMIC EFFECT TO THE DRAG COEFFICIENT AND THE INERTIA COEFFICIENT OF AN INCLINED CYLINDER.
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ABSTRACT

Investigation on the effect of the angle of inclination to the drag coefficient (Cd) and the inertia coefficient (Cm) was carried out by performing hydrodynamic tests on an inclined smooth cylinder in a 234.5x11x5.5 meters tank equipped with wave generator flaps. The inclination angle of the cylinder was varied with respect to a vertical plane parallel to the direction of wave propagation (plane A) and a vertical plane parallel to the wave crest (plane B), and forces due to regular waves exerted on the cylinder were measured. The test covered a Reynolds number range of 3.444x104 < Re < 1.549x105. The drag coefficient and the inertia coefficient are determined based on the measured local forces on the cylinder, Morison equation and least square method.

The results show that on plane A the drag coefficient and the inertia coefficient increase with the increase of the angle of inclination (measured from vertical position). For an inclined cylinder on plane B it is concluded that there is no apparent change on Cd due to the inclination of the cylinder, while significant decrease on Cm due to the increase of the angle of inclination only happens in the 1.033x105 < Re < 1.549x105 range.

The drag coefficient and the inertia coefficient are shown as functions of the Reynolds number. There is a rapid decrease on the drag coefficient in the 3.444x104 < Re < 6.888x104 range.

Key words : Cd, Cm, drag coefficient, inertia coefficient, regular wave force, inclined cylinder, hydrodynamic experiment.

lilikmudjininglik, Friday, June 26, 2009