The dynamic behaviour of a surface hose attached to a calm buoy
Abstract
The objective of this study is a quantitative understanding of the
mechanisms by which bending moments and axial loads are induced on a
floating hose-string attached to a CALM buoy by the combined action of
waves and buoy motions.
The study is based on physical model tests in which the CALM buoy wi th
floating hose-string attached is modelled in a wave basin facility.
Simul taneous measurements are recorded of the waves, buoy motions and
bending moments or axial loads along the hose-string.
orthogonal planes is considered: vertical bending
Bending in two
in the plane
perpendicular to the water surface and horizontal bending in the plane of
the water surface. The latter is due to the "snaking" of the hose-string.
The analysis of the model test data is based, for the most part, on
spectral analysis techniques.
The experimental work is augmented by theoretical analysis. Considering
the heave, surge and pitch of the buoy as uncoupled s.d.o.f. systems leads
to models for the prediction of the SBM's response in waves. Analytical
models, based on engineer's bending theory, are developed for the
prediction of the vertical and snake-induced horizontal bending moments
along the hose-string.
Conclusions are reached regarding the response of the CALM buoy in waves
and the dependence of vertical bending, horizontal bending and axial loads
on the waves and buoy motions.