Riser Fairing For Reduced Drag And Vortex Supression

Instability analysis of deepwater riser with fairings

“…To investigate the effect of key parameters on the critical velocity, a typical drilling riser was selected. Grant and Patterson (1977) properties of the system. Hence, with reference to a study on short fairings (Lee et al, 2004), damping coefficients are selected in the lower bound, i.e.…”

“…This results in a lower critical current velocity. The fairing was tested in the wind-tunnel (Grant and Patterson, 1977) Figure 6 shows that the instability onset is not particularly sensitive to the drag coefficient. The drag coefficient came into play through the process of finding instantaneous angle of attack (AoA) and emerged in hydrodynamic damping terms.…”

“…Several methods have been proposed to rectify the problem, e.g. trailing-edge fins or adding vortex generators (Calkins, 1984;Gardner and Cole, 1982;Grant and Patterson, 1977;Meyer et al, 1995). On the other hand, large hydrodynamic damping that some fairings generate (Lee et al, 2004) can be a key reason for their dynamically stable response as well as dominant suppression mechanism (Lee and Allen, 2005).…”

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

“…Laboratory tests and design studies were conducted in the mid 1970's to develop a riser fairing that would allow a semisubmersible drilling vessel to operate off the coast of Brazil in 152m (500 ft) of water and in strong surface currents up to 4.1 m/s '(8 kt). These tests resulted in the deveropment of an economic and practical fairing device to suppress any vortex-excited oscillations (72).…”

Otec cold water pipe design for problems caused by vortex-excited oscillations

“…X 152m (500 ft) of water and in strong surface currents up to 4.1 m/s '(8 kt). These tests resulted in the deveropment of an economic and practical fairing device to suppress any vortex-excited oscillations (72).…”