Fairings provide exceptional protection against vortex-induced vibration (VIV) forces by streamlining the flow of currents around a tubular, effectively ameliorating the vortices that cause oscillating forces on its surface. As they encounter an oncoming flow, fairings are designed to rotate freely around the tubular and self-orient with the tail pointing downstream.
One key advantage of fairings is that they significantly reduce drag. Fairings are especially beneficial in high-current regions, or in the upper region of the water column where surface currents dominate. Fairing tail geometry can be customized to achieve maximum performance. Additionally, fairings are somewhat less susceptible to marine growth performance degradation than other types of suppression devices.
Fairings can be manufactured in a variety of shapes, though their performance is very much affected by their geometry. The most widely used class of fairings are known as teardrop fairings while U-shaped fairings have also gained a measure of popularity in recent years.
Thrust collars are installed between fairing bodies and serve as a bearing surface for fairing rotation. They help the fairings maintain their axial position along the riser string. Specialized collars are used on tubulars with insulation to accommodate diameter changes caused by hydrostatic shrinkage.
- Teardrop or U-shaped fairing
- Cd ~ 0.25 – 1.05
- Suppression efficiency ≥ 98%