Suppression system for offshore cylinders under vortex induced vibration

Vortex Induced Vibration (VIV) is a major challenge in the design of tubular member under second order wave effects. Providing helical strakes have proven to eliminate presence o VIV, but at the cost of increased drag. Two different approaches of VIV suppression are discusse in the present study and compared. Concept of suppressing vibration by tripping the boundar layer of incoming flow using stripping wires is experimentally investigated. It is seen that th position at which boundary separates has an important role in response behavior of the cylinder Effect of lock-in point at higher reduced velocities is quantified. Alternative study is also carrie out by disrupting the correlation of flow in a stepped cylinder where an abrupt change in diamete in imposed by design. For comparison, vibration of stepped cylinder, attached with tripping wir is also examined. Results from the studies showed VIV suppression under both the independen configurations but a significant improvement is seen in the latter case.