Kinetic characteristics of a moored floating structure with a liquid column vibration absorber (LCVA)

Abstract

The pitch motion of offshore floating structures under external forces is critical. This study examines the effectiveness of a liquid column vibration absorber (LCVA), a passive damping device with an oscillating liquid in a U-tube, in mitigating pitch motion and vibration. A motion equation describing the LCVA-structure interaction was derived, and a two-dimensional numerical model based on the boundary element method and Airy wave theory was developed. Flume experiments validated the numerical results. Parametric analyses investigated the effects of LCVA and structural characteristics, including the cross-section and water level of the vertical liquid column, as well as the floating structure's draft and length. Results show that an LCVA can reduce pitch motion amplitude by approximately 75%. Structural parameters significantly affect heave motion, while vertical water level strongly influences pitch. Thus, proper LCVA tuning can effectively mitigate pitch motion. Additionally, the floating structure's pitch interacts with the liquid column's amplitude.