Heave resonance phenomenon in air-cushion supported floating platforms

Understanding the resonance behaviour is essential for air-cushion supported floating structure (ASFS), as the variation in the air-cushion static height or the water plug height and the corresponding draught would shift the natural frequency. Amplified excitation of a mono-cushion platform during heave resonance causes variation in the metacentric height ( GM ) and it might lead to an increase in destabilizing moments acting on the sidewalls while significantly impacting system dynamics . To effectively mitigate resonance effects, the ASFS geometry must be meticulously optimized to improve response characteristics while maintaining structural stability. In the present study, the computational fluid dynamics (CFD) model for air-cushion supported structures is formulated and validated with experimental measurements. Free decay tests are performed on models featuring two different skirts and five varying length-to-breadth ratios. Each model is tested with five water plug heights and three draughts. An increase in the skirt height ( S ) and the draught ( T ) leads to a significant decrease in resonance frequency . For a 50 % increase in skirt height, the heave natural frequency decreases by about 7 %–14 % at constant T/S . From the parametric analysis , a simplified heave resonance frequency model for air-cushion supported structures is proposed and validated with the experimental measurements. • A new attempt is made to setup an experimentally validated CFD model under STAR-CCM+ incorporating compressible air. • The effects of geometry and air-cushion parameters on heave resonance frequency have been studied extensively. • The parametric analysis reveals that heave resonance is primarily governed by draught ( T ). • A simplified heave resonance frequency model is proposed and validated.