||Floating structures are widely used in marine engineering, for example, wave absorption facilities for the protection of the coast, offshore platforms for the exploitation of marine resources, the sea cages platform for aquaculture. How to design stable floating structures to capture marine energy has become one of the main interests in ocean engineering. This study is to investigate the liquid oscillatory phenomenon inside the tuned liquid column damper (TLCD) and the dynamic behaviors of its floating platform under regular waves conditions.|
The nonlinear numerical wave tank, developed based on the velocity potential function and the boundary element method (BEM), is used to simulate dynamic properties including surge, heave, pitch, and tension responses. In addition, a physical model of the floating platform with a TLCD was tested in a hydrodynamic wave tank to validate a 2-D numerical model for simulation of wave- structure interaction.
The experimental results indicate that when the incident wave frequency near the natural frequency of the TLCD, fluid in the TLCD column would oscillate vigorously but other motions such as surge, pitch and heave will be suppressed. The comparisons of numerical simulations and experimental data indicate that the numerical predictions are larger than measurements especially at frequencies near to the resonant frequency. This discrepancy is probably due to the fluid viscous effect. To overcome this problem, an uncoupled damping ratio (ζ) is adopted and incorporated into the vibration system. The results showed that when damping ratio ζ=0.06 the responses of body motion near the resonant frequency have significantly reduced and matched to the measurements. The results of the liquid column oscillation in TLCD reveal that the increase of effective length of liquid column (Le), the resonant frequency of TLCD would move downward. The peak value of the amplitude ratio (A2/A1) would increase as the length of the horizontal column (b), the cross-sectional area of the vertical column (Av), the cross-sectional area of the horizontal column (Ah), and the ratio of the cross-sectional areas (Av/ Ah) were reduced.