Application of tuned liquid column damper for motion reduction of semisubmersible platforms

Incorporation of a tuned liquid column damper (TLCD) into a semisubmersible drilling platform is numerically investigated in this paper. First, a governing equation for liquid fluctuation in the TLCD is derived for the planar motion of the TLCD in conjunction with the motion of the platform. Then, the real-time response of the platform under irregular waves is analyzed using radiation/diffraction theory in which TLCD loading is exerted on the platform at each time-step. This facilitates capture of the difference-frequency and sum frequency second order wave forces and the low-frequency motion of the platform. The results show that the effect of the rotational motion of the platform on the TLCD is significant and the TLCD has a reciprocal effect on this rotational motion of the platform. It is shown that the TLCD decreases the low-frequency motion of the platform and has no considerable effect on the wave-frequency motion. Also, the sensitivity of the platform motion to the main specifications of the TLCD is assessed by a parametric study.