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.