Numerical calculation and analysis of resonance of drillship in waves

Abstract

Objectives With the sustained demand for improving operational efficiency and safety of the offshore platforms with moonpools, the resonance problems become more critical due to the motion of platforms in waves and fluid flow in the moonpools.Methods To effectively solve this problem based on the constant boundary element method of potential flow theory, this paper developed a numerical simulation program to calculate the interaction between wave currents and three-dimensional objects. By selecting an drillship , we carried out frequency-domain numerical calculations for its motion, compared the calculation results of those of AQWA, verified the reliability of the program, then compared the calculation results of wave and current conditions with those of the experiment, and verified the accuracy of the numerical method.Results By comparing the resonance phenomena of ships containing the moonpool in the heave and sway motion under varying length-width ratio conditions and different drafts of the moonpool, different wave incidence angles and with or without sailing speed, the introduction of velocity in the upstream situation will modulate and intensify the common vibration of the moonpool.Conclusions The research can provide a reference for predicting the ship's motion response with the moonpool and reduce the risk of resonance.

Keywords

• resonance
• moonpool
• waves
• current
• potential flow theory