Study on dynamic responses of hydraulic pneumatic tensioner for a TLP under hydraulic component failure

Abstract

This paper takes the hydraulic pneumatic tensioner as the research object. In order to study the dynamic response of hydraulic pneumatic tensioner, a coupled model of tension leg platform was established. Three kinds of sea conditions including first-order irregular wave, second-order wave and freak wave are simulated. The dynamic response of the hydraulic pneumatic tensioner is analyzed under the action of different pressure accumulators. It is found that the greater the pressure of accumulator, the smaller the displacement of hydraulic cylinder and the greater the tension under the action of the second-order wave force and the freak wave force. In the second-order waves, the average drift force has great influence on the amplitude of displacement and tension of hydraulic cylinder, while the second-order sum frequency force has great influence on the frequency of displacement and tension of hydraulic cylinder. In addition, the dynamic responses of the tensioner under second-order waves are also studied when one cylinder fails. When one cylinder fails or is in semi-failure state, the hydraulic pneumatic tensioner can still provide a nearly constant tension to the riser. The remaining normal piston cylinders’ tensions will increase, but the total tension will decrease.