Wave-free characteristic of heave motion response for new sandglass-type model

ABSTRACT

This paper mainly studies the wave-free characteristic of heave motion of a sandglass-type floating body to overcome the limitations of traditional ship-type and cylindrical floating, production, storage and offloading units. In the first instance, the theoretical and numerical methods are used to determine the added mass and damping wherein the heave motion can be decoupled. The existence of wave-free characteristic of heave motion is theoretically and numerically verified. Moreover, the heaving quadratic transfer function of second-order wave drift force is calculated and its performance has been discussed. Finally, the relationship between wave-free frequency and wave spectrum is selected as the design principle of the shape parameters. On this basis, some experiments of new sandglass-type and cylindrical models are carried out, which coincide with the numerical predictions very well and show that the new design based on wave-free frequency can significantly improve the heave motion performance.

KEYWORDS:

• Sandglass-type model
• heave motion response
• wave-free characteristic
• wave-free frequency
• nonlinear F–K and hydrostatic force
• quadratic transfer function

Acknowledgments

The authors are grateful to all organisations that funded the research in this paper, which was financially supported by the National Innovation Team Foundation under grant number 50921001 (China), the National Natural Science Foundation of China (General Program) (grant number 51679034), the National Natural Science Foundation of China (grant number 11202047), the Scientific research innovation team project under grant number DUT16TD11 (China) and Natural Science Foundation of Liaoning Province under grant number 2015020157 (China).

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

National Innovation Team Foundation [grant number 50921001] (China); the National Natural Science Foundation of China (General Program) [grant number 51679034]; the National Natural Science Foundation of China [grant number 11202047]; the Scientific research innovation team project [grant number DUT16TD11] (China); Natural Science Foundation of Liaoning Province [grant number 2015020157] (China).