Abstract

The ocean towing system plays an important role in the ocean development process. The motion of a towed body is closely coupled with the motion of a towing cable. In this paper, the lumped mass method is used to discrete a towing cable into a lumped mass model. At the same time, on the basis of some assumptions, the relationship between the expression of Munk moments in the classical towed body kinematics and the expression of the Munk moments in the hydrodynamic analysis software OrcaFlex is established. Based on the above assumptions and the derivation, combined with the specific parameters of a certain sea state and a certain towing system, the dynamic simulation of the towing system is made by OrcaFlex. By changing the different Munk moment coefficients, the real-time response of the cable tension and the towed underwater body under different Munk moments is achieved. The effects of different Munk moment coefficients on the change of the tension are obtained; the six degrees of freedom of the towed body under the action of different Munk moment coefficients are shown. To obtain the spectral density of the six degrees of freedom of the towed body under the action of different Munk moment coefficients, Fast Fourier Transform is performed on the calculated results of the towed body in the time domain. The results provide a theoretical basis for the optimal design of a cable and towed body.

Highlights

  • Academic Editor: Haruo MimuraThe survival and development of human beings are inseparable from sustainability.The second half of the 20th century to the present day, represents a golden age to actively develop ocean resources

  • Based on the above derivation, combined with the specific parameters of a certain sea condition and towing cable system, the hydrodynamic response of a marine cable system under different Munk moment coefficients is modeled by OrcaFlex, and its motion is calculated by the time-domain-coupled dynamic analysis method

  • In this paper, OrcaFlex is used as the simulation platform to establish the model of the towed cable array under different Munk moment coefficients during direct sailing, and the dynamic response of the towed body is analyzed

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Summary

Introduction

The survival and development of human beings are inseparable from sustainability. The second half of the 20th century to the present day, represents a golden age to actively develop ocean resources. Choo and Casarella [7] and Chapman [8] carried out steady state analysis of underwater towing systems The results of both studies played an important role in the subsequent research on the configuration of towing cables, and the concept of critical radius was given by Chapman in his paper. Based on the previous research results, the lumped mass method was summarized and extended by Chai’s paper [18], in which the influence of the seabed interaction on the towing cable was considered, and the numerical simulation was carried out to study the motion characteristics of the cable, riser and towing cable under various conditions. Based on the above derivation, combined with the specific parameters of a certain sea condition and towing cable system, the hydrodynamic response of a marine cable system under different Munk moment coefficients is modeled by OrcaFlex, and its motion is calculated by the time-domain-coupled dynamic analysis method. Based on the hydrodynamic performance of the system, some suggestions are given

Mathematical Model
Basic Assumptions
Definition of Kinematic Parameters
Munk Moment
Numerical Model Setup
The Variation of the Effective Tension of the Towing Cable
The this phenomenon is that when thetowed
The Variation of Bending of the Towing Cable
The Variation of the Towed Body
Conclusions

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