The Design Of Buoy Body "Bai Long" And Its Dynamics Analysis

A small-size deep-sea data-collecting buoy, as an offshore observation platform, is anindispensable tool for people to acknowledge, to explore, to develope and to utilize the ocean,which also plays a significant role in the development of the marine economy. Because of thecomplex situation in the deep sea environment, with winds, waves and currents, the designs ofthe body and mooring systems of the buoy should not only take the equipped devices’ weightand structure into account, but also anticipate its dynamic performance through calculations,simulations and other means.This paper uses a data-collecting buoy called “Bai Long”, which is applied to the depthof3000m in the Andaman Sea in the Bay of Bengal, as the research subject. We completed adeep-sea buoy with good quality through designing, simulating and field test and othermeans.After researching a large number of literatures, the author identifies the workingconditions of “Bai Long” buoy, and thus designs the scheme of the effective loads of the buoy,including data-collecting system, data transmission system, power system and control system.Considering the different dynamic performance between three types of buoys, the authoridentifies a class hemispherical structure as the body of the buoy, and finishes thecorresponding parts’ design. The statics calculation shows that the buoy performed well inmetacenter, static stability angle, large dip angle and other aspects. The dynamic calculationshows the inherent frequency of buoy is about3.15rad/s in heave and2.99rad/s in roll, whichavoids the frequency range of the ocean waves. Finally, based on the special requirements inthe buoy deploying and recycling, the author designs a single focal point anchor tension typemooring scheme.This paper uses the AQWA module of ANSYS to analyze the overall hydrodynamicperformance of the structure of the buoy. The simulation results indicate:(1) the impact offirst-order wave to the buoy is small, within the range of the breaking load for the mooringsystem;(2) the heaving and rolling appending quality coefficient and damping coefficientcurve are in a reasonable range;(3) the slow drifting of the buoy influenced by thesecond-order wave force is in the reasonable range in200s movement simulation;(4) RAOrespond of the buoy is small with the incentive of JONSWAP random ocean wave spectrum,which infers that the inherent frequency of the buoy is3.2rad/s, and the influence whichresults from the JONSWAP spectrum on the buoy is small.Finally, the author assembles, adjusts and makes offshore field tests on the prototype of “Bai Long” and successfully deploys it into3000m depth sea. The data collected from thebuoy indicates that design scheme of the”Bai Long” buoy and its structure meet the basicdemand of practical work, but still have some details to be modified. Finally, the authorproposes some improved methods for further studies on the mechanical property of thestructure of buoy.The design, theoretical simulation and the experiment on “Bai Long” buoy in this paperoffer good reference for the studies on the small-size deep-sea data-collecting buoy. It alsohelps to accumulate good experience for developing other buoys in the practical project.