Going Quietly to the Deep Ocean——Notes on the R&D Course of Donfanghong 3, Global Largest Displacement Silent Research Vessel

By Qu Ningning and Ding Ju

On May 30, the “Dongfanghong 3” research training vessel, developed and designed by the CSSC No.708 Research Institute (Maric) for China Ocean University, was delivered at CSSC Jiangnan Shipbuilding (Group) Co.,Ltd., and was classified with CCS. The successful delivery of the ship marks the great improvement of the design and construction level of the scientific research ship in China, and will also further establish the international voice of Chinese marine research data outcomes.

At the delivery ceremony,Dongfanghong 3 was formally awarded the most stringent DNV GL SILENT-R certificate for underwater radiation noise,becoming China's first and world's fourth marine integrated scientific research ship to obtain SILENT-R certificate,and also the marine integrated scientific research ship with the largest displacement for SILENT-R certificate in the world,which marked that Dongfanghong 3 reached the highest international standard in underwater radiation noise control.Prior to this, Dongfanghong 3 successfully passed the major test -- a special sea trial for verifying underwater radiation noise level: near-field measurement and farfield measurement.

R&D and Design Highlights

Dongfanghong 3 is a new 5,000-tonnage comprehensive dep and far sea scientific research ship. It is mainly focused on the cultivation of innovative talents in deep sea,integrating scientific research, scientific investigation, and high-tech R&D. The ship has a total length of 103.8m and a molded breadth of 18m. It can navigate in the infinite navigation area of the world. With maritime endurance up to 60 days, the vessel can sail 15,000 nautical miles continuously. It has a 110 personnel carrying capacity, including 82 researchers, and the deck operation area and laboratory work area are both over 600m2. The ship is a new generation oceanic comprehensive research vessel with the world's quietest, most fixed number of staff, highest requirements for economical, vibration noise,electromagnetic compatibility and other indicators, largest utilization ratio of operating deck and laboratory area, and most complete research functions.

Dongfanghong 3 is the most fuelsaving twin-screw propelled research vessel. The ship adopts the multi-beam pod patent design which is integrated with the ship bow line, so that the total ship resistance is reduced by 15%-20% and the oil consumption is greatly reduced under the premise of ensuring the multi-beam measurement performance;and under the same oil tank volume,endurance is improved considerably, and the ship can sail to a farther deep-sea ocean for survey.

It remains a difficult problem to reduce the radiation noise level of the research vessel itself, so that the detection can be clearer and undisturbed.Dongfanghong 3 adopts the whole ship vibration and noise reduction analysis and optimal design, analyzes and validates the main noise sources and carries on the strict single acceptance in the factory acceptance test (FAT).Finally, it is ensured that the ship meets the most stringent underwater noise index requirements in the world and obtains the SILENT-R certificate of DNV GL.Dongfanghong 3 has the highest precision detection capability of the whole sea deep-terrain bottom face. For the first time, the ship introduced two sets of high-resolution medium-shallow water and all-sea deep multi-beam systems in China (only one ship was so installed in the world). The key technologies of ship line design, construction and installation processes were solved jointly by the design unit and shipyard, and the detection capability of China's whole sea deep-terrain bottom face was improved.

Dongfanghong 3 is equipped with the most advanced water body,atmosphere, seafloor detection and remote sensing information observation and application system in the world,which can be used for rapid detection and analysis of multi-disciplinary marine elements in marine space. Equipped with two more than 10000m CTD winches,one 10000m cable-spinning winch,one 10000m optical cable winch, one 12000m fiber cable winch, the depth and reliability of operation detection is ensured, its operating depth covers the deepest Mariana trench in the world.

Dongfanghong 3 has a strong scientific research data and ship data network, and realizes the integration of ship and shore. The ship is equipped with an independent research data network system, and equipped with double 10 gigabytes core, space-time synchronous research data acquisition, transmission,storage, processing and integration,data results can have online display and remote transmission. Equipped with shipshore integrated ship data information network system, it supports WIFI and wired access, and achieves VSAT realtime communication between ship and shore. Electromagnetic compatibility of key equipment of hull and ship, hull vibration and noise, underwater radiation noise, all kinds of strong and weak electricity with all kinds of cables, as well as ship dynamics and attitude and other information achieve on-line monitoring,provided with alarm systems.

Overcome a Number of Technical Difficulties

As the type of ship engaged in marine scientific research, the research ship is provided with a large number of precise acoustic instruments. The instruments, like clairvoyances, installed at the bottom of the ship, see the geologic landform of the water depth of many thousand meters by transmitting into and receiving from sound waves. The smaller the external interference, the better these acoustic equipment works.Therefore, the research ship should not only pay attention to the comfort of the environment on board, but also ensure that its least own noise is transmitted to the water.

The bow area of Dongfanghong 3 is equipped with the most precise multibeam acoustic equipment in the world(aside from Dongfanghong 3, only one ship in the world is installed with the equipment). China Ocean University suggests that the ship should meet the high requirements of DNV GL underwater radiation noise SILENT-R symbol. At that time, the research on underwater noise of domestic scientific research ships was just in its infancy, which was the most demanding challenge in the design of the vessel for the designers of Maric.

The requirements for underwater radiation noise are the systematic and comprehensive requirements of the whole ship, which will affect the ship line type and attachment form, propulsion system,hull structure design, equipment selection and arrangement, empty ship gravity center control, shipyard production lofting and construction technology, etc., and no leakage can be made in any link. For this reason, Maric designers, on the one hand,strengthen their own technical research,on the other hand, combine with DNV GL, domestic and foreign high-quality equipment / system suppliers, carry out vibration and noise reduction top-level planning and the whole process control from the beginning of the scheme design,summed up three key technologies of low noise propeller design, main generator set double-layer vibration isolation design and low speed ultra-silence propulsion motor selection.

In addition, the silent propeller of the “Dongfanghong 3” is also independently developed and designed by Maric. The propeller radiation noise is the main underwater noise source of the whole ship, whether silent propeller can be designed plays a decisive role in the noise control of the whole ship, and the larger the displacement, the greater the difficulty of the propeller mute design.

The propeller meeting the requirements of SILENT-R symbol is not only the first in China, but also means that it has reached the international leading level. From the earlier propulsive system scheme demonstration to the roundafter-round propeller optimization design,from the performance calculation to the model test verification, from participating in the real propeller processing to the real ship trial voyage, Maric propeller design team has finally handed over a beautiful answer paper after more than 5 years of technical research and unremitting efforts.

In addition to low noise, other properties of the propeller are also very excellent. According to the model test report provided by the international authoritative pool, the performance of the propeller is evaluated as the highest level, the efficiency of the propeller is 8.2% higher than that of the inventory propeller, and the speed of the propeller is better than that of the index requirement. The cavitation performance of the propeller is excellent and no cavitation occurs under various assessment conditions. The prediction results of the model test are also verified by the test results of the speed, shaft power, vibration and cabin noise of the real ship.

Similarly, two years ago, the“Jiageng” research ship, whose mute propeller was designed by the team,obtained the first SILENT A+S low noise certificate of DNV GL in China. Now the "Dongfanghong 3" mute propeller is successful once again, which has further established the leading position in the field of mute propeller design of Maric domestic research ships and expanded its international influence.

The successful control of underwater noise of Dongfanghong 3 not only meets the needs of shipowners, but also provides very valuable experience for the design of underwater noise of subsequent research ships. At the same time, it also gives China more voice in the development of new codes and rules for underwater noise of scientific research ships in the future, and provides sufficient technical support for more ships to meet the new requirements in the future.