Three Dimensional Numerical Simulation on the Characteristic of Bow-Spray for Trailing Suction Hopper Dredger
- Jifu Yin (National Engineering Research Center) | Feixin Wang (National Engineering Research Center) | Guojun Hong (National Engineering Research Center) | Lihua Wang (CCCC Shanghai Dredging Co., Ltd.)
- Document ID
- International Society of Offshore and Polar Engineers
- The 28th International Ocean and Polar Engineering Conference, 10-15 June, Sapporo, Japan
- Publication Date
- Document Type
- Conference Paper
- 2018. International Society of Offshore and Polar Engineers
- Three dimensional, Numerical simulation, Trailing Suction Hopper Dredger(TSHD), Bow-spray
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- 11 since 2007
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The three dimensional multiphase flow CFD method was used to simulate the spatial movement trajectory and the ground distribution characteristics of bow-spray for Trailing Suction Hopper Dredger (TSHD). The numerical simulation results are agreeing with the date form construction site. The results show that the numerical simulation method can accurately predict the path curve and the bow distance of the bow-spray on TSHD. The angle of the spray in the construction can be selected according to the actual situation. The stem spray landing area can’t be measured in real time limited by the safety factors during the construction process, so the results of numerical simulation can effectively predict the spatial movement trajectory and the ground distribution characteristics and provide reference basis for the construction.
Bow-spray operation is one of the commonly used for hydraulic filling construction methods of trailing suction hopper dredger, which sprays slurry directly from bow nozzle, delivering a large number of sand and mud to shoal or shore. It is often used for beach sand filling and the island construction of open water. In the initial stage of rapid hydraulic filling construction, bow-spray technology can be utilized to form a shoal quickly, thereby creating conditions for subsequent construction (Gao, 2006, Li, 2009, Cheng, 2012). Because bow-spray process does not require a float tube and a shore pipe, it can save additional equipment and time, usually saving approximately 30% of the additional cost. At present, most large dredger can exceed the effective spray distance of 150m. The maximum output of giant dredger in bow- spray can be higher than 25000m3 / h in the first10 minutes. And it has been used in the island construction at home and abroad.
The range of spray distance and landing range of bow-spray is an important limiting factor of bow-spray process, which not only determines whether the bow-spray process is feasible, but also the key factor of the location selection of the dredger. At present, the bow-spray research is limited to the free parabolic motion theory which ignores air resistance. A spray distance calculation model was established considering air resistance by drawing lessons from the theory of projectile motion. Therefrom the precision of calculation is greatly increased (Dmitri, 2000, Wang, 2017). The reference(Yin, 2017) carries out two-dimensional numerical simulation of trajectory and flow field characteristics for different bow-spray conditions, thereby the distance of bow-spray and the flow field characteristics of the middle section are obtained.
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