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Gong X.,Zhejiang Ocean University | Gong X.,Key Laboratory of Offshore Engineering Technology of Zhejiang Province | Sun Z.,Zhejiang Ocean University | Gao H.,Zhejiang Ocean University | Hu Z.,Zhejiang Ocean University
Proceedings of the International Offshore and Polar Engineering Conference | Year: 2015

In this paper, the sediment-laden flow around a circular cylinder is numerically simulated in order to obtain better understanding of hydrodynamics associated. A range of cases with different Reynolds numbers (Re) are studies. The effects of the concentration of the sediment on the drag coefficient are investigated. Results show that due to the fact that the laden sand particle colliding the cylinder, it amplifies the drag coefficients, which increase as the increase of the sediment concentration, within the range of the application of the study. It is also observed that as the flow becomes more turbulent (higher Re), the effects of the laden particle on the drag coefficients become more significant. Copyright © 2015 by the International Society of Offshore and Polar Engineers (ISOPE). Source

Wang H.,Zhejiang Ocean University | Wang H.,Key Laboratory of Offshore Engineering Technology of Zhejiang Province | Tu L.,Zhejiang Ocean University | Chen L.,Zhejiang Ocean University | Zhao C.,Zhejiang Ocean University
Ship Building of China | Year: 2016

In most cases, a ship is launched in open water, where the flow may be quite different and would have an impact on the safety of the launched ship. Currently, calculations of the launching are mostly done with hydrostatic method, and the influence of flow, especially transverse flow, is usually ignored. In fact, transverse flow at high speed could make ship not only rotate around the pivot near the bow, but also move transversely. The ship with large lateral movement may collide with the bank. In present study, a 50000 DWT multi-purpose carrier is discussed. A series of model tests is performed in still water and under different transverse flow conditions. Curves of ship's draft at stern, transverse drift, direction angle and traction versus slippage are obtained with Froude conversion method. The effect of transverse flow on the launching ship is analyzed, which could be helpful to assess the safety of ship launching. © 2016, Editorial Office of Ship Building of China. All right reserved. Source

Liao J.,Jinhua Polytechnic | Yang J.,Zhejiang Ocean University | Fan W.,Zhejiang Ocean University | Li Q.,Zhejiang Ocean University | And 3 more authors.
International Journal of Electrochemical Science | Year: 2016

In this work, Ni-Sn-P electroless plating treatment was performed on surface of Crack Free(CF) steel to improve its corrosion resistance in seawater. The electrochemical properties, microstructure and phase structure of CF steel after electroless plating for different periods of time were studied by polarization curves and AC impedance test, scanning electronic microscope(SEM) and X-ray diffraction(XRD) analysis. Results showed that with a period of electroless plating process over 1h, dense and homogeneous amorphous alloy layer generated on the surface of CF steel and served as a barrier to inhibit the anodic reaction, thus the corrosion resistance was improved. Source

Bai X.-L.,Zhejiang Ocean University | Bai X.-L.,Key Laboratory of Offshore Engineering Technology of Zhejiang Province | Huang W.-P.,Ocean University of China | Xie Y.-H.,Zhejiang Ocean University | Zhao C.-H.,Zhejiang Ocean University
Zhendong yu Chongji/Journal of Vibration and Shock | Year: 2015

Here, the interaction behavior between SCR and seabed was simulated based on the P-y curve, the influence of a nonlinear seabed stiffness model on the dynamic response of SCR was studied using an elastic foundation beam to simulate SCR flow line. It was shown that the riser-seabed interaction depends on several factors, such as, soil stiffness, riser characteristics, and development of trenches. In the current most methods, the seabed was taken as a linear or nonlinear spring system not considering plastic deformation of soil and its suction effect. The P-y curve was used to simulate the relation between seabed resistance force and the vertical penetration of the riser into seabed during their interaction. The interaction between SCR and soil's hysteretic load-penetration curve, the depth of penetration and the envelop curve of seabed contributed force under cyclic heave motion and linear wave were obtained. Time histories of the contact points between SCR and soil's vertical displacement, bending moment, effective tension and stresses were analyzed. The results using the nonlinear seabed model were compared with those using the linear seabed model. The results showed that the nonlinear seabed stiffness model has a significant influence on the dynamic responses of SCR; the elastic foundation beam element simulates the SCR's flow line better, and the load-penetration curve reveals the genearation and release of suction. ©, 2015, Chinese Vibration Engineering Society. All right reserved. Source

Chen Z.,Zhejiang Ocean University | Chen Z.,Key Laboratory of Offshore Engineering Technology of Zhejiang Province | Liu Y.,Zhejiang Ocean University | Liu Y.,Zhejiang Ouhua Shipbuilding Co | And 2 more authors.
Shuili Fadian Xuebao/Journal of Hydroelectric Engineering | Year: 2015

3D numerical simulations of the wake flows behind axial-flow tidal current turbines have been carried out using a CFD software to study the interference between the wakes behind different impellers in different conditions of rotor installation, focusing on a single-rotor model without duct and a ducted dual-rotor model with a shaft spacing of 1.8D (where D is the blade diameter) for comparison. Results show that, the wake flow of single-rotor model was relatively stable with a velocity nearly the same as outside the wake, except for the lower velocity in a small wake region of less than 1D from the rotor. In the case of dual-rotor model, we observed a stronger interference between the two rotors, a lower velocity in the wakes, and a lower energy loss in the wakes than the single-rotor case. This leads to a considerable increasement in energy conversion ratio of the rotors. Physical model tests have been conducted and the measurements verified the main conclusions above and the effectiveness of our CFD method. © All right reserved. Source

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