Chuan Bo Li Xue/Journal of Ship Mechanics

Accurate assessment of flexible connection characteristic is very important for structural safety of connectors and very large floating structure(VLFS), and yet model test is necessary measure to acquire flexible connection characteristic of VLFS. In this paper, a flexible connector model is designed base on calculation results of dynamic response of flexible connectors according to a VLFS with shallow draft and transverse pontoon. Rigidity of the flexible connector model is studied through series static tension and compression test with different amplitude and combined load and effect of combined load is also analyzed. Dynamic response of the flexible connector model is studied through series longitudinal dynamic load test and structural safety and applicability are also verified. Test results show that the flexible connector model is performing well under static and dynamic load and the structure is safety. The measurement results of load,displacement and stress of the flexible connector model can provide a basis for verifying connector structural design and calculation method.

QI En-ron

Chuanbo lixue

Experimental study of functional simulation for flexible connectors of very large floating structure

超大型浮式结构柔性连接器功能模拟实验研究

This paper studies the mechanism of Tip Leakage Vortex(TLV) in ducted propeller through numerical simulation and presents a method to delay TLV cavitation. From the analysis of the TLV cavitation number in different clearances, it is discovered that with increasing tip clearance, the position of the minimum cavitation number moves downstream and closer to the suction side of the blade, and the value of the minimum cavitation number decreases. The mechanism how tip clearance affects the TLV cavitation number is very complicated and can be interpreted in terms of three aspects:(1) The change of tip clearance alters the velocity of the tip leakage flow, hence its hydrodynamic parameters;(2) It affects the pressure distribution near blade tip, along with the pressure in TLV;(3) It influences generation and development of the vorticity in tip clearance as well as in TLV.Since TLV core is the primary cavitation inception position in a ducted propeller, in order to delay cavitation inception, the blade tip injection(BTI) is numerically investigated to reduce pressure drop in TLV core. Influence of BTI parameters of injection velocity, injector gap height and injection angle on TLV cavitation number is studied. Simulation results reveal that the BTI can decrease the tip foil loading, therefore improve the TLV core pressure and delay TLV cavitation. The higher injection velocity can more effectively raise TLV core pressure comparing different injection velocities, and the injection of sufficient velocity even blows off TLV. The analysis of injectors of different gap heights indicates that higher gap is better at raising core pressure, but also decreases propeller thrust, as the higher gap reduces blade tip loading at larger region. The investigation of injection angle states that the injection with a slight positive pre-whirl flow is beneficial to TLV cavitation delay.

Zhou Jun-we

Mechanism Study on Tip Leakage Vortex in Ducted Propeller and a Method to Delay TLV Cavitation

导管螺旋桨叶尖泄漏涡机理研究及延缓TLV空化的方法

The method of hydro-elasticity considering the fluid and structure interaction could calculate structural safety of floating structures effectively based on the rigid characteristics of very large floating structures(VLFS), which is used here to analyze the global wave loading and structural stress responses of single module of VLFS. In this paper, the natural mode and shape of vibration and intrinsic frequency are calculated by 3D FEM for single module. Then the harmonic frequency and principal coordinate responses of single module are obtained by mode superposition method and BEM method. Forwards, the structural stress responses of each mode and global stress responses are investigated; meanwhile the dangerous loading cases and the structural strength of single module are assessed. The results provide a certain guiding meanings for structural optimized design and safety assessment of VLFS.

Yang Pen

Analysis on the hydroelastic responses and structural strength of VLFS module

超大型浮体模块水弹性响应与结构强度分析

The towed system includes towing ship, cable and towed body. The main disturbances come from towing ship's heave and pitch motion induced by sea wave and wind. Sea surface disturbances are transferred along cable to cause towed body bad performance. The reduced ship motion mathematical model,cable dynamics model, and towed body motion model are initially integrated as a new disturbance propagation model by connection conditions in this paper. A computer program simulates the surface regular wave disturbance propagation property of two part towed system according to the model. The integral method can be used in the design of sea towed system.

Wang Zhi-b

Towed system motion transfer calculation

拖曳系统运动传递计算

In order to have comprehensive design and investigation of the vane wheel after propeller, the propeller vortex theory is adopted to design the vane wheel with the forward propeller is given. The interaction between the forward propeller and the vane wheel is considered through the induced velocities. The induced velocities are obtained through the potential based low order surface panel method employing the hyperboloidal quadrilateral panels and are circumferentially averaged. Therefore, the unsteady problem is translated to steady state. For the purpose to determine the diameter of the turbine section of vane wheel,the wake flow field of the forward propeller is analyzed through the surface panel method. The surface panel method is used to predict the hydrodynamic performance of the system. An iterative calculation method is used until the hydrodynamic performance of the system converges. The analysis of an instance shows that at lower advance speed, the vane wheel after propeller designed through this method can get greater yield and the increase of efficiency can be up to 14.42%.

Hou Li-xu

Theoretical design method investigation of vane wheel after propeller

螺旋桨后导流叶片轮的理论设计方法研究

It usually causes the crushed ice to sink on the bow when ships sail in the ice zone. The crushed ice is gradually sliding to the flow field in front of propeller along the hull, resulting in high-speed rotation of the propeller and ice milling, so that the propeller receives severe deformation and damage. In order to further analyze and study various loads in propeller-ice milling process, the testing apparatus of propellerice milling was setup in towing tank, and the measurement equipment and model ice feeding mechanism are described in detail. And, the feasibility and reliability of the testing apparatus are validated by the repeatability analysis and the comparison with the results of other scholars. Finally, the loads of the propeller-ice milling in air as well as in water were analyzed in detail. The experimental results show that the construction of the testing apparatus of propeller-ice milling is feasible and can do a better measure of milling loads of propeller-ice. The faster the model ice moves, the greater the compressive load on the propeller. Detailed description of contact load during propeller-ice milling has an important engineering significance and applications value for the structure design of the ice propeller.

Chun-Yu Guo

Pei Xu

Wan-Zhen Luo

Lian-Zhou Wang

Experimental research on contact loads during propeller-ice milling 螺旋桨-冰接触工况下载荷试验研究

螺旋桨-冰接触工况下载荷试验研究

Y Xu

Z-Q Hu

G Chen

Y-J Xu

Overview of the investigating methods for ship-ice interaction analysis [船冰相互作用研究方法综述]

船冰相互作用研究方法综述

The fatigue crack propagation in the bulb-flat, which is widely used in ship and bridge engineer ing, is one of the basic parameters for structures'fatigue life prediction. In this paper, the shape of a three dimensional surface crack in full-scale bulb-flat was measured and estimated by Nominalization Crack Opening Displacement (NCOD) method. Then the obtained crack shape was used to predict the fatigue crack propagation in the bulb-flat based on the two dimensional Paris formula and the Linear Finite Element Analysis (LFEA) method. Finally, the predicted fatigue crack propagation was verified by the full-scale fa tigue test on a typical ship structure in detail. This method proposed in this paper may provide reference to the definition of failure criterion of bulb-flat.

Z. Dang

J. Yue

Wengang Mao

Prediction of fatigue crack propagation in bulb-flat by experimental and numerical method

实验与数值方法预测球扁钢疲劳裂纹扩展

J Xiao

Z Peng

X Tian

W Yang

Numerical simulations on the dynamic characteristics of a shallow-draft spar-type floating wind turbine

浅吃水Spar型浮式风力发电机动态特性的数值模拟

浅吃水 spar 型浮式风力机动力特性的数值模拟

ISSN	1007-7294
h-index	22

Publication Information	Publisher: China Ship Scientific Research Center，Publishing cycle: ，Journal Type: journal，Open Access Journals: No
Basic data	Year of publication: 1998，Proportion of original research papers: 0.00%，Self Citation Rate:N.A.， Gold OA Rate: 0.00%

Chuan Bo Li Xue/Journal of Ship Mechanics

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Experimental study of functional simulation for flexible connectors of very large floating structure

Mechanism Study on Tip Leakage Vortex in Ducted Propeller and a Method to Delay TLV Cavitation

Analysis on the hydroelastic responses and structural strength of VLFS module

Towed system motion transfer calculation

Theoretical design method investigation of vane wheel after propeller

Experimental research on contact loads during propeller-ice milling 螺旋桨-冰接触工况下载荷试验研究

Overview of the investigating methods for ship-ice interaction analysis [船冰相互作用研究方法综述]

Prediction of fatigue crack propagation in bulb-flat by experimental and numerical method

Numerical simulations on the dynamic characteristics of a shallow-draft spar-type floating wind turbine

Numerical simulations on the dynamic characteristics of a shallow-draft spar-type floating wind turbine