平台内TMD对新型Barge浮式风机振动抑制的研究

Barge型浮式风机是发展海上风电的重要装备,其运动响应可以通过被动控制装置调谐质量阻尼器(tuned mass damper,TMD)有效抑制。基于ITI Energy Barge风机,本研究设计了新型Barge浮式风机基础,建立平台配置TMD的风机动力学模型,在浮动平台内配置不同位置、质量、阻尼参数TMD,研究风浪载荷作用下风机平台配置最优参数TMD前后浮式风机运动响应的变化。结果表明:在新型风机平台内浮筒顶部配置质量比3%、阻尼比6%的TMD后,风机塔顶前后和左右位移分别减小15.56%、44.93%,平台纵摇和横摇抑制率达到22.97%、62.79%,风机塔基前后和左右弯矩分别减少15.62%、39.8%。此时,TMD控制效果最佳,风机整体稳定性大幅提高。

Research on optimization of valve open time of the launch barge's ballast tanks

Launch barge is an effective tool for transporting ship segments from one place to another in shipyards. During shifting of segments onto a barge, the slideway on the barge＇s deck must be adjusted to maintain the same level as the wharf and also the barge must be kept level by adjusting the water in the ballast tanks. When to open the adjusting valves is an important factor influencing the barge＇s trim during the water-adjustment process. Because these adjustments are complex a mathematical model was formulated,after analyzing the characteristics of the process of moving the segments onto the barges deck, and considering the effects of this movement＇s speed and variations in tidal levels during the move. Then the model was solved by the penalty function method, the grid method, and improved simulated annealing, respectively. The best optimization model and its corresponding solution were then determined. Finally, it was proven that the model and the method adopted are correct and suitable, by calculating and analysing an example.

The influence of up-wave barge motion on the water resonance at a narrow gap between two rectangular barges underwaves in the sea

A three-dimensional time-domain potential flow model is developed and applied to simulate the wave resonance in a gap between two side-by-side rectangular barges. A fourth-order predict-correct method is implemented to update free surface boundary conditions. The response of an up-wave barge is predicted by solving the motion equation with the Newmark-β method. Following the validation of the developed numerical model for wave radiation and diffraction around two side-by-side barges, the influence of up-wave barge motion on the gap surfaceresonance is investigated in two different locations of the up-wave barge relative to the back-wave barge at various frequencies. The results reveal that the freely floating up-wave barge significantly influences the resonance frequency and the resonance wave amplitude. Simultaneously, the up-wave barge located in the middle of the back-wave barge leads to a reduction in the resonance wave amplitude and motion response when compared with other configurations.

极限海况下Barge平台漂浮式风电场动态响应

为提高漂浮式风力机平台稳定性,以Barge平台漂浮式风力机为研究对象,建立共用系泊系统3×3阵列Barge平台的漂浮式风电场。以叶素动量理论为基础,利用水动力学软件AQWA并结合有限元方法,对Barge平台漂浮式风电场和单个Barge平台在极限海况下考虑风波耦合作用的动态响应进行对比研究。结果表明,相较于单个Barge平台,风电场中各个平台的纵荡响应均小于单个Barge平台,位于两侧的各个平台产生不规则的横荡运动,但均较小;其次,Barge平台风电场的垂荡、纵摇及机舱加速度响应均优于单个Barge平台;同时,风电场中各平台表现出很好的首摇、横摇稳定性,波动幅度均未超过2°。研究结果验证了所建立的Barge平台漂浮式风电场的可行性,可为进一步开展新型漂浮式风电场研究提供理论依据。

Barge平台漂浮式风力机动态响应及稳定性控制研究

将调谐质量阻尼器(TMD)配置于漂浮式风力机机舱或塔架可提高其整体稳定性,但加剧了塔基疲劳载荷。为此,在平台内部配置TMD进行减振控制,以ITI Barge平台为研究对象,建立漂浮式风力机动力学模型,研究塔顶前后和侧向位移随TMD质量、阻尼及安装位置的变化规律,采用多岛遗传算法求得最优TMD参数,对比分析风波载荷作用下无TMD控制、机舱TMD控制及平台TMD控制对漂浮式风力机动态响应特性的影响。结果表明:塔顶前后和侧向位移随平台TMD参数变化较为显著,当位于相同位置处TMD质量和阻尼较大时,塔顶前后和侧向位移明显减小,平台TMD质量和阻尼不变时,塔顶前后和侧向位移随TMD位置升高逐渐减小。风波载荷作用下,TMD对漂浮式风力机动态响应控制效果较为明显,但各部位控制效果不同,塔顶侧向位移、平台横摇角及塔基横摇弯矩控制效果最为显著。此外,较之机舱TMD控制,平台TMD控制时漂浮式风力机稳定性更好。

Study on TMD Control on Stability Improvement of Barge-Supported Floating Offshore Wind Turbine Based on the Multi-Island Genetic Algorithm

A floating offshore wind turbine (FOWT) has a great potential in producing renewable energy as offshore wind resource is rich in deep sea area (water deeper than 60 m) where fixed foundations are cost-effective or deployable. However, compared with a fixed-bottom installation, FOWT has to suffer more extreme loads due to its extra degrees of freedom. Therefore, the stability of an FOWT is a key challenge in exploiting offshore deep-water wind. Focusing on the stability of barge-type FOWT, this paper is to investigate the effect of passive structural control by equipping a tuned mass damper (TMD) on the nacelle. The turbulent wind with sharp fluctuations is established both in velocity and inflow direction based on standard Kaimal turbulence spectrum as suggested in the standard IEC61400-2. The irregular wave is generated according to the Pierson-Moskowitz spectrum. The dynamic structural characteristics of FOWT are calculated based on the fully coupled aero-hydro-servo-elastic solver FAST. Evidence has shown that the proposed method of the nacelle-based TMD is effective in controlling stability of an FOWT, as the sway and roll motions of barge and the side-side displacement of tower top decreased significantly. With the increase of mass, the side-side displacement of tower-top and the amplitude of roll motion of barge reveal a trend of increasing first and then decreasing. The stiffness and damping have little effect. Furthermore, the multi-island genetic optimization algorithm (MIGA) is employed to find globally optimum structural parameters (mass, stiffness and damping) of the TMD. The optimum structure parameters of TMD are achieved when the mass is 21393 kg, damping is 13635 N/(m/s) and stiffness is 6828 N/m. By adopting the optimized TMD, stability of roll motion of barge and side-side displacement of tower-top increase up to 53% and 50% respectively when compared with the normal TMD. The simulation results verify the validity and reliability of the proposed TMD control and the optimization methods.

Dynamic Response of Offshore Wind Turbine on 3×3 Barge Array Floating Platform under Extreme Sea Conditions

Offshore wind farm construction is nowadays state of the art in the wind power generation technology.However,deep water areas with huge amount of wind energy require innovative floating platforms to arrange and install wind turbines in order to harness wind energy and generate electricity.The conventional floating offshore wind turbine system is typically in the state of force imbalance due to the unique sway characteristics caused by the unfixed foundation and the high center of gravity of the platform.Therefore,a floating wind farm for 3×3 barge array platforms with shared mooring system is presented here to increase stability for floating platform.The NREL 5 MW wind turbine and ITI Energy barge reference model is taken as a basis for this work.Furthermore,the unsteady aerodynamic load solution model of the floating wind turbine is established considering the tip loss,hub loss and dynamic stall correction based on the blade element momentum(BEM)theory.The second development of AQWA is realized by FORTRAN programming language,and aerodynamic-hydrodynamic-Mooring coupled dynamics model is established to realize the algorithm solution of the model.Finally,the 6 degrees of freedom(DOF)dynamic response of single barge platform and barge array under extreme sea condition considering the coupling effect of wind and wave were observed and investigated in detail.The research results validate the feasibility of establishing barge array floating wind farm,and provide theoretical basis for further research on new floating wind farm.

Comparison of Microbubble and Air Layer Injection with Porous Media for Drag Reduction on a Self-propelled Barge Ship Model

Ship resistance issues are related to fuel economy,speed,and cost efficiency.Air lubrication is a promising technique for lowering hull frictional resistance as it is supposed to modify the energy in the turbulent boundary layer and thereby reduce hull friction.In this paper,the objective is to identify the optimum type of air lubrication using microbubble drag reduction(MBDR)and air layer drag reduction(ALDR)techniques to reduce the resistance of a 56-m Indonesian self-propelled barge(SPB).A model with the following dimensions was constructed:length L=2000 mm,breadth B=521.60 mm,and draft T=52.50 mm.The ship model was towed using standard towing tank experimental parameters.The speed was varied over the Froude number range 0.11–0.31.The air layer flow rate was varied at 80,85,and 90 standard liters per minute(SLPM)and the microbubble injection coefficient over the range 0.20–0.60.The results show that the ship model using the air layer had the highest drag reduction up to a maximum of 90%.Based on the characteristics of the SPB,which operates at low speed,the optimum air lubrication type to reduce resistance in this instance is ALDR.

Numerical investigation of influence of wave directionality on the water resonance at a narrow gap between two rectangular barges

A three-dimensional time-domain potential flow model with second-order nonlinearity was applied to simulate the wave resonance in a gap between two side-by-side rectangular barges. In the model, the velocity potential was decomposed into the incident potential and unknown scattered potential which was obtained by solving the boundary integral equation. The fourth-order predict-correct method was applied to enforce the free surface conditions in the time integration. The influence of the wave direction on the first and second-order gap surface elevations was investigated. The results reveal that the incident wave angle does not affect the resonant wave frequency and the maximum surface elevation at resonance always occurs at the middle location along the gap. However, the corresponding maximum wave surface elevation at resonance varies with the incident wave angle. The location of the maximum wave elevation shifts either upstream or downstream along the gap, depending on the relative magnitude of incident wave frequency to the resonant frequency.

Coupled Responses of Sewol,Twin Barges and Slings During Salvage

Korean Sewol is successfully lifted up with the strand jack system based on twin barges. During the salvage operation, two barges and Sewol encounter offshore environmental conditions of wave, current and wind. It is inevitable that the relative motions among the three bodies are coupled with the sling tensions, which may cause big dynamic loads for the lifting system. During the project engineering phase and the site operation, it is necessary to build up a simulation model that can precisely generate the coupled responses in order to define a suitable weather window and monitor risks for the salvage operation. A special method for calculating multibody coupled responses is introduced into Sewol salvage project. Each body’s hydrodynamic force and moment in multibody configuration is calculated in the way that one body is treated as freely moving in space, while other bodies are set as fixed globally.The hydrodynamic force and moment are then applied into a numerical simulation model with some calibration coefficients being inserted. These coefficients are calibrated with the model test results. The simulation model built up this way can predict coupled responses with the similar accuracy as the model test and full scale measurement,and particularly generate multibody shielding effects. Site measured responses and the responses only resulted from from the simulation keep project management simultaneously to judge risks of each salvage stage, which are important for success of Sewol salvage.

Evaluating the maneuverability of a new type of self-propelled barge

A new type of self-propelled barge was designed specifically for use on the Chishui River. This paper presents experimental results of its performance from tests in water of different depths,while bearing different loads. For test purposes,one of the best self-propelled barges from the Chishui River was used as a performance reference. The comparison showed that the new design has better maneuvering performance.

Fluid Resonance Between Twin Floating Barges with Roll Motion Under Wave Action

The wave-induced fluid resonance between twin side-by-side rectangular barges coupled with the roll motion of the twin barges is investigated by both numerical simulation and physical model test.A 2D numerical wave flume,based on an open source computational fluid dynamics(CFD)package OpenFOAM,is applied for the numerical simulation.After numerical validations and convergent verifications,the characteristics of the fluid resonance in the gap between the twin rolling side-by-side barges are examined.The resonant frequency of the oscillating fluid in the gap between the twin rolling barges decreases compared with that between the twin fixed barges.Generally,the twin barges roll in the opposite directions,and their equilibrium positions lean oppositely with respect to the initial vertical direction.A physical model test is carried out for a further investigation,in which the twin barges are set oppositely leaning and fixed.From the present experimental results,a linear decrease of the resonant frequency with the increasing leaning angle is found.Combined with the numerical results,the deflection of the equilibrium positions of the twin barges is a relevant factor for the resonant frequency.Besides,the effects of the gap width and incident wave height on the fluid resonance coupled with roll motion are examined.

Predicting 3-DoF motions of a moored barge by machine learning

The real-time prediction of a floating platform or a vessel is essential for motion-sensitive maritime activ-ities.It can enhance the performance of motion compensation system and provide useful early-warning information.In this paper,we apply a machine learning technique to predict the surge,heave,and pitch motions of a moored rectangular barge excited by an irregular wave,which is purely based on the mo-tion data.The dataset came from a model test performed in the deep-water ocean basin,at Shanghai Jiao Tong University,China.Using the trained machine learning model,the predictions of 3-DoF(degrees of freedom)motions can extend two to four wave cycles into the future with good accuracy.It shows great potential for applying the machine learning technique to forecast the motions of offshore platforms or vessels.

基于MTMD的Barge型漂浮式风力机稳定性控制研究

为提高漂浮式风力机的稳定性,以NREL 5 MW风力机及ITI Barge平台为控制对象,在传统单个调谐质量阻尼器（STMD）基础上提出风力机机舱及塔架中配置不同动力特性调谐质量阻尼器（TMD）的新型多重调谐质量阻尼器（MTMD）控制方法,分别研究其在环境载荷作用下队海上漂浮式风力机稳定性的控制效果。研究表明：STMD及MTMD对漂浮式风力机塔顶左右位移控制效果较明显,波动范围分别减小38%和45%,稳定性分别提高41%和46%;在STMD及MTMD控制下,漂浮式风力机平台横荡和横摇降幅明显;MTMD对漂浮式风力机塔架和平台的动态响应控制效果优于STMD控制。

Numerical modeling of nonlinear sloshing of liquid in a container coupled with barge subjected to regular excitation

The sloshing phenomenon of liquid in a partially filled tank mounted rigidly within a barge exposed to regular wave field has been considered for numerical investigation.This paper details the numerical scheme developed in time domain to study the interaction of wave induced barge motion with sloshing oscillations in a partially filled container.The sloshing time history results obtained from the numerical scheme adopted are validated with experimental measurements of Nasar et al.(2008)The harmonics present in the sloshing oscillation for the liquid fill levels(25%,50%and 75%)have been analyzed.

Experimental investigation of motion responses of tunnel element immerging by moored barge

In this paper, the barge effect on the motion responses of the ttmnel element immerging by the moored barge under waves is investigated experimentally. Both the motion responses of the tunnel element and the moored barge in the experiment are simultaneously acquired by the Untouched 6-D Measurement System. The results show that the sway motion responses of the tunnel element immerging by the moored barge are different from those without the barge. For the system of the tunnel element and the moored barge, the moored barge has two motion components in the sway direction. The high frequency motion of the moored barge has little effect on the high frequency motion of the tunnel element with moored barge. However, the low frequency motion of the moored barge has a significant effect on the sway motion of the tunnel element. The motion responses of the tunnel element and the barge in the heave and roll directions are mainly the high frequency motion.

Barge Capsizes Approaching Nude Beach

[提示]美国的德克萨斯州有一个著名的nude beach(汉语似可简译咸"裸滩"), 一艘游艇在靠近这个裸滩时数十名乘客居然拥向游艇之一侧,致使游艇倾覆,游 客纷纷落水。

2种海上风力机漂浮式风电场平台动态响应对比

为研究不同海上风力机漂浮式风电场平台风浪流联合作用下动态响应,分别建立基于OC3-Hywind Spar与ITI Energy Barge平台漂浮式风力机的2×2阵列漂浮式风电场,结合辐射/绕射理论与有限元方法,使用海洋工程软件AQWA及风力机仿真软件FAST分别进行水动力学与气动载荷计算,分析2种漂浮式风电场平台时频响应特性。结果表明:Spar与Barge平台频域响应均集中在2.00 rad/s以下低频区域,在2种风电场中,Spar风电场各平台在垂荡、纵摇、横摇、艏摇4自由度及机舱振动加速度上稳定性较好;风电场中平台横荡、纵荡及机舱振动加速度大小与其在风电场中所处位置有关。