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Modeling and Analysis of a Novel Offshore Binary Species Free-Floating Longline Macroalgal Farming System 一种新型近海二元物种自由漂浮长线大型藻类养殖系统的建模与分析
IF 1.6 4区 工程技术 Q3 ENGINEERING, MECHANICAL Pub Date : 2022-09-27 DOI: 10.1115/1.4055803
Ming Chen, S. Yim, D. Cox, Zhaoqing Yang, M. Huesemann, T. Mumford, Taiping Wang
The investigation of innovative macroalgal cultivation is important and needed to optimize farming operations, increase biomass production, reduce the impact on the ecosystem, and lower system and operational costs. However, most macroalgal farming systems (MFSs) are stationary, which need to occupy a substantial coastal area, require extensive investment in farm infrastructure, and cost high fertilizer and anchoring expenses. This study aims to model, analyze, and support a novel binary species free-floating longline macroalgal cultivation concept. The expected outcomes could provide a basis for the design and application of the novel MFS to improve biomass production, decrease costs, and reduce the impact on the local ecosystem. In this paper, the Saccharina latissima and Nereocystis luetkeana were modeled and validated and coupled with longline to simulate the binary species MFS free float in various growth periods and associated locations along the U.S. west coast. The numerical predictions indicated the possibility of failure on the longline and breakage at the kelp holdfasts is low. However, the large forces due to instantaneous change in dynamic loads caused by loss of hydrostatic buoyancy when the longline stretches out of the water would damage the kelps. Buoy-longline contact interactions could damage the buoy, resulting in the loss of the system by sinking. Furthermore, the kelp-longline and kelp-kelp entanglements could potentially cause kelp damage.
研究创新的大型藻类养殖对于优化农业运营、增加生物量生产、减少对生态系统的影响以及降低系统和运营成本是重要和必要的。然而,大多数大型藻类养殖系统(MFS)是固定的,需要占用大量沿海地区,需要对农场基础设施进行大量投资,并且需要高昂的肥料和锚定费用。本研究旨在建模、分析和支持一种新的二元物种自由漂浮延绳大型藻类培养概念。预期结果可以为新型MFS的设计和应用提供基础,以提高生物质产量、降低成本并减少对当地生态系统的影响。在本文中,对宽糖精和蓝囊藻进行了建模和验证,并与延绳钓相结合,以模拟二元物种MFS在美国西海岸不同生长期和相关位置的自由漂浮。数值预测表明,延绳断裂和海带支架断裂的可能性很低。然而,当延绳伸出水面时,由于静水浮力的损失导致动态载荷的瞬时变化而产生的巨大力会损坏海带。浮标-延绳接触的相互作用可能会损坏浮标,导致下沉造成系统损失。此外,海带延绳和海带与海带的纠缠可能会对海带造成损害。
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引用次数: 0
Efficient calculation of hydrodynamic loads on offshore wind substructures including slamming forces 海上风电场子结构水动力载荷包括撞击力的有效计算
IF 1.6 4区 工程技术 Q3 ENGINEERING, MECHANICAL Pub Date : 2022-09-21 DOI: 10.1115/1.4055701
Csaba Pákozdi, A. Kamath, Weizhi Wang, T. Martin, H. Bihs
Estimation of the hydrodynamic loads based on strip theory using the Morrison equation provides an inexpen- sive method for load estimation for the offshore industry. The advantage of this approach is that it requires only the undisturbed wave kinematics along with inertia and viscous force coefficients. Over the recent years, the de- velopment in numerical wave tank simulations makes it possible to simulate nonlinear three-hour sea states, with computational times in the order of real time. This presents the possibility to calculate loads using wave spectrum input in numerical simulations with reasonable computational time and effort. In the current paper, the open-source fully nonlinear potential flow model REEF3D::FNPF is employed for calculating the nonlinear wave kinematics. Here, the Laplace equation for the velocity potential is solved on a s-coordinate mesh with the nonlinear free sur- face boundary conditions to close the system. A technique to calculate the total acceleration on the σ-coordinate grid is introduced which makes it possible to apply strip theory in a moving grid framework. With the combination of strip theory and three-hour wave simulations, a unique possibility to estimate the hydrodynamic loads in real time for all discrete positions in space within the domain of the numerical wave tank is presented in this paper. The numerical results for inline forces on an offshore wind mono-pile substructure are compared with measurements, and the new approach shows good agreement.
基于莫里森方程的条形理论的水动力载荷估计为海上工业提供了一种成本低廉的载荷估计方法。这种方法的优点是它只需要不受干扰的波运动学以及惯性和粘性力系数。近年来,波浪槽数值模拟的发展使模拟非线性三小时海况成为可能,计算次数按实时数量级计算。这就提供了在合理的计算时间和精力下,在数值模拟中利用波谱输入计算载荷的可能性。本文采用开源的全非线性势流模型REEF3D::FNPF进行非线性波动运动学计算。在这里,速度势的拉普拉斯方程在s坐标网格上求解,非线性自由曲面边界条件使系统闭合。介绍了一种在σ坐标网格上计算总加速度的方法,使条形理论在移动网格框架中的应用成为可能。本文将条形理论与三小时波浪模拟相结合,提供了一种独特的可能性,可以在数值波浪槽的范围内实时估计空间中所有离散位置的水动力载荷。将海上风电单桩基础结构的内线力计算结果与实测结果进行了比较,表明新方法与实测结果吻合较好。
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引用次数: 0
Dissipation of gravity waves due to submerged porous plate coupled with porous structures 水下多孔板耦合多孔结构对重力波的耗散
IF 1.6 4区 工程技术 Q3 ENGINEERING, MECHANICAL Pub Date : 2022-09-21 DOI: 10.1115/1.4055702
Athul Krishna, Khansa Abdulla, D. Karmakar
The present study focuses on the wave trapping due to the submerged horizontal porous plate combined with bottom-standing porous structure and surface-piercing porous structure. The submerged plate thickness is considered to be negligible as compared to the incident wavelength and water depth and the porous structure is considered to be of finite width. The orthogonal mode-coupling relation is used to analyse the wave interaction with the combined structure. The reflection, transmission and dissipation coefficients along with wave force on the porous structure and surface deflection in the incident and transmitted region is investigated for the study of hydrodynamic performance of the composite porous breakwater system. Further, the effect of porosity of submerged plate and structure, friction factor, submerged depth of plate and structure angle of incidence and gap between the submerged plate and porous structure are investigated to analyse the effective wave dissipation by the porous breakwater system. In addition, the comparative study of the present method is performed with the results available in the literatures. The study noted that wave damping due to the submerged porous plate backed by surface-piercing porous structure is more as compared to the submerged porous plate backed by bottom-standing porous structure. The study will be helpful to scientist and engineers in the design of suitable composite breakwater system for wave attenuation in the coastal region.
本研究的重点是浸没水平多孔板与底部直立多孔结构和表面穿透多孔结构相结合所引起的波浪捕获。与入射波长和水深相比,浸没板的厚度被认为是可以忽略的,并且多孔结构被认为是有限宽度的。采用正交模式耦合关系分析了组合结构与波浪的相互作用。为了研究复合多孔防波堤系统的水动力性能,研究了波在多孔结构上的反射、透射和耗散系数以及入射和透射区域的表面偏转。此外,还研究了淹没板和结构的孔隙率、摩擦系数、板的淹没深度以及结构的入射角和淹没板与多孔结构之间的间隙对多孔防波堤系统有效消波的影响。此外,本方法还与文献中的结果进行了比较研究。该研究指出,与底部直立多孔结构支撑的浸没多孔板相比,由表面穿透多孔结构支撑在水中的多孔板引起的波浪阻尼更大。该研究将有助于科学家和工程师设计适合沿海地区波浪衰减的复合防波堤系统。
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引用次数: 2
Digital twin based virtual sensor for online fatigue damage monitoring in offshore wind turbine drivetrains 基于数字孪生虚拟传感器的海上风机传动系统疲劳损伤在线监测
IF 1.6 4区 工程技术 Q3 ENGINEERING, MECHANICAL Pub Date : 2022-09-08 DOI: 10.1115/1.4055551
F. C. Mehlan, A. Nejad, Zhenghua Gao
In this article a virtual sensor for online load monitoring and subsequent remaining useful life (RUL) assessment of wind turbine gearbox bearings is presented. Utilizing a Digital Twin framework the virtual sensor combines data from readily available sensors of the condition monitoring (CMS) and supervisory control and data acquisition (SCADA) system with a physics-based gearbox model. Different state estimation methods including Kalman Filter, Least Square estimator and a quasi-static approach are employed for load estimation. For RUL assessment the accumulated fatigue damage is calculated with the Palmgren-Miner model. A case study using simulation measurements from a high-fidelity gearbox model is conducted to evaluate the proposed method. Estimated loads at the considered IMS and HSS bearings show moderate to high correlation (R = 0.50-0.96) to measurements, as lower frequency internal dynamics are not fully captured. The estimated fatigue damage differs by 5-15 % from measurements.
本文介绍了一种用于风电齿轮箱轴承在线负荷监测和后续剩余使用寿命评估的虚拟传感器。利用数字孪生框架,虚拟传感器将状态监测(CMS)和监控与数据采集(SCADA)系统的现成传感器的数据与基于物理的变速箱模型相结合。负荷估计采用了卡尔曼滤波、最小二乘估计和准静态估计等不同的状态估计方法。在RUL评估中,使用Palmgren-Miner模型计算累积疲劳损伤。通过高保真齿轮箱模型的仿真测量,对所提出的方法进行了验证。所考虑的IMS和HSS轴承的估计载荷与测量值显示出中度到高度的相关性(R = 0.50-0.96),因为低频内部动态没有完全捕获。估计的疲劳损伤与测量值相差5- 15%。
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引用次数: 10
Numerical evaluation of an efficient deep-water mooring configuration designed to allow a fast identification of failure events 设计用于快速识别故障事件的高效深水系泊配置的数值评估
IF 1.6 4区 工程技术 Q3 ENGINEERING, MECHANICAL Pub Date : 2022-09-08 DOI: 10.1115/1.4055550
Rodrigo M Kochem, Fabrício Nogueira Correa, B. P. Jacob
This work proposes a taut-leg deep-water mooring configuration with buoys, designed specifically to allow a quick and easy visual identification of the rupture of any mooring line of the system. This addresses one of the main concerns of the offshore oil & gas industry: the significant number of events of mooring line failure that has been recently observed in actual operations in deep and ultra-deep water scenarios; field experience indicates that, in current spread-mooring systems, several weeks may pass until a failure is detected. The proposed configuration also presents the additional advantages of reducing the mooring radius and the tensions on the top of the lines. The configuration is evaluated and compared with a standard taut-leg system, considering the same base case study of a typical deep-water FPSO, and using up-to-date numerical methods implemented into an in-house fully coupled nonlinear time-domain dynamic analysis tool. The results indicated that the proposed configuration provided significant improvements in the cost and performance of the mooring system, in terms of line lengths, mooring radii, tensions and offsets; and confirmed that the buoy emerges and reaches the surface in the event of a line rupture, irrespective of the point where the line has broken. This indicates that the resulting configuration is a promising technical alternative to traditional standard taut-leg systems in deep and ultra-deep water scenarios.
这项工作提出了一种带浮标的紧腿深水系泊配置,专门设计用于快速方便地视觉识别系统任何系泊线的断裂。这解决了海上油气行业的一个主要问题:最近在深水和超深水的实际作业中观察到大量系泊线故障事件;现场经验表明,在目前的扩展系泊系统中,可能需要几周的时间才能检测到故障。提出的配置还具有减少系泊半径和索顶张力的额外优势。考虑到典型深水FPSO的基本案例研究,并使用最新的数值方法实现了内部全耦合非线性时域动态分析工具,对该配置进行了评估,并与标准的紧腿系统进行了比较。结果表明,在缆绳长度、系泊半径、张力和偏移量方面,拟议的配置显著改善了系泊系统的成本和性能;并确认在缆绳断裂的情况下,浮标出现并到达水面,而不管缆绳在哪里断裂。这表明,在深水和超深水环境中,这种配置是传统标准紧腿系统的一种有前途的技术替代方案。
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引用次数: 0
A generalized framework for risk-based extreme load analysis in offshore system design 海上系统设计中基于风险的极限负荷分析的广义框架
IF 1.6 4区 工程技术 Q3 ENGINEERING, MECHANICAL Pub Date : 2022-09-08 DOI: 10.1115/1.4055553
Mohammad Arif, Faisal Khan, Salim Ahmed, S. Imtiaz
The primary aim of this research is to consider the correlation among environmental factors in calculating 100 and 1000 years of extreme load design criteria. This is done by considering load as energy transferred from external environment to the offshore system. Also, incorporating spatial and temporal dependence of environmental variables in the context of offshore design. A bivariate extreme value distribution and a conditional joint return level function are developed using the Gumbel- Hougaard copula. The offshore design risk criteria are developed for the finer grid locations (0.10 × 0.10 latitude/longitude grid) considering joint extreme wind and wave energy. The developed approach is tested using data for the Flemish Pass basin off the east coast of Canada. Along with the primary aim, the impact of climate change is investigated (time and space variability) by implementing the proposed methodology in two cases: the periods from 1959 to 1988 and 1989 to 2018. This study observed that climate change has caused 30% less correlation between wind speed and wave height in recent years [1989-2018] compared to the period of 1959 to 1988. The proposed extreme design wind speed is 39.7 m/s, significant wave height is 16.4 m; their joint exceeding probability is 5.80E-05 over an annual basis for a scenario of 100-year.
本研究的主要目的是在计算100年和1000年极端荷载设计标准时考虑环境因素之间的相关性。这是通过将负载视为从外部环境传递到海上系统的能量来实现的。此外,在海上设计的背景下,结合环境变量的空间和时间依赖性。利用Gumbel-Hougaard copula建立了二元极值分布和条件联合收益水平函数。考虑到联合极端风能和波浪能,为更精细的网格位置(0.10×0.10纬度/经度网格)制定了海上设计风险标准。利用加拿大东海岸弗拉芒山口盆地的数据对所开发的方法进行了测试。除了主要目标外,还通过在两种情况下实施所提出的方法来调查气候变化的影响(时间和空间可变性):1959年至1988年和1989年至2018年。这项研究观察到,与1959年至1988年相比,气候变化导致近年来[1989-2018]风速和波高之间的相关性降低了30%。拟定的极端设计风速为39.7m/s,有效波高为16.4m;在100年的情况下,它们的联合超额概率为5.80E-05。
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引用次数: 1
REMOTELY OPERATED VEHICLE TAXONOMY AND EMERGING METHODS OF INSPECTION, MAINTENANCE AND REPAIR OPERATIONS: AN OVERVIEW AND OUTLOOK 远程操作车辆分类和新兴的检查、维护和维修操作方法:概述和展望
IF 1.6 4区 工程技术 Q3 ENGINEERING, MECHANICAL Pub Date : 2022-09-02 DOI: 10.1115/1.4055476
Abdullahi Abba Dalhatu, A. M. Sa'ad, R. Cabral, G. de Tomi
Remotely Operated Vehicle (ROV) based Inspection, Maintenance and Repairs (IMR) services are costly be- cause operations are traditionally executed by a hired subsea contractor, who then hires a specialized vessel with an entire crew from the vessel owner or the shipping company. Even though this is an established method considered relatively reliable in comparison to human divers, there is a growing need for more versatile, efficient and economical IMR methods. Innovations that require no or less use of support vessels are mitigating this challenge. The current ROV classifications do not adapt to these innovations. Hence, the lack of a widely accepted ROV classification. Thus, this paper reviews ROV classifications and proposes a classification that poses no hindrance to innovation and conforms to modern developments. The paper then illustrates and reviews the emerging methods of conducting IMR operations by putting together in a concise, yet resourceful manner the ROV technologies and their various configurations to provide a basic meaningful understanding to the audience. This paper also provides a summary of the comparison of the methods and some of their challenges.
基于遥控潜水器(ROV)的检查、维护和维修(IMR)服务成本高昂,因为传统上,操作由雇佣的海底承包商执行,然后由船东或航运公司雇佣一艘配备全体船员的专业船只。尽管与人类潜水员相比,这是一种公认的相对可靠的方法,但人们越来越需要更通用、高效和经济的IMR方法。不需要或更少使用支援船的创新正在缓解这一挑战。目前的ROV分类不适应这些创新。因此,缺乏被广泛接受的ROV分类。因此,本文回顾了ROV的分类,并提出了一种不妨碍创新并符合现代发展的分类。然后,本文通过简洁而足智多谋的方式将ROV技术及其各种配置组合在一起,向观众提供基本而有意义的理解,阐述并回顾了进行IMR操作的新兴方法。本文还总结了这些方法的比较及其面临的一些挑战。
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引用次数: 4
The impact of the spectral tail on the evolution of the kurtosis of random seas 谱尾对随机海峰度演化的影响
IF 1.6 4区 工程技术 Q3 ENGINEERING, MECHANICAL Pub Date : 2022-09-02 DOI: 10.1115/1.4055480
D. Barratt, T. S. van den Bremer, Thomas A. A. Adcock
We perform simulations of random seas based on narrow-banded spectra with directional spreading. Our wavefields are spatially homogeneous and non-stationary in time. We truncate the spectral tail for the initial conditions at different cut-off wavenumbers to assess the impact of the spectral tail on the kurtosis and spectral evolution. We consider two cases based on truncation of the wavenumber tail at k/kp = 2.4 and k/kp = 6. Our simulations indicate that the peak kurtosis value increases if the tail is truncated at |k|/kp = 2.4 rather than k/kp = 6. For the case with a wavenumber cut-off at k/kp = 2.4, augmented kurtosis is accompanied by comparatively more aggressive spectral changes including redevelopment of the spectral tail. Similar trends are observed for the case with a wavenumber cut-off at |k|/kp = 6, but the spectral changes are less substantial. Thus, the spectral tail appears to play an important role in a form of spectral equilibrium that reduces spectral changes and decreases the peak kurtosis value. Our findings suggest that care should be taken when truncating the spectral tail for the purpose of simulations/experiments. We also find that the equation of Fedele (2015, textit{J. Fluid Mech.}, vol. 782, pp. 25--36) provides an excellent estimate of the peak kurtosis value. However, the bandwidth parameter must account for the spectral tail to provide accurate estimates of the peak kurtosis.
我们基于具有方向扩展的窄带谱对随机海进行模拟。我们的波场在空间上是均匀的,在时间上是非平稳的。我们截断了不同截止波数下初始条件下的谱尾,以评估谱尾对峰度和谱演化的影响。我们考虑两种基于在k/kp=2.4和k/kp=6处波数尾的截断的情况。我们的模拟表明,如果尾部在|k|/kp=2.4而不是k/kp=6处截断,则峰值峰度值会增加。对于波数截止为k/kp=2.4的情况,峰度增加伴随着相对更积极的光谱变化,包括光谱尾部的再开发。在波数截止值为|k|/kp=6的情况下观察到类似的趋势,但光谱变化不那么显著。因此,光谱尾部似乎在减少光谱变化并降低峰值峰度值的光谱平衡形式中发挥着重要作用。我们的研究结果表明,为了模拟/实验的目的,在截断光谱尾部时应该小心。我们还发现Fedele方程(2015,textit{J.Fluid Mech.},第782卷,第25-36页)提供了峰度峰值的极好估计。然而,带宽参数必须考虑到谱尾,以提供峰值峰度的精确估计。
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引用次数: 2
Diffraction and refraction of nonlinear waves by the Green-Naghdi equations 用Green-Naghdi方程求解非线性波的衍射和折射
IF 1.6 4区 工程技术 Q3 ENGINEERING, MECHANICAL Pub Date : 2022-09-02 DOI: 10.1115/1.4055484
M. Hayatdavoodi, Cengiz Ertekin, R. Cengiz
Diffraction and refraction of nonlinear shallow water waves due to uneven bathymetry are studied by use of the Green-Naghdi (GN) equations in two and three dimensions. A numerical wave tank consisting of deep, transitional and shallow regions is created. Various forms of three-dimensional bathymetry, consisting of ramps with nonuniform profiles and large slopes are used to connect the deep-water side of the tank to the shallow-water shelf. A wavemaker is placed at the upwave side of the domain, capable of generating solitary and cnoidal waves of the GN equations. A numerical wave absorber is located downwave of the domain to minimize the wave reflection back into the domain. The system of equations are solved numerically in time domain by use of a second-order finite difference approach for spatial discretization, and in a boundary-fitted coordinate system, and by use of the Modified Euler method for time marching. Results include solitary and cnoidal wave surface elevation and particle velocities and are compared with the existing solutions where possible. Overall very good agreement is observed. Discussion is provided on the nonlinearity and dispersion effects on the wave diffraction and refraction by the various forms of the ramps, as well as on the performance of the GN equations in solving these problems.
利用Green-Naghdi (GN)方程从二维和三维研究了水深不均匀引起的非线性浅水波的衍射和折射。建立了一个由深区、过渡区和浅区组成的数值波槽。采用各种形式的三维测深技术,包括具有不均匀轮廓和大坡度的坡道,将水箱的深水侧与浅水架连接起来。在区域的上波侧放置一个造波器,能够产生GN方程的孤立波和余弦波。数值波吸收器位于该区域的下波处,以尽量减少波反射回该区域。用二阶有限差分法进行空间离散,在边界拟合坐标系中,用修正欧拉法进行时间推进,在时域中对方程组进行数值求解。结果包括孤立波和余弦波表面高程和粒子速度,并在可能的情况下与现有的解进行比较。总的来说,观察到非常好的一致性。讨论了各种形式的坡道对波的衍射和折射的非线性和色散效应,以及求解这些问题时GN方程的性能。
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引用次数: 3
A Simplified Method to Analyse Dynamic Response of VLFS Based on the Kane Method 基于凯恩法的VLFS动态响应分析简化方法
IF 1.6 4区 工程技术 Q3 ENGINEERING, MECHANICAL Pub Date : 2022-09-02 DOI: 10.1115/1.4055487
Jun-yi Liu, Xunjun Chen, Heng Huang, Song Ji, Qunzhang Tu
A two-dimensional (2D) simplified model of the very large floating structure (VLFS) is formulated based on Huston's interpretation of the Kane methodology. In this proposed model, the VLFS is considered as a serial of discrete floating bodies connected by elastic hinges. The rotation stiffness of elastic hinges has a great influence on the dynamic responses of VLFS and its value is determined based on the vertical displacements equivalent between the simply supported beam model and the elastically hinged multiple bodies model with the same boundary conditions on a concentrated load. Reduced Kane equations are used in the actual dynamic analysis, once initial conditions and mechanical analysis of system have been formulated. Validation of the Kane-based method and the reliability of corresponding program developed are established by several comparative study on a continuous structure and a hinged structure with three parts. The predictions based on the proposed method are essentially identical to the model test data and calculation results provided by related literatures.
基于Huston对Kane方法的解释,建立了超大浮式结构的二维简化模型。在该模型中,VLFS被认为是一系列由弹性铰链连接的离散浮体。弹性铰链的转动刚度对VLFS的动力响应有很大影响,其值是根据集中荷载下相同边界条件下简支梁模型和弹性铰链多体模型之间的垂直位移等效值确定的。在建立了系统的初始条件和力学分析后,在实际的动力学分析中使用了简化的Kane方程。通过对一个连续结构和一个由三部分组成的铰接结构的几次比较研究,建立了基于Kane方法的验证和相应程序的可靠性。基于该方法的预测与相关文献提供的模型试验数据和计算结果基本一致。
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引用次数: 1
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