Article
Energy & Fuels
Teng Zhou, Jingwen Guo
Summary: A lined layer made from nitrile rubber is developed for suppressing underwater noise radiation from offshore wind turbines. The lined layer contains periodically distributed axial cavities, which consist of a circular truncated cone and a cylinder. The acoustic performance of the lined layer is analysed using the equivalent medium method and the transfer matrix method. An optimal configuration targeting low-frequency range is designed based on the analytical prediction model, with an absorption coefficient of up to 0.96 at 2500 Hz. The presence of the lined layer can lower the sound pressure level by up to 18 dB and change the radiation angle of the sound wave front.
Article
Energy & Fuels
Aemilius A. W. van Vondelen, Alexandros Iliopoulos, Sachin T. Navalkar, Daan C. van der Hoek, Jan-Willem van Wingerden
Summary: Operational modal analysis is crucial for understanding the dynamics of offshore wind turbines, but the classical algorithms are not suitable for operational turbines due to periodic excitation. This paper presents an enhanced version of the Kalman filter-based stochastic subspace identification method, which can handle periodic excitation by concatenating multiple datasets. The enhanced method is applied to an operational offshore wind turbine and compared with other OMA methods, showing more accurate and stable estimates.
Article
Construction & Building Technology
Mansureh-Sadat Nabiyan, Faramarz Khoshnoudian, Babak Moaveni, Hamed Ebrahimian
Summary: Offshore wind turbines require remote monitoring technologies for damage diagnosis and prognosis. This study focuses on developing mechanics-based digital twins through a model-updating process, allowing for accurate response prediction and identification of input loads and uncertainty quantification. The Bayesian approach leads to slightly better results in accurate response prediction compared to the classical modal-based model updating method.
STRUCTURAL CONTROL & HEALTH MONITORING
(2021)
Article
Engineering, Marine
Jieyan Chen, Moo-Hyun Kim
Summary: As international efforts to address climate change grow, many countries and companies have set clear net zero goals by accelerating renewable energy development. Offshore wind energy, as a renewable energy source, has attracted attention and is an active research area. However, the design of offshore wind turbine structures faces challenges, requiring advanced optimization technology to address them.
JOURNAL OF MARINE SCIENCE AND ENGINEERING
(2022)
Article
Environmental Sciences
Young Geul Yoon, Dong-Gyun Han, Jee Woong Choi
Summary: As interest in renewable energy development grows, numerous offshore wind farms are being constructed worldwide. Consequently, the potential effects of underwater operational noise on marine ecosystems have become a concern, necessitating an understanding of the mechanisms and acoustic characteristics of such noise for environmental impact assessments.
FRONTIERS IN MARINE SCIENCE
(2023)
Article
Engineering, Marine
Nasim Partovi-Mehr, Emmanuel Branlard, Mingming Song, Babak Moaveni, Eric M. Hines, Amy Robertson
Summary: This paper investigates the variation and sensitivity analysis of an offshore wind turbine's modal parameters under operational and environmental conditions, and validates the model predictions using experimental measurements. The results show that the first fore-aft (FA) natural frequency is mainly influenced by rotor speed, while the damping ratio is primarily affected by wind speed. Yaw angle and mean sea level have minimal impact on the modal parameters.
JOURNAL OF MARINE SCIENCE AND ENGINEERING
(2023)
Article
Mechanics
Josue Pacheco-Cherrez, Diego Cardenas, Arturo Delgado-Gutierrez, Oliver Probst
Summary: This paper demonstrates the feasibility of detecting and quantifying crack-type damage features in rotating wind turbine blades by Operational Modal Analysis (OMA) under noisy measurement conditions. The methodology developed in this study allows for reliable detection of small cracks with high sensitivity, even at low signal-to-noise ratios (SNR), and the construction of calibration curves for crack lengths and center positions. This proposed approach holds potential for the implementation of robust and low-cost structural health monitoring systems for wind turbines at difficult-to-access locations, such as offshore environments.
COMPOSITE STRUCTURES
(2023)
Article
Acoustics
Xiangyu Lu, Huaihai Chen, Xudong He
Summary: Operational modal analysis involves analyzing the modal properties of a structure while in operation, using only the output vibration signal. Despite being based on the assumption of white noise excitation, the algorithm can still be used to identify modal parameters even when the excitation is correlated.
JOURNAL OF VIBRATION AND CONTROL
(2022)
Article
Engineering, Mechanical
Yuanchang Chen, D. Todd Griffith
Summary: Early detection of rotor imbalance is a promising approach to improve wind turbine durability. This study proposes a novel method for identifying and estimating blade mass imbalance in wind turbine rotors. The method can determine the presence of mass imbalance, identify the imbalanced blade, and quantify the severity of the imbalance. It requires minimal input data and can be applied to stationary rotors prior to operation. The method has been validated through numerical simulation and experimental tests, demonstrating its effectiveness and potential for application in different wind turbine configurations and other rotating machinery.
MECHANICAL SYSTEMS AND SIGNAL PROCESSING
(2023)
Article
Engineering, Mechanical
Jonas Gad Kjeld, Luis David Avendano-Valencia, Anders Brandt, Silas Sverre Christensen, Jacob Karottki Falk Andersen
Summary: This paper aims to experimentally determine the damping values and their uncertainty bounds for the first two modes of an idling offshore wind turbine. Field measurements from a 3.6 MW offshore wind turbine were used for this purpose. The proposed methodology confined the 90% confidence intervals of the damping ratio estimates within specific percentage points in different directions.
MECHANICAL SYSTEMS AND SIGNAL PROCESSING
(2023)
Article
Oceanography
Li Ying, Wang Bin, Liu Qiang, Gao Shan, Lu Sujie
Summary: In the measurement of offshore wind turbines, the measured accelerations often contain noise which makes it difficult to identify structural modal parameters. This paper proposes a displacement conversion strategy to study the modal parameter identification of offshore wind turbines with high-pile foundations. The strategy includes zero-order correction, high-pass filtering, and modal parameter identification using displacement. The results show that the developed strategy is advantageous in identifying modal parameters with high accuracy.
JOURNAL OF OCEAN UNIVERSITY OF CHINA
(2022)
Article
Engineering, Multidisciplinary
Marcin M. Luczak, Riccardo Riva, Suleyman C. Yeniceli, Steen Hjelm Madsen, Emilio Di Lorenzo
Summary: Modal testing of different test artefacts involves a series of decisions before the test, active experiment, and analyses stages. The impact of test setups on blade modal properties, particularly in fatigue tests, is important to evaluate. Experimental evidence shows that mounting blades on a test block alters the system's structural dynamics, affecting frequencies and potentially introducing new coupled modes. Additionally, adding exciters of similar mass to the blade influences natural frequencies and structural damping ratios.
Article
Green & Sustainable Science & Technology
Christopher Jung, Dirk Schindler
Summary: The goal of this study is to quantify the meteorological, geographical, and technical properties of the current global offshore wind turbine fleet. The factors studied show high regional variability, with European wind turbine sites providing higher wind resources compared to Asian sites, where turbines operate in shallower water closer to the shores. These findings suggest that wind potential and siting criteria for wind turbines differ depending on the country.
RENEWABLE & SUSTAINABLE ENERGY REVIEWS
(2023)
Article
Green & Sustainable Science & Technology
Daniel Micallef, Abdolrahim Rezaeiha
Summary: Over the past decade, there has been a steady increase in scientific articles on rotor aerodynamics of offshore wind turbines, highlighting the critical role of aerodynamics in overcoming specific barriers in multi-physics systems. Current trends in research focus on the interaction between aerodynamics and other fields, such as platform hydrodynamics and control, with common approaches being coupled or uncoupled studies. The literature mainly addresses isolated floating turbines, while studies on interactions between floating turbines are limited.
RENEWABLE & SUSTAINABLE ENERGY REVIEWS
(2021)
Article
Chemistry, Multidisciplinary
Rafael A. Figueroa-Diaz, Pedro Cruz-Alcantar, Antonio de J Balvantin-Garcia
Summary: This study presents an identification methodology that allows identifying characteristic patterns of close modes in frequency through coordinate transformation and a modal parameter extraction tool, offering robustness and applicability when applied in the study of a system in the field.
APPLIED SCIENCES-BASEL
(2021)
Article
Engineering, Marine
Alba Ricondo, Laura Cagigal, Beatriz Perez-Diaz, Fernando J. Mendez
Summary: This research presents a site-specific metamodel based on the SWASH numerical model simulations, which can predict coastal hydrodynamic variables in a fast and efficient manner. The metamodel uses downscaled and dimensionality reduced synthetic database to accurately reproduce wave setup, wave heights associated with different frequency bands, and wave runup. This method has great potential in coastal risk assessments, early warning systems, and climate change projections.
Article
Engineering, Marine
Xiao Yu, Wangjun Ren, Bukui Zhou, Li Chen, Xiangyun Xu, Genmao Ren
Summary: This study investigated and compared the compression responses and energy absorption capacities of coral sand and silica sand at a strain rate of approximately 1000 s-1. The results showed that coral sand had significantly higher energy absorption capacity than silica sand due to its higher compressibility. The study findings suggest that using poorly graded coral sand can improve its energy absorption capacity.
Article
Engineering, Marine
Jingxi Zhang, Junmin Mou, Linying Chen, Pengfei Chen, Mengxia Li
Summary: This paper proposes a cooperative control scheme for ship formation tracking based on Model Predictive Control. A predictive observer is designed to estimate the current motion states of the leader ship using delayed motion information. Comparative simulations demonstrate the effectiveness and robustness of the proposed controller.
Article
Engineering, Marine
Yu Yao, Danni Zhong, Qijia Shi, Ji Wu, Jiangxia Li
Summary: This study proposes a 2DH numerical model based on Boussinesq equations to investigate the impact of dredging reef-flat sand on wave characteristics and wave-driven current. The model is verified through wave flume experiments and wave basin experiments, and the influences of incident wave conditions and pit morphological features on wave characteristics are examined.
Article
Engineering, Marine
Jayanta Shounda, Krishnendu Barman, Koustuv Debnath
Summary: This study investigates the double-average turbulence characteristics of combined wave-current flow over a rough bed with different spacing arrangements. The results show that a spacing ratio of p/r=4 offers the highest resistance to the flow, and the double-average Reynolds stress decreases throughout the flow depth. The advection of momentum-flux of normal stress shows an increase at the outer layer and a decrease near the bed region after wave imposition. Maximum turbulence kinetic energy production and diffusion occur at different layers. The turbulence structure is strongly anisotropic at the bottom region and near the outer layer, with a decrease in anisotropy observed with an increase in roughness spacing.
Article
Engineering, Marine
Meng Zhang, Lianghui Sun, Yaoguo Xie
Summary: The research proposes a method for online identification of wave bending and torsional moment in hull structures. For structures without large openings, the method optimizes sensor positions and establishes a mathematical model to improve accuracy. For structures with large openings, a joint dual-section monitoring method is proposed to simultaneously identify bending and torsional moments in multiple key cross sections.
Article
Engineering, Marine
Longming Chen, Shutao Li, Yeqing Chen, Dong Guo, Wanli Wei, Qiushi Yan
Summary: This study investigated the dynamic response characteristics and damage modes of pile wharves subjected to underwater explosions. The results showed that the main damaged components of the pile wharf were the piles, and inclined piles had a higher probability of moderate or more significant damage compared to vertical piles. The study also suggested that replacing inclined piles with alternative optimized structures benefits the blast resistance of pile wharves.
Article
Engineering, Marine
I. -C Kim, G. Ducrozet, V. Leroy, F. Bonnefoy, Y. Perignon, S. Bourguignon
Summary: Previous research focused on the accuracy and efficiency of short-term wave fields in specific prediction zones, while we developed algorithms for continuous wave prediction based on the practical prediction zone and discussed important time factors and strategies to reduce computational costs.
Article
Engineering, Marine
Hang Xie, Xianglin Dai, Fang Liu, Xinyu Liu
Summary: This study investigates the load characteristics of a three-dimensional stern model with pitch angle through a drop test, and reveals complex characteristics of pressure distribution near the stern shaft. The study also shows that the vibration characteristics of the load are influenced by the drop height and pitch angle, with the drop height having a greater effect on the high-frequency components.
Article
Engineering, Marine
Hangyuan Zhang, Wanli Yang, Dewen Liu, Xiaokun Geng, Wangyu Dai, Yuzhi Zhang
Summary: The deep-water bridge is more vulnerable to earthquake damage than the bridge standing in air. The larger blocking ratio has a significant impact on the added mass coefficient, which requires further comprehensive study. The generation mechanism of block effect is analyzed using numerical simulation software ANSYS Fluent. The results show that the recirculation zone with focus reduces the pressure on the back surface of the cylinder, resulting in the peak value of in-line force not occurring synchronously with the peak value of acceleration. The change in position and intensity of the recirculation zone with focus, as well as the change in water flow around the cylinder surface, are identified as the generation mechanism of the block effect, which has a 10% influence on the hydrodynamic force. The changing rule of the added mass coefficient with blocking ratio is discussed in detail, and a modification approach to the current added mass coefficient calculation method is suggested. Physical experiments are conducted to validate the modification approach, and the results show that it is accurate and can be used in further study and real practice.
Article
Engineering, Marine
Golnesa Karimi-Zindashti, Ozgur Kurc
Summary: This study examines the performance of an in-house code utilizing a deterministic vortex method on the rotation of circular and square cylinders. The results show that rotational motion reduces drag forces, suppresses fluctuating forces, and increases lift forces. The code accurately predicts vortex shedding suppression and identifies the emergence of near-field wakes in the flow over rotating square cylinders.
Article
Engineering, Marine
George Dafermos, George Zaraphonitis
Summary: The survivability of damaged ships is of great importance and the regulatory framework is constantly updated. The introduction of the probabilistic damage stability framework has rationalized the assessment procedure. Flooding simulation tools can be used to investigate the dynamic response of damaged ships.
Article
Engineering, Marine
Xuyue Chen, Xu Du, Chengkai Weng, Jin Yang, Deli Gao, Dongyu Su, Gan Wang
Summary: This paper proposes a real-time drilling parameters optimization method for offshore large-scale cluster extended reach drilling based on intelligent optimization algorithm and machine learning. By establishing a ROP model with long short-term memory neurons, and combining genetic algorithm, differential evolution algorithm, and particle swarm algorithm, the method achieves real-time optimization of drilling parameters and significantly improves the ROP.
Article
Engineering, Marine
Sung-Jae Kim, Chungkuk Jin, MooHyun Kim
Summary: This study investigates the dynamic behavior of a moored submerged floating tunnel (SFT) under tsunami-like waves through numerical simulations and sensitivity tests. The results show that design parameters significantly affect the dynamics of the SFT system and mooring tensions, with shorter-duration and higher-elevation tsunamis having a greater impact.
Article
Engineering, Marine
G. Clarindo, C. Guedes Soares
Summary: Environmental contours are constructed using the Inverse-First Order Reliability Method based on return periods. The paper proposes the use of the Burr distribution to model the marginal distribution of long-term significant wave heights. The newly implemented scheme results in different environmental contours compared to the reference approach.