Numerical wind load estimation of offshore floating structures through sustainable maritime atmospheric boundary layer

Abstract. The paper presents the measurement strategy and dataset collected during the COTUR (COherence of TURbulence with lidars) campaign. This field experiment took place from February 2019 to April 2020 on the southwestern coast of Norway. The coherence quantifies the spatial correlation of eddies and is little known in the marine atmospheric boundary layer. The study was motivated by the need to better characterize the lateral coherence, which partly governs the dynamic wind load on multi-megawatt offshore wind turbines. During the COTUR campaign, the coherence was studied using land-based remote sensing technology. The instrument setup consisted of three long-range scanning Doppler wind lidars, one Doppler wind lidar profiler and one passive microwave radiometer. Both the WindScanner software and Lidar Planner software were used jointly to simultaneously orient the three scanner heads into the mean wind direction, which was provided by the lidar wind profiler. The radiometer instrument complemented these measurements by providing temperature and humidity profiles in the atmospheric boundary layer. The preliminary results show an undocumented variation of the lateral coherence with the distance from the coast. The scanning beams were pointed slightly upwards to record turbulence characteristics both within and above the surface layer, providing further insight on the applicability of surface-layer scaling to model the turbulent wind load on offshore wind turbines.

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Investigation of the atmospheric boundary layer characteristics on gust factor for the calculation of wind load

10.1063/1.4984496 ◽

2017 ◽

Cited By ~ 2

Author(s):

Farzin Ghanadi ◽

Matthew Emes ◽

Jeremy Yu ◽

Maziar Arjomandi ◽

Richard Kelso

Keyword(s):

Boundary Layer ◽

Atmospheric Boundary Layer ◽

Wind Load ◽

Gust Factor

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Numerical Modeling Practice and Verification of the Wind Load Estimation for FPSO and Semi-Submersible

Volume 1: Offshore Technology; Offshore Geotechnics ◽

10.1115/omae2019-96429 ◽

2019 ◽

Author(s):

SeongMo Yeon ◽

Hyunchul Jang ◽

Jang Whan Kim ◽

JooSung Kim ◽

Bo Woo Nam ◽

...

Keyword(s):

Boundary Layer ◽

Model Test ◽

Wind Profile ◽

Domain Size ◽

Wind Load ◽

Computational Domain ◽

Ocean Engineering ◽

Blind Test ◽

Floating Structures ◽

Modeling Practice

Abstract This paper summarizes a joint effort, TESK JDP, initiated by TechnipFMC, ExxonMobil Upstream Research Company (EMURC), Samsung Heavy Industries (SHI) and Korea Research Institute of Ships & Ocean Engineering (KRISO) in order to develop reliable modeling practices for the application of Computational Fluid Dynamics (CFD) to the design of the offshore floating structures. The modeling practice for the wind load on offshore floating structures, which was one of the topics in this JDP, was studied and verified against model test results. The wind load on the offshore floating structures mostly depends on the shape of the wind profile rather than the design wind speed. Much weight is put on the generation and retainment of the wind profile within the computational domain. The modeling practice for generating the wind profile referred to as sustainable atmospheric boundary layer (ABL) or horizontally homogeneous turbulent boundary layer (HHTBL) as well as domain size, mesh strategy, turbulence model are used to perform wind load simulations for a semi-submersible and FPSO respectively as a blind test between JDP members. In order to minimize uncertainties from geometric similarity, special care was taken during the simulation and model test for the FPSO due to the complicated top side modules. Given the modeling practice, the results are compared between JDP members and show consistent tendency. Also, a good agreement was observed for the hydrodynamic coefficients of the wind load for both the FPSO and semi-submersible.

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Numerical Modeling of Neutrally-Stable and Sustainable Atmospheric Boundary Layer for the Wind Load Estimation on an Offshore Platform

Volume 1: Offshore Technology ◽

10.1115/omae2018-78699 ◽

2018 ◽

Cited By ~ 2

Author(s):

Jang Whan Kim ◽

Hyunchul Jang ◽

Wei Xu ◽

Zhirong Shen ◽

Mustafa Kara ◽

...

Keyword(s):

Boundary Layer ◽

Numerical Modeling ◽

Wind Profile ◽

Task Force ◽

Wind Load ◽

Load Estimation ◽

Joint Effort ◽

Cfd Simulations ◽

Research Institutes ◽

Offshore Industry

This paper summarizes a joint effort among operators, class societies, research institutes, shipyards, and engineering companies to verify a common modeling practice to generate a sustainable wind profile in CFD simulations for wind tunnel tests. The same numerical guideline is applied to various CFD software commonly used in the offshore industry. This is part of the effort from the CFD Task Force under the SNAME OC-8 Panel, “Guidance on Wind Technologies.” The verification results show that the sustainable wind profile can be generated within 1% tolerance from the target wind profile, for all five CFD software participated. The uncertainties in the wind load are also contained within 4% for the semisubmersible hull tested in this study with a traditional turbulence model and the 1%-tolerance wind profile, regardless of the CFD software.

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The COTUR project: remote sensing of offshore turbulence for wind energy application

Atmospheric Measurement Techniques ◽

10.5194/amt-14-6137-2021 ◽

2021 ◽

Vol 14 (9) ◽

pp. 6137-6157

Author(s):

Etienne Cheynet ◽

Martin Flügge ◽

Joachim Reuder ◽

Jasna B. Jakobsen ◽

Yngve Heggelund ◽

...

Keyword(s):

Remote Sensing ◽

Boundary Layer ◽

Surface Layer ◽

Atmospheric Boundary Layer ◽

Wind Turbines ◽

Microwave Radiometer ◽

Wind Load ◽

Offshore Wind ◽

Data Set ◽

Offshore Wind Turbines

Abstract. The paper presents the measurement strategy and data set collected during the COTUR (COherence of TURbulence with lidars) campaign. This field experiment took place from February 2019 to April 2020 on the southwestern coast of Norway. The coherence quantifies the spatial correlation of eddies and is little known in the marine atmospheric boundary layer. The study was motivated by the need to better characterize the lateral coherence, which partly governs the dynamic wind load on multi-megawatt offshore wind turbines. During the COTUR campaign, the coherence was studied using land-based remote sensing technology. The instrument setup consisted of three long-range scanning Doppler wind lidars, one Doppler wind lidar profiler and one passive microwave radiometer. Both the WindScanner software and LidarPlanner software were used jointly to simultaneously orient the three scanner heads into the mean wind direction, which was provided by the lidar wind profiler. The radiometer instrument complemented these measurements by providing temperature and humidity profiles in the atmospheric boundary layer. The scanning beams were pointed slightly upwards to record turbulence characteristics both within and above the surface layer, providing further insight on the applicability of surface-layer scaling to model the turbulent wind load on offshore wind turbines. The preliminary results show limited variations of the lateral coherence with the scanning distance. A slight increase in the identified Davenport decay coefficient with the height is partly due to the limited pointing accuracy of the instruments. These results underline the importance of achieving pointing errors under 0.1∘ to study properly the lateral coherence of turbulence at scanning distances of several kilometres.

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