Session: 09-02-08 Wind Energy: System Testing

Submission Number: 180956

Experimental Study on Hydrodynamic Forces for Semi-Submersible Floaters With Long Pontoons Considering Scale Effects 

This study examines the behavior of the 6MW floating offshore wind turbine (FOWT) design ‘Optiflow’, a single-point turret mooring semi-submersible floater that can weathervane with a guy-wire supported tower. The aim of the project is to test the feasibility of the design as a cheaper alternative to present-day FOWTs suitable for the Japanese ocean. The scope of this paper extends to experimentally understanding, at a model scale, how flow and regular waves affect forces at three of its outer columns as measured using load cells while the model is fixed to the towing carriage. Using these measurements, we calculate the net forces and moments the body experiences. The angles of attack for each case were performed at 0 and 180 degrees (or 60 degrees, due to its trigonal symmetry). The test cases were repeated by attaching vortex generator strips to two of its long pontoons to increase the flow Reynolds Number, which allows us to study the scale effects of this for design considerations at a prototype scale. The results show that as the flow speed increases, the non-dimensionalized magnitudes of heave force, roll moment, and pitch moment approach an asymptote. Additionally, the angular dependence decreases as the speed increases.

Presenting Author: Swagoto Surjo Dutta Department of Ocean Engineering and Naval Architecture, Indian Institute of Technology Kharagpur

Presenting Author Biography: Mr. Dutta is pursuing a Dual Degree (B.Tech + M.Tech) in Ocean Engineering and Naval Architecture at the Indian Institute of Technology Kharagpur, India, with expected graduation in July 2026. He is currently working on his Master's Thesis under the supervision of Dr. S. Hirabayashi (The University of Tokyo) and Dr. S. De Chowdhury (IIT Kharagpur), focusing on validating CFD models for vortex-induced motion phenomena and improving scaling through vortex generators for floating offshore wind turbines. The work continues research conducted during a Special Research Studentship at the University of Tokyo.

He demonstrated competencies in fluid-structure interaction and towing tank model testing, showcased through projects and international collaborations. With a strong foundation in technical problem-solving and research, his goal is to contribute to advancements in offshore technology and related fields by learning through practical experiences and bridging theoretical insights with experimental and real-world applications.

Authors:

Swagoto Surjo Dutta Department of Ocean Engineering and Naval Architecture, Indian Institute of Technology Kharagpur
Shinichiro Hirabayashi Department of Ocean Technology, Policy, and Environment, Graduate School of Frontier Sciences, The University of Tokyo
Kanta Matsushima Department of Ocean Technology, Policy, and Environment, Graduate School of Frontier Sciences, The University of Tokyo
Swapnadip De Chowdhury Department of Ocean Engineering and Naval Architecture, Indian Institute of Technology Kharagpur