Hull

About: Hull is a research topic. Over the lifetime, 13969 publications have been published within this topic receiving 82658 citations.

WindFloat: A floating foundation for offshore wind turbines

Abstract: This manuscript summarizes the feasibility study conducted for the WindFloat technology. The WindFloat is a three-legged floating foundation for multimegawatt offshore wind turbines. It is designed to accommodate a wind turbine, 5 MW or larger, on one of the columns of the hull with minimal modifications to the nacelle and rotor. Potential redesign of the tower and of the turbine control software can be expected. Technologies for floating foundations for offshore wind turbines are evolving. It is agreed by most experts that the offshore wind industry will see a significant increase in activity in the near future. Fixed offshore turbines are limited in water depth to ∼30–50 m. Market transition to deeper waters is inevitable, provided that suitable technologies can be developed. Despite the increase in complexity, a floating foundation offers the following distinct advantages: Flexibility in site location; access to superior wind resources further offshore; ability to locate in coastal regions with limited shallow continental shelf; ability to locate further offshore to eliminate visual impacts; an integrated hull, without a need to redesign the transition piece between the tower and the submerged structure for every project; simplified offshore installation procedures. Anchors are significantly cheaper to install than fixed foundations and large diameter towers. This paper focuses first on the design basis for wind turbine floating foundations and explores the requirements that must be addressed by design teams in this new field. It shows that the design of the hull for a large wind turbine must draw on the synergies with oil and gas offshore platform technology, while accounting for the different design requirements and functionality of the wind turbine. This paper describes next the hydrodynamic analysis of the hull, as well as ongoing work consisting of coupling hull hydrodynamics with wind turbine aerodynamic forces. Three main approaches are presented: The numerical hydrodynamic model of the platform and its mooring system; wave tank testing of a scale model of the platform with simplified aerodynamic simulation of the wind turbine; FAST, an aeroservoelastic software package for wind turbine analysis with the ability to be coupled to the hydrodynamic model. Finally, this paper focuses on the structural engineering that was performed as part of the feasibility study conducted for qualification of the technology. Specifically, the preliminary scantling is described and the strength and fatigue analysis methodologies are explained, focusing on the following aspects: The coupling between the wind turbine and the hull and the interface between the hydrodynamic loading and the structural response.

Hydroelasticity of Ships

Abstract: Preface 1. Ship response 2. The dry hull 3. More accurate analysis of hull dynamics 4. The characteristics of practical hulls 5. Ship distortion in still water 6. Wave theory 7. Symmetric generalised fluid forces 8. Symmetric response 9. Transient loading 10. Antisymmetric response to wave excitation 11. Statistical analysis of ship response 12. Responses of other marine structures to waves Bibliography Index.

The Theory of Ship Motions

Abstract: Publisher Summary This chapter highlights that the oceangoing ships are designed to operate in a wave environment that is frequently uncomfortable and sometimes hostile Unsteady motions and structural loading of the ship hull are two of the principal engineering problems that result Ships generally move with a mean forward velocity and their oscillatory motions in waves are superposed upon a steady flow field The solution of the steady-state problem is itself of interest, particularly with regard to the calculation of wave resistance in calm water The problem of ship motions in waves can be regarded as a superposition of these two special cases, but interactions between the steady and oscillatory flow fields complicate the more general problem The chapter also discusses the dynamics of ship motions that are governed by the equations of motion that balance the external forces and moments acting upon the ship, with the internal force and moment because of gravity and inertia Assuming the ship to be in stable equilibrium in calm water, its weight is balanced by the force of hydrostatic pressure Similarly, the steady drag and propulsive force are balanced These steady forces may be neglected and attention is focused on the unsteady perturbations

Measurement of flows around modern commercial ship models

Abstract: To document the details of flow characteristics around modern commercial ships, global force, wave pattern, and local mean velocity components were measured in the towing tank. Three modern commercial hull models of a container ship (KRISO container ship = KCS) and of two very large crude-oil carriers (VLCCs) with the same forebody and slightly different afterbody (KVLCC and KVLCC2) having bow and stern bulbs were selected for the test. Uncertainty analysis was performed for the measured data using the procedure recommended by the ITTC. Obtained experimental data will provide a good opportunity to explore integrated flow phenomena around practical hull forms of today. Those can be also used as the validation data for the computational fluid dynamics (CFD) code of both inviscid and viscous flow calculations.