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The motion damping characteristics of wind energy devices

Sinclair, Fiona Mary; (1991) The motion damping characteristics of wind energy devices. Doctoral thesis (Ph.D), UCL (University College London). Green open access

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Abstract

Wind Assisted Ship Propulsion (WASP) uses wind energy devices such as wingsails, boundary layer control systems, wind turbines and others to augment the thrust provided by the ship's propeller. Ship motions in a seaway, particularly roll motions, can be reduced with consequent reductions in added hydrodynamic resistance, to yield fuel savings exceeding those predicted on the basis of thrust augmentation alone. Some wind assist devices compare favourably with the responses of conventional roll stabilisers. Attention is restricted to devices which are exterior to the hull and which apply direct aerodynamic forces or moments to the hull. A theoretical analysis has been developed to examine wingsails for roll, pitch and yaw derivatives (both damping and inertia) due to harmonic excitation in roll at different headings and frequencies. Unsteady lifting surface theory has been used, linearised to first order in motion velocity. The theory has been augmented by experiments in the wind tunnel. Some measurements from a fishing boat with and without sails are also included. Other devices - wind turbines, Flettner rotors, Cousteau Turbosails and conventional roll stabilisers have been examined theoretically in roll only, using a quasisteady version of the above theory, as a comparison. Published data on steady lift and drag curves have been used, but these do not account for the motion of the separation point on the surface of the rotor and cylinder in unsteady motion. Although offshore wind turbines are stationary, which makes resistance and propulsion irrelevant, they suffer from excitations due to wave motion which are unknown on land-based wind turbines, and also from shallow water effects and interactions with the aerodynamics which are unknown to deep-water offshore installations. The aerodynamic damping provided by the wind turbine will reduce the induced motions of the supporting structure. The emphasis has been on the aerodynamics, rather than the hydrodynamics, because the hydrodynamic components of roll damping have been extensively researched elsewhere, and have proved impossible to evaluate in any generally applicable manner.

Type: Thesis (Doctoral)
Qualification: Ph.D
Title: The motion damping characteristics of wind energy devices
Open access status: An open access version is available from UCL Discovery
Language: English
Additional information: Thesis digitised by ProQuest.
Keywords: Applied sciences; Ship propulsion
URI: https://discovery.ucl.ac.uk/id/eprint/10120830
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