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Title: Accelerated testing of tidal turbine main bearing in a full scale nacelle test rig
Author: Karikari-Boateng, Kwaku Ampea
ISNI:       0000 0004 6498 5072
Awarding Body: University of Exeter
Current Institution: University of Exeter
Date of Award: 2016
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Tidal Energy is one of the growing renewable energy technologies that is aimed at tackling global energy challenges. The Horizontal Axis Tidal Turbine (HATT) is an in-stream Tidal Energy Converter (TEC) which extracts kinetic energy from tidal flows. These tidal turbines face many reliability challenges due to their complexity, harsh operating environment and low accessibility. One of the component contributing significantly to the reliability of a TEC is the bearing supporting the rotating shaft within the nacelle. The reliability assessment of this component is essential during the design process and before their eventual deployments. This work is describes shaft bearing reliability assessment procedures. In recent years, the Offshore Renewable Energy (ORE) Catapult’s National Renewable Energy Centre has developed a dedicated multi axis test facility for full scale testing of tidal turbine nacelles and components (i.e. Nautilus). This work presents a methodology for testing tidal turbine shaft bearings in a representative manner in the full scale nacelle test rig, Nautilus. Two aspects are considered, namely the damage assessment and the damage replication in an accelerated manner. The damage assessment process considers the global loading on the shaft bearing and a Rigid Dynamics (RD) model has been applied to identify the local bearing loads. Local loads are converted to stress enabling the identification of stress-life relationship and bearing damage. The damage replication process is aimed to evaluate the 20 year damage and the Acceleration by Phase-shift (AbP) method has been developed to accelerate the cumulative damage. The AbP method enables the assessment of performance characteristics of shaft bearings in a laboratory environment, reducing failure rates, validate performance in a cost effective manner by reduced testing times. Within this work, novel processes for shaft bearing reliability assessments and demonstration are suggested and it concludes with the presentation of a recommended test plan for carrying out accelerated tests on a full scale bearing.
Supervisor: Johanning, Lars ; Ng, Chong ; Mueller, Markus ; Nigel, Barltrop Sponsor: Engineering and Physical Sciences Research Council (EPSRC)
Qualification Name: Thesis (Eng.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available
Keywords: Tidal Turbine ; Main bearing ; Accelerated testing ; Nacelle test ; Test plan