Ultimately tidal turbines will be installed in arrays in order to make a significant contribution to energy supply. Various factors will impact upon the optimal spacing of devices with such arrays, perhaps the most important of which will be turbine wake.
The wake may impact on downstream turbines by:
• Reducing flow velocity; resulting in lower energy production by downstream turbines.
• Increasing flow turbulence intensity; affecting the energy capture factor, and potentially increasing fatigue loading on devices downstream.
A number of experimental techniques are being applied in order to measure the velocity and turbulence characteristics of downstream wake of horizontal axis tidal turbine models at various scales.
Comparison tests include:
1. Large scale towing tests in a lake with a 10th scale model with a 1.5m diameter turbine. Measurements of the downstream wake will be made using Vector acoustic Doppler velocimeters (ADVs) and acoustic Doppler current profilers (ADCPs).
2. Tests in a laboratory flume with a 0.14m diameter turbine model. Measurements of the downstream wake will be made using particle image velocimetry (PIV).
3. Tests in a laboratory flume with a 0.25m diameter turbine model. Measurements of the downstream wake will be made using Vectrino acoustic Doppler velocimeters (ADVs).
Data from each of these experiments will be used to investigate how the different measurement techniques compare. Some discussion of scale effects will also be offered, however, this will be complicated by the use of different turbine geometries by each contributor.
Publication at EWTEC 2011:
Investigating Experimental Techniques for Measurement of the
Downstream Wake of a Tidal Turbine
Andrew Good1, Sam Rose2, Mairead Atcheson1, Gerard Hamill1, Cameron Johnstone2, Pauline MacKinnon1, Des Robinson1, Andrew Grant2 and Trevor Whittaker1
1: Queens University, Belfast, United Kingdom
2: University of Strathclyde, Glasgow, United Kingdom
Abstract: A number of experimental techniques have been applied in order to measure the velocity and turbulence characteristics of the downstream wake of horizontal axis tidal turbine models at various scales. This paper describes three such experiments undertaken at Queen’s University Belfast and the University of Strathclyde. Data from each of the experiments are presented and discussed. The advantages and disadvantages of the two data capture methods (Acoustic Doppler Velocimetry or ADV, and particle image velocimetry or PIV) are mentioned, drawing attention to the suitability of each method for certain purposes.
- Contact information
- Mairéad Atcheson, Andrew Good and Sam Rose
- Contact email
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