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PerAWaT - Performance and Wake Structure of a Full-Scale Horizontal Axis Axial Flow Turbine


Citation Fleming, C.F., McIntosh, S.C. and Willden, R.H.J. PerAWaT - Performance and Wake Structure of a Full-Scale Horizontal Axis Axial Flow Turbine, ETI, 2012. https://doi.org/10.5286/UKERC.EDC.000413.
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Author(s) Fleming, C.F., McIntosh, S.C. and Willden, R.H.J.
Project partner(s) University of Oxford
Publisher ETI
DOI https://doi.org/10.5286/UKERC.EDC.000413
Download MRN_MA1003_23.pdf document type
Abstract The Performance Assessment of Wave and Tidal Array Systems (PerAWaT) project, launched in October 2009 with £8m of ETI investment. The project delivered validated, commercial software tools capable of significantly reducing the levels of uncertainty associated with predicting the energy yield of major wave and tidal stream energy arrays. It also produced information that will help reduce commercial risk of future large scale wave and tidal array developments.

This report contains results and analysis of 3D RANS simulated flows through a generic full scale tidal turbine operating in various flow conditions. Conditions simulated include varying levels of shear, vertical position through the water column, turbine spacing and yaw angle. Additionally simulations of a towerless rotor are presented, including a comparison to the results of the University of Edinburgh model ofthe same towerless rotor. Results presented include thrust and power metrics as well as wake profiles. Results are analysed and contrasted with respect to perturbations in each flow condition leading to observations on their influence.

In particular shear is observed to increase the power delivered by the turbine (with mass flux through the channel held constant), as is increasing the elevation of the turbine through the shear profile. Additionally shear is observed to increase the rate of wake recovery. Reducing the lateral spacing, and therefore increasing the area blockage ratio, increases the thrust and power delivered by the turbine, consistent with existing theory. Removing the tower from the simulations increases the thrust and power experienced by the turbine, as well as removing the torque ripple. Lower power is extracted by the turbine when operating in yawed flows,and a lower thrust coefficient is observed. However, the blade loading is distinctly different from the unyawed cases, as shown in plots of azimuthally-distributed rotor torque.

Comparison to the University of Edinburgh simulation results is done on a consistent area blockage basis.

The turbine wake is parameterised by considering a force balance for a turbine operating in a confined flow, and converting the resulting ‘top-hat’ wake velocity profile into an Gaussian distribution with equivalent momentum and standard deviation. This model is valid at the end of the near-wake. The near-wake ends at a downstream location where the pressure has equalised in the cross-stream directionand the velocity profile exhibits a self-similar form. For the current set of simulations this point has been identified at a distance of five diameters downstream of the rotor plane.

Relationships between operating conditions and wake model parameters are determined.

All of the results presented here are based on unsteady blade-resolved simulations, where the simulated flow field has been averaged over one full rotor revolution.
Associated Project(s) ETI-MA1003: Performance Assessment of Wave and Tidal Array Systems (PerAWaT)
Associated Dataset(s) No associated datasets
Associated Publication(s)

ETI Insights Report - Wave Energy

PerAWaT - A Parameterization of the end-of-Near-Wake Region for a Conventional Low Solidity and an Open-Centre High-Solidity Tidal Current Turbine (WG3 WP5 D3)

PerAWaT - An Investigation into the effect of Ambient Turbulence Levels on the Wakes of a Conventional Low-Solidity and an Open-Centre High-Solidity Tidal Current Turbine (WG3 WP5 D4)

PerAWaT - Array Scale Experiment Specification (WG4 WP2 D1)

PerAWaT - Array Scale Experimental Test Report (WG4 WP2 D5)

PerAWaT - Calibration Report for Scale Model Experiments (WG4 WP2 D4)

PerAWaT - Choice of Numerical Model (WG3 WP6 D1)

PerAWaT - Code Development in TELEMAC2D and TELEMAC3D in order to allow for the implementation of Parametric Characterization of Arrays (WG3 WP3 D2)

PerAWaT - Comparison with EDF (WG3 WP6 D6)

PerAWaT - Consent Licence for Installation of 1:10th Scale Tidal Turbines in Strangford Lough, Northern Ireland (WG4 WP5 D1)

PerAWaT - DIA Methodology Report

PerAWaT - Design and Characterisation of Array Emulators (WG4 WP4 D2)

PerAWaT - Design and Specification of Ducted Disc Experiments (WG4 WP3 D1)

PerAWaT - Design and Testing Specification (WG4 WP4 D1)

PerAWaT - Design of Equipment for Scale Model Experiments (WG4 WP2 D2)

PerAWaT - Development of Free Surface Wave Model for an Axial Flow Tidal Turbine

PerAWaT - Development of a Computational Fluid Dynamics Mesoscale Tidal Channel Model

PerAWaT - Development of a Computational Fluid Dynamics Model for a Horizontal Axis Tidal Current Turbine WG3 WP5 D1)

PerAWaT - Development of a Computational Fluid Dynamics Model for an Open-Centre Tidal Current Turbine (WG3 WP5 D2)

PerAWaT - Experiment Data, Quality Controlled and Delivered (WG4 WP3 D2)

PerAWaT - Experimental and Computation Investigations into Ducted Porous Discs and Rotors at Low Blockage (WG4 WP3 D3)

PerAWaT - Final Summary Report

PerAWaT - GH Blockage Modelling Report (WG3 WP4 D1)

PerAWaT - GH Device Scale Modelling Report

PerAWaT - GH Far Wake Modelling Report (WG3 WP4 D5)

PerAWaT - GH Inter-Array Scale Modelling Report (WG3 WP4 D6)

PerAWaT - GH Near Wake Modelling Report (WG3 WP4 D2)

PerAWaT - Identification of Test Requirements and Physical Model Design (WG4 WP1 D1)

PerAWaT - Implementation Report: Frequency-Domain Model (WG1 WP1 D2)

PerAWaT - Implementation Report: Time-Domain Model (WG1 WP1 D3)

PerAWaT - Implementation of Wave Energy Converters in Spectral Wave Models (WG1 WP2 D2)

PerAWaT - Influence of Free Surface Waves on the Performance and Wake Structure of a Ducted Horizontal Axis Tidal Turbine (WG3 WP1 D7)

PerAWaT - Influence of Free Surface Waves on the Performance and Wake Structure of a Horizontal Axis Tidal Turbine

PerAWaT - Large Array Testing

PerAWaT - Methodology Report (WG1 WP1 D1B)

PerAWaT - Methodology and site case analysis for the SpecWEC modelling tool

PerAWaT - Non-Linear Model Description Report (WG1 WP1 D7)

PerAWaT - Numerical Modelling of Tidal Turbine Arrays Involving Interactions within an Array: Development of the Level-Set Free Surface Model

PerAWaT - Numerical Modelling of Tidal Turbine Arrays Involving Interactions within an Array: Implementation of the Zero Tangential Shear Condition

PerAWaT - Performance and Wake Structure of a Model Horizontal Axis Axial Flow Turbine

PerAWaT - Rationalised Flow Field Modelling Report (WG3 WP4 D4)

PerAWaT - Regional Scale Plug-In Protocol (WG3 WP4 D10)

PerAWaT - Report of Calibrated Numerical Models of Anglesey and the Bristol Channel, including Validation Against Measured Data (WG3 WP6 D4B)

PerAWaT - Report on Assessment of the Impact of Energy Extraction for the Horizontal Axis Tidal Turbine on Large Scale Tidal Characteristics at Example UK Sites (WG3 WP6 D8)

PerAWaT - Report on Characterisation and Assessment of the Availability of Resource at Example UK Sites (WG3 WP6 D7)

PerAWaT - Report on Comparisons of Nonlinear Models with Experimental Data for both Single Devices and Arrays of Devices (WG1 WP1 D1)

PerAWaT - Report on Model Setup for Ducted Horizontal-Axis Axial Flow Turbines

PerAWaT - Report on Model Setup for Horizontal Axis Axial Flow Turbines (WG3 WP1 D1)

PerAWaT - Report on Non-Linear Analysis of Single and Arrays of Free Floating Devices (WG1 WP1 D9)

PerAWaT - Report on Nonlinear Analysis of a Single Controlled Device in Irregular Seas (WG1 WP1 D11), AND Report on Nonlinear Analysis of Controlled Arrays in Irregular Seas (WG1 WP1 D12)

PerAWaT - Report on Responses and Power Take-Off from Controlled Devices in Regular Waves (WG1 WP1 D10)

PerAWaT - Report on the Inclusion of FDC Tidal Arrays into DG-ADCIRC Model (WG3 WP6 D5)

PerAWaT - Representation of Wave Energy Converters in Spectral Wave Models (WG1 WP2 D1)

PerAWaT - Scientific Report for the SpecWEC Modelling Tool - Part 1

PerAWaT - Selection of Appropriate Example Sites and Acquisition of Necessary Data to define Site Characteristics (WG3 WP6 D3)

PerAWaT - SpecWec Beta Version Release

PerAWaT - Test Schedule and Test System Design of 1:10th Scale Tidal Turbines in Strangford Lough, Northern Ireland (WG4 WP5 D2)

PerAWaT - Tidal Array Scale Numerical Modelling Interactions within a Farm (Steady Flow) WG3 WP2 D5a

PerAWaT - Tidal Array Scale Numerical Modelling: Interactions within a Farm (Unsteady Flow) WG3 WP2 D5b

PerAWaT - Tidal Array Scale Numerical Modelling: Level Set Technique Implementation within Code Saturne, Validation of the Combined Implementation (Flow Solver)

PerAWaT - Tidal Basin Modelling: the Alderney Race, the Pentland Firth and the Paimpol-Bréhat Sites Modelled in Telemac Software WG3 WP3 D1

PerAWaT - Tidal Farm Modelling: the Alderney Race, the Pentland Firth and the Paimpol-Bréhat Sites Modelled in Telemac Software (WG3 WP3 D3)

PerAWaT - Tidalfarmer Interim Model Validation Report (WG3 WP4 D18)

PerAWaT - Tidalfarmer Model Validation And Uncertainties (WG3 WP4 D19)

PerAWaT - User Report for the SpecWEC Modelling Tool - Part 2

PerAWaT - Validation and Verification of the SpecWEC Numerical Modeling Tool

PerAWaT - Verification of Code (WG3 WP6 D2)

PerAWaT - Weakly-Nonlinear Hydrodynamics of Freely Floating WECS (WG1 WP1 D8)

PerAWaT- Report of Calibrated Numerical Models of Pentland Firth, including Validation Against Measured Data (WG3 WP6 D4A )

PerAWaT- Tidal Coastal Basin Numerical Modelling: Large Scale Effects of Tidal Energy Extraction (WG3 WP3 D4)