Determining the performance of a Diffuser Augmented Wind Turbine using a combined CFD/BEM method

Joss E Kesby,David R Bradney,Philip D Clausen,David Goodfield

doi:10.1051/rees/2017032

Abstract

Traditionally, the optimisation of a Diffuser Augmented Wind Turbine has focused on maximising power output. However, due to the often less than ideal location of small-scale turbines, cut-in speed and starting time are of equal importance in maximising Annual Energy Production, which is the ultimate goal of any wind turbine design. This paper proposes a method of determining power output, cut-in speed and starting time using a combination of Computational Fluid Dynamics and Blade Element Momentum theory. The proposed method has been validated against published experimental data.

Highlights

The wind conditions found on a typical small wind turbine site are well suited for a Diffuser Augmented Wind Turbine (DAWT)
The work presented in this paper is part of an ongoing project aimed at producing a DAWT designed to maximise the Annual Energy Production (AEP) for a typical small-scale wind turbine site
The velocity augmentation of the empty diffuser is integral to the combined Computational Fluid Dynamics (CFD)/Blade Element Momentum (BEM) method for predicting both power output and starting performance. van Dorst provides experimental results for the relative velocity profile 70 mm behind the blade plane for three unspecified wind tunnel inlet velocities [11]

Summary

Introduction

The wind conditions found on a typical small wind turbine site are well suited for a Diffuser Augmented Wind Turbine (DAWT). The work presented in this paper is part of an ongoing project aimed at producing a DAWT designed to maximise the Annual Energy Production (AEP) for a typical small-scale wind turbine site. Due to the lower average wind speed and higher variability of wind on a typical small wind turbine site, three additional performance characteristics have been identified as being important for high AEP: the cut-in speed, starting time and cut-out speed of the turbine. Research into optimising the starting time and cut-in speed for a DAWT has been very limited, similar research for a small-scale horizontal-axis wind turbine has indicated that the parameters are conflicting and an optimisation process will result in a Pareto Front of optimal solutions [5]

Methods

Results

Conclusion