Characterisation of current and turbulence in the FloWave Ocean Energy Research Facility

Duncan R.J Sutherland,Donald R Noble,Jeffrey Steynor,Thomas Davey,Tom Bruce

doi:10.1016/j.oceaneng.2017.02.028

Duncan R.J Sutherland, Donald R Noble + Show 3 more

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https://doi.org/10.1016/j.oceaneng.2017.02.028

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Journal: Ocean Engineering	Publication Date: May 3, 2017
Citations: 30	License type: cc-by

Affiliation: University of Edinburgh

Abstract

Tidal energy is a developing industry and requires high precision test facilities which replicate the full-scale flows as accurately as possible to develop new technologies. In particular, the spatial and temporal variation must be well understood. FloWave is a state-of-the-art test facility with the ability to produce multi-directional waves and currents. This work investigates the mean and turbulent flow parameters throughout the tank using an ADV. The goal is to provide a comprehensive characterisation of the flow in the tank, in a robust and repeatable manner. These flow parameters are then compared to sample data from field measurements for context.The turbulence intensities are normally distributed in the range of 5–11% and integral lengthscales were log-normally distributed over a 0.18–0.41m range across the test area. The Reynolds stresses showed the streamwise-vertical pair were relatively constant throughout the depth, with values in the range −0.31 to 0.15Pa, while the transverse-vertical pair show high vertical variation with values of −1.35 to 0.20Pa. For the majority of locations the flow metrics are generally realistic compared with those measured at the Fall of Warness site. This work improves the understanding of flow behaviour in the tank, facilitating higher confidence testing of scaled devices.

Highlights

The FloWave Ocean Energy Research Facility allows the scale testing of marine energy extraction devices, with the ability to create realistic sea-states comprising combined waves and current
The goal of this work is to present a comprehensive flow characterisation of the FloWave facility. This will allow developers to reference the flow metrics for their own tests at the facility and give context of how they compare to full-scale site conditions
The measurement technique proved successful with the accelerometer accounting for non-turbulent fluctuations due to vibration in the Acoustic Doppler Velocimeter (ADV) data

Summary

Introduction

The FloWave Ocean Energy Research Facility allows the scale testing of marine energy extraction devices, with the ability to create realistic sea-states comprising combined waves and current. For tidal developers it is vital that the spatial and temporal variation of current is well characterised. This needs to consider variation with both depth and across the test area, as well as small scale temporal variation, i.e. turbulence. The goal of this work is to present a comprehensive flow characterisation of the FloWave facility. This will allow developers to reference the flow metrics for their own tests at the facility and give context of how they compare to full-scale site conditions. This work presents flow metrics which are used to characterise full-scale sites, assessing their variation

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