Studying the Wake of a Tidal Turbine with an IBM-LBM Approach Using Realistic Inflow Conditions

Mickael Grondeau,Jean Charles Poirier,Emmnuel Poizot,Philippe Mercier,Sylvain S Guillou,Yann Méar

doi:10.3390/en15062092

Mickael Grondeau, Jean Charles Poirier + Show 4 more

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https://doi.org/10.3390/en15062092

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Abstract

The lattice Boltzmann method is used to model a horizontal axis tidal turbine. Because tidal turbines generally operate in highly turbulent flows, a synthetic eddy method is implemented to generate realistic turbulent inflow condition. The approach makes use of the open-source code Palabos. Large eddy simulation is employed. A coupling between an immersed boundary method and a wall model is realized to model the turbine. Calculations are performed at two different turbulence rates. The upstream flow condition is first set up to match with experimental results. Numerical simulations of a tidal turbine with realistic turbulent inflow conditions are then realized with the lattice Boltzmann method. The approach is found to be in good agreement with experimental data. Cases with three different inflow turbulence rates are simulated. An almost linear evolution with the turbulence rate is observed for the axial velocity deficit. An analysis of the propagation of tip-vortices in the close wake is carried out. It is found that turbulence has a great impact on the tip-vortices propagation envelope.

Highlights

Worldwide energy consumption keeps increasing and some areas still do not have access to electricity
The slope linear regression through the data points employed in [43,44] was used to estimate the rate of change in the distance from the inlet of the lattice Boltzmann method (LBM) domain with turbulence rates
Simulations results are compared with experimental results, investigated wake quantities are the average axial velocity and the average turbulence rate

Summary

Introduction

Worldwide energy consumption keeps increasing and some areas still do not have access to electricity. In order to provide more clean energy, new concepts have been created by academia and industry. Among those concepts are renewable marine energy devices and more precisely tidal turbines. Induced displacements are not constant and can highly vary from one place to another In some sites, they create a strong current, like in the Alderney Race where it can go up to 5 ms−1. Milne et al [4] observed that the stream-wise turbulence rate varies between 7% and more than 20% along a tidal cycle at the sound of Islay, Scotland. The project Turbulence In Marine Environment (TIME) [2] lists several problems associated with marine turbulence It quotes that turbulence may affect the turbines’ integrity, performance and hydrodynamics.

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