# Rotor Loading Characteristics of a Full-Scale Tidal Turbine

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## Abstract

**:**

## 1. Introduction

## 2. Location

#### 2.1. Ramsey Sound

#### 2.2. Tidal Resource

## 3. Turbine Description

#### 3.1. Overview

#### 3.2. Designed Rotor Characteristics

#### 3.3. Instrumentation

## 4. Results and Discussion

#### 4.1. Site Layout and Characterisation

#### 4.2. Turbine Operation

#### 4.3. Hydrodynamic Loading Coefficients

#### 4.4. Instantaneous Structural Loadings

## 5. Conclusions

## Author Contributions

## Funding

## Conflicts of Interest

## References

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**Figure 2.**Flow strength and directionality data obtained at the turbine location prior to its installation.

**Figure 7.**Time-series of the flow velocity at hub height (

**top**) and turbulence intensity (

**bottom**) averaged over 10-min periods during two full tidal cycles.

**Figure 8.**Vertical profiles of velocity (

**a**,

**b**) and turbulence intensity (

**c**,

**d**) averaged over 10 min at three selected time instances during ebb ($\mathit{e}1$, $\mathit{e}2$ and $\mathit{e}3$) and flood ($\mathit{f}1$, $\mathit{f}3$ and $\mathit{f}3$) tides and transition from ebb to flood ($e-f$) and flood to ebb ($f-e$). Dashed lines indicate turbine top and bottom tips.

**Figure 9.**Power spectral distribution of streamwise velocity during ebb (

**left**) and flood (

**right**) tides.

**Figure 10.**Normalised hub height approach flow velocity (

**top**) and turbulence intensity (

**bottom**) profiles measured with the turbine ADP during peak ebb and flood tides, i.e., $e2$ and $f2$. Comparison with vortex sheet theory predictions (Equation (7)) for different ${c}_{t}$.

**Figure 11.**Time-series of approach flow velocity (U

_{0}), turbine rotational speed (Ω), tip speed ratio (λ) and blade 1 root bending moment (${M}_{{y}_{\mathrm{root}}}$) during a test that took place in an ebb tide.

**Figure 12.**Measured dimensionless rotor loading curves in ebb (

**left**) and flood (

**right**) tides: ${c}_{{M}_{{y}_{\mathrm{root}}}}$ (

**top**); ${c}_{{F}_{{x}_{\mathrm{root}}}}$ (

**middle**); ${c}_{t}$ (

**bottom**).

**Figure 13.**Time-series of instantaneous velocity at hub height at relative distances of $x/D$ = 0.8 and 1.7 upstream of the turbine (

**a**); axial loads ${F}_{{x}_{\mathrm{root}}}$ (

**b**) and bending moments ${M}_{{y}_{\mathrm{root}}}$ (

**c**) at the root of the three blades. Data correspond to the interval the turbine operated at maximum rotational speed.

**Figure 14.**Power Spectral Density of ${F}_{{x}_{\mathrm{root}}}$ and ${M}_{{y}_{\mathrm{root}}}$ computed over a 5-min interval during ebb tide at a maximum rotational speed of $\mathsf{\Omega}$ = 11.61 RPM. The spectra were obtained from an individual blade, with the spectral energy of ${F}_{{x}_{\mathrm{root}}}$ multiplied by ${10}^{2}$ to facilitate comparison.

© 2019 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (http://creativecommons.org/licenses/by/4.0/).

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**MDPI and ACS Style**

Harrold, M.; Ouro, P. Rotor Loading Characteristics of a Full-Scale Tidal Turbine. *Energies* **2019**, *12*, 1035.
https://doi.org/10.3390/en12061035

**AMA Style**

Harrold M, Ouro P. Rotor Loading Characteristics of a Full-Scale Tidal Turbine. *Energies*. 2019; 12(6):1035.
https://doi.org/10.3390/en12061035

**Chicago/Turabian Style**

Harrold, Magnus, and Pablo Ouro. 2019. "Rotor Loading Characteristics of a Full-Scale Tidal Turbine" *Energies* 12, no. 6: 1035.
https://doi.org/10.3390/en12061035