# Fluid-Structure Interaction of Wind Turbine Blade Using Four Different Materials: Numerical Investigation

^{*}

## Abstract

**:**

## 1. Introduction

- In the published literature, there have been several studies that have investigated the effectiveness of the pitch angle on the HAWT output, either using just a few pitch angle values or using lower fidelity modeling. Consequently, a current understanding of how the pitch angle influences the turbine output is inadequate. The present study supplements the current information by using CFD calculations and FEA calculations that are validated against the standard empirical equations to investigate the impact of the blade pitch angle on the output parameter.
- The investigated operating conditions include five-pitch angles with increments of 4° and eight different wind speeds. No previous study has used these operating conditions to investigate the effects of pitch angles, which provides a more detailed understanding of how the wind turbine behavior changes for different pitch angles.
- In the previous literature, primarily the influence of pitch angles on the turbine output parameter has been studied. At the same time, the present research explains thoroughly how turbine blade pressures are altered in various pitch angles and wind speeds. Along with the change in pitch angle, this helps realistic assumptions to be made for the next step in the improvement of a horizontal axis wind turbine (HAWT) efficiency.
- The current study provides a comparison between the Von-Mises stress distribution of turbine blades for different pitch angles, different wind speeds, and different materials. To the best of our knowledge, this is the first study to report the pitch angle effect on Von-Mises stress distribution.
- Although the one-way fluid-structure interaction has been performed for the wind turbine, this technique has not been applied to study the effect of pitch angles on the performance parameter of the wind turbine blade by applying four different materials for structural analysis. A detailed analysis is conducted to clarify the influence of pitch angle on HAWT aerodynamics. The research examines the torque, power variance, pressure distribution, stress distribution, and deformation after changing various pitch angles, which the authors have previously not conducted in such detail for such turbines. The knowledge presented will significantly help researchers and design engineers to develop creative wind turbines that are more economical.

## 2. Methodology

#### 2.1. CFD Modeling

#### 2.1.1. Design of Wind Turbine Model

#### 2.1.2. Computational Domain and Boundary Conditions

#### 2.1.3. Meshing

#### 2.1.4. Turbulence Modeling

_{k}represents the generation of turbulence kinetic energy due to mean velocity gradients, and G

_{w}represents the generation of ω. Whereas Γ

_{k}, Γ

_{w}represents the effective diffusivity of k and ω and Y

_{k}, Y

_{w}represents the dissipation of k and ω, D

_{w}represents the cross-diffusion term, and S

_{w}are user-defined source terms.

#### 2.1.5. Solution Setup

^{3}and 1.7894 × 103 kg/ms.

#### 2.1.6. Residuals Convergence Criteria

#### 2.2. FEA Modeling

#### 2.3. One-way FSI Coupling

## 3. Results and Discussion

#### 3.1. Three-Dimensional Simulations

#### 3.1.1. Estimation of Torque and Power

#### 3.1.2. Verifications

^{2}

#### 3.1.3. Pressure Distributions

#### 3.1.4. Deformation and Von-Mises Stress

## 4. Conclusions

- A pitch angle of 16° is not suitable for the analysis and for the experimental purpose as it shows a decrease in the power value for wind speed.
- A pitch angle of 0°, 4°, and 8° has shown a better power outcome as compared to other pitches.
- The torque acting on the blade is maximum when a pitch angle of 4° and 8° is considered for the analysis.
- For every pitch angle and wind speed, a maximum deformation of the blade obtained for Kevlar, Technora, and Glass-s comes to be lower than the clearance of the tower (3.3 m), suggesting that, under all operating conditions, the blade cannot hit the tower.
- The maximum equivalent stress (Von-Mises stress) for Kevlar, Glass-S, and Glass-E are found to be well suited to the design limit.
- It is observed that for a pitch angle of 0°, velocity 11 m/s, pitch angle of 8°, velocity 20 m/s, pitch angle of 4°, velocity 24 m/s, and pitch angle of 10°, and velocity 10 m/s blade deformation exceeds the tower clearance when the Swancor-2511 A material is considered.
- The finding of the current study supports improvement of the aerodynamic performance of a horizontal axis wind turbine in the following ways:
- Optimization of the wind turbine blade is conceivable by detecting the best pitch angle.
- It is possible to boost the mean electrical power significance by outfitting wind turbines with section pitch angles distributions.
- Identifying best pitch angles can help in developing a control strategy to reduce loads fluctuation and regulate the power output.
- The results from the numerical simulation can help in developing a small wind turbine with various pitch angles, which can be tested inside a low-speed wind tunnel. This experiment can help in verifying the feasibility and efficiency of the turbine. The experimental results can be excellent benchmark data for the computational and theoretical modelers to validate their models before undertaking simulations of more realistic conditions both in terms of turbine support and geometry.
- This article can help the researcher derive an optimal blade pitch function based on the best pitch angle, which can further help in designing the blade pitch control device.
- From this study, one can identify the desirable pitch angle and can reduce the strength of the unsteady load caused by the wave current action without too much loss of power.

## Author Contributions

## Funding

## Conflicts of Interest

## References

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**Figure 1.**(

**a**) Three-dimensional wind turbine blade; (

**b**) airfoil used in the blade; (

**c**) chord and twist distribution of airfoil.

**Figure 4.**Computational fluid dynamics (CFD) mesh: (

**a**) Mesh of the computational domain; (

**b**) intricate view of the mesh around the blade; (

**c**) inflation layer; (

**d**) sphere of influence.

**Figure 11.**(

**a**) Tangential velocity along the span; (

**b**) reaction force acting radially towards the hub.

**Figure 12.**Pressure distribution of blade for different wind speeds at various pitch angles: (

**a**) Maximum pressure; (

**b**) minimum pressure.

**Figure 13.**Pressure distribution of blade for different pitch angles at various wind speeds: (

**a**) Maximum pressure; (

**b**) minimum pressure.

**Figure 14.**Deformation and Von-Mises stress of the blade for different materials and a zero-degree pitch angle at different wind speedsA. (

**a**) Glass-S; (

**b**) Kevlar; (

**c**) Technora (

**d**) Swancor-2511 A

Parameters | Value | Unit |
---|---|---|

Rated power | 1500 | KW |

No. of blades | 3.0 | Not Applicable |

Rotor diameter | 86.5 | Metre |

Rated wind speed | 11.5 | m/s |

Rotational velocities | 21.21 | rpm |

Pitch angle | 0, 4, 8, 12, 16, | degree |

Velocities | 8, 9, 10, 11, 12, 16, 20, 24 | m/s |

Factors | Values |
---|---|

Side boundaries | Periodic boundary condition |

Pressure outlet | 1 atm |

Turbulent intensity | 5% |

Turbulent viscosity | 10 |

Parameter | Mesh Size at the Blade Surface | |||
---|---|---|---|---|

0.5 m | 0.4 m | 0.3 m | 0.2 m | |

Torque (Nm) | 12,895 | 18,365 | 22,518 | 23,097 |

elements | 163,217 | 208,431 | 356,628 | 624,099 |

Control Method | Type of Mesh | Sizing | |||
---|---|---|---|---|---|

Global mesh control | Tetrahedral | Advance size function | |||

Curvature (coarse) | Proximity (medium) | ||||

nodes | elements | nodes | Elements | ||

32,736 | 185,999 | 60,778 | 34,3017 | ||

Local mesh control | hexahedral | Steps | nodes | element | |

Match control | 71,643 | 356,628 | |||

Element size | 0.3 | ||||

Inflation | |||||

Sphere of influence | |||||

Sphere radius | 30 m | ||||

Element size | 2 m |

Material Name | Elastic Modulus [GPa] | Density [Kg/m^{3}] |
---|---|---|

Kevlar | 179 | 1470 |

Technora | 70 | 1390 |

Glass-S | 88 | 2540 |

Swancor-2511A | 19.2 | 1859 |

Pitch (Degree) | V (m/s) | Tangential Velocity | ||
---|---|---|---|---|

Numerical | Analytical | Error (%) | ||

8° | 12 | 98 | 96.015 | 2.067 |

Material | Radial Force (N) | Material | Radial Force (N) | ||||
---|---|---|---|---|---|---|---|

Kevlar | Technora | ||||||

Pitch (Degree) | V (m/s) | Numerical | Analytical | Error (%) | Numerical | Analytical | Error (%) |

8° | 12 | 1.50 × 10^{6} | 1,473,265.61 | 1.92323677 | 1.42 × 10^{6} | 1,418,564 | 0.101206 |

Material | Radial Force (N) | Material | Radial Force (N) | ||||
---|---|---|---|---|---|---|---|

Swancor-2511 A | Glass-S | ||||||

Pitch (Degree) | V (m/s) | Numerical | Analytical | Error (%) | Numerical | Analytical | Error (%) |

8° | 12 | 1.89 × 10^{6} | 1,888,030.386 | 0.088431517 | 2.59 × 10^{6} | 2,592,159.361 | 0.059435 |

Velocity (m/s) | Glass-S (m) | Kevlar (m) | Technora (m) | Swancor-2511 A (m) |
---|---|---|---|---|

8 | 0.55123 | 0.29617 | 0.70182 | 1.7665 |

9 | 0.61139 | 0.33111 | 0.78548 | 1.9949 |

10 | 0.67586 | 0.36432 | 0.86468 | 2.1908 |

11 | 0.73686 | 0.39832 | 0.94582 | 3.3891 |

12 | 0.79715 | 0.43714 | 1.0252 | 2.5813 |

16 | 1.1564 | 0.56919 | 1.4525 | 5.1838 |

20 | 0.050511 | 0.016281 | 0.036135 | 0.12669 |

24 | 1.2694 | 0.69886 | 1.6568 | 4.1439 |

Velocity (m/s) | Glass-S (m) | Kevlar (m) | Technora (m) | Swancor-2511 A (m) |
---|---|---|---|---|

8 | 0.22622 | 0.11255 | 0.26859 | 0.70576 |

9 | 0.26927 | 0.14384 | 0.34039 | 0.8738 |

10 | 0.3363 | 0.17497 | 0.41434 | 1.0701 |

11 | 0.39292 | 0.20617 | 0.48803 | 1.2587 |

12 | 0.45096 | 0.23819 | 0.56308 | 1.4486 |

16 | 0.67612 | 0.3682 | 0.87393 | 2.2185 |

20 | 0.90612 | 0.49018 | 1.1666 | 2.9492 |

24 | 1.0938 | 0.5971 | 1.4175 | 3.5604 |

Velocity (m/s) | Glass-S (m) | Kevlar (m) | Technora (m) | Swancor-2511 A (m) |
---|---|---|---|---|

8 | 0.13246 | 0.060564 | 0.14079 | 0.39237 |

9 | 0.18135 | 1.19 ×10^{7} | 0.21102 | 0.56543 |

10 | 0.23053 | 0.11691 | 0.27955 | 0.73666 |

11 | 0.27816 | 0.14886 | 0.3526 | 0.90654 |

12 | 0.3461 | 0.17977 | 0.42606 | 1.1046 |

16 | 0.57654 | 0.30864 | 0.73251 | 1.876 |

20 | 1.6784 | 0.92248 | 2.1815 | 5.4573 |

24 | 1.008 | 0.54747 | 1.301 | 3.2951 |

Velocity (m/s) | Glass-S (m) | Kevlar (m) | Technora (m) | Swancor-2511 A (m) |
---|---|---|---|---|

8 | 0.05974 | 0.061052 | 0.13894 | 0.23501 |

9 | 0.26174 | 0.16522 | 0.39661 | 0.9515 |

10 | 0.22748 | 0.14308 | 0.3439 | 0.83118 |

11 | 0.52217 | 0.11596 | 0.2827 | 0.6858 |

12 | 0.14146 | 0.090755 | 0.21136 | 0.52744 |

16 | 0.061012 | 0.032496 | 0.047455 | 0.15458 |

20 | 0.27501 | 0.14175 | 0.34118 | 0.89583 |

24 | 0.51484 | 0.27271 | 0.64256 | 1.6647 |

Velocity (m/s) | Glass-S (m) | Kevlar (m) | Technora (m) | Swancor-2511 A (m) |
---|---|---|---|---|

8 | 0.49259 | 0.28613 | 0.68602 | 1.7075 |

9 | 1.4003 | 0.27395 | 0.65709 | 1.636 |

10 | 0.89309 | 0.4395 | 1.1227 | 4.0426 |

11 | 0.043996 | 0.21269 | 0.53191 | 1.7097 |

12 | 0.45884 | 0.23969 | 0.61567 | 2.1882 |

16 | 0.22886 | 0.1448 | 0.34868 | 0.84425 |

20 | 0.039418 | 0.034896 | 0.086884 | 0.19509 |

24 | 0.21318 | 0.0905 | 0.22869 | 0.89097 |

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**MDPI and ACS Style**

Roul, R.; Kumar, A.
Fluid-Structure Interaction of Wind Turbine Blade Using Four Different Materials: Numerical Investigation. *Symmetry* **2020**, *12*, 1467.
https://doi.org/10.3390/sym12091467

**AMA Style**

Roul R, Kumar A.
Fluid-Structure Interaction of Wind Turbine Blade Using Four Different Materials: Numerical Investigation. *Symmetry*. 2020; 12(9):1467.
https://doi.org/10.3390/sym12091467

**Chicago/Turabian Style**

Roul, Rajendra, and Awadhesh Kumar.
2020. "Fluid-Structure Interaction of Wind Turbine Blade Using Four Different Materials: Numerical Investigation" *Symmetry* 12, no. 9: 1467.
https://doi.org/10.3390/sym12091467