# Investigation and Optimisation of High-Lift Airfoils for Airborne Wind Energy Systems at High Reynolds Numbers

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## Abstract

**:**

## 1. Introduction

## 2. Design Process

#### 2.1. Parametrisation

#### 2.2. Optimisation Process

- Algorithm

- Objectives

- Design Parameters

- Constraints

#### 2.3. Numerical Setup for Optimisation Evaluations

#### 2.4. Preliminary Geometry

## 3. Numerical Setup

#### 3.1. Mesh

#### 3.2. Turbulence Model

## 4. Experiment Setup

#### 4.1. Facilities and Measurement Techniques

- Force Measurements

- Pressure Measurements

#### 4.2. Model Airfoils

## 5. Results

#### 5.1. Baseline Airfoil (S1223)

#### 5.2. Optimised Airfoil with Slat (EW01)

## 6. Discussion

## 7. Summary and Conclusions

## Author Contributions

## Funding

## Data Availability Statement

## Acknowledgments

## Conflicts of Interest

## Abbreviations

AWE | Airborne wind energy |

CFD | Computational fluid dynamics |

RANS | Reynolds-averaged Navier-Stokes |

SST | Shear stress transport |

EW01 | name for optimised airfoil and slat |

IDDES | Improved delayed detached eddy simulation |

GroWiKa | Large wind tunnel at TU Berlin |

GFRP | Glass-fiber reinforced plastic |

CFRP | Carbon-fiber reinforced plastic |

FDM | Fused deposition modeling |

PET-G | Polyethylene terephthalate |

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**Figure 1.**Operation of a generic ground-gen (pumping mode) AWE system [10].

**Figure 2.**Parametrisation: thickness distribution (blue) and camber line (green), slat camber line (red).

**Figure 12.**Turbulence intensity without (left) and with transition modeling (right) at $Re\phantom{\rule{3.33333pt}{0ex}}=\phantom{\rule{3.33333pt}{0ex}}1.5\times {10}^{6}$.

**Figure 13.**Velocity-field of EW01 at $Re\phantom{\rule{3.33333pt}{0ex}}=\phantom{\rule{3.33333pt}{0ex}}1.5\times {10}^{6}$ for selected $\alpha $.

**Table 1.**Cell size $\mathsf{\Delta}$ in relation to airfoil chord c for different regions of the mesh.

Region | $\mathsf{\Delta}\xb7\mathit{c}$ |
---|---|

airfoil surface | 0.0015 |

slat surface | 0.00075 |

slat leading & trailing edge | 0.0001 |

refinement area around slat | 0.0015 |

circular refinement area | 0.01 |

outer mesh | 1 |

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**MDPI and ACS Style**

Fischer, D.; Church, B.; Nayeri, C.N.; Paschereit, C.O.
Investigation and Optimisation of High-Lift Airfoils for Airborne Wind Energy Systems at High Reynolds Numbers. *Wind* **2023**, *3*, 273-290.
https://doi.org/10.3390/wind3020016

**AMA Style**

Fischer D, Church B, Nayeri CN, Paschereit CO.
Investigation and Optimisation of High-Lift Airfoils for Airborne Wind Energy Systems at High Reynolds Numbers. *Wind*. 2023; 3(2):273-290.
https://doi.org/10.3390/wind3020016

**Chicago/Turabian Style**

Fischer, Denes, Benjamin Church, Christian Navid Nayeri, and Christian Oliver Paschereit.
2023. "Investigation and Optimisation of High-Lift Airfoils for Airborne Wind Energy Systems at High Reynolds Numbers" *Wind* 3, no. 2: 273-290.
https://doi.org/10.3390/wind3020016