# The Effects of a Morphed Trailing-Edge Flap on the Aeroacoustic and Aerodynamic Performance of a 30P30N Aerofoil

^{*}

## Abstract

**:**

_{l}/C

_{d}ratio compared with the conventional flap. The methodology reported here for the 30P30N is a quick tool for initial estimates of the far-field noise and aerodynamic performance of a morphing flap at the design stage.

## 1. Introduction

## 2. Materials and Methods

#### 2.1. Governing Equations and Numerical Schemes

#### 2.2. Geometry and Computational Domain

#### 2.3. Mesh

#### 2.4. Solver Method

^{−5}s) was chosen to achieve a Courant number of ~1. There were 10 inner iterations per timestep. A Courant number of 1 was used (refer to Timestep Study, Section 2.5), flow velocity was 30 m/s, and ∆x was the smallest mesh element size in the flow-wise direction; this gives $\Delta t=1.07\times {10}^{-5}$ seconds.

#### 2.5. Timestep Study

## 3. Results and Discussion

#### 3.1. Validation

#### 3.2. Results of Morphed and Conventional Flap Design

_{l}/C

_{d}ratio, see Table 2), compared with a higher C

_{l}/C

_{d}ratio for the conventional reference design (see Table 1).

## 4. Conclusions and Future Work

## Author Contributions

## Funding

## Acknowledgments

## Conflicts of Interest

## References

- Chen, T.-J.; Chen, S.-S.; Hsieh, P.-Y.; Chiang, H.-C. Auditory Effects of Aircraft Noise on People Living Near an Airport. Arch. Environ. Health Int. J.
**1997**, 52, 45–50. [Google Scholar] [CrossRef] [PubMed] - Whitfield, C. Nasa’s quiet aircraft technology project. In Proceedings of the 24th Congress of the International Council of the Aeronautical Sciences (ICAS 2004), Hampton, VA, USA, 1 January 2004. [Google Scholar]
- Murayama, M.; Nakakita, K.; Yamamoto, K.; Ura, H.; Ito, Y.; Choudhari, M.M. Experimental Study on Slat Noise from 30P30N Three-Element High-Lift Airfoil at JAXA Hard-Wall Lowspeed Wind Tunnel. In Proceedings of the 20th AIAA/CEAS Aeroacoustics Conference, Atlanta, GA, USA, 16–20 June 2014. [Google Scholar] [CrossRef] [Green Version]
- Jawahar, H.K.; Ali, S.A.S.; Azarpeyvand, M.; da Silva, C.R.I. Aerodynamic and aeroacoustic performance of high-lift airfoil fitted with slat cove fillers. J. Sound Vib.
**2020**, 479, 115347. [Google Scholar] [CrossRef] - Choudhari, M.M.; Lockard, D.P. Assessment of Slat Noise Predictions for 30P30N High-Lift Configuration from BANC-III Workshop. In Proceedings of the 21st AIAA/CEAS Aeroacoustics Conference, Dallas, TX, USA, 22–26 June 2015. [Google Scholar] [CrossRef] [Green Version]
- Streett, C.; Casper, J.; Lockard, D.; Khorrami, M.; Stoker, R.; Elkoby, R.; Wenneman, W.; Underbrink, J. Aerodynamic Noise Reduction for High-Lift Devices on a Swept Wing Model. In Proceedings of the 44th AIAA Aerospace Sciences Meeting and Exhibit, Reno, NV, USA, 9–12 January 2006. [Google Scholar] [CrossRef]
- Li, L.; Liu, P.; Guo, H.; Hou, Y.; Geng, X.; Wang, J. Aeroacoustic measurement of 30P30N high-lift configuration in the test section with Kevlar cloth and perforated plate. Aerosp. Sci. Technol.
**2017**, 70, 590–599. [Google Scholar] [CrossRef] - Evans, C.; Harmer, M.; Marks, O.; Tiley, S.; Willis, T.; Bouferrouk, A.; Yao, Y. Development and testing of a varia-ble camber morphing wing mechanism. In Proceedings of the International Symposium of Sustainable Aviation (ISSA), Istanbul, Turkey, 29 May–1 June 2016. [Google Scholar]
- Loudon, K.; Bouferrouk, A.; Coleman, B.; Hughes, F.; Lewis, B.; Parsons, B.; Cole, A.; Yao, Y. Further development of a variable camber morphing mechanism using the direct control airfoil geometry concept. In Proceedings of the International Symposium of Sustainable Aviation, Rome, Italy, 9–11 July 2018. [Google Scholar]
- Abdessemed, C.; Bouferrouk, A.; Yao, Y. Aerodynamic and aeroacoustic analysis of a harmonically morphing air-foil using dynamic meshing. Acoustics
**2021**, 3, 177–199. [Google Scholar] [CrossRef] - Li, W.; Liu, H. Noise Generation in Flow over a Full-Span Trailing-Edge Flap. AIAA J.
**2017**, 55, 561–571. [Google Scholar] [CrossRef] - Badshah, M.; VanZwieten, J.; Badshah, S.; Jan, S. CFD study of blockage ratio and boundary proximity effects on the performance of a tidal turbine. IET Renew. Power Gener.
**2019**, 13, 744–749. [Google Scholar] [CrossRef] - ISO. Acoustics—Noise Emitted by Machinery and Equipment—Rules for the Drafting and Presentation of a Noise Test Code; ISO 12001; ISO: Geneva, Switzerland, 1996. [Google Scholar]
- ANSYS. Ansys Fluent Theory Guide; ANSYS, Inc.: Canonsburg, PA, USA, 2019. [Google Scholar]
- Courant, R.; Friedrichs, K.; Lewy, H. On the Partial Difference Equations of Mathematical Physics. IBM J. Res. Dev.
**1967**, 11, 215–234. [Google Scholar] [CrossRef] - IdealSimulations, Courant Number. Available online: www.idealsimulations.com/resources/courant-number-cfd/ (accessed on 19 December 2021).
- Gracia, M.; Vanelderen, B.; De Roeck, W.; Desmet, W. Accurate interfacing schemes for the coupling of CFD data with high order DG methods for aeroacoustic propagation. In Proceedings of the 26th Conference on Noise and Vibration Engineering (ISMA2014), Leuven, Belgium, 15–17 September 2014; pp. 1333–1346. [Google Scholar]
- Jawahar, H.K.; Vemuri, S.; Azarpeyvand, M. Aerodynamic noise characteristics of airfoils with morphed trailing edg-es. Int. J. Heat Fluid Flow
**2022**, 93, 108892. [Google Scholar] [CrossRef] - Thomareis, N.; Papadakis, G. Effect of trailing edge shape on the separated flow characteristics around an airfoil at low Reynolds number: A numerical study. Phys. Fluids
**2017**, 29, 014101. [Google Scholar] [CrossRef] [Green Version] - Abdessemed, C.; Yao, Y.; Bouferrouk, A. Near Stall Unsteady Flow Responses to Morphing Flap Deflections. Fluids
**2021**, 6, 180. [Google Scholar] [CrossRef] - Watkins, J.C.; Bouferrouk, A. Evaluating the Effects of a Morphed Trailing Edge Flap for Aeroacoustics Applications. In Proceedings of the International Symposium on Aircraft Technology (ISATECH), Budapest, Hungary, 28–30 June 2021; Available online: https://2021.isatech.org/ (accessed on 19 December 2021).

**Figure 3.**CML flap design (CML circled in blue): wind tunnel model from (

**a**) pressure side and (

**b**) suction side (Streett et al. [6]).

**Figure 6.**Representation of CFL condition and Courant number (C), and their effects on timestep across grid spacing (each red square is the next data point).

**Figure 8.**SPL vs. frequency plot of varying CFL numbers. Tonal peaks at 4.5 kHz and 9 kHz only detectable with C = 0.7 and C = 1.

**Figure 9.**Pressure coefficient plots of numerical data against experimental data for the 30P30N aerofoil, from the work of Murayama et al. (2014) [3]: (

**a**) 3° AoA; (

**b**) 8° AoA.

**Figure 10.**Lift coefficient vs. angle of attack comparison of current numerical data with the experimental and numerical data of Murayama et al. [3].

**Figure 11.**SPL vs. Strouhal number comparison of numerical data with the experimental data of Jawahar et al. [4].

**Figure 12.**SPL vs. frequency at an 8° AoA for conventional and morphed flap designs across all flap deflections tested: (

**a**) 5° flap deflection; (

**b**) 10° flap deflection; (

**c**) 15° flap deflection; (

**d**) 20° flap deflection; (

**e**) 25° flap deflection.

**Figure 15.**3rd octave band plot for morphed and conventional flap configurations, where a mean value is made for each frequency band, representing all flap deflections in one plot.

**Figure 16.**Turbulent kinetic energy (TKE) plot at 5° flap deflection: (

**a**) conventional design; (

**b**) morphed design.

**Figure 17.**Static pressure contour plots at 20° flap deflection for: (

**a**) conventional configuration; (

**b**) morphed configuration.

**Figure 18.**Plots of velocity magnitude on streamlines around the trailing edge region at 20° flap deflection: (

**a**) conventional configuration; (

**b**) morphed configuration.

Flap Deflection (°) | ${\mathit{C}}_{\mathit{l}}$ | ${\mathit{C}}_{\mathit{d}}$ | ${\mathit{C}}_{\mathit{l}}$$/{\mathit{C}}_{\mathit{d}}$ |
---|---|---|---|

5 | 1.24 | 0.0758 | 16.37 |

10 | 1.51 | 0.0873 | 17.34 |

15 | 1.8 | 0.114 | 15.81 |

20 | 2.02 | 0.127 | 15.95 |

25 | 1.91 | 0.139 | 13.77 |

Flap Deflection (°) | ${\mathit{C}}_{\mathit{l}}$ | ${\mathit{C}}_{\mathit{d}}$ | ${\mathit{C}}_{\mathit{l}}$$/{\mathit{C}}_{\mathit{d}}$ |
---|---|---|---|

5 | 1.33 | 0.0734 | 18.08 |

10 | 1.66 | 0.0919 | 18.05 |

15 | 1.69 | 0.110 | 15.41 |

20 | 1.94 | 0.146 | 13.25 |

25 | 2.06 | 0.182 | 11.30 |

Publisher’s Note: MDPI stays neutral with regard to jurisdictional claims in published maps and institutional affiliations. |

© 2022 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 (https://creativecommons.org/licenses/by/4.0/).

## Share and Cite

**MDPI and ACS Style**

Watkins, J.; Bouferrouk, A.
The Effects of a Morphed Trailing-Edge Flap on the Aeroacoustic and Aerodynamic Performance of a 30P30N Aerofoil. *Acoustics* **2022**, *4*, 248-267.
https://doi.org/10.3390/acoustics4010015

**AMA Style**

Watkins J, Bouferrouk A.
The Effects of a Morphed Trailing-Edge Flap on the Aeroacoustic and Aerodynamic Performance of a 30P30N Aerofoil. *Acoustics*. 2022; 4(1):248-267.
https://doi.org/10.3390/acoustics4010015

**Chicago/Turabian Style**

Watkins, Joseph, and Abdessalem Bouferrouk.
2022. "The Effects of a Morphed Trailing-Edge Flap on the Aeroacoustic and Aerodynamic Performance of a 30P30N Aerofoil" *Acoustics* 4, no. 1: 248-267.
https://doi.org/10.3390/acoustics4010015