# Gust Response of Spanwise Morphing Wing by Simulation and Wind Tunnel Testing

^{*}

## Abstract

**:**

## 1. Introduction

## 2. Test Model and Method

#### 2.1. Wind Tunnel Test Model

#### 2.2. Test Process and Data Processing Method

#### 2.2.1. Test Process

#### 2.2.2. Data Processing

_{n}and a

_{t}represent the circumferential and radial acceleration of flapping, respectively.

_{n}and F

_{t}are inertial forces in the circumferential and radial directions, respectively;

_{x}and F

_{y}in the geodetic coordinate system are obtained, where F

_{y}is the inertial force in the direction of the lift force.

#### 2.3. Selection Reasons of the Testing Parameters

#### 2.3.1. Morphing Part Length

#### 2.3.2. Flapping Amplitude

#### 2.3.3. Morphing Frequency

## 3. Results and Discussions

#### 3.1. Influence of Morphing Parameters

#### 3.1.1. The Gust Frequency Is Equal to the Morphing Frequency

#### 3.1.2. The Gust Frequency Is Different from the Morphing Frequency

#### 3.2. Gust Alleviation Effect of Instantaneous Lift Force

#### 3.3. Numerical Results and Analysis

#### 3.3.1. Numerical Simulation Model

_{m}denotes the length of the morphing part, ${\theta}^{\prime}$ denotes the morphing angle at the previous time and f denotes morphing frequency.

#### 3.3.2. Pressure and Flow Field Analysis

## 4. Conclusions

- The wind tunnel results of the spanwise morphing wing show that when the gust frequency and morphing frequency are equal, the wing with a b/3 morphing part length has the greatest lift but also produces greater drag. When the gust frequency is greater than the morphing frequency, the lift force of the gust alleviation is very close to the lift force of the gust response, and the lift curves with different morphing part lengths cross with each other, but the drag forces all increase. When the gust frequency is less than the morphing frequency, the spanwise morphing wing not only faces difficulty in achieving the effect of gust alleviation but also has the possibility of deterioration.
- The results of the instantaneous lift force show that the lift fluctuation is more stable when the morphing part length is larger and the AOA is small. When the AOA is large, the appropriate morphing part length will also make the lift fluctuation stable. Therefore, the appropriate morphing part length can improve flight performance.
- The numerical results show that from the distribution of the pressure coefficient and the change in the vortex structure, it can be seen that the lift force decreases to the minimum in the downward flapping process and increases to the maximum in the upward flapping process. The lift force variation of the spanwise morphing wing is mainly affected by the distribution of the vortex structure at the trailing edge of the wing. In the process of morphing, the morphing part flaps down/up, making the lift increase/decrease. The upward flapping and downward flapping of the wing will simultaneously reduce the effective area of the wing and reduce the lift force. The change in lift force comes from the combined effect of the two.

## Author Contributions

## Funding

## Institutional Review Board Statement

## Informed Consent Statement

## Data Availability Statement

## Conflicts of Interest

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**Figure 8.**Comparison between the original data and the pure aerodynamic lift force (morphing part length b/3, AOA 4°).

**Figure 18.**Lift force variation of different morphing part lengths at 4° AOA. (

**a**) b/4 morphing part length, (

**b**) b/3 morphing part length and (

**c**) b/2 morphing part length.

**Figure 19.**Lift force variation of different morphing part lengths at 10° AOA. (

**a**) b/4 morphing part length, (

**b**) b/3 morphing part length and (

**c**) b/2 morphing part length.

**Figure 21.**Pressure distribution of spanwise morphing wing at 10° AOA. (

**a**) Time of 0/4 T, (

**b**) time of 1/4 T, (

**c**) time of 2/4 T and (

**d**) time of 3/4 T.

**Figure 22.**Q criterion of spanwise morphing wing at 10°AOA (Q = 50,000). (

**a**) Time of 0/4 T, (

**b**) time of 1/4 T, (

**c**) time of 2/4 T and (

**d**) time of 3/4 T.

Morphing Part Length | Angle of Attack | Gust Model | Morphing Parameters |
---|---|---|---|

b/2 | 0° | G1(deflection frequency 1 Hz) | Frequency: 1 Hz Amplitude: 40° |

b/3 | 4° | G2(deflection frequency 0.5 Hz) | |

10° | |||

b/4 | 12° | G3(deflection frequency 2 Hz) |

Morphing Part Length | Weight m (g) | Distance to the Rotation Axis r (mm) |
---|---|---|

b/2 | 55.38 | 127.5 |

b/3 | 27.31 | 85.4 |

b/4 | 17.08 | 63.9 |

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**MDPI and ACS Style**

Yao, Z.; Kan, Z.; Li, D. Gust Response of Spanwise Morphing Wing by Simulation and Wind Tunnel Testing. *Aerospace* **2023**, *10*, 328.
https://doi.org/10.3390/aerospace10040328

**AMA Style**

Yao Z, Kan Z, Li D. Gust Response of Spanwise Morphing Wing by Simulation and Wind Tunnel Testing. *Aerospace*. 2023; 10(4):328.
https://doi.org/10.3390/aerospace10040328

**Chicago/Turabian Style**

Yao, Zhuoer, Zi Kan, and Daochun Li. 2023. "Gust Response of Spanwise Morphing Wing by Simulation and Wind Tunnel Testing" *Aerospace* 10, no. 4: 328.
https://doi.org/10.3390/aerospace10040328