# Acquisition of Swept Aerodynamic Data by the Consecutive Changing of Wing Model Configuration in a Wind Tunnel Test Using Remote Feedback Control

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## Abstract

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## 1. Introduction

## 2. System Outline

#### 2.1. Wind Tunnel Test Model

- A symmetrical airfoil shape. After the validation of the aerodynamic forces measurement, this study assumes that hysteresis can be properly captured.
- The thinnest 3D wing geometry among the transonic WTT models owned by JAXA. If the drive mechanism can be incorporated into the thinnest model, it can included in the mechanism in other models.

#### 2.2. Drive Mechanism for Remote Control

- DC servo motor: 0824D012B AESM-4096 made by Faulhaber Minimotor SA (Croglio, Switzerland). The motor is equipped with an absolute encoder and gearhead. The motor’s starting torque is $3.34\times {10}^{-3}$ N·m, the maximum speed is 90,000 rpm, the encoder resolution is 0.088${}^{\circ}$, and the gearhead reduction ratio is 1/650. In addition, the motor adopts a mechanism that eliminates backlash for high-precision positioning.
- Motor controller: MCBL3002F AES made by Faulhaber Minimotor SA (Croglio, Switzerland).

#### 2.3. Optical Measurement for Feedback Control

- Marker: Optical measurements need markers attached to the WTT model surface. The number of circular markers was reduced from two to one per location and improved the model’s surface roughness. Moreover, the color was altered from black and white to fluorescent orange and changed the diameter from 8 to 9 mm to enhance the recognition rate of the camera.
- Lighting device: Xenon light source developed by Hamamatsu Photonics K. K. (Hamamatsu, Shizuoka-prefecture, Japan). Since the marker’s color turned into fluorescent orange, a light emitting diode (LED) (300 mm square head) with a 460 mm wavelength was used to fit the optimal excitation wavelength of fluorescent orange.
- Camera: Manta G-1236B made by Ad Science Inc. (Funabashi, Chiba-prefecture, Japan). The camera uses a Nikon F mount 24 mm lens to which a bandpass filter O56 was attached to suppress the influence of light emitted from sources other than the markers. In the consecutive sweeping mode, the frame rate was set to 8 fps.

#### 2.4. Aerodynamic Measurement

- Six-component balance: LMC-61359 made by NISSYO-ELECTRIC-WORKS CO., LTD. (Tokyo, Japan). The rated loads corresponding to lift coefficient (${C}_{L}$), drag coefficient (${C}_{D}$), and pitching moment coefficient (${C}_{m}$) are ±50 N, ±50 N, and ±10 N·m, respectively.
- DC amplifier: RS2603, made by Nippon Avionics Co. Ltd. (Yokohama, Japan), amplified the voltage output from the detector.
- Manual secondary calibrator: CAL-200-3B-09 made by NISSYO-ELECTRIC-WORKS CO., LTD. (Tokyo, Japan). The nominal accuracy is ±0.2% FS (full scale).
- Digital pressure gauge: MT210 made by Yokogawa Electric Co. (Tokyo, Japan).
- I/O device: NI USB-6216 manufactured by National Instruments Co. (Austin, TX, USA).

## 3. Problem Setting

#### 3.1. Preliminary Attempt

- stepwise mode
- Uniform flow velocity ${U}_{\infty}$: 40 m/s;
- Angle of attack $\alpha $: ${0}^{\circ}$;
- Deflection angle of flap $\delta $: $-{24}^{\circ}\le \delta \le +{24}^{\circ}$.The angle near the limit where the flap can operate smoothly under the constant angular velocity of the flap in this model is 24${}^{\circ}$. ${\delta}_{\mathrm{target}}$ was placed in the order of $-{24}^{\circ}\to {0}^{\circ}\to +{24}^{\circ}\to {0}^{\circ}\to -{24}^{\circ}$, every 2${}^{\circ}$. After the feedback control converges at each angle, the result is the average value of the data acquired for 10 s as the representative one.

Data were obtained for three round trips when one round trip was defined as starting the measurement at $-{24}^{\circ}$ and returning to $-{24}^{\circ}$, viz., data were acquired for a total of six times, three times for the outward trip (from $-{24}^{\circ}$ to $+{24}^{\circ}$) and three times for the homeward trip (from $+{24}^{\circ}$ to $-{24}^{\circ}$) for each target angle. - sweeping mode
- ${U}_{\infty}$: 40 m/s;
- $\alpha $: ${0}^{\circ}$;
- $-{24}^{\circ}\le \delta \le +{24}^{\circ}$.$\delta $ is moved in the order of $-{24}^{\circ}\to {0}^{\circ}\to +{24}^{\circ}\to {0}^{\circ}\to -{24}^{\circ}$ and is defined as one round trip, one experimental condition.
- Angular velocity of flap $\dot{\delta}$ has four cases: 0.8, 4.0, 8.0 and 16.0 ${}^{\circ}$/s.

Three measurements are taken under identical conditions.

#### 3.2. Main Trial: Large-Scale Consecutive Acquisition of Aerodynamic Data

- ${U}_{\infty}$: 40 m/s;
- $-{24}^{\circ}\le \alpha \le +{24}^{\circ}$ every 2${}^{\circ}$;
- $-{24}^{\circ}\le \delta \le +{24}^{\circ}$.The data would be distinguished from $\delta $ of $-{24}^{\circ}$ to $+{24}^{\circ}$ (“down-wise route”) and those from $\delta $ of $+{24}^{\circ}$ to $-{24}^{\circ}$ (“up-wise route”) in this trial to investigate the hysteresis.
- $\dot{\delta}=8.{0}^{\circ}/\mathrm{s}$.

## 4. Results

#### 4.1. Preliminary Attempt 1—Stepwise Mode

#### 4.2. Preliminary Attempt 2—Sweeping Mode

#### 4.3. Data Confirmation on the Main Trial

## 5. Conclusions

## Author Contributions

## Funding

## Institutional Review Board Statement

## Informed Consent Statement

## Data Availability Statement

## Acknowledgments

## Conflicts of Interest

## Abbreviations

${C}_{L}$ | lift coefficient |

${C}_{D}$ | drag coefficient |

${C}_{m}$ | pitching moment coefficient |

CFD | computational fluid dynamics |

EFD | experimental fluid dynamics |

JAXA | Japan Aerospace Exploration Agency |

NACA | National Advisory Committee for Aeronautics |

NASA | National Aeronautics and Space Administration |

CRM | common research model |

WTT | wind tunnel test |

PSP | pressure-sensitive paint |

DC | direct current |

LED | light emitting diode |

FS | full scale |

3D | three-dimensional |

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**Figure 2.**The WTT model and the integrated flap actuating system. (

**a**) External appearance. (

**b**) Installed drive mechanism. (

**c**) Magnified view of the drive mechanism; (1): flap; (2): linkage; (3): DC servo motor; (4): motor controller.

**Figure 3.**Detection of the model surface markers using optical measurement. (

**a**) Markers attached to the model. (

**b**) Image data shot by the camera. (

**c**) Markers detected from image data.

**Figure 4.**The ${C}_{D}$ result of the preliminary attempt in the stepwise mode under the conditions of ${U}_{\infty}=40$ m/s and $\alpha ={0}^{\circ}$.

**Figure 5.**The results from a preliminary attempt in the sweeping mode under the conditions of $\dot{\delta}=0.8$ ${}^{\circ}$/s, ${U}_{\infty}=40$ m/s, and $\alpha ={0}^{\circ}$ compared with that in the stepwise mode.

**Figure 6.**The results from a preliminary attempt in the sweeping mode under the conditions of $\dot{\delta}=4.0$${}^{\circ}$/s, ${U}_{\infty}=40$ m/s, and $\alpha ={0}^{\circ}$ compared with that in the stepwise mode.

**Figure 7.**The results from a preliminary attempt in the sweeping mode under the conditions of $\dot{\delta}=8.0$${}^{\circ}$/s, ${U}_{\infty}=40$ m/s, and $\alpha ={0}^{\circ}$ compared with that in the stepwise mode.

**Figure 8.**The results from a preliminary attempt in the sweeping mode under the conditions of $\dot{\delta}=16.0$${}^{\circ}$/s, ${U}_{\infty}=40$ m/s, and $\alpha ={0}^{\circ}$ compared with that in the stepwise mode.

Part | Symbol | Length | Unit |
---|---|---|---|

reference chord | c | 113.3 | mm |

wing span | b | 244.4 | mm |

wing projected area | A | $2.769\times {10}^{-2}$ | m${}^{2}$ |

flap reference chord | $0.3c$ | mm | |

flap span | 236.9 | mm |

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**MDPI and ACS Style**

Wakimoto, K.; Chiba, K.; Kato, H.; Nakakita, K.
Acquisition of Swept Aerodynamic Data by the Consecutive Changing of Wing Model Configuration in a Wind Tunnel Test Using Remote Feedback Control. *Aerospace* **2021**, *8*, 217.
https://doi.org/10.3390/aerospace8080217

**AMA Style**

Wakimoto K, Chiba K, Kato H, Nakakita K.
Acquisition of Swept Aerodynamic Data by the Consecutive Changing of Wing Model Configuration in a Wind Tunnel Test Using Remote Feedback Control. *Aerospace*. 2021; 8(8):217.
https://doi.org/10.3390/aerospace8080217

**Chicago/Turabian Style**

Wakimoto, Ken, Kazuhisa Chiba, Hiroyuki Kato, and Kazuyuki Nakakita.
2021. "Acquisition of Swept Aerodynamic Data by the Consecutive Changing of Wing Model Configuration in a Wind Tunnel Test Using Remote Feedback Control" *Aerospace* 8, no. 8: 217.
https://doi.org/10.3390/aerospace8080217