Wing response to large transverse gusts

Motivation

• Wide range of application for commute and cargo, UAVs, UAMs, e/VTOL (rotary-wing, fixed-wing)
• Low speed operation, small aspect ratio, low Reynolds number 𝑅𝑒: 𝑂(104 −105)Re: O(104 -105)
• Operate in urban environment
• Subjected to large wind gusts encounters

Canonical gust shapes

• Reynolds numbers, 𝑂(104)O(10^4) Re = 20k, 40k in free atmosphere
• A transverse gust with various shapes:

1. Sine-squared
2. Top-hat
3. Step

Gust characterization

• Flat plates at 0 degrees angle of incidence
• Three canonical gust shapes: Sine-squared; top-hat; step
• Gust widths, ranging from 0.25c to 9c width
• Various gust amplitudes, 𝑮𝑹=𝑽𝑼=0.25 −1.2 GR=V/U=0.25 -1.2   

 

Gust Modeling - Split Velocity Method (SVM)

 

• Gust velocity is prescribed to the grid time metrics using analytical function
• Source terms were derived to capture the effect of the airfoil on the gust
• SVM previously been used to model airfoil–vortex interaction and gust responses
• No numerical dissipation by larger cells, coarser mesh can be used away from the surfaces, reducing the computational cost

Validation

• W= 2c;  GR=1; Re= 40k
• Cambridge University Engineering, Ref. Corkery et. al, 2018, Department (CUED)
• Dye trace for visualization

Some outcomes

• Flat-plate; 𝛼𝑔=0α_g=0;  𝑅𝑒 = 40𝑘 Re = 40k ; free atmosphere

Methodology to model large gust encounters and unsteady kinematics

• Physics based computational tool to model unsteadiness: i) kinematics  ii) flow disturbances
• RANS-based with (𝛾−𝑅𝑒𝜃)(γ-Re_θ) computations in a good agreement with RANS/LES (IDDES)
• Efficient computational method using Split Velocity Method (SVM) for large gust response
• The classical unsteady theory does not account for unsteadiness that arises from massive flow separation, a nonplanar wake, and three-dimensional effects.

Read more about the methodology and results in the following publications and proceedings:

1. Badrya, C., Baeder J. D., and Jones, A. R., Application of Prescribed Velocity Methods to a Large-Amplitude Flat-Plate Gust Encounters, AIAA Journal Vol. 57, No. 8(2019), DOI: 10.2514/1.J057978
2. Biler, H., Badrya, C., and Jones, A. R., Experimental and Computational Investigation of Transverse Gust Encounters, AIAA Journal Vol. 57, No. 11, 2019. DOI: 10.2514/1.J057646
3. Badrya, C., Biler., H., Jones, A. R., and Baeder J. D., Effect of Gust Width on Flat-Plate Response in Large Transverse Gust, AIAA Journal, December 2020. DOI:10.2514/1.J059678
4. Badrya, C., Jones, A. R., and Baeder, J. D., Unsteady Aerodynamic Response of a Flat-Plate Encountering Large-Amplitude Sharp-Edged Gust, AIAA Journal. DOI: 10.2514/1.J060683