Physics and simulation of pitching wing

Motivation

  • Wide range of application for commute and cargo  (UAVs, UAMs, e/VTOL (rotary-wing, fixed-wing)
  • Operate in urban environment
  • Subjected to large disturbances: large wind gusts encounters
  • BL characteristics:  separated,  vortex-dominated, and unsteady flow 
  • Low speed operation, small aspect ratio, low Reynolds number
    • Re: 𝑂(104βˆ’105)O(10^4-10^5)Γ  Poor L/D

Research questions

  1. What are the underlying physics under unsteady conditions at π‘…𝑒(104βˆ’105) Re(10^4-10^5)?
  2. Is the classical unsteady aerodynamics theory β€œsmall flow perturbations” applicable for flow complex at 𝑅𝑒104βˆ’105?Re(10^4-10^5 )?

Objective

To advance the aerodynamic performance by the physical understanding of the fluid interactions at π‘…𝑒(104βˆ’105) Re(10^4-10^5)

Infographic chart of insects, birds and airplanes

Key results

  • Validation: Water-tunnel experiments (In collaboration with AFRL)
    • 46x61 cm test section
    • 𝛼𝑑=5 π‘‘𝑒𝑔sin(πœ”π‘‘)Ξ±(t)=5 deg sin⁑〖(Ο‰tγ€—)
    • π‘˜=0.5,π‘˜=0.05k=0.5,k=0.05
    • 𝑅𝑒=2π‘₯104Re=2x10^4
Image of lab on left and on right three charts
Three charts
Three charts
  • Highly unsteady, π‘…𝑒=2Γ—104, π‘˜=0.5Re=2Γ—10^4, k=0.5
  • RANS/LES (IDDES)
GIF of green waves infographic
GIF of blue and red waves
  • Unsteady, 𝑅𝑒=2Γ—104, π‘˜=0.05Re=2Γ—10^4, k=0.05
  • RANS/LES (IDDES)
GIF of green waves infographic
GIF of blue and red waves
  • 𝑅𝑒=2Γ—104 Re=2Γ—10^4 
  • 2D URANS w. transition model

π‘˜=0.05k=0.05

GIF of rainbow colored waves

π‘˜=0.5k=0.5

GIF of rainbow colored waves

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

  1. Badrya, C., Govindarajan, B., Medina, A., Yang, S. J., and Chopra, I., Unsteady Aerodynamic Characteristics of Pitching Flat Plates at Low Reynolds Numbers, Journal of Aircraft, Volume 58, Number 4 July 2021, DOI:10.2514/1.C036028
  2. Catlett, M. R., Anderson J. M, Badrya, C., and Baeder, J. D., Unsteady response of airfoils due to small-scale pitching motion with considerations for foil thickness and wake motion. Journal of Fluids and Structures, Vol.94, 2020. DOI: 10.1016/j.jfluidstructs.2020.102889
  3. Catlett, M. R., Anderson, J. M., Badrya, C., Govindarajan, B., and Baeder, J. D., Numerical Investigation of Aeroelastic Forces and Pressures on Joukowski Foils of Variable Thickness due to Pitching Motion, 2018 AIAA Aviation, June 2018, Dallas, TX. DOI: 10.2514/6.2018-2906
  4. Badrya, C., Govindarajan, B., and Chopra, I., Basic Understanding of Unsteady Airfoil Aerodynamics at Low Reynolds Numbers, AIAA Aerospace Sciences Meeting, January 2018, Kissimmee, FL. DOI: 10.2514/6.2018-206