HAFB – Flow Separation Delay on NACA Airfoil

Team: Carson Howard, Jacob Thompson, Josh Wright, Benson Dickey

Sponsor: Hill AFB A-10 Sustainment

Increasing Lift Coefficient

Problem Description

Hill Air Force Base tasked our group with finding possible designs that we could attach to the airfoil to increase the coefficient of lift on the NACA 6717 airfoil for the A 10 Warthog at higher angles of attack to prevent stall.

Different Design Considerations

  • Slotted Airfoil
  • Dimples toward the leading edge
  • Vortex Generators

Vortex Generators

How Vortex Generators Work

Transfers energy into the boundary layer using vortices.

This energy can then be used to combat adverse pressure gradients resulting in less flow separation.

Models used for wind tunnel testing

Models used for wind tunnel testing

Mesh visualization for use in CFD simulations.

Mesh visualization for use in CFD simulations.

Performance Review

A combination of wind tunnel and CFD testing was used to evaluate design performance

Wind Tunnel Setup

Wind Tunnel Setup

CFD visualization of flow velocity (in/s)

CFD visualization of flow velocity (in/s)

Coefficient of Lift vs Angle of Attack graph

Conclusion

  • The design met the design constraints shown above but were unable to meet the performance requirements with reliable confidence. This low confidence is due to the inconsistency between the wind tunnel results and the CFD results,
  • Lessons Learned: It would have been best to start wind tunnel testing soon after starting with CFD simulation to start confirming CFD results before progressing too far. It is essential to quantifying any improvement in performance.
  • Recommended Future Work: Further study of all configurations is recommended. These tests were inconclusive in confirming the CFD methodology was correct.