1. Delta-Wing Vortex Lift Enhancement Using Oblique Channel Distribution
Advisor: Dr. McClain Project Manager: Meag McNary
Ruben Nunez
Adam Eaker
Ryan Parker
Drew Waggoner
ME LAB Final Presentation

2. Overview Initial Objective Final Objective Theory Experimentation
Schedule Summary
Results
Significance
Summary
Recommendations
Questions

3. Initial Objective
Quantify the steady flow effects of oblique element distributions interacting with vortical structures attached to a delta wing micro unmanned air vehicle
Areas of interest:
High angle of attack
Roughness elements
Lift and Drag

4. Final Objective
Quantify the steady flow effects of obliquely aligned channels interacting with vortical structures on a delta wing micro unmanned air vehicle
Areas of interest:
High angles of attack
Low Reynolds Numbers
Obliquely aligned channels
Lift and Drag

5. Theory – Delta Wing
Seen in fighter aircraft where maneuverability and stability are crucial
Highly swept wing
Triangular planform
Able to achieve higher angles of attack without stall
At moderate to high angles of attack can generate increased lift with better aircraft stability and control
Constraining mechanism to this effectiveness is the vortical flow at leading edge of wing

6. Theory – Vortex Behavior
Unpredictable behavior
Leading-edge vortices
Induces additional lift by pressure decrease on suction surface
Vortex breakdown
Vortex expands into highly fluctuating structure
Induced by high angles of attack or pressure rise
Vortex separates from wing
Disadvantages:
Wing fluttering
Loss of performance
Decrease in lift
Vortex Behavior is unpredictable. Understanding of vortex flow physics allows prediction techniques for macro and micro-electromechanical systems
Counter-Rotating leading edge vortices
Increase lift
Vortex Breakdown

7. Theory – Vortex Breakdown Control
Delay bursting of vortices
Increases performance
Controlled by increasing ωθ and induce secondary flow
Methods:
Mechanical
Local action by contouring surface
Pneumatic
Introduce perturbations through air flow VL Vθ
Leading-edge separation line
Vortex separation line reattachment line
Control element
region
Obliquely aligned elements
Delta wing vortices at low Reynolds numbers are very relevant to micro-air vehicles and reconnaissance
Elements prevent breakdown of vortices by directing air flow and produce high lift forces
Elements prevent buffeting and oscillations, and thus limit drag forces

8. Jet Flaps Leading or Trailing edge Can be difficult to implement.
Leading edge:
+ large increase on lift,
- large increase on drag.
Trailing edge:
+ increase stability
- small increase on lift,

9. Piezoelectric Strips
Bonded on delta wing for active control of oscillations.
Serve as sensors and actuators.
Voltages applied across strips create forces to counter oscillations.
Lightweight, cheap, and easy to manufacture.

10. Obliquely Aligned Elements
Elements prevent breakdown of vortices by directing air flow and produce high lift forces.
Elements also prevent buffeting and oscillations.
Moderate drag penalty.
Leading-edge separation line
Vortex separation line reattachment line
Control element
region
Oscillations caused by asymmetrical vortical breakdown which cause oscillations

11. Obliquely Aligned Channels
Designed to stabilize the vortical flow.
Restrict pressure rises that precipitate breakdown.
Increase ωθ and induce secondary flow
Promote Reattatchment

12. Experimentation
Set up to determine the lift and drag coefficients on a Delta Wing with varying angles of attack
Measurements:
Data Acquisition
LABVIEW
Angle of Attack (0° to 45°)
Using a set screw to adjust attack
angle in 5° increments
Lift and Drag Force
Force Balance
Static Pressure Difference
Using a Pitot-Static Tube and
the PCL2A
Delta Wing
Wind Direction
Test Section
WIND TUNNEL
Figure 1: Wind tunnel experiment set-up to determine lift and drag coefficients on a Delta Wing with a fixed wind velocity.

13. Initial Schedule Summary

14. Final Schedule Summary

15. Results

16. Results

17. Results Overall trend is the same for both wings
Lift and drag are less in the channeled
Increased difference in lift just before stall
Stall occurred at approximately 35°
Lift after stall was greater for the channeled

18. Significance Oblique channels do not increase performance
The effects after stall might suggest improvement is possible

19. Summary There are multiple ways to manipulate the vortical breakdown
Mechanical
Pneumatic
Channeled wing does not drastically increase performance
Lift force reduced
Drag force reduced

20. Recommendations
Improvements in the channeled design might allow for better performance than current model
Test at higher Reynolds numbers
Resume original test criteria
Oblique elemental
distributions
Arrangement of the

21. Questions?