Active Lift Control: Top Surface Air Injection

Erik Nelson

Brian Smith

Harrison Yates

Pressurized air through front

Angled to 30° from horizontal

Suction through back

Normal to surface

Tubes inserted into side

Airfoil Design

Wind Tunnel at 120 rpm 16 m/s

Determine angle of first separation

Approximately 20°

Control case, then with pressure

Lacked sufficient suction source

Flow Visualization

Control, α = 20°

Pressure, α = 20°

Video, α = 20°

Control, α = 30°

Pressure, α = 30°

Video, α = 30°

Control, α = 40°

Pressure, α = 40°

Video, α = 40°

Compare 0:00 to 0:42

Control, α = 45°

Pressure, α = 45°

Video, α = 45°

Red Tunnel at 500 rpm ≈ 17.5 m/s

Three experimental cases:

Control

5 psi

10 psi

Coefficients of Lift, Drag calculated

Force Balance

Experimental Setup

Experimental Setup

Lift Coefficients

0 5 10 15 20 25 30 35 40-0.2

0

0.2

0.4

0.6

0.8

1

Lift Coefficients

Angle of Attack (Degrees)

cL

Control

5 psi

10 psi

Drag Coefficients

0 5 10 15 20 25 30 35 400.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

Drag Coefficients

Angle of Attack (Degrees)

cD

Control

5 psi

10 psi

Lift / Drag Coefficient Ratios

0 5 10 15 20 25 30 35 40-0.5

0

0.5

1

1.5

2

2.5

3

Lift / Drag Ratios

Angle of Attack (Degrees)

cL / c

D

Control

5 psi

10 psi

Slight improvement in lift above α ≈ 25°

Only for 10 psi case

Improvement of drag above α ≈ 15°

5 psi good, 10 psi better

CL / CD ratio improved at high α – values

Most effective in near-stall situations

Force Balance Results

Questions?