Open Wind Tunnel Design and Construction

An experimental project to design, build and test a functional open wind tunnel for aerodynamic testing and research.

The complete assembled wind tunnel

Read the original paper in dutch or the translated version*
More pictures can be found in the presentation

_{^{*Translation is done by Google Translate and contains errors.}}

Key Features

• Open-circuit design with 5.09:1 contraction ratio
• Maximum air speed of 33 km/h (9.2 m/s)
• Laminar flow generation capabilities
• Transparent test section for flow visualization
• Digital speed control system

Technical Design

The wind tunnel consists of six main components. From left to right:

1. Honeycomb Flow Straightener

• 6600 plastic straws arranged in a grid
• 6mm diameter, 60mm length
• Mounted at tunnel inlet
• Reduces lateral turbulence

2. Flow Conditioning Screens

• Two screens with 64% open area
• Nylon mesh construction
• 45mm spacing between screens
• Reduces axial turbulence

3. Contraction Section

• 5.09:1 contraction ratio
• Fifth-order polynomial curve profile
• Optimized for minimal flow separation
• MDF construction with external skeleton

4. Test Section

• Dimensions: 180mm × 190mm × 580mm
• Plexiglass windows for visualization
• Bottom access port for force measurements

5. Diffuser

• 9.9° expansion angle
• 574mm length
• Gradual velocity reduction
• Pressure recovery section

6. Drive System

• 4 × 210W brushless motors
• Three-blade propellers
• Electronic speed controllers
• Servo tester for power control
• 7.4V LiPo battery power source

Experimental Results

Airfoil Testing

Conducted comprehensive testing using NACA 4412 airfoil:

• Lift coefficient measurements
• Angle of attack comparison
• Speed dependency analysis

Key findings:

1. Maximum lift achieved at 30° angle of attack
2. Experimental results closely matched theoretical predictions

Technologies Used

• Fusion 360 for CAD design
• Laser cutting for precision components
• 3D printing for custom parts
• Pitot tube airspeed measurement
• Digital force measurement system

Testing Methods

1. Air Speed Measurement

   • Pitot tube system
   • Fluid manometer measurement
   • Multiple test points across section
   • Speed range: 0-33 km/h

2. Flow Quality Assessment

   • Smoke visualization
   • Flow uniformity testing

3. Force Measurement

   • Digital scale
   • Multiple angle testing

Contributors

• Maarten Espeel
• Kobe Vlasselaer
• Wolf Vierbergen

Acknowledgments

Special thanks to:

• Ludo Verluyten (Mentor)
• Bike Valley Team
• Heilig-Hartinstituut Heverlee

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Note: For detailed technical specifications, experimental procedures, and complete results, please refer to the full thesis document.