The document describes different types of wind tunnels and their components. It discusses wind tunnels classified by air velocity as subsonic, supersonic, hypersonic, or transonic. It also describes open and closed circuit wind tunnels. The key components of wind tunnels are then outlined as the settling chamber, contraction cone, test section, diffuser, and drive section. Examples and purposes of each component are provided.

1. Introduction:
The wind tunnel is an aerodynamic device used
to test and analyze the behavior, movement and
flow of air around any engineering object to
facilitate its design process more smoothly and
more comprehensively.

2. Classification of Wind Tunnel:
 According to the Velocity
1. Subsonic wind tunnel
2. Supersonic wind tunnel
3. Hypersonic wind tunnel
4. Transonic wind tunnel
 According to the Shape
1. Open circuit wind tunnel
2. Closed circuit wind tunnel

3. Open Circuit
Wind Tunnel
• Air is drawn in from the
laboratory environment,
passes through the test
section and is returned back
to the lab through the tunnel
exhaust.
Fig1. Open circuit wind tunnel

4. Closed Circuit
Wind Tunnel
• Air is conducted from the
exit of the test section back to
the fan by a series of turning
vanes.
• Same air recirculated inside
the wind tunnel.
Fig.2 Closed Circuit wind Tunnel

5. Subsonic
Wind Tunnel
• Low-speed wind tunnels are
used for operations at very
low Mach Number (up to
M=0.4) with speeds in the test
section up to 480 km/h (~ 134
m/s ,M= 0.4)
• Open Circuit and Closed
circuit wind tunnels comes in
its type
Fig.3 Open circuit wind tunnel
Fig.4 Closed circuit wind tunnel

6. Supersonic
Wind Tunnel
• High speed wind tunnels are
used for operations at Mach
Number (0.2<M<5)
• Nozzle geometry determines
Mach number and Reynold
number values
• Needs a drying or a pre-
heating facilities
• A large power demand, so
mostly designed for intermittent
instead of continuous
operation.
Fig.5 Supersonic Wind Tunnel

7. Hypersonic
Wind Tunnel
• High speed wind tunnels
are used for operations at
Mach Number (5<M<15)
Fig.6 Hypersonic Wind Tunnel

8. Transonic
Wind Tunnel
• Wind tunnels are used for
operations at Mach Number
(0.3<M<1.3)
Fig.7 Transonic Wind Tunnel
Fig. 8 Transonic Wind Tunnel

9. Components of Wind Tunnel:
1. Settling Camber
2. Contraction Cone
3. Test Section
4. Diffuser
5. Drive Section
Four main components of
open circuit wind tunnel:
Fig.9 Subsonic Wind Tunnel

10. CAD model of Wind Tunnel :
Fig.10a CAD Model of Subsonic Wind Tunnel using FUSION 360

11. CAD model of Wind Tunnel :
Fig.10b CAD Model of Subsonic Wind Tunnel using FUSION 360

12. Settling Chamber:
The Settling Chamber is at the very front of the wind tunnel, and is made up of
screens and honeycomb-shaped mesh, which straighten out the air and reduce
turbulence
Description Values
Material MDF board
Inlet area 42’’ * 42’’
Outlet area 42’’*42’’
Contraction ratio 1:1
Contraction angle 0
Length 6’’
Fig.11 Settling Chamber

13. Contraction Cone:
The Contraction Cone forces a large volume of air through a
small opening in order to increase the wind velocity in the
tunnel
Fig.12 Contraction Cone
Description Values
Input area of cross-section 42’’*42’’
Output area of cross-section 12’’*12’’
Contraction ratio 12.25
Length 42’’

14. Test Section:
Test Section is the place where a model is mounted on
sensors
Fig.13 Test Section
Description Values
Material used MDF Board
Length 24’’
Input area of cross-section 12’’*12’’
Output area of cross-section 12’’*12’’

15. Diffuser :
The Diffuser is mounted at the end of the Test Section, and keeps
the air running smoothly as it goes toward the back. It also
increases in volume in order to slow the air down as it exits the
tunnel.
Fig.14 Diffuser
Description Values
Input area of cross-section 12’’*12’’
Output area of cross-section 22’’*22’’
Diffuser ratio 3.36
Diffuser length 63’’
Expansion angle 4.54 °

16. Without Diffuser
With Diffuser
What is the role of Diffuser?

17. Drive Section:
The Drive Section is at the very back of the wind tunnel and it is where the fan is
housed. It will draw air into the wind tunnel by blowing air out of it
Fig.15 Drive Section
FAN Description Values
Input area of cross-section 22’’*22’’
Output area of cross-section 22’’*22’’
Length 6’’
Material Used MDF Board

18. References:
• https://flight.engr.ucdavis.edu/facilities/aeronautical-wind-tunnel/
• https://www.sciencebuddies.org/science-fair-projects/references/how-to-build-a-wind-
tunnel#testing/
• https://www.grc.nasa.gov/WWW/K-12/WindTunnel/wandering_windtunnel.html

19. Thank You