1. 1
WIND TUNNEL
TESTING

2. Wind Tunnels
Objective
• Accurately simulate the fluid flow about
atmospheric vehicles
• Measure -Forces, moments, pressure, shear
stress, heat transfer, flow field
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3. Working of wind tunnel
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4. WIND TUNNEL LAYOUTS
 Closed Return
 Open Return
 Double Return
 Annular Return
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Closed Return(OpenTest Section)

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15 Hp. Dual
Centrifugal Blower
Exhaust
Exhaust
Louvers
for Speed
Adjustment
Test Section
18 inch Diameter
25 to 1 Contraction
Screens High Contraction Wind Tunnel
Top View
Diffuser
Open Return(Closed Section)

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Double Return

8. 8
Annular Wind
Tunnel

9. TYPES OF WIND TUNNELS
 Subsonic
 Transonic
 Supersonic
 Hypersonic
 Specialty (Automobiles)
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10. SUBSONIC TUNNELS
 Low speed wind tunnels are used for
operations at very low mach
number(M<0.5), with speeds in the test
section up to 480 km/hThey may be of
open-return type with air moved by a
propulsion system.
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80X120
NASA AMES

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80x120 WindTunnel
NASA Ames

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12 Foot PressureTunnel

14. TRANSONIC WIND TUNNELS
 High subsonic wind tunnels (0.4 < M < 0.75)
or transonic wind tunnels (0.75 < M < 1.2)
are designed on the same principles as the
subsonic wind tunnels.
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15. TRANSONIC WIND TUNNEL
 Testing at transonic speeds presents
additional problems, mainly due to the
reflection of the shock waves from the walls
of the test section
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8x6 Functions & Capabilities
The 8x6 Foot Supersonic WindTunnel provides
customers with a Facility capable of testing large
scale aero propulsion hardware
Relative altitude 1000 - 35000 ft
Dynamic Pressure 3.6 - 4.8 x 106/f
Temperature 60 - 250oF

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8X6AT NASA LEWIS

18. SUPERSONIC WIND TUNNELS
 A supersonic wind tunnel is a wind tunnel
that produces supersonic speeds (1.2<M<5)
The Mach number and flow are determined
by the nozzle geometry.
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22. HYPERSONIC WIND TUNNELS
 A hypersonic wind tunnel is designed to
generate a hypersonic flow field in the
working section.
 The speed of these tunnels vary from Mach
5 to 15.
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25. AUTOMOBILE WIND TUNNELS
External flow tunnels - Used to study the
external flow through the chassis
 Climatic tunnels - Used to evaluate the
performance of door systems, braking
systems etc. under various climatic
conditions.
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27. TYPES OF WIND TUNNEL
TESTING
 ForceTest
 Force measurement requires a force to be
exerted (lift & drag forces so termed force
test)
 The balance can measure only two forces:
lift & drag
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29. TYPES OF WIND TUNNEL
TESTING
 PressureTests
 Insert tiny tubes into the model surface or
airstream and connect them to a pressure
measuring device
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30.  PressureTest:
 Lowered pressure over the wing surface
reduced the pressure in the manometer
tubes and draws the water level up to a high
level
 The lower the pressure, the higher the water
level goes
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31. TYPES OF WIND TUNNEL
TESTING
 Flow Patterns
 Allow the streamlines of air flow to look at
the body’s aerodynamic properties
 Tufting allows for the flow pattern
visualization
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Flow Patterns

33. INSTRUMENTS USED IN
WIND TUNNELS
 1.Force Balance
 2.Static Pressure Measurement
 3.Strain gauge
 4.Spring Gauge
 5.Laser DopplerVelocimetry
 6.Laser Sheet
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34. FORCE BALANCE
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35. STATIC PRESSURE
MEASUREMNT
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36. STRAIN GAUGE
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37. SPRING GAUGE
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38. LASER DOPPLER
VELOCIMETRY
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39. LASER SHEET
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40. HOW ARE CARS TESTED IN
WIND TUNNELS??
 It is used to quantify and validate what is going
on aerodynamically to the vehicle by
measuring forces exerted on the body through
a 6 component balance.
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41. HOW ARE CARS TESTED IN
WIND TUNNELS??
 Adding a rear wing to your car might gain you
down force, but a wind tunnel will tell you in
fact if it is, how much, and how it affected the
overall front to rear balance of your car.
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42. HOW ARE CARS TESTED IN
WIND TUNNELS??
 Each test will output the drag, down force
(front & rear), and side force (front &
rear), yaw/pitch/roll moments, in order to see
the big picture of what is really happening for
any given configuration.
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Few
Examples

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45. COST OF A WIND TUNNEL
 A high quality portable vertical wind tunnel
will cost you anywhere from 1.6crores to
4.1crores.This type of tunnel can
accommodate skydivers as well as tourists.
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46. WIND TUNNELS IN THE
WORLD
1.Altitude IcingWindTunnel(Ontario Canada)
2.Wright BrothersWindTunnel(MIT
Massachusetts USA)
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48. WIND TUNNELS IN THE
WORLD
 3.WindTunnel at NASA Ames (World’s
Largest USA)
 4.Langley Low PressureTurbulenceWind
Tunnel(NASAVirginia USA)
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50. REFERENCES
 www.wikipedia.com
 www.nasa.org
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51. THANK YOU
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