Lecture # 3: Wind Tunnels and Water Tunnels · 2015-01-27 · Barlow, Rae, & Pope, “Low-speed...

Copyright © by Dr. Hui Hu @ Iowa State University. All Rights Reserved!

Dr. Hui Hu

Dr. Rye M. Waldman

Department of Aerospace Engineering

Iowa State University

Ames, Iowa 50011, U.S.A

Lecture # 3: Wind Tunnels and Water Tunnels

AerE 344 - Lecture Notes

Sources/ Further reading: Barlow, Rae, & Pope, “Low-speed wind tunnel testing,” Ch 2 & 3


Function of Wind Tunnels and Water Tunnels

• Producing the desired flow field with controlled conditions

http://www.solarnavigator.net/propellers.htm


Function of Wind Tunnels and Water Tunnels

Wind tunnel vs water tunnel testing

ReUd

-5

3

2-5

kg1.2 , 1.85 10 Pa•s

m

m1.5 10

s

-3

3

2-5

kg1000 , 1.00 10 Pa•s

m

m1.0 10

s

2

FF U C

3

PP U C

Air:

Water:

Power:

Force:


Types of Wind Tunnels

Based on Flow Speed:

• Subsonic or low speed wind tunnels (M<<1.0)

• Transonic wind tunnels (M1.0)

• Supersonic wing tunnels (1.0 <M<5.0)

• Hypersonic wind tunnels (M>5.0)

Based on Shape:

• Open circuit wind tunnel:

• Closed circuit wind tunnel:


Open Circuit Wind Tunnel

• Suction wind tunnel: With the inlet open to atmosphere, axial fan or

centrifugal blower is installed after test section.

• Blow down wind tunnel: A blower is installed at the inlet of wind tunnel

which throws the air into wind tunnel.


Closed circuit wind tunnel


Components of a Wind Tunnel

• Test section

• Contraction section

• Diffuser section

• Setting chamber

• Screens and similar structures

• Cooling system / radiators

• Motors /fans


Function of Contraction

Va

ΔVa~10%

ΔVb =?

Vb a

b

Ac

A

2

1 0.10.001

100

b a

b a

V V

V c V

0.1a

b

Vif

V

Aa

Ab



Va

ΔVa

ΔVb =?

a

b

Ac

A

2

2 2

2 2

1

2

1 1

2 2

1( 1)

2

x x

a a b b

b a a

p V const

p V p V

p p V c

a a b b

b a

V A V A

V cV

Aa Ab

ΔVb

Mass cons:

Bernoulli:

At the perturbation:

2 2 2 2

2 2 2

2 2 2 2

1 1 1( ) ( 1) ( )

2 2 2

1 1( 2 ) ( 2 )

2 2

2 2

a a a a a b b

a a a b b b

a a a a a b

p V V p V c V V

c V V V V V V

c V V V c V cV V



Va

ΔVa

ΔVb =?

a

b

Ac

A

2

2 2

2 2

1

2

1 1

2 2

1( 1)

2

x x

a a b b

b a a

p V const

p V p V

p p V c

a a b b

b a

V A V A

V cV

Aa Ab

ΔVb

Mass cons:

Bernoulli:

At the perturbation:

2 2 2 2

2

2 2

1

a a a a a b

a a a b

a a a b a b

a b a b

c V V V c V cV V

V V cV V

V V cV V V V

cV V c V V


Water Tunnels


Towing Tank


Test section

Contraction

section

A

E

V

Settling

chamber

Lab#02: Wind Tunnel Calibration


2

2

1*

*

VC

qC

ppp

T

EA

Test section

Contraction

section

A

E

V

Settling

chamber



2

2

1*

*

VC

qC

ppp

T

EA

Test section

Contraction

section

A

E

V

Settling

chamber

0

20

40

60

80

100

120

140

0 20 40 60 80 100 120 140

Linear curve fittingExperimental data

P = PA-P

E (Pa)

q =

0.5

*V

2



Before you do the Labs…

• Choose 1~2 member as the Lead Operators

• Bring you own flash drive for the data storage.

• Do not touch other research equipments in the wind tunnel laboratory.

• Keep the wind tunnel laboratory clean and organized.

Lecture # 3: Wind Tunnels and Water Tunnels · 2015-01-27 · Barlow, Rae, & Pope, “Low-speed...

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