Lecture # 1: Syllabus and Policies Introductions of ...

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

Dr. Hui Hu

Department of Aerospace Engineering

Iowa State University

Ames, Iowa 50011, U.S.A

Lecture # 1: Syllabus and Policies

&

Introductions of Similitude of Experiments

AerE344 - Lecture Notes


Course Introduction

• Online lectures will be given on Tuesdays only.

• The lecture time on Thursday mornings is reserved for ad hoc meetings or used for each group to meet to prepare/write lab reports.

• WebEx online lectures:https://iastate.webex.com/iastate/j.php?MTID=m27e31b526f9decce2463ee9e17c2fed3

• Meeting number: 120 437 1682

• Password: AMLt_XOxtZYFHw

• Host key: 544564

https://iastate.webex.com/iastate/j.php?MTID=m27e31b526f9decce2463ee9e17c2fed3


Course Introduction

• Syllabus.

• Course policy.

• According to ISU policy, you will need to read, sign and submit back "AerE344: Experimental Course Participation Agreement" before you are allowed to do the lab experiments.

• Lab attendance is mandatory. Unexcused absences from lab exercises will result in an “F” in the grade for the entire course!

• 3~5 students will be assigned to work together as a group.


About Lab Report

• About teamwork

– Good communication among group members

– Rotating roles within the group

– Peer review

• About plagiarism

– Please respect other people’s original work and intellectualproperty.

– Never “copy-and-paste” other’s work in your lab report.

– Use ~ 5 same words in a sentence as the referencematerials will be counted as plagiarism unless it is notedclearly as the direct quote from the reference materials.


Peer Review Form


AFD, CFD and EFD

Flow Physics

Computational

Fluid Dynamics

(CFD)

Analytical Fluid

Dynamics

(AFD)

Experimental Fluid

Dynamics

(EFD)


Measurable Properties

•Material Properties:

(Most of them can be found in handbooks)

•Kinematic Properties: Describes the fluid motion w/o considering the force.

(Position, V, displacement, acceleration,

momentum, volume flow rate, mass flow rate, etc)

•Dynamic properties: Related to applied forces.

(Pressure, shear stress , Torque)

•Thermodynamic properties: Heat and Work.

(T, e, h, S)

D,,volume,specific ,,m


Descriptions of Flow Motion

t

LV

t

=

→ 0lim

( ) ( )txVtxU ii ,, 0=

+

+

+

=

•+

=

=

domainEulerianx

UU

x

UU

x

UU

t

U

UUt

Ua

domainLangragianDt

VDa

3

3

2

2

1

1

)(

+

=

j

i

j

iij

x

U

x

Ue

2

1

+

=

j

i

j

iij

x

U

x

U

• Lagrangian Method Focused on fluid particles

• Eulerian Method: Focused on space location.

Acceleration:

Rate of Strain:

Shear stress:


Primary Properties and Secondary properties

• Primary Properties: Properties which are independent to each other

• Secondary Properties: Related to other properties through their definition or basic principles

Name Abbreviations Unit

Length L M

Mass m kg

Time t s

Temperature T K

Electric current I A

Amount of substance mole mol

Luminous intensity Candela Cd

Plane Angle Radius rad

Solid Angle Storadian Sr


Similitude and Dimensional Analysis

• Similitude:

• The study of predicting prototype conditions

from model observations.

F-22 Raptor Air Superiority Fighter


Similitude and Dimensional Analysis

),,,( VDfpl =

)(2

VD

V

p=


Buckingham - Theorem

• Step 1: List all the variables that are involved in the problem.

• Step 2: Express each of the variables in terms of basic dimensions.

– Basic dimension: M, L,T, F

– Force - F=MLT-2, density - =ML-3; or =FL-3T2.

• Step 3: Determine the required number of pi-terms.

– Number of pi-terms is equal to k-r, where k is the number of vearibel in

the problem, r is the number if reference dimensions required to described

the variables.

• Step 4: Select a number of repeating variables, where the number required is equal to

the number of reference dimensions.

• Step 5; Form a pi-term by multiplying one of the non-repeating variables by the

product of repeating variables, each raised to an exponent that will make the

combination dimensionless.

• Step 6: Repeat Step 5 for each of the remaining non-repeating variables.

• Step 7: Check all the resulting pi terms to make sure they are dimensionless

• Step 8: Express the final form as a relationship among the pi-terms, and think about

what it means.

),( ,321 rk−=


Buckingham - Theorem

• Example

neededistermsrK −== 23;5

TFL

LTV

TFL

LD

FLpl

2

1

24

3

−

−

−

−

=

=

=

=

=

),,,( VDfpl =

cba

l VDp =1

cbaVD =2

21

0002413

1

2

1

02

043

01

)()())((V

Dp

c

b

a

cb

cba

c

LTFTFLLTLFL lcba

=

−=

−=

=

=+−

=−++−

=+

=−−−

VDc

b

a

cb

cba

c

LTFTFLLTLTFL cba

=

−=

−=

−=

=+−

=−++−

=+

=−−−

2

0002412

1

1

1

021

042

01

)()())((


Commonly used dimensionless parameters

force tensionsurface

force inertialWe Number,Weber

force inertial

force lcentrifugaStr Number, Strohal

forcegravity

force inertial

lg FrNumber, Froude

mass

momentum:NumberSchmidt

diffusionheat

diffusion momentumPr:Number Prandtl

force inertial

Lift

2

1:tCoefficienLift

force inertial

Drag

2

1:tCoefficien Drag

force inertial

force pressure

2

1 Eunumber,Euler

force viscous

force inertial Renumber, Reynolds

forcelity compressib

force inertial MNumber, Mach

2

2

2

2

=

=

=

==

==

==

==

=

=

=

lV

V

l

V

USc

V

SV

LC

SV

DC

V

p

VL

c

V

c

L

D


Similitude

• Geometric similarity: the model has the same

shape as the prototype:

F-16 F-22

http://www.wallpapergate.com/data/media/2183/F_16_Falcon_6.jpg


Similitude

• Kinematic similarity: condition where the velocity ratio is a constant between all corresponding points in the flow field.

– The streamline pattern around the model is the same as that around the prototype


Similitude

• Dynamic similarity: Forces which act on corresponding masses in the model flow and prototype flow are in the same ratio through out the entire flow.

pm

pg

pI

mg

mI

pg

mg

pI

mI

pm

p

pI

m

mI

p

m

pI

mI

pm

pp

pI

mp

mI

pp

mp

pI

mI

pg

mg

p

m

pp

mp

pI

mI

FrFrF

F

F

F

F

F

F

F

F

F

F

F

F

F

F

F

EuEuF

F

F

F

F

F

F

F

F

F

F

F

F

F

F

F

===

===

===

====

)(

)(

)(

)(

)(

)(

)(

)(

ReRe)(

)(

)(

)(

)(

)(

)(

)(

)(

)(

)(

)(

)(

)(

)(

)(

constant)(

)(

)(

)(

)(

)(

)(

)(

Lecture # 1: Syllabus and Policies Introductions of ...

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