lecture # 1: syllabus and policies introductions of
TRANSCRIPT
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
Copyright © by Dr. Hui Hu @ Iowa State University. All Rights Reserved!
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
Copyright © by Dr. Hui Hu @ Iowa State University. All Rights Reserved!
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.
Copyright © by Dr. Hui Hu @ Iowa State University. All Rights Reserved!
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.
Copyright © by Dr. Hui Hu @ Iowa State University. All Rights Reserved!
Peer Review Form
Copyright © by Dr. Hui Hu @ Iowa State University. All Rights Reserved!
AFD, CFD and EFD
Flow Physics
Computational
Fluid Dynamics
(CFD)
Analytical Fluid
Dynamics
(AFD)
Experimental Fluid
Dynamics
(EFD)
Copyright © by Dr. Hui Hu @ Iowa State University. All Rights Reserved!
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
Copyright © by Dr. Hui Hu @ Iowa State University. All Rights Reserved!
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:
Copyright © by Dr. Hui Hu @ Iowa State University. All Rights Reserved!
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
Copyright © by Dr. Hui Hu @ Iowa State University. All Rights Reserved!
Similitude and Dimensional Analysis
• Similitude:
• The study of predicting prototype conditions
from model observations.
F-22 Raptor Air Superiority Fighter
Copyright © by Dr. Hui Hu @ Iowa State University. All Rights Reserved!
Similitude and Dimensional Analysis
),,,( VDfpl =
)(2
VD
V
p=
Copyright © by Dr. Hui Hu @ Iowa State University. All Rights Reserved!
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−=
Copyright © by Dr. Hui Hu @ Iowa State University. All Rights Reserved!
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
)()())((
Copyright © by Dr. Hui Hu @ Iowa State University. All Rights Reserved!
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
Copyright © by Dr. Hui Hu @ Iowa State University. All Rights Reserved!
Similitude
• Geometric similarity: the model has the same
shape as the prototype:
F-16 F-22
Copyright © by Dr. Hui Hu @ Iowa State University. All Rights Reserved!
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
Copyright © by Dr. Hui Hu @ Iowa State University. All Rights Reserved!
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
===
===
===
====
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