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Introduction to Introduction to Aerodynamic Laboratory I Aerodynamic Laboratory I ––AerE243LAerE243L
Dr. Hui HUDr. Hui HUDepartment of Aerospace EngineeringDepartment of Aerospace Engineering
Iowa State UniversityIowa State UniversityRoom 2251, Howe HallRoom 2251, Howe Hall
Tel: 515Tel: 515--294294--0094 / Email: 0094 / Email: [email protected]@iastate.edu
Aerodynamics Laboratory I AerE 243L:
AIM : Qualitative and quantitative understanding of aerodynamic characteristics of bodies.
Theory class (AFD) integrates with experimental lab (EFD).
FlowLab integrates CFD with AFD and EFD.
Flow Physics
ComputationalFluid Dynamics
(CFD)
Analytical Method(AFD)
ExperimentalMethod(EFD)
What is CFD ?
numerically solve the governing equations that describe the physical
phenomena.
Continuity equation
N-S equation (momentum equation)
Energy conservation equation
State equation
computer-based analysis technique
0)( =•∇+∂∂ V
t
rρρ
fPVVtV rrrr
ρτρρ−•∇+−∇=•∇+
∂∂ ~)()(
TRP ρ=
Components of CFD Analysis
Preprocessing (Mesh generation)
Solving controlling equations
Post processing (analyzing results)
Grid generationThe aim is to create a highly automated structured viscous body-fitted grid generator hybridized with a Cartesian unstructured grid.
CH-46, V-22 and LHA
CFD Applications
Experimental techniques for fluid Experimental techniques for fluid diagnosticsdiagnostics
Flow Flow diagnosticdiagnostictechniquestechniques
Traditional Traditional (intrusive)(intrusive)
OpticalOptical––based based NonNon--intrusiveintrusive
•• PitotPitot probeprobe•• hotwire, hot filmhotwire, hot film•• thermocouplesthermocouples•• etc ...etc ...
•• Laser Doppler Laser Doppler VelocimetryVelocimetry (LDV)(LDV)•• Planar Doppler Planar Doppler VelocimetryVelocimetry (PDV)(PDV)•• Particle Image Particle Image VelocimetryVelocimetry (PIV(PIV))•• etcetc……
particleparticle--based based techniquestechniques
•• Laser Induced Fluorescence (LIF)Laser Induced Fluorescence (LIF)•• Molecular Tagging Molecular Tagging VelocimetryVelocimetry (MTV)(MTV)•• Molecular Tagging Molecular Tagging TherometryTherometry (MTT)(MTT)•• etc etc ……
moleculemolecule--based based techniquestechniques
Velocity, temperature, density (concentration), etc..
Intrusive Velocimetry TechniquesIntrusive Velocimetry Techniques
• Hot Wire technique
• Pitot Tube
ρ21
statictotal PPV −=
senses the changes in heat transfer as the flow speed variessenses the changes in heat transfer as the flow speed varies
Particle Image Particle Image VelocimetryVelocimetry (PIV) (PIV) techniquetechnique
The technical basis of the PIV: The technical basis of the PIV: to to measure the displacementsmeasure the displacements of the of the tracer particlestracer particlesseeded in the flow in a fixed time interval. seeded in the flow in a fixed time interval.
tLUΔΔ
=
t=t0
t= t0+ΔtΔL
Particle Image Particle Image VelocimetryVelocimetry (PIV) Technique(PIV) Technique
To seed fluid flows with small particles, and assume the tracer particles to have the same velocity as fluid flows.To measure the displacements (ΔL) of the tracer particles between known time interval (Δt). The local velocity of fluid flow is calculated by U= Δ L/Δt .
Illumination system(Laser and optics)
cameraSynchronizer
seed flow withtracer particles
Host computer
A. t=t0 B. t=t0+4ms
PIV measurement in a sloshing flow
-50 0 50 100 150 200 250 300-50
0
50
100
150
200-25.00 -20.00 -15.00 -10.00 -5.00 0.00 5.00 10.00 15.00 20.00 25.00
Spanwise Vorticity ( Z-direction )
Re =6,700
Uin = 0.33 m/s
X mm
Ym
m
Uou
t
water free surface
AeroAero--engine:engine:enhance mixing between hot highenhance mixing between hot high--speed flow exhaust from speed flow exhaust from corecore--engineenginewith cold lowwith cold low--speed bypass flowspeed bypass flow•• civilian airplanes: civilian airplanes: reduce jet noise during takereduce jet noise during take--off and landingoff and landingthrust augmentationthrust augmentation
•• Military airplanes: Military airplanes: reduce the length of the hot plume, therefore, reduce the length of the hot plume, therefore, reduce the infrared emission signals to improve reduce the infrared emission signals to improve its survivability from the attack of infrared its survivability from the attack of infrared guided missiles. guided missiles.
Combustion: Combustion: enhance mixing between the fuel with enhance mixing between the fuel with air in the combustion chamberair in the combustion chamber•• improve combustion efficiencyimprove combustion efficiency•• suppression pollutant formationsuppression pollutant formation
Concept of Lobed Mixer/NozzleConcept of Lobed Mixer/Nozzle
Lobed Lobed mixer/nozzle mixer/nozzle
NASA modelNASA model
Turbo-fan aero-engine
Laser Induced Fluorescence (LIF) Flow Laser Induced Fluorescence (LIF) Flow Visualization Results (Axial Slices, Visualization Results (Axial Slices, Re=6,000)Re=6,000)
Lobe trough sliceLobe peak slice
Lobe trough sliceLobe peak slice
X/D=1.0 X/D=1.5 X/D=2.0
X/D=0.25 X/D=0.5 X/D=0.75
Laser Induced Fluorescence (LIF) Flow Laser Induced Fluorescence (LIF) Flow Visualization ResultsVisualization Results(Cross Sections, Re=3,000)(Cross Sections, Re=3,000)
-30-20
-100
1020
30X mm
-30
-20
-10
0
10
20
30
Ym
m
X
Y
Z W m/s20.0019.0018.0017.0016.0015.0014.0013.0012.0011.0010.00
9.008.007.006.005.004.003.00
20 m/s
A. Instantaneous velocity field at Z=10mm plane
B. the simultaneous velocity field at Z=12mm plane
The Simultaneous Measurement Results of theThe Simultaneous Measurement Results of theDualDual--plane Stereoscopic PIV System at Two Parallel Planesplane Stereoscopic PIV System at Two Parallel Planes
-30-20
-100
1020
30X mm
-30
-20
-10
0
10
20
30
Ym
m
X
Y
Z W m/s20.0019.0018.0017.0016.0015.0014.0013.0012.0011.0010.00
9.008.007.006.005.004.003.00
20 m/s
-11.
0
-11.0
-11.0
-11.0
-9.0
-9.0-9.0
-9.0
-7.0
-7.0-7.0
-7.0
-7.0
-7.0
-5.0
-5.0
-5.0
-5.0
-5.0
-3.0
-3.0
-3.0 -3.0
-3.0
-3.0
-1. 0
-1.0
-1.0
-1.0
-1 .0
-1.0
-1.0
-1.0
1.0
1.0
1.0
1.0
1.0
1.0
3.0
3.0
3.0
3.0
3.0
5.0
5.0
5.0
5.0
7.0
7.0
7.0
7.0
7.0
9.0
9.0
9.0
9.0
9.0
11.0
11.0
11.0
11.0
11.0
X mm
Ym
m
-40 -20 0 20 40
-30
-20
-10
0
10
20
30
40
11.009.007.005.003.001.00
-1.00-3.00-5.00-7.00-9.00
-11.00
Vorticity distribution(Y-component)
-11.0
-7.0
-7.0
-5.0
-5.0
-3.0
-3.0
-3.0
-3.0
-1.0
-1.0
-1.0
-1.0
-1.0
-1.0
-1.0
1.0
1.0
1.01.0
1.0
1.0
3.0
3.0
3.03.0
3.0
3.0
3.0
3.0
5.0
5.0
5.0
5.0
5.0
5.0
5.0
7.0
7.0 7.0
7.0
9.011.0
X mm
Ym
m
-40 -20 0 20 40
-30
-20
-10
0
10
20
30
40
11.009.007.005.003.001.00
-1.00-3.00-5.00-7.00-9.00
-11.00
Vorticity distribution(X-component)
X mm
Ym
m
-40 -20 0 20 40
-30
-20
-10
0
10
20
30
40
15.0014.0013.0012.0011.0010.00
9.008.007.006.005.004.00
Vorticity distribution(in-plane)
-4.5
-4.5
-3.5
-2.5
-2.5
-2.5 -2.5
-1.5
-1.5
-1.5
-0.5-0.5
-0.5
-0.5
-0.5
-0.5
-0.5
-0.5
0.5
0.50.5
0.5
0.5
1.5
1.5
1.5
1.5
2.53.5
4.5
X mm
Ym
m
-40 -20 0 20 40
-30
-20
-10
0
10
20
30
40
4.503.502.501.500.50
-0.50-1.50-2.50-3.50-4.50
Vorticity distribution(Z-component)
22yxplanein ϖϖϖ +=−
xw
zu
y ∂∂
−∂∂
=ϖzv
yw
x ∂∂
−∂∂
=ϖyu
xv
z ∂∂
−∂∂
=ϖ
x
zY
a. three-dimensional velocity vectors b.iso-surface of velocity field
Reconstructed ThreeReconstructed Three--dimensional Flow Fielddimensional Flow Field
Applications: MTV Measurements of the Applications: MTV Measurements of the Vortex Shedding from an Oscillating AirfoilVortex Shedding from an Oscillating Airfoil
Strong concentrated vortices are formed immediately at the trailing edge.
Instantaneous streamlines are highly curved near the trailing edge.
Note the location and sign of the vortices formed at the trailing edge.
BioBio--inspired Airfoil Designs for Microinspired Airfoil Designs for Micro--AirAir--Vehicles (MAV) ApplicationsVehicles (MAV) Applications
Micro-Air-Vehicles (MAVs) refer to palm-sized aircraft with maximum dimension ~15cm and flight speed ~10m/s.
““macromacro--scalescale”” aircraft:aircraft: ReReCC = 10= 106 6 ~10~108 8
MAV:MAV: ReReCC = 10= 1033 ~10~1055
““ScaleScale--downdown”” of conventional airfoils of conventional airfoils could notcould not provide provide sufficient sufficient aerodynamic performanceaerodynamic performance for MAV applications.for MAV applications.
It is very necessary and important to establish It is very necessary and important to establish novel novel airfoil airfoil shape and wing shape and wing planformplanform design design paradigmsparadigms for for MAVsMAVs in in order to achieve order to achieve superbsuperb aerodynamic performances to aerodynamic performances to improve their flight improve their flight agilityagility and and versatility.versatility.
(from McMaster and Henderson, 1980)(from McMaster and Henderson, 1980)
interest for interest for MAV MAV applicationsapplications
310 610410 510
010
110
210
310
710
μρ CU∞=Re
MAXD
L
CC
Streamlined airfoilStreamlined airfoil
rough airfoilrough airfoil
MAVsMAVs developed by the University of Floridadeveloped by the University of Florida
b. Flat plateb. Flat plate
a. streamlined airfoila. streamlined airfoil
C. corrugated dragonfly C. corrugated dragonfly airfoilairfoil
Which one is better for Which one is better for MAVsMAVs? Why???? Why???
BioBio--inspired Airfoil for Microinspired Airfoil for Micro--AirAir--Vehicle (MAV) ApplicationsVehicle (MAV) ApplicationsVein networkVein network
MembranesMembranes
11 22 33
11
22
33
Profiles taken from Profiles taken from KeselKesel, A. B., Journal of Experimental , A. B., Journal of Experimental Biology, Vol. 203, 2000, pp. 3125Biology, Vol. 203, 2000, pp. 3125--3135 3135 0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1.0
1.1
1.2
1.3
2 4 6 8 10 12 14 16 18 20
CL - flat plateCD- flat plateCL- GA (W)-1 airfoilCD- GA (W)-1 airfoilCL- corrugated airfoilCD- corrugated airfoil
Angle of Attack (degrees)
CL, C
D
Re=34,000Re=34,000
PIV Measurement Results at AOA = 10.0 deg, Re=34,000PIV Measurement Results at AOA = 10.0 deg, Re=34,000
A. instantaneous resultsA. instantaneous results
B. ensembleB. ensemble--averaged resultsaveraged resultsX (mm)
Y(m
m)
-50 0 50 100 150
-60
-40
-20
0
20
40
60
80
100
-1.0 0.0 1.0 2.0 3.0 4.0 5.0 6.0 7.05.0 m/sstreamwise
velocity (m/s)
shadow region
GA(W)-1 airfoil
X (mm)
Y(m
m)
-50 0 50 100 150
-60
-40
-20
0
20
40
60
80
100
-0.9 -0.7 -0.5 -0.3 -0.1 0.1 0.3 0.5 0.7 0.95.0 m/sspanwise
vorticity (1/s)
shadow region
GA(W)-1 airfoil
X (mm)
Y(m
m)
-50 0 50 100 150
-60
-40
-20
0
20
40
60
80
100
-1.0 0.0 1.0 2.0 3.0 4.0 5.0 6.0 7.05.0 m/sstreamwise
velocity (m/s)
shadow region
X (mm)Y
(mm
)-50 0 50 100 150
-60
-40
-20
0
20
40
60
80
100
-0.9 -0.7 -0.5 -0.3 -0.1 0.1 0.3 0.5 0.7 0.95.0 m/svorticity
(1/s)
shadow region
X (mm)
Y(m
m)
0 50 100 150
-60
-40
-20
0
20
40
60
80-1.0 0.0 1.0 2.0 3.0 4.0 5.0 6.0 7.0
5.0 m/sstreamwisevelocity (m/s)
shadow region
X (mm)
Y(m
m)
0 50 100 150
-60
-40
-20
0
20
40
60
80-0.9 -0.7 -0.5 -0.3 -0.1 0.1 0.3 0.5 0.7 0.9
5.0 m/svorticity(1/s)
shadow region
Flow Structures Around the Corrugated Dragonfly Airfoil Flow Structures Around the Corrugated Dragonfly Airfoil (AOA = 10.0 degrees)(AOA = 10.0 degrees)
B. ensembleB. ensemble--averaged resultsaveraged results
A. instantaneous resultsA. instantaneous results
X (mm)
Y(m
m)
0 5 10 15 20 25 30 35 40 45 50 55
-5
0
5
10
15
6.505.504.503.502.501.500.50
-0.50
5.0 m/s
streamwisevelocity (m/s)
X (mm)
Y(m
m)
0 5 10 15 20 25 30 35 40 45 50 55
-5
0
5
10
15
6.505.504.503.502.501.500.50
-0.50
streamwisevelocity (m/s)
X (mm)
Y(m
m)
0 5 10 15 20 25 30 35 40 45 50 55
-5
0
5
10
15
6.505.504.503.502.501.500.50
-0.50
streamwisevelocity (m/s)
X (mm)
Y(m
m)
0 5 10 15 20 25 30 35 40 45 50 55
-5
0
5
10
15
2.501.500.50
-0.50-1.50-2.50-3.50-4.50-5.50
spanwisevorticity (1/s)
5.0 m/s
Flexible Membrane Flexible Membrane Wings of MammalsWings of Mammals–– Bats, Flying Squirrels Bats, Flying Squirrels and Sugar Glidersand Sugar Gliders
sugar glidersugar glider
flying squirrelflying squirrel BatBat
Flexible Membrane AirfoilsFlexible Membrane Airfoils
•• Cross section: Cross section: S5010 airfoilS5010 airfoil•• Airfoil thickness: Airfoil thickness: 2% of chord length.2% of chord length.
•• The S5010 airfoil is popular used for MAV The S5010 airfoil is popular used for MAV applications. applications.
•• It is featured with a slight reflex in the trailing It is featured with a slight reflex in the trailing edge to reduce the strength of the inherent, edge to reduce the strength of the inherent, negative pitching moment.negative pitching moment.
CChh
Force Measurement Results (Re=80,000)Force Measurement Results (Re=80,000)
0
0.1
0.2
0.3
0.4
0.5
0.6
0 2 4 6 8 10 12 14 16 18 20
CF10
CF03
CF02
CF01
CF00
CS
Angle of attack (degrees)C
D
-0.2
0
0.2
0.4
0.6
0.8
1.0
1.2
1.4
1.6
1.8
0 2 4 6 8 10 12 14 16 18 20
CF10
CF03
CF02
CF01
CF00
CS
Angle of attack (degrees)
CL
Lift coefficient vs. angle of attack Drag coefficient vs. angle of attack
PIV Measurement Results (AOA=12 deg, Re=80,000)PIV Measurement Results (AOA=12 deg, Re=80,000)
Measurement PlaneMeasurement PlaneCF02CF02
Measurement Plane Measurement Plane CSCS
Paint Ball Aerodynamics
Paintball is a sport that started in the 1980’s
The goal is to eliminate the other team or other special objectives
Teams consist from 2 to 500+ people
Games can last from 5 min. to 48 hours
0.68” standard size
Shell color can be any color
Fill color can be any color but red
Room for Improvement
Laminar flow around a sphere creates a high pressure drag
Induce a turbulent flow around the sphere to reduce the pressure drag
Size of 0.685” to 0.693”Initial velocity of 300 ft/sec
Reynolds number Re= 107,000
Laminar flow about the front face of the ball CD = 0.5
X/D
Y/D
-101234
-1
0
1
2
U m/s: -10 -5 0 5 10 15 20 25 30 35 40
X/D
Y/D
-101234
-1
0
1
2 U m/s: -10 -5 0 5 10 15 20 25 30 35 40
X/D
Y/D
-101234
-1
0
1
2 U m/s: -10 -5 0 5 10 15 20 25 30 35 40
Smooth ball
Rough ballGolf ball
Center line Velocity
-0.4
-0.2
0
0.2
0.4
0.6
0.8
1.0
-2.0 -1.5 -1.0 -0.5 0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0
smooth-ballrough-ballgolf-ball
Distance (X/D)
Cen
terli
ne V
eloc
ity (U
/U∞)
AerE 243L Loboratory
(Report #4 due)Dec. 11, 2007
(Report #4 due)Dec. 09, 2007
Week 16Final exam for AerE 243L
(Data processing for Lab#4 )
Dec. 04, 2007
(Data processing for Lab #4)
Dec. 02, 2007
Week 15Lab 5: PIV measurement of the flow field around an airfoil before and after airfoil stall
Thanksgiving breakThanksgiving breakWeek 14
(Report #3 due)Nov. 20, 2007
(Report #3 due)Nov. 18, 2007
Week 13Lab 4: Aerodynamic characteristics of an airfoil
Data processing(processed data
submitted to TA by Tuesday)
Data processing(processed data
submitted to TA by Tuesday)
Week 12Lab 3: Flow around a circular cylinder
(Report #2 due)Nov. 06. 2007
(Report #2 due)Nov. 04, 2007
Week 11Lab 3: Flow around a circular cylinder
(Report #1 due)Oct. 30, 2008
(Report #1 due)Oct. 28, 2008
Week 10Lab 2: Calibration of low speed wind tunnel
Oct. 23, 2008Oct. 21, 2008Week 9Lab 1: Flow visualization
Section 2Thursday
(1:10~3:00pm)
Section 1Tuesday
(3:10~5:00pm)
AerE 243L: Incompressible Aerodynamics
Lab # 1:AFD : streamlines, pathlines and streaklinesEFD : flow visualization
Flow around airfoils: blunt bodies, cambered airfoils
Flow Visualization
Flow Visualization
Streamlines (experiment)
AerE 243L: Incompressible Aerodynamics
Lab #2: Calibration of low speed wind tunnel :AFD : Bernoulli’s equationEFD : wind tunnel calibration
Wind Tunnel Calibration
AerE 243L: Incompressible Aerodynamics
Lab # 3:
AFD : potential flow over a cylinder
EFD : flow over a cylinder
pressure distribution on the cylinder and drag estimation
CFD : all of the above and flow field analysis and visualization
Flow over a Circular Cylinder
Synthesis of lifting flow over a circular cylinder
Flow over a Circular Cylinder
Experimental model for measuring the pressure distributions along the circular cylinder surface (outside diameter = 3.25 inch)
Flow over a Circular Cylinder
Mesh for the numerical calculation of the flow over a circular cylinder
Flow over a Circular Cylinder
Numerical results for the velocity magnitude and pressure distributions over a circular cylinder using FlowLab(Vh=35.8 m/s, Re=1.89E+05)
Flow over a Circular Cylinder
Cp distributions over a circular cylinder
-3.5
-3
-2.5
-2
-1.5
-1
-0.5
0
0.5
1
1.5
0 1 2 3 4 5 6 7
theta (rad ) -->
cp --
>
EFDCFDAFD
AerE 243L: Incompressible Aerodynamics
Lab# 4:AFD : introduction to airfoil characteristics
( Cl vs α, Cd vs α and Cm vs α )
EFD : same as AFD and analysis of the pressure distribution.
CFD : all of the above and flow field analysis and visualization
Flow over an Airfoil
Schematic of lift coefficient variation with angle of attack for an airfoil
Flow over an Airfoil
Experimental data for lift coefficient and moment coefficient about the ¼ chord point for an NACA 2412 airfoil
Flow over an Airfoil
Experimental data for profile drag coefficient and moment coefficient about the aerodynamic center for the NACA 2412 airfoil
Flow over an Airfoil
Experimental model for measuring the pressure distributionsalong the LS(1)-0417 airfoil surface
Flow over an Airfoil
airfoil (New airfoil Structured mesh for the numerical calculation of the flow over a LS(1)-0417 template)
Flow over an Airfoil
Numerical results for the Mach number and pressure distributions over LS(1)-0417 airfoil using the FlowLab(angle of attack=4 degree, Mh=0.025, Re=2.0E+05)
Flow over an Airfoil-1.5
-1
-0.5
0
0.5
1
1.5
0 0.2 0.4 0.6 0.8 1 1.2
x/c -->
c p --
>
EFD
CFD
Cp distributions over LS(1)-0417 airfoil
AerE 243L: Incompressible Aerodynamics
Lab # 5:Advanced Fluid Diagnostic technique: Particle Image velocimetry.
Flow visualization of vortex structures around an airfoil
Flow separations and airfoil stall
X (mm)
Y(m
m)
-20 0 20 40 60 80 100 120 140-60
-40
-20
0
20
40
60 -3.2 -2.7 -2.2 -1.7 -1.2 -0.7 -0.2 0.3 0.8 1.3 1.810 m/sspanwise
vorticity (1/s)
shadow region
GA(W)-1 airfoil
X (mm)
Y(m
m)
-20 0 20 40 60 80 100 120 140
-60
-40
-20
0
20
40
60 -3.2 -2.7 -2.2 -1.7 -1.2 -0.7 -0.2 0.3 0.8 1.3 1.810 m/sspanwise
vorticity (1/s)
shadow region
GA(W)-1 airfoil
AOA= 6 degreesAOA= 6 degrees AOA= 12 degreesAOA= 12 degreesRe=70,000Re=70,000
Questions?
