scholars day 04/20/2009 steven mart mentor: dr. stephen t. mcclain
TRANSCRIPT
Scholars Day04/20/2009
Steven MartMentor: Dr. Stephen T. McClain
Aircraft Icing & Henry et al. Small Test Piece
◦ New Mylar Application Technique◦ Results & Conclusions
Large Test Plate◦ Construction◦ Results
◦ Apparent Enhancement of Elements◦ Flow Characteristics
Conclusions & Improvements Future Research
Aircraft icing is a serious flight safety concern and is not completely understood
Initial heat transfer influences how ice formations grow on aircraft surfaces
By analyzing the local heat transfer coefficient we can better understand how ice develops
Continuation of research by Henry et al. Used gold deposited Mylar
film to study the local heattransfer
Thin, uniform coating of gold over Mylar
Applied by vacuum sputter deposition
Highly susceptible to degradation and contamination (scratches, oils, etc.)
Used to apply a constant heat flux boundary condition
Need to mount metallic roughness elements to gold Mylar
Traditional application orients film gold-side up
Mounting high thermal conductivity elements creates local hot spots
Negates the constant heat flux boundary Needed a way to mount elements without
disrupting the boundary condition
Developed new gold-side down orientation Elements attached to non-conductive side Maintains constant flux boundary condition Requires consideration of additional heat
transfer modes◦ Mylar conduction◦ Plexiglas conduction
Mylar Film
Gold DepositionLayer
PlexiglasSubstrate
Air
Air
3.9% variation within central region of plate
Encouraging due to small size of Mylar used
New mounting procedure verified as a viable mounting solution
Constant flux boundary condition still maintained
Allows for the mounting of roughness elements
Transitioned into creation and testing of full scale test plate
9.53 mm Steel Roughness Element
9.53 mm Plastic Roughness Element
5.0 mm Plastic Roughness Element
IR Camera
Test Plate
IR Temperature Gun
Investigated apparent enhancement (AE) of elements
Indicates how much heat transfer has increased due to the presence of protuberances vs. unperturbed regions
Not a true enhancement measurement but still useful
Compared to data of Henry et al. Also analyzed flow characteristics
53 54 55 56 57 580
1
2
3
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7
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v = 1.0 m/sv = 2.5 m/sv = 5.0 m/sv = 7.5 m/sv = 10.0 m/sv = 15.0 m/sv = 20.0 m/s
Distance from Leading Edge (cm)
App
aren
t Enh
ance
men
t
53 54 55 56 57 580
1
2
3
4
5
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7
8
v = 1.0 m/sv = 2.5 m/sv = 5.0 m/sv = 7.5 m/sv = 10.0 m/sv = 15.0 m/sv = 20.0 m/s
Distance from Leading Edge (cm)
App
aren
t Enh
ance
men
t
53 54 55 56 57 580.5
1
1.5
2
2.5
3
v = 1.0 m/sv = 2.5 m/sv = 5.0 m/sv = 7.5 m/sv = 10.0 m/sv = 15.0 m/sv = 20.0 m/s
Distance from Leading Edge (cm)
App
aren
t Enh
ance
men
t
53 54 55 56 57 580.5
1
1.5
2
2.5
3
v = 1.0 m/sv = 2.5 m/sv = 5.0 m/sv = 7.5 m/sv = 10.0 m/sv = 15.0 m/sv = 20.0 m/s
Distance from Leading Edge (cm)
App
aren
t Enh
ance
men
t
AE for Large Plastic Element AE for Large Steel Element
53 54 55 56 57 580
1
2
3
4
5
v = 1.0 m/sv = 2.5 m/sv = 5.0 m/sv = 7.5 m/sv = 10.0 m/sv = 15.0 m/sv = 20.0 m/s
Distance from Leading Edge (cm)
App
aren
t Enh
ance
men
t
53 54 55 56 57 580
1
2
3
4
5
v = 1.0 m/sv = 2.5 m/sv = 5.0 m/sv = 7.5 m/sv = 10.0 m/sv = 15.0 m/sv = 20.0 m/s
Distance from Leading Edge (cm)
App
aren
t Enh
ance
men
t
AE for Small Plastic Element Material properties and
size influence AE Increasing
enhancement for increasing velocity
Vortices Flow Separation
3.4 104 3.5 10
4 3.6 104 3.7 10
4 3.8 104
0.9
1.1
1.3
1.5
1.7
9.53-mm ABS Element5.0-mm ABS Element9.53-mm Steel Element
Local Plate Reynolds Number
App
aren
t Enh
ance
men
t
3.4 104 3.5 10
4 3.6 104 3.7 10
4 3.8 104
0.9
1.1
1.3
1.5
1.7
9.53-mm ABS Element5.0-mm ABS Element9.53-mm Steel Element
Local Plate Reynolds Number
App
aren
t Enh
ance
men
t
1.7 105 1.75 10
5 1.8 105 1.85 10
50.9
1.3
1.7
2.1
2.5
2.9
9.53-mm ABS Element5.0-mm ABS Element9.53-mm Steel Element
Local Plate Reynolds Number
App
aren
t Enh
ance
men
t
1.7 105 1.75 10
5 1.8 105 1.85 10
50.9
1.3
1.7
2.1
2.5
2.9
9.53-mm ABS Element5.0-mm ABS Element9.53-mm Steel Element
Local Plate Reynolds Number
App
aren
t Enh
ance
men
t
3.3 105 3.4 10
5 3.5 105 3.6 10
50.9
1.6
2.3
3
3.7
4.4
9.53-mm ABS Element5.0-mm ABS Element9.53-mm Steel Element
Local Plate Reynolds Number
App
aren
t Enh
ance
men
t
3.3 105 3.4 10
5 3.5 105 3.6 10
50.9
1.6
2.3
3
3.7
4.4
9.53-mm ABS Element5.0-mm ABS Element9.53-mm Steel Element
Local Plate Reynolds Number
App
aren
t Enh
ance
men
t
6.8 105 7 10
5 7.2 105 7.4 10
50.9
1.9
2.9
3.9
4.9
5.9
6.9
7.9
9.53-mm ABS Element5.0-mm ABS Element9.53-mm Steel Element
Local Plate Reynolds Number
App
aren
t Enh
ance
men
t
6.8 105 7 10
5 7.2 105 7.4 10
50.9
1.9
2.9
3.9
4.9
5.9
6.9
7.9
9.53-mm ABS Element5.0-mm ABS Element9.53-mm Steel Element
Local Plate Reynolds Number
App
aren
t Enh
ance
men
t
1 mps 5 mps
10 mps 20 mps
Flow from bottom to top, increasing left to right
Flow separation and reattachment
Again, influence of material and size
Large Plastic Element Large Steel Element
Small Plastic Element
Greater and more uniform temperature profile for steel due to its conductive properties
Effects of separation vortices visible at high speeds
Elongation of profiles also visible
Large Plastic Element
Large Steel Element
Small Plastic Element
Apparent enhancement results in general agreement with those of Henry et al.
Need to compare data to flat plate correlations
New higher amperage power supply needed◦ Eliminate power issues◦ Needed for higher velocity tests
Automation of voltage, current and pressure measurements
Tests at higher flow velocities◦ Influence of turbulent flow on AE
Accelerating/Decelerating Flow Large roughness element distribution
(400+)◦ Plastic Element Distribution◦ Steel Element Distribution
Dr. Stephen McClain Dr. Kenneth Van Treuren Dr. Ian Gravagne Mr. Ashley Orr Gilbert Narvaez III John Miller
[1] Henry, R. C., Hansman, R. J., Breuer, K. S., “Heat Transfer Variation on Protuberances and Surface Roughness Elements”, Journal of Thermophysics and Heat Transfer, Vol. 9, No. 1, March 1995.
Questions?