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National Aeronautics and Space Administration
www.nasa.gov
Status of 3D Ice Shape Measurement Effort
Sam Lee
ASRC Aerospace, Inc.
2011 Annual Technical Meeting
May 10–12, 2011
St. Louis, MO
National Aeronautics and Space Administration
www.nasa.gov 2
Outline
• Introduction
• Research Plan
• Project Status
• Future Plans
National Aeronautics and Space Administration
www.nasa.gov 3
Introduction• Main goal of the Airframe Icing Technical Challenge is to
achieve acceptance of experimental and computational icing simulation tools– Supercooled Large Droplet Icing (SLD) conditions
– 3D airframe components including swept wings.
• It is necessary to develop suitable means of recording and archiving fully 3D descriptions of experimental ice accretion geometry.
• Past research has shown that commercial laser scanners have the potential to be adapted to this task.
• A research plan has been developed to implement and validate the use of this technology for experimental ice accretions.
National Aeronautics and Space Administration
www.nasa.gov 4
Introduction (cont’d)• Phase 1 – Identify most suitable scanning system
– Focus specifically upon measuring ice accreted in the NASA Icing Research Tunnel (IRT).
– Built on recent demonstration tests of portable scanners in IRT.
– Follow-on IRT testing and demonstrations conducted to complete a down-selection process to the most promising and suitable technology.
• Phase 2 – Validation exercises to define scanning capability.– Calibration block
– 2D geometric and aerodynamic comparisons
– Swept-wing geometric comparisons
National Aeronautics and Space Administration
www.nasa.gov 5
NASA Milestones
• Level 3 milestone– “Select Candidate Laser Scanning System”
– Q1 FY2012
• Level 1 milestone– “Declare 3D Ice Accretion Measurement Capability”
– Q4 FY2013
National Aeronautics and Space Administration
www.nasa.gov 6
Research Plan – 1st Phase• Evaluate candidate laser scanning system in IRT.
– Demonstrate capability to operate in the IRT environment.
– Evaluated on the basis of criteria having to do with operations, scanning capability/accuracy and cost.
• Evaluate candidate software used to post-process the scanner data .– Demonstrate ability to create “water-tight” surface.
– Evaluated on the basis of criteria having to do with operations, efficiency, ease of use, and cost.
• Assessment of rapid-prototyping capability. – Scan data of ice accretion will be processed to water-tight surface.
– Various RPM (rapid-prototype model) vendors will be contacted to ascertain the current state of capability to manufacture artificial ice shapes.
National Aeronautics and Space Administration
www.nasa.gov 7
Research Plan – 1st Phase (cont’d)
• The outcome of Phase I will be a selection of both laser scanning hardware system and post-processing software.– This will satisfy the AEST level 3 milestone.
Define
Scanner
Selection
Criteria
Evaluate
Scanners
in IRT
Define
Software
Selection
Criteria
Down-
Select &
Purchase
Scanner
Evaluate
Software
Down-
Select &
Purchase
Software
RPM
Assessment
Phase I Roadmap
Evaluate
Scan
Data
Le
ve
l 3
Mile
sto
ne
:
Se
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tio
n o
f S
ca
nn
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an
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oft
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National Aeronautics and Space Administration
www.nasa.gov 8
1st Phase Research Task
• Define evaluation/selection criteria for scanner hardware and software.
• Define specific laser scanner systems (hardware) and post-processing software to be evaluated.
• Develop test and evaluation plans.
• Evaluate candidate current laser-scanning systems in IRT.
• Evaluate candidate software systems.
• Conduct assessment of Rapid Prototype Method (RPM) capability.
• Down-select one hardware system and one software system for Phase II.
• Purchase hardware and software.
National Aeronautics and Space Administration
www.nasa.gov 9
Selection Criteria - Hardware
• IRT test section capability– Environment - operate in a wide range of IRT test section
environment.
– Usability
• Portability
• Ease of use.
• Convenience of measurement procedure
• Scanning capability– Scan resolution
– Scan speed
– Ability to scan gaps and holes.
– Accuracy
• Cost vs. capability
National Aeronautics and Space Administration
www.nasa.gov 10
Selection Criteria - Software
• Scanner compatibility
• Water-tight modeling ability
• Noise filtering
• Efficiency– Ease of use
– Speed
– Processing time
– Large file capability
• Cost vs. capability
National Aeronautics and Space Administration
www.nasa.gov 11
Research Plan – 2nd Phase• Implementation and validation of the selected system.
• Validation exercise with known geometry to define the measurement capability. – Benchmark measurements performed on the metal calibration blocks.
– These data can be used as a type of check standard to ensure uniform capability over time.
National Aeronautics and Space Administration
www.nasa.gov 12
Research Plan – 2nd Phase (cont’d)• “Circular” validation along with aerodynamic assessment
based upon a 2D airfoil geometry.– Perform laser scans and pour molds of selected ice accretion.
– Use scan data to create high-fidelity (RPM) artificial ice shapes along with castings from molds.
– Compare scanned and cast geometries
National Aeronautics and Space Administration
www.nasa.gov 13
Research Plan – 2nd Phase (cont’d)• A closely related 2D aerodynamic evaluation will also be
conducted– RPM artificial shapes made from ice scans will be tested against
castings.
– Use methods established during NASA/ONERA/UIUC Aerosim Project
– These validations (both geometric and aerodynamic) should be conducted for each of the four basic categories of ice accretion: roughness, horn, streamwise and spanwise ridge.
(deg)
-6 -4 -2 0 2 4 6 8 10 12 14 16 18 20-0.8
-0.6
-0.4
-0.2
0.0
0.2
0.4
0.6
0.8
1.0
1.2
1.4
1.6
1.8
2.0
-0.08
-0.06
-0.04
-0.02
0.00
0.02
0.04
0.06
0.08
0.10
0.12
0.14
0.16
0.18
0.20
Cm
Cl
National Aeronautics and Space Administration
www.nasa.gov 14
Research Plan – 2nd Phase (cont’d)
• Geometric validation test on a swept-wing model.– This exercise will consist of scanning an ice accretion, making a mold
and casting of that ice accretion.
– The scan data used to create an RPM artificial shape that can be scanned and compared to the original ice accretion.
– A scan of the casting can also be compared to the original ice accretion scan.
– Aerodynamic assessment not possible at this time due to lack of established method.
National Aeronautics and Space Administration
www.nasa.gov 15
Research Plan – 2nd Phase (cont’d)• Develop procedures for using the scanner in the IRT as well as
for post-processing the data.– Document to serve as an internal reference guide for continued IRT
testing and use of the scanner and software system.
– Include all aspects of the measurement
• Preparation of the ice accretion (e.g., “painting”)
• Set-up of the scanning (e.g., any in-situ calibration or homing)
• Scanning of the ice (e.g., software settings, resolution vs. time and desired accuracy)
• Saving of the data (e.g., file types and sizes)
• Post-processing of the data (e.g., procedures for hole-filing, software settings, extracting tracings, etc.).
• The outcome of Phase II will be declaration of 3D ice accretion measurement capability.– This will satisfy the AEST level 1 milestone.
National Aeronautics and Space Administration
www.nasa.gov 16
Research Plan – 2nd Phase (cont’d)
Benchmark
Measurements
Rqmts
Met?
Le
ve
l 1
Mile
sto
ne
:
3D
Ic
e S
ha
pe
Me
as
ure
men
t C
ap
ab
ilit
y
Declare
Swept
Wing
Capability
Y
N
Phase II Roadmap
RPM of
Scan
Shapes
Mold/Cast
Ice Shapes
IRT Ice
Accretion
Test
Aero test/
Comparisons
Geometric
Comparisons
Geometric
Comparisons
RPM of
Scan
Shapes
Mold/Cast
Ice Shapes
2D Airfoil Validation
Swept Wing Validation
IRT Ice
Accretion
Test
Declare 2D
Capability
Ph
as
e I:
Se
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n o
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ca
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an
d S
oft
wa
re
National Aeronautics and Space Administration
www.nasa.gov 17
2nd Phase Research Tasks
• Benchmark scanner with calibration blocks
• 2D airfoil model evaluation– Geometry comparisons
– Aerodynamic comparisons
• Swept wing model evaluation– Geometry comparisons
• Standardize methods for laser scan data acquisition and post-processing.– Write process description with quantifiable standards
• Declare 3D ice accretion measurement capability.– Satisfy AEST Level 1 milestone.
National Aeronautics and Space Administration
www.nasa.gov 18
Project Status
• Hardware/software selection criteria established
• Evaluated candidate scanners in IRT– Creaform – Oct 2009
– Faro Arm– Nov 2009, March and April 2011
– Romer – March 2011
– nVision – April 2011
• Tested ice shapes from identical model and icing conditions– Glaze, rime, roughness on straight NACA 0012
– Scallop ice shape on 45 deg swept NACA 0012
• Purchased software to evaluate scan data (Geomagic)
National Aeronautics and Space Administration
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IRT Scanner Evaluation Procedure
1. Accrete ice on test article
2. Photograph ice
3. Spray paint accreted ice using airbrush
4. Install/set up laser scanner
5. Scan ice
6. Cut ice and make tracing
National Aeronautics and Space Administration
www.nasa.gov 20
IRT Scanner Evaluation
Painting ice with air brush paint
Painted ice
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IRT Scanner Evaluation
Scanning ice shape with 3D scanner.
National Aeronautics and Space Administration
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IRT Scanner Evaluation
Hand tracing of ice shapes for
comparison to scanner.
National Aeronautics and Space Administration
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Water Tight Scanned DataGlaze Ice
National Aeronautics and Space Administration
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Water Tight Scanned DataRime ice
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Scanned Data3D Scallop Ice
National Aeronautics and Space Administration
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Comparison of 3D Scanned Data to Hand Tracing
x (in)
-1 0 1 2 3 4 5
y (
in)
-2
-1
0
1
2
Clean Model
Hand Traced
3D Scanner
Glaze ice
x (in)
-1 0 1 2 3 4 5
y (
in)
-2
-1
0
1
2
Clean Model
Hand Traced
3D Scanner
Rime ice
x (in)
-2 0 2 4 6
y (
in)
-3
-2
-1
0
1
2
3
Clean Model
Hand Traced
3D Scanner
3D scallop ice
National Aeronautics and Space Administration
www.nasa.gov 27
Future Plans
• Evaluate data from candidate scanners
• Down-select and purchase scanner
– Q1 FY2012 (L3 milestone)
• Assess and validate scanning system and methods
– Straight and swept wing geometry
– Compare aero results with scanned and cast ice shapes
• Declare 3D ice shape scanning capability
– Q4 FY 2013 (L1 milestone)