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Implementation and Validation of 3-D Ice Accretion Measurement Methodology

Sam LeeVantage Partners, LLC

Andy BroerenRichard KreegerMark Potapczuk

NASA Glenn Research Center

Lloyd UttUniversity of Akron

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https://ntrs.nasa.gov/search.jsp?R=20150000704 2018-06-17T11:04:32+00:00Z

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Outline

• Introduction• Scan Data Acquisition/Processing Procedure• Straight Wing Results• Swept Wing Results• Conclusion

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Introduction

• NASA currently undertaking multi-year research program to answer “How good is good enough” for swept wing icing.

• Documentation of the ice accretion key piece of data in icing-wind-tunnel tests.

• Currently used options for documenting ice accretion• Photography• Pencil tracings• Mold and casting

• Current methods have limitation that affect usability.

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Introduction (cont’d)• NASA incorporated development of three-

dimensional ice accretion digitization methods into its current research plans.

• Phase 1• Romer Absolute SI scanner and

Geomagic Studio software selected for further development.

• Phase 2• The selected scanner system used to

implement and validate the use of this technology through a series of icing and aerodynamic tunnel tests.

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Introduction (cont’d)• Benchmark measurements were performed on a metal

“roughness sample” block.• Geometric and aerodynamic assessment on a straight

wing airfoil geometry.• Comparison of scanned ice shapes to castings of the same ice

shape.• Scan data were also used to create Rapid Prototype

Manufacturing (RPM) artificial shapes that were scanned and compared to the original ice accretion.

• An aerodynamic evaluation was also conducted• Four basic categories of ice accretion: glaze horn, roughness,

rime and runback. • Geometric validation performed on a swept-wing

geometry.• Quantified the limitations of capturing very complicated scallop

geometries.• Did not contain an aerodynamic assessment.

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Data Acquisition Procedure

The IRT scanner data acquisition procedure consisted of the following six steps:

1. Accrete ice on the test article2. Photograph the ice3. Spray the ice with white paint4. Install and set up the scanner5. Scan the ice shape6. Make mold of ice shape

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Data Processing Procedure

The IRT scanner data processing procedure consisted of the following five steps:

1. Align/combine scan passes2. Reduce data set3. Wrap surface4. Repair mesh/fill holes5. Coordinate transformation

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Benchmark Measurement Results

• Benchmark results on “roughness” block:• Used to simulate roughness on horn shape• 3 roughness sizes• 2 roughness patterns

0.063” diam. hemisphere 0.031” diam. hemisphereScan vs. CAD model

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Straight Wing ResultsRoughness Shape

Cross section cutWater-tight modelX(in)

-0.2 0.0 0.2 0.4 0.6 0.8 1.0 1.2 1.4

Y(in

)

-0.4

-0.2

0.0

0.2

0.4

0.6

0.8

NACA 23012IceRPMCasting

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RPM vs original ice scan deviation map

Cast vs original ice scan deviation map

Straight Wing ResultsRoughness Shape

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Straight Wing ResultsRoughness Shape

Cast ShapeRPM Shape

Local Deviation Map

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Straight Wing ResultsRime Shape

Cross section cutWater-tight modelX (in)

-0.5 0.0 0.5 1.0 1.5

Y (in

)

-0.6

-0.4

-0.2

0.0

0.2

0.4

0.6

0.8

1.0

NACA 23012IceRPMCasting

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RPM vs original ice scan deviation map

Cast vs original ice scan deviation map

Straight Wing ResultsRime Shape

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Straight Wing ResultsRime Shape

Cast ShapeRPM Shape

Local Deviation Map

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Straight Wing ResultsRunback Shape

Cross section cutWater-tight model X (in)

0 1 2 3 4

Y (in

)

-1

0

1

2

NACA 23012IceRPMCasting

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RPM vs original ice scan deviation map

Cast vs original ice scan deviation map

Straight Wing ResultsRunback Shape

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Swept Wing ResultsComplete Scallop Shape

Cross section cutWater-tight modelX(in)

-2 0 2 4 6

Y(in

)

-3

-2

-1

0

1

2

3

NACA 0012IceCasting LaserCasting CT

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Laser Scan of Casting vs. Original Ice Scan

CT vs. Laser Scan of Casting

Swept Wing ResultsComplete Scallop Shape

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Swept Wing ResultsIncomplete Scallop Shape

Cross section cutWater-tight model X(in)

-2 0 2 4 6

Y(in

)

-3

-2

-1

0

1

2

3

NACA 0012IceCasting

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Casting vs. Original Ice Scan Deviation Map

Swept Wing ResultsIncomplete Scallop Shape

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Conclusion

• A research program implemented to develop and validate the use of a 3D laser scanning system to record ice accretion shapes in the NASA Icing Research Tunnel.

• Phase 1 - Identify the most suitable laser scanning hardware and software for further development.

• Phase 2 - Selected scanner system will be used to implement and validate the use of this technology through a series of icing and aerodynamic tunnel tests.

• Straight-wing ice shape models generated through the scan/RPM process compared well with the cast shapes.• Cast shapes appear to have shrunk during the mold/casting process.• Rapid prototype manufacturing process reproduce the original ice

accretion scan normally within 0.01-inch.

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Conclusion (cont’d)

• Swept wing results showed similar good results.• Significant portions of the scallop features were captured with the laser

scanner• Results compared very well with the CT scanning method, except for

the deep gaps between the scallops.• It is currently not known how aerodynamically important these deep

gap regions are.• Missing scallop and feather features on the cast shapes that broke off

during the mold/casting process.

• Increased utility of icing tests by developing robust means of recording and archiving fully 3-D descriptions of experimental ice accretion geometry.

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