Analysis of Supercooled Large Drop Velocity Measurement in the NASA Icing Research Tunnel

National Aeronautics and Space Administration

Analysis of Supercooled Large Drop

Velocity Measurement in the NASA Icing

Research Tunnel

Jen - Ching Tsao

Ohio Aerospace Institute

Mario Vargas, Zaid Sabri, Eric Insana

NASA Glenn Research Center

Eric Stewart

Naval Air Warfare Center Aircraft Division (NAWCAD)

Emily Timko

Jacobs Technology, Inc.

Gregory Payne

Artium Technologies, Inc.

SAE International Conference on Icing of Aircraft, Engines, and Structures 20 - 22 June 2023, Vienna, Austria This material is a work of the U . S . Government and is not subject to copyright protection in the United States www.nasa.gov 1

National Aeronautics and Space Administration Outline • Introduction • Experimental Approach • Key Results • Conclusions • Recommendations • Acknowledgements www.nasa.gov 2

National Aeronautics and Space Administration

Introduction

• The FAA Part 25 Appendix O was issued in 2015 to define a representative icing environment for supercooled large drops (SLD) including ▪ freezing drizzle (FZDZ) and freezing rain (FZRA) conditions • The NASA Icing Research Tunnel (IRT) is a sea level icing test facility that operates* in ▪ Appendix C conditions ▪ Limited SLD conditions in FZDZ • The SLD cloud development & calibration in the IRT need to be expanded to consider ▪ Velocity deficit (or slip velocity) of large drops *Timko, Emily. N.; King - Steen, Laura. E.; Van Zante, Judith. F.; Acosta, Waldo. J.: NASA Glenn Icing Research Tunnel: 2019 Cloud Calibration Procedure and Results NASA/TM - 20205009045, 2021 https://ntrs.nasa.gov www.nasa.gov 3

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Artium PI - PTV

Particle Imaging - Particle Tracking Velocimetry

Probe Specifications & Upgrades • 4.5 microns/pixel; 9 – 1800 um • 1936 x 1464 pixels (2.8 Mpixels) • Sample area = 11.7 mm x 9.7 mm • Frame rate 400 fps • Illumination LED at ~30 ns • Double pulse capability, 20 - 40 us • Ran with and w/o Velocity mode (double pulse) • The AIMS software controls the probe and allows for data analysis • Additional heaters in the leading edge to avoid/reduce icing www.nasa.gov 4

National Aeronautics and Space Administration

Artium PI - PTV

with mounting stand on rail system

Safety Line Station 1 Station 2 Station 3* Station 4 x = 0” X = 90” X = 108.5” X = 180” *At the end of the tunnel contraction www.nasa.gov 5

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Test Description

• NASA Glenn Icing Research Tunnel (IRT)

• A 10 - day test entry (Sep12 – 23, 2022)

• Measure spray cloud drop size, velocity, shape and number

density distributions at 4 different stations in the IRT

• Test Conditions

▪ Tunnel Velocities: 130 kt, 170 kt, 210 kt and 250 kt ▪ Tunnel Temperature: at - 5 ºC total temperature ▪ Cloud Conditions: ▪ Mod1 spraybar nozzles ▪ P = 2 psig and  P = 30, 40, 50 & 60 psid (MVD↑ as  P ↑) air water water ▪ Some SLD Scaling reference sprays www.nasa.gov 6

National Aeronautics and Space Administration

Test Conditions

on 9/13/22

Station # AIMS STAMP Spray Spray Total Velocity D D MVD LWC Density Pair DeltaP M v0.5 v0.99 Delay Time Temp, of Drops TTTSC 1 hour minute sec [s] [min] [C] [kts] [um] [um] [um] [g/m3] #/cc [psig] [psid] ± 1 ± 1 ± 0.1 ± 0.5 PI-PTV Wing-shape approx calc'd approx Run # 2019 cal 1 17 24 50 30 10 -5 250 393 1125 472 1.08 305 2 60 2 174907 30 10 -5 250 379 1075 412 0.97 264 2 50 3 18 36 50 30 10 -5 250 320 1025 347 0.85 236 2 40 272 925 180 2 30 4 19 01 34 30 10 -5 250 277 0.72 250 200 726 250 3 31.5 5 19 38 13 30 7 -5 200 0.69 6 19 56 24 30 7 -5 250 242 780 242 0.79 275 3 38.8 200 775 250 3 31.5 7 20 13 06 30 7 -5 250 200 0.69 150 580 275 4 33.6 8 20 33 35 30 5 -5 250 150 0.68 100 575 250 4 23.4 9 20 48 51 30 5 -5 250 100 0.54 10 21 03 00 30 10 -5 250 393 1125 472 1.08 305 2 60 11 21 23 25 30 10 -5 250 379 1075 412 0.97 264 2 50 12 21 44 22 30 10 -5 210 393 1125 472 1.26 305 2 60 These values came from data collected with the OAP - 230Y during the 2019 calibration www.nasa.gov 7

National Aeronautics and Space Administration Key Results AIMS imaging data (a mp4 video) www.nasa.gov 8

National Aeronautics and Space Administration

Key Results

AIMS imaging data

Station 1 613 μm All deformed drops !

V drop Station 3 576 μm Flow direction www.nasa.gov 9

National Aeronautics and Space Administration

Key Results

AIMS imaging data

Faulty speed measurements due to misidentification of drops (~ 0.5% data) www.nasa.gov 10

National Aeronautics and Space Administration

Key Results

AIMS imaging data

Drop data repeats well !

www.nasa.gov 11

National Aeronautics and Space Administration

Key Results

AIMS imaging data

The PTV geometry effect www.nasa.gov 12

National Aeronautics and Space Administration

Key Results

AIMS imaging data

40 kt speed drop www.nasa.gov 13

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Pitot Probe Position

( measure the local air velocity )

The local air velocity measured by the Pitot is affected by the PTV stand 20.5” The air velocity measurement further deteriorated as icing spray turned on www.nasa.gov 14

National Aeronautics and Space Administration

PTV Geometry Effect on Air Velocity

Pitot @Stations 1 - 3, V = 130 , 170, 210, 250 kt

tunnel

X = 0 Can we still use larger drop velocity data from PTV for calculation of the slip velocity?

→ Identify large drop size threshold www.nasa.gov 15

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Key Results

PTV geometry effect on air velocity, V =130 kt

tunnel (u/u ) ∞ www.nasa.gov 16

National Aeronautics and Space Administration

Key Results

PTV geometry effect on air velocity, V =250 kt

tunnel The PTV geometry clearly affects the air velocity characteristics!

(u/u )

∞ www.nasa.gov 17

National Aeronautics and Space Administration

Key Results

PTV stand influences the Pitot probe measurement

Pitot probe w stand Pitot probe wo stand V Station 1 Station 2 Station 3* tunnel 250 kt x = 0” X = 90” X = 108.5” V , Pitot probe w stand 243.4 kt 240.6 kt 238.8 kt air V , Pitot probe wo stand 250 kt 250 kt 248.5 kt air *At the end of the tunnel contraction www.nasa.gov 18

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Key Results

Large drop size threshold for PTV

ANSYS DROP 3 D : The following are the run conditions with drop velocity inputs extracted from PTV measurements at Station 3 (x= 108 . 5 ”) . Run a L - D 7 - bin spray of 300 μm MVD at 248 . 5 kt moving toward the PTV stand at station 1 (x= 0 ) position .

Velocity Velocity P T T T AOA static static total total Test O O O Configuration K K C knts m/s Pa degrees PTV Only 248.5 127.8 94214 259.9 268.2 -5 0 D (μm) 93 156 213 300 411 522 666 V (kt) 242 233 227 221 210 207 206 d 3 Safety Line www.nasa.gov 19

National Aeronautics and Space Administration Key Results Large drop size threshold for PTV www.nasa.gov 20

National Aeronautics and Space Administration

Key Results

Large drop size threshold for PTV

D (μm) 93 156 213 300 411 522 666 V (kt) 242 233 227 221 210 207 206 d 3 PTV V (kt) 243 239 236 228 221 218 214 d 1 DROP3D V (kt) 246 242 238 232 224 219 216 d 1 (spherical drops) PTV effect stronger for smaller drops Drop - size threshold Large drop inertia dominating www.nasa.gov 21

National Aeronautics and Space Administration

Conclusions

• A 10 - day test entry in the IRT was performed in September 12 - 23,

2022, to evaluate the planned operation of the PTV probe to obtain

the supercooled larger drop velocity characteristics

1. The probe did obtain valid drop size, drop shape and drop velocity data from the SLD icing spray conditions tested in the IRT with measured drop sizes up to 700 μm 2. The drop velocity distribution at a given air speed in the IRT test section is not affected by different spray bar pressure settings. So, it is desirable to have more shorter spray repeats than fewer longer sprays 3. The larger drops (e.g., D > 500 μm) generated in the IRT clearly experience significant velocity deficit in comparison with the tunnel airspeed. For an airspeed of 250 kt in the IRT, the velocity of the largest drop measured at the Station 1 was about 40 knots slower 4. The probe also produces a small fraction of faulty velocity measurements for smaller size drops, and these could be easily filtered out 5. The PTV probe head influences the smaller drop velocity measurements, but larger drops (D ≥ 300 μm) won’t be affected due to large inertia www.nasa.gov 22

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Recommendations

• Additional test is required to develop the procedure for traversing the PTV probe in the IRT test section to fully characterize the large drop size velocity distribution.

• Attention should also be given to understand what the large drop velocity deficit may do to SLD ice shapes via numerical ice accretion simulation studies • The SLD cloud development & calibration in the IRT needs to be expanded also to consider ▪ supercooling deficit of large drops • New methodology to obtain the supercooling deficit of SLD clouds generated in the IRT test section is needed www.nasa.gov 23

National Aeronautics and Space Administration Acknowledgements ➢ NASA Aeronautics Evaluation and Test Capabilities Project ➢ The entire IRT staff for their excellent support ➢ Special thanks to Julien Manin from Artium Technologies, Inc for his technical support ..

www.nasa.gov 24