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National Aeronautics and Space Administration
Ice Crystal Icing Research at NASA
Ashlie B. Flegel
NASA Glenn Research Center
AIAA Aviation Atmospheric and Space Environments Conference June 5 - 9, 2017 www.nasa.gov National Aeronautics and Space Administration
Motivation
Engine Ice Crystal Icing events have led to increased need of understanding the
mechanisms of engine icing .
NASA Advanced Air Transport Technology (AATT) Project key technology area
is to develop engineering model and icing risk assessment tools and improve
understanding of the physics of ice crystal icing through fundamental and
engine testing .
• Enable analysis of ice crystal icing effects on turbofan engines.
• Provide guidance for safe operation of current and future propulsion systems.
NASA Aeronautics Evaluation and Test Capabilities (AETC) Project investing in
the development of the Propulsion Systems Laboratory engine icing capability .
• Understand the differences between PSL Cloud and natural environment ingested in the engine.
• Instrumentation to measure IC Cloud upstream and inside test hardware flow path.
• Characterize PSL Cloud • Standardize PSL Icing Test Methodology National Aeronautics and Space Administration 2
2011 NASA Technical Plan
• Research Areas of Focus : 1. Flight Characterization of the High Ice Water Content (HIWC) environment .
2. Classical Research in the area of altitude testing for engine, engine components, and fundamental studies of ice particle aero - thermodynamics .
3. Computational research to simulate engine performance, ice accretion, and engine control methods .
SIDE VIEW Ice Accretion Flight Characterization Classical Research Com putational Research National Aeronautics and Space Administration 3
NASA ICI Research Overview
3D Risk Assessment Tools 0D/1D Risk Assessment Tools Identify inlet conditions that will lead to accretion in core flowpath.
Identify location and accretion Flight characteristics.
Characterization Understand the Understand the underlying physics of underlying physics of ICI at the engine ICI accretion and system level particle breakup National Aeronautics and Space Administration Y our Title Here 4 Engine/ Rig Tests Fundamental Physics
FACILITIES AND CLASSICAL
RESEARCH
National Aeronautics and Space Administration Y our Title Here 5
Propulsion Systems Laboratory (PSL)
Specification Min Max Engine / Rig Dia. (in | cm ) 24 | 60 _ 72 | 180 Air Flow Rate (lbm/s | kg/s ) 10 | 5 _ 330 | 150 Altitude, pressure (kft | km ) - _ 4 | 1.2 50 | 15 Total Temp ( ° F | ° C ) - 60 | - 50 50 | 10 Mach Number 0.15 0.80 TWC ( g/m ) 0.5 8.0 * # MVD (um) 15 >100 * Evidence that probe under - measured # Particles larger than ~ 90 microns are NOT fully glaciated PSL - 3 Icing Operating Envelope National Aeronautics and Space Administration 6
Engine Testing
• Goal: Understand the mechanisms of ICI inside engine core flowpath at relevant
flight and environmental conditions.
• Tests conducted on unmodified ALF502R - 5
• Demonstrated Facility Capability (repeatability, Peak TWC simulations, flight descent,...)
• Made key observations on engine response and accretion during parameter sweeps.
• Evaluated an approach for altitude scaling.
• Evaluated measurements techniques • Future Work: • Understand how the fan processes the IC cloud.
• Develop measurement techniques which can help quantify the icing effects.
LF11 vs. LF01 Full Rollback Rollback Indicators - FLT850 Ice Accretion at FLT850 EGV2 EGV2 Average Load (lbf) Temperature (F), %N, Cloud Cloud ON Cloud OFF Time EGV2 EGV1LE LF11 EGV1LE LF01 EGV1TE LF11 EGV1TE LF01 EGV2LE LF11 EGV2LE LF01 FLOW National Aeronautics and Space Administration 7 EGV2TE LF11 EGV2TE LF01 cloud LF11 cloud LF01 N2 LF11 N2 LF01 OS_AVG LF11 OS_AVG LF01 N1 LF11 N1 LF01 Load LF11 Load LF01
Instrumentation
˗ Internal Engine C ameras ˗ Raman Scattering Probe
˗ NASA Ice/water sensor ˗ Tomography (inlet)
˗ NRC Ultrasound Ice ˗ Light Extinction Probes
Accretion sensor
Light Extinction Probe Planes Tomography Plane Metal Temperature Camera Region of Ice/Water 1. EGV1 LE, Pressure Side 2. EGV1 TE, Suction Side sensors and camera 3. EGV2 LE, Suction Side 4. EGV2 TE, Pressure Side views.
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Fundamental Icing Physics Tests
• Goal : Investigate the fundamental physical mechanisms of accretion that occurs in core compressor regions of jet engines when ingesting ice crystals .
• Initial studies at NRC found the importance of local T melt ratio, humidity, and cloud wb, particle size distribution on the accretion process.
• 1D thermodynamic model was developed to simulate the complex interaction of the cloud particles and free stream air .
Tool to ensure facility is set - up appropriately to achieve desired conditions at the test section.
• 2016, First Fundamental Test conducted in PSL.
Characterized various icing parameters such as water content, particle size distribution, and uniformity.
Acquired videos of ice accretions on a NACA 0012 airfoil under mixed - phase cloud conditions.
• Future: • Demonstrate the ability to prescribe a particular ice crystal icing condition at the test section • Understand the erosion process • Focused on tests with more relevant geometry in an effort to generate a more representative ice accretion National Aeronautics and Space Administration 9 POC: Peter Struk, Tadas Bartkus, Paul Tsao
Fundamental Icing Physics Tests
Sample of Ice Shapes from FT#1 Test Set - up National Aeronautics and Space Administration 10
Ballistics Impact Laboratory
• Ice particles generated by:
Dropping calibrated amount of distilled water into liquid nitrogen
Compressing ice in a metallic mold.
This method ensure particle uniformity Captures velocity and particle diameter Capture post - impact fragmentation and measure size distribution National Aeronautics and Space Administration 11
Particle Impact and Break - up Physics
• Goal: Evaluate the impact characteristics of ice crystals on engine components in terms of post - impact: particle size distribution, particle velocity distribution and direction of travel, effect of partial melting of crystals • In house and collaborative efforts (Penn State NRA) • Recent efforts studied the effect of particle velocity. High speed images and high speed infrared data were obtained .
Ice Particle Impact on Flat Target • Future Work: Investigate the ability to control the melt ratio of the particle before impact Move towards more complex geometries (i.e. fan blade) Fragments Equivalent Diameter Distribution Histogram National Aeronautics and Space Administration 12 POC: Mario Vargas
COMPUTATIONAL RESEARCH
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Particle Path for 0D/1D Analysis
Engine Inlet Ice Particle Path Modeled with Melt The COMDES - MELT code models the thermodynamic state of the ice particles as they pass through the Inlet, Fan - Core and LPC blading. Includes models for sublimation, particle temperature rise, melting, and evaporation.
Computational Process for Determining the Icing Risk
Turbofan Engine Aerothermodynamic Cycle Code (Engine Customer Deck (CD) or NPSS) Engine system performance to establish Fan - HPC boundary conditions Test Data Air Flow Rate Air Flow Rate LPC Speed: N1 LPC Speed: N1 HPC Speed: N2 Change Following for HPC Speed: N2 Engine Inlet Pt and Tt Prediction Mode: Engine Inlet Pt Fuel Flow Rate and Tt • Ambient Temp EGV Wall Fuel Flow Rate • Flight Mach Number P static • Fan RPM (N1) 1. Calibration/ N Analysis Mode : COMDES – MELT : Flow and Particle State O Used for further Analysis of Fan - Core & LPC • Blade row by blade row compressor aerodynamics . Refinement of • GASPLUS: Fluid properties of air / water vapor Wedge Icing • Relative Humidity • Blockage Growth Rate Risk Criteria YES 2. Predication • Static Wet Bulb Temperature “Wedge” Mode : Identify as • Ice - Water Flow Rate / Air Flow Rate Ratio ( potential icing IWAR ) • Particle Melt Ratio, Enthalpy, Evaporation, condition Sublimation
0D/1D Modeling
Goal : Develop in - house tool to predict the engine risk to ice particle ingestion to
evaluate the risk of icing .
Recent Work : • Estimated the risk of accretion for the ALF 502 , LF 11 engine test points .
• Pre - test evaluation
• Guided the formulation of the altitude study test points
• Post - test evaluation of the test points and defined icing risk criteria
• Relationship between blockage growth rate, ice - water flow rate to air flow rate ratio
(IWAR), and static wet bulb temperature was observed and plotted generating an
“Icing Wedge” .
Future Work :
• Apply model to new geometries
• Continue to enhance the code
5/25/2017 POC: Joe Veres and Phil Jorgenson
“Icing Wedge” – Risk of Ice Accretion
Criteria
1 .) Static wet bulb temperature is within the range of 492R - 498R
2.) IWAR is above 0.002
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0D/1D Modeling
Future Work : • Estimated the risk of accretion for the ALF 502 , LF 11 engine test points .
• Pre - test evaluation
• Guided the formulation of the altitude study test points
• Post - test evaluation of the test points and defined icing risk criteria
• Relationship between blockage growth rate, ice - water flow rate to air flow rate ratio
(IWAR), and static wet bulb temperature was observed and plotted generating an
“Icing Wedge” .
5/25/2017 18 POC: Joe Veres and Phil Jorgenson
High Fidelity Engine Icing Simulations
• Goal: Develop a system of codes that can model the accretion process in current and future engine designs and characterize the accretion risk due to ice crystal ingestion at high altitude.
• Codes: • LEWICE: 2D tool that evaluates the freezing process thermodynamics that occur when super - cooled droplets impinge on a body and generate a 2D ice shape.
Initial module development (break - up and erosion) which is compared to the Fundamental Test ice shapes.
• LEWICE3D: 3D tool that predicts the accumulation of ice on three - dimensional aircraft surfaces given the flight and meteorological conditions.
Trajectory and accretion analysis.
• GlennHT: 3D gas turbine flow and convective heat transfer code.
Provides flow analysis to LEWICE3D Analysis to calculate heat transfer coefficients.
• Future Direction : • Couple GlennHT and LEW ICE 3 D simulations more tightly to allow for effect of ice particles on the air flow and include effects of ice growth on air flow .
• GlennHT Modifications : • Inclusion of real gas effects, accounting for humidity and wet bulb temperature • Modelling of tip clearance region • Investigating turbulence models to produce accurate heat transfer prediction during the ice accretion process .
• Develop mechanism to pass heat transfer coefficient distribution to LEWICE 3 D Collection Efficiency on surfaces 5/25/2017 19 POC: Bill Wright, David Rigby, Ali Ameri, Christopher Porter
Summary
• Focus on experimental efforts that will provide a strong basis of
understanding into the fundamental physics of ice accretion and
particle behavior
Fundamental experimental work will evolve into more relevant and complex
geometries to enable three - dimensional model validation
PSL full engine and rig tests are desired to continue the development of the
facility’s capability and computational tools
• Continued development of measurement methods and techniques
• 0D/1D COMDES and LEWICE3D/ GlennHT codes are needed to enable
the assessment of the icing risk on current and future propulsion
designs
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Acknowledgements
Engine Icing Team: Peter Struk, Mario Vargas, Paul Tsao, Tadas Bartkus, Tom Ratvasky, Philip Jorgenson, Joe Veres, Ali Ameri, Christopher Porter, David Rigby,
William Wright, Don Simon, Aidan Reinhardt, Juan Agui, Judith Van
Zante .
This work is supported by the NASA Advanced Air Vehicles Program, Advanced Air Transport Technology Project.
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