Document
www.nasa.gov
June 9, 2009
Airframe Icing Workshop
Past and Current NASA Glenn Research Center
Cleveland, Ohio
NASA Airframe Icing Research Overview
National Aeronautics and Space Administration NASA/CP—2009-215797 1 www.nasa.gov
NASA Airframe Icing Research
– examination of the underlying physics of icing – analytical model development – software development and maintenance – experimental methods development – creation of experimental databases related to ice formation and its effects Approach • Development of new experimental methods and advanced icing simulation software • Highly integrated, multi-disciplinary effort Objective The objective of fundamental research in airframe icing has been to provide the aviation community with the design and analysis tools needed to accomplish better and safer designs of aircraft and aircraft sub-systems, with respect to operations in icing conditions. The tools developed in the NASA Glenn Icing Branch are used for a variety of purposes including but not limited to, ice accretion shape prediction, ice protection system performance evaluation, and examination of the effects of ice accretion on aircraft aerodynamics. These tools have an impact in design, testing, construction, and certification and qualification of aircraft and aircraft sub-systems.
National Aeronautics and Space Administration NASA/CP—2009-215797 2 www.nasa.gov
Historical timeline Highlights Development of major products
• • •
Past and Current
NASA Airframe Icing Research Overview
Outline • Experimental Methods • Computational Methods • Flight Dynamics • Experimental Databases National Aeronautics and Space Administration NASA/CP—2009-215797 3 www.nasa.gov 2000s Development of SLD simulation capability in IRT Extension of scaling laws to SLD icing conditions Investigations of SLD droplet splashing, break-up and associated mass loss Development of methods for sub- scale aero testing of complete aircraft with artificial ice shapes Full scale iced airfoil performance testing at flight Reynolds numbers in ONERA F1 pressurized wind tunnel Swept wing ice shape generation and performance testing on representative business jet model Extension of collection efficiency measurement methods to iced airfoil geometries • • • • • • • 1990s Experimental Methods 3D laser scanner for ice shape measurement Significant progress in extension of scaling laws to greater range of sizes and conditions Investigations of Reynolds number effects on iced airfoil performance using cast ice shapes Tailplane Icing Project develops methods for evaluation of stability and control parameters for iced aircraft Shed ice particle tracking with high speed cameras • • • • •
Historical Progress in Technology
1980s Ice shape tracing methods Development of accurate ice shape casting technique Scaling laws identified and tested De-icing fluid aerodynamic tests conducted in IRT Aircraft performance testing with artificial ice shapes using Twin Otter Icing cloud droplet size and liquid water content probes tested in IRT and in flight Development of methods for measurement of collection efficiency on clean airfoils • • • • • • • National Aeronautics and Space Administration NASA/CP—2009-215797 4 www.nasa.gov m) Droplet Size, ( Blended LWC Histogram, (g/m3/dLogD)
Otter flight in SLD
LWC histogram for Twin-
0 1 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.1 1.2 1.3 1.4 1.5 LWC, (g/m3/dLogD)
Particle sizing probe
mounted on Twin Otter
Experimental Methods
Stereoscopic imaging for ice shape documentation
9.0 8.0 7.0 6.0 5.0 e: 15:05:51; Span= 18 4.0 3.0 inches 2.0 1.0 0.0 – Icing cloud characterization – Ice shape measurements – Instrumentation development – Aircraft performance measurements with simulated ice shapes – Aircraft handling and stability & control characteristics with simulated ice shapes -1.0
In-Flight Testing Projects
-2.0 Flight No.9768 ; Flight Date: 12/11/97; Time: 15:05:51; Span= 18 -3.0 0.0 1.0 2.0 3.0 4.0 5.0 6.0 7.0 -5.0 -4.0 -3.0 -2.0 -1.0 inches National Aeronautics and Space Administration NASA/CP—2009-215797 5 www.nasa.gov
Click to play movie
new physical models &
IRT Test - ice shape growth
Experimental Methods
National Aeronautics and Space Administration Ice Accretion Studies Research needed to de-construct ice growth stages into micro-physical phenomena from roughness to ice feathers to ice shape improved CFD tools NASA/CP—2009-215797 6 www.nasa.gov 0.1 0.05 X/C Iced Airfoil Profile - Run 31 -0.05 0.1 -0.1 0.05 -0.05 Y/C
Experimental Methods
– Ice shape tracing – Ice shape molds and castings – Utilization of 3D scanner technology National Aeronautics and Space Administration
Ice shape Measurement Methods
NASA/CP—2009-215797 7 www.nasa.gov – Ice shape tracing – Ice shape molds and castings – Utilization of 3D scanner technology
Ice shape Measurement Methods
Experimental Methods
National Aeronautics and Space Administration NASA/CP—2009-215797 8 www.nasa.gov From DrIFT Images
Click to play movie
Experimental Methods
ice/water/air interface measurement methods for regions upstream and surrounding test targets entire flow surrounding the iced geometry – Fluid-thermal measurements in the region near the – Non-intrusive liquid water and droplet diameter – Unsteady, high-speed velocity measurements in the – Automated ice shape measurement techniques National Aeronautics and Space Administration
Advanced Measurement Techniques
NASA/CP—2009-215797 9 www.nasa.gov Modeling Roughness
Vertical Icing Studies Tunnel Ve
Experimental Methods
Droplet Splashing Imaging
Multi-phase region at the ice surface: water film thickness and velocity, the ice surface topology, detailed airflow temperatures and velocities
–
Scalloped Ice
Shape Studies
Microphysical Studies
National Aeronautics and Space Administration NASA/CP—2009-215797 10 www.nasa.gov Ma = 0.12 Reynolds Number Effects on 22.5-minute Glaze Ice Shape (944 casting) at Effect of Reynolds number at constant Mach number on performance for the clean GLC-305 airfoil.
Experimental Methods
Pressure and force measurements on airfoils and wings with leading edge artificial ice shapes Ice shapes can be 3D castings, extrusions from 2D ice shape tracings, or geometric shapes representing ice shapes (e.g. spoiler shapes used to simulate ice horns) Most testing has been at moderate Reynolds numbers using 2D ice shapes on airfoil models; some 3D testing and high Reynolds number
– – –
Aerodynamic Performance Measurements
National Aeronautics and Space Administration NASA/CP—2009-215797 11 www.nasa.gov
Experimental Methods
High Re Aerodynamic Performance Measurements at ONERA F1 Facility
National Aeronautics and Space Administration NASA/CP—2009-215797 12 and www.nasa.gov Re = 1x10 Contour vector and streamline plots of an instantaneous velocity field at mid- span for the NACA0012 airfoil with 2D glaze ice simulation at = 2.7º and = 2.7º
Experimental Methods
Re = 1x10 Regions containing vortex shedding, vortex interaction from several regions of interest, flow separation and reattachment, separation bubble reattachment unsteadiness, and extended regions of boundary layer transition
–
research
Iced Aircraft CFD Modeling Validation - near-stall condition flow field
Contour plot of the average velocity field at mid-span for the NACA 0012 airfoil with 2D glaze ice simulation at National Aeronautics and Space Administration NASA/CP—2009-215797 13 www.nasa.gov m has been demonstrated
Experimental Methods
Scaling to App C for MVD’s up to 160 Geometric and physical parameter scaling methods have been developed and used when models are too large for the experimental facility or the icing conditions of interest cannot be obtained in the facility
–
Scaling Methods
National Aeronautics and Space Administration NASA/CP—2009-215797 14 www.nasa.gov Natural ice cloud characterization, icing instrumentation development, ice detection & protection systems evaluations NASA/FAA Tailplane Icing Program: explored factors that lead to ice contaminated tailplane stall; developed and evaluated flight test methods and recovery procedures NASA/FAA/NCAR SLD Icing Flight program: cloud characterization, ice shape & performance measurements. Data used to develop SLD icing certification envelope. Alliance Icing Research Study: Icing remote sensing validation Piloted Icing Flight Simulator: flight data used to validate an ice contamination effects flight training simulator Smart Icing Systems Flight Tests: flight data to develop and evaluate systems identification methods for isolating icing effects on airplane performance, stability & control
Historical Progress in Technology
Experimental Methods – In-flight Testing
1983-1992 1994-1997 1997-1999 2000 2001 2001-2002
National Aeronautics and Space Administration NASA/CP—2009-215797 15 www.nasa.gov
Historical Progress in Technology
Developed methods for testing aerodynamic penalties resulting from application of de-icing fluids Developed ice casting methods for creation of realistic ice shape models to be used in dry-air wind tunnel performance testing airfoils, wings, engine inlets and other aircraft surfaces Developed visualization methods for shed ice particle tracking Adapted laser sheet flow visualization methods for use in icing cloud; examined effects of ice growth on delta wing leading edge vortices ranging from castings to simplified representations of ice shape features; examination of Reynolds and Mach number effects Development of methods for simulation of SLD icing conditions
Experimental Methods – Ground-based Testing
1989 1985-1990 1985-Present Developed methodology for collection efficiency measurements on 1990-1995 1995 1990-Present Developed procedures for aero-testing of ice shape geometries 2003-2006 National Aeronautics and Space Administration NASA/CP—2009-215797 16 www.nasa.gov Preliminary tests of methods to scale model size or test conditions using combinations of matched similarity parameters Experimental evaluation of early scaling methods; scaling for rime ice demonstrated; ability to scale LWC shown using Olsen method Importance of surface phenomena demonstrated; demonstrated significant improvement by including Weber number in scaling methodology Preliminary study of scaling for intercycle ice accretion performed; scaling methods incorporating water-film thickness proposed and evaluated; scaling for SLD conditions begun; effect of drop MVD on ice shape being mapped Release of Icing Scaling Manual Addendum to Icing Scaling Manual to include SLD scaling
Historical Progress in Technology
Experimental Methods – Icing Scaling
1982 – 1989 1990 – 1993 1993 – 1999 2000 – present 2003 2006
National Aeronautics and Space Administration NASA/CP—2009-215797 17 LES www.nasa.gov RANS 2000s Release of LEWICE3D version 2 Collaboration with Boeing on use of LEWICE3D for 787 analysis Release of LEWICE 3.2.2; includes initial modifications for SLD International release of LEWICE Automated grid generation for LEWICE Release of SmaggICE 2.0 Unsteady DES methods for iced performance analysis Thermal IPS model in LEWICE 2.2 • • • • • • • • 1990s Computational Methods LEWICE3D development Release of LEWICE 2.0 2D grid sensitivity and turbulence model evaluations Early 3D performance analysis studies Development of stand alone thermal IPS simulation methods • • • • •
Historical Progress in Technology
1980s LEWICE development Early 2D performance analysis studies • • National Aeronautics and Space Administration NASA/CP—2009-215797 18 www.nasa.gov
Click to play movie
(splashing, break-up, re- impingement) shape formation
– Droplet impact dynamics – Surface water transport – Heat transfer – Roughness formation – Phase change kinetics – Scallop ice (swept wing) Examine the physics of ice accretion to understand: Modeling Roughness
growth
Feather
Ice Accretion Modeling
Water film movement Formation Roughness National Aeronautics and Space Administration
Click to play movie
NASA/CP—2009-215797 19 www.nasa.gov glaze
LEWICE – 2D Ice Accretion Code
LEWICE Difference Experiment Variation mixed rime
Ice Accretion Computational Modeling
10 20 30 40 50 Ice Shape Tracing; Validation Database %Chord difference from Experiment Ice Shape Comparison Results Comp. vs. Exp.
National Aeronautics and Space Administration NASA/CP—2009-215797 20 www.nasa.gov
LEWICE3D – 3D Ice Accretion Code
Ice Accretion Computational Modeling
National Aeronautics and Space Administration NASA/CP—2009-215797 21 www.nasa.gov Scanned solid to CFD grid
Iced Aircraft CFD Modeling
Geometry preparation, blocking, gridding, link to flow solver, aero properties Ice feature effects Identification of critical ice shapes Surface modeling and grid generation Turbulence modeling and multi-phase flow Time dependent/adaptive gridding CFD modeling for 3D surfaces Roughness effects (unsteady, multi-scale) 3D particle tracking through unsteady/separated flow National Aeronautics and Space Administration • • • • • • • • NASA/CP—2009-215797 22 www.nasa.gov
3D surfaces
3.) CFD modeling for
multi-scale) 4.) Roughness effects (unsteady,
Iced Aircraft CFD
Turbulence generation behind a leading edge ice shape
2.) Turbulence modeling and time dependent/ adaptive gridding for icing topology
National Aeronautics and Space Administration
1.) Ice feature effects, identification of critical ice shapes
CFD Studies
NASA/CP—2009-215797 23 www.nasa.gov
Historical Progress in Technology
Computational Methods - LEWICE
accretion capability accretions, enhancements to usability and robustness; implemented industry-standard software development and maintenance methods; transition from research tool to production tool protection systems adaptive grid Navier-Stokes code 1991 – Release of LEWICE version 1.0; capable of predicting rime ice 1993 – Release of LEWICE 1.3; enhancements to glaze ice accretion 1995 – Release of LEWICE 1.6; improved ability to simulate long duration ice 1998 – Release of LEWICE 2.0; major overhaul to improve accuracy, reliability, 2002 – Release of LEWICE 2.2; added capability to analyze thermal ice 2004 – Release of LEWICE 3.0; added capability to use LEWICE with an 2006 – Release of LEWICE 3.2.2; added SLD capabilities National Aeronautics and Space Administration NASA/CP—2009-215797 24 www.nasa.gov Initial version of LEWICE3D with integrated 3D Hess-Smith Panel Code Initial version of grid based LEWICE3D for body fitted grids Support for unstructured flow solutions added. Support for simple cartesian grids added for 3D panel code interface Support for Oct-tree type grids add for improved 3D panel code interface. ICEGRID3D developed to generate Oct-tree type grids about panel models. Monte-Carlo trajectory algorithm developed for complex regions such as ducts, radomes, wing roots Capability to handle Navier-Stokes based grids added. Developed simpler, faster, Oct-tree type grid code for 3D panel code interface (PATCHGRID). Development of LEWICE3D post-processor to generate off-body concentration ratios (CONFAC3D) Parallelization of LEWICE3D, with both Open MP and MPI, leads to significant decreases in turn around time
Historical Progress in Technology
Computational Methods – LEWICE3D
1991 1993 1994 1995 1996 1997 1998 1999 2001 2002–Present National Aeronautics and Space Administration NASA/CP—2009-215797 25 www.nasa.gov Examined use of existing 2D and 3D CFD tools; results indicated that methods could be used for pre-stall conditions; difficult to generate grids for ice shape geometries; identified approach for analysis of rotorcraft performance losses due to icing Investigated use of new turbulence models and began development of tools to aid in grid generation for ice shape geometries; use of new turbulence models improved capability to determine stall behavior however will require move to unsteady analysis and LES/DES methods; grid sensitivity studies indicate that some smoothing of surface geometry to allow easier grid generation is allowable First release of SmaggICE, computational tool to aid in development of grids for ice shape geometries Use 3D unsteady methods to identify stall behavior of iced aircraft
Historical Progress in Technology
Computational Methods – Performance Analysis
1983 – 1991 1995 – 1999 2000 – present Current
National Aeronautics and Space Administration NASA/CP—2009-215797 26 www.nasa.gov 2000s Subscale model testing of Twin Otter in Bihrle Applied Research spin tunnel Iced aircraft state assessment research at UTSI supported through NRA Flight testing to develop parameter ID methods in support of Smart Icing Systems studies and Systems Technology, Inc. SBIR. Development of Ice Contamination Effects Flight Training Device (ICEFTD) to train pilots on effects of ice accretion. Development of iced aircraft flight simulation model of Twin Otter and Cessna business jet. Dynamic wind tunnel testing of iced S-3B Viking to obtain data for simulation model.
• • • • • • 1990s Flight Dynamics Refinement of analysis techniques and flight test techniques with artificial ice shapes Tailplane Icing Project builds upon prior experience to quantify iced tailplane effects Investigations of scale model tailplane performance parameters Investigation of effects of tailplane icing using scaled and full-scale wind tunnel tests.
• • • •
Historical Progress in Technology
1980s Initial testing of stability & control parameters on NASA Twin Otter Classic longitudinal flight test techniques with artificial ice shapes Application of digital inertial data system for stability and control derivative estimation for artificial ice and natural conditions Tailplane Icing Project develops methods for evaluation of stability and control parameters for iced aircraft • • • • National Aeronautics and Space Administration NASA/CP—2009-215797 27 www.nasa.gov – Simulated and natural ice records with flight dynamics package Analysis of flight data (existing and future) using PID methods Develop and use iced aerodynamic CFD tools to predict aircraft response Alert pilots through IIFD products to exit icing conditions and/or change flight condition Limit flight envelope to enable recovery and safe landing
Icing Effects on Aircraft Controllability
• • • •
S&C models are affected by ice accretions determine the S&C authority margins as ice accretes on airframe or as flight conditions lead to upset recovery – Develop understanding of how “clean” aero-performance and – Develop onboard vehicle state assessment technologies to – Develop modified control laws to prevent LOC or manage
Technical Approach
Preventing Iced Flight Dynamics Loss of Control •
National Aeronautics and Space Administration NASA/CP—2009-215797 28 www.nasa.gov degradation on performance parameters pushover maneuver – Various artificial ice shapes tested – Static testing performed to determine – Dynamic testing performed using zero-G
Tailplane Icing Effects
Fligth Dynamics
National Aeronautics and Space Administration NASA/CP—2009-215797 29 www.nasa.gov
Roselawn, IN
1994 - ATR-72,
reversal with ridge of ice beyond the deicing boots
• 68 fatalities • Aileron hinge moment
Click to play movie
Icing Effects on Aircraft Controllability
IPS usually operating, autopilot masked control changes Identification and modeling: premature stall and control authority margin Reconfigurable controls for recovery Envelope limiting methodology for continued flight through landing – – – – Multiple incidents and fatal accidents have occurred recently in which ice accretions were a causal factor Aircraft icing LOC research areas
Iced Flight Dynamics Loss of Control (LOC) • •
National Aeronautics and Space Administration NASA/CP—2009-215797 30 www.nasa.gov “The accident and may have been airplane’s left roll tendency was precipitated by a thin layer of rough ice” further affected by an asymmetric ice shed or aileron deflection • The Findings state: Final NTSB report on Comair Flight 3272 released on November 4, 1998
(SIS)
Research in Iced Flight Dynamics
Concept that senses the presence of ice, activates and manages the IPS, provides the pilot with information on aircraft performance and S&C PID methods were researched to characterize aerodynamic state of the vehicle. Flight envelope and autopilot models were developed. Flight management systems were examined for control response automation GRC iced aero CFD tools identified premature stall and subsequent roll-off in aircraft trajectory consistent with DFDR data – – – Smart Icing Systems Aero-performance CFD National Aeronautics and Space Administration • • NASA/CP—2009-215797 31 www.nasa.gov 2000s Extension of ice shape profiles and collection efficiency databases to include SLD conditions Scaling databases extended to include SLD conditions Creation of droplet splashing and ice mass databases; aid in identification of SLD conditions and in validation of SLD computer simulation codes Performance degradation data for finite swept wing with scallop ice shape castings Stability and control data from sub-scale and full scale iced Twin Otter models • • • • • Particle Sizing Probe 1990s Experimental Databases Iced airfoil performance characteristics using complex casts of actual ice shape geometries Scaled ice shape data covering an extensive range of App. C conditions Collection efficiency data covering a range of airfoil and engine inlet geometries Icing cloud data for characterization of SLD icing environment Ice shape castings and photos from swept wing geometries used to identify mechanism of scalloped ice shape formation • • • • •
Historical Progress in Technology
1980s Ice shape profiles from various airfoils obtained in the IRT Ice shape profiles and icing cloud conditions from in-flight measurements on the NASA Twin Otter Iced airfoil performance characteristics using simplified artificial ice shape geometries • • • National Aeronautics and Space Administration NASA/CP—2009-215797 32 www.nasa.gov Ongoing accumulation of ice shape tracings provides extensive data for use in validation of ice shape simulation methods; Database made available to public via Web Development of collection efficiency database in collaboration with Wichita State University Modern Airfoil Project develops ice shape and associated airfoil performance database on airfoils representative of current usage Electro-thermal ice protection system model tested to provide database for validation of thermal ice protection system simulation software Tailplane Icing effects on sub-scale & full-scale business jet T-Tail Testing of swept wing model to determine effects of sweep on ice shape development and resulting performance losses Development of SLD ice shape database for validation of simulation tools
Historical Progress in Technology
Experimental Database Development
1983 – present 1985 – 2001 1995 – 2000 1996 1999-2002 2002 2007
National Aeronautics and Space Administration NASA/CP—2009-215797 33 www.nasa.gov
Summary of Airframe Icing Goals
Continue to meet customer needs for icing simulation tools and databases Reduce costs of icing certification through use of simulation methods Enhance safety of flight by allowing simulation of conditions unattainable through flight testing Improve accuracy, reliability, range, and usability of simulation tools through creation of comprehensive validation databases
National Aeronautics and Space Administration NASA/CP—2009-215797 34