Overview of Icing Research at NASA Glenn

Overview of Icing Research at NASA Glenn

Eric Kreeger NASA Glenn Research Center Icing Branch 25 February, 2013 Glenn Research Center at Lewis Field

Outline • The Icing Problem • Types of Ice • Icing Effects on Aircraft Performance • Icing Research Facilities • Icing Codes Glenn Research Center at Lewis Field

Aircraft Icing

Ground Icing Ice build-up results in significant changes to the aerodynamics of the vehicle This degrades the performance and controllability of the aircraft In-Flight Icing 3 3 Glenn Research Center at Lewis Field

Aircraft Icing

During an in-flight encounter with icing conditions, ice can build up on all unprotected surfaces.

Glenn Research Center at Lewis Field

Recent Commercial Aircraft Accidents

• ATR-72: Roselawn, IN; October 1994 – 68 fatalities, hull loss – NTSB findings: probable cause of accident was aileron hinge moment reversal due to an ice ridge that formed aft of the protected areas • EMB-120: Monroe, MI; January 1997 – 29 fatalities, hull loss – NTSB findings: probable cause of accident was loss-of-control due to ice contaminated wing stall • EMB-120: West Palm Beach, FL; March 2001 – 0 fatalities, no hull loss, significant damage to wing control surfaces – NTSB findings: probable cause was loss-of-control due to increased stall speeds while operating in icing conditions (8K feet altitude loss prior to recovery)

• Bombardier DHC-8-400: Clarence Center, NY; February 2009

– 50 fatalities, hull loss – NTSB findings: probable cause was captain’s inappropriate response to icing condition Glenn Research Center at Lewis Field

Where Does Icing Occur?

Glenn Research Center at Lewis Field

Where Does Icing Occur?

Glenn Research Center at Lewis Field

How Ice Forms

• In visible moisture (cloud & precip) • Temperature range around -20° to +2°C • Cloud contains supercooled liquid water, ice crystals Ice Accretion Parameters: • Velocity • Drop Size (MVD) • Liquid Water Content • Temperature • Accretion Time Glenn Research Center at Lewis Field

How Ice Forms

Icing Freezing Freezing Certification Envelope Drizzle Rain “App C” 15 - 50 μ m 500 μ m 2000 μ m Glenn Research Center at Lewis Field

Types of Ice Accretions

Glenn Research Center at Lewis Field

Types of Ice Accretions

Glaze (Clear) Ice

• In general occurs at temperatures near o 32 F and high LWCs • Clear everywhere • Horns may appear • Drops do not freeze on impact • Surface tends to be covered with roughness elements V=225 mph O T =25 F total • Physical mechanism of formation not LWC=0.75 g/m well understood MVD=20 μ m τ =5 minutes Glenn Research Center at Lewis Field

Types of Ice Accretions

Rime Ice

• In general occurs at temperatures o below -10 F • White and opaque • Horns do not appear • Drops freeze on impact • Surface tends to be smoother than for glaze ice • Physical mechanism of formation well From Bidwell understood Glenn Research Center at Lewis Field

Types of Ice Accretions

Mixed Ice

• Ice accretion exhibits glaze ice around stagnation line and rime ice away from it • Clear near the stagnation line, white and opaque away from it • Horns may appear V=150 mph O T = 5 F total LWC=0.75 g/m MVD=20 μ m τ =2 minutes Glenn Research Center at Lewis Field

Types of Ice Accretions

Swept Wing Icing View from the side Λ Λ Λ o o o Λ = 45 View from behind Λ = 15 Λ = 30 Glenn Research Center at Lewis Field

Types of Ice Accretions

Time Lapse Glenn Research Center at Lewis Field

Icing Effects on Airplane Performance

• Reduce maximum Lift – Increase stall speed – Stall warn system may not compensate for ice • Increases Drag – Reduces Climb rate – Reduces max speed – May reduce speed to the point of stall.

• Increases Weight – Usually not significant, fuel burn will offset • Thrust – Increased thrust required, due to drag increase – GA aircraft are, typically, power limited Glenn Research Center at Lewis Field

Icing Effects on Airplane Performance

Drag from unprotected surfaces Glenn Research Center at Lewis Field

Icing Effects on Airplane Performance

2 min

Performance Data on Wing

2.0 Clean 2 min 1.5 6 min 22 min 1.0 0.5 Effect of Ice on Drag (at AOA) Lift Coefficient, Cl 0.0 0.05 -0.5 -10 -5 0 5 10 15 20 0.04 0.03 Angle of Attack, deg Cd 0.02

*Airfoil in

0.01

Icing

Research

0 5 10 15 20 25

Tunnel

Exposure Time (minutes)

Glenn Research Center at Lewis Field

Icing Effects on Airplane Performance

Comparison of iced-airfoil performance for Re = 15.9x10 , M = 0.20

2.0 0.20 Clean EG1164 Horn 1.8 0.18 EG1162 Streamwise #1 1.6 0.16 EG1126 Roughness #1 1.4 0.14 EG1159 Spanwise Ridge 1.2 0.12 0.08

C

m 1.0 0.10

C

0.07 l

C

0.8 0.08 d 0.06 0.6 0.06 0.05 0.4 0.04 0.2 0.02 0.04 0.0 0.00 0.03 -0.2 -0.02 0.02 -0.4 -0.04 0.01 -0.6 -0.06 -0.8 -0.08 0.00 -8 -6 -4 -2 0 2 4 6 8 10 12 14 16 18 20 -8 -6 -4 -2 0 2 4 6 8 10 12 14 16

α (deg) α (deg.)

Glenn Research Center at Lewis Field

Icing Effects on Airplane Performance

Iced Flight Dynamics Loss of Control (LOC) • Multiple incidents and fatal accidents have occurred recently in which ice accretions were a causal factor – IPS usually operating, autopilot masked control changes 1994 - ATR-72, Roselawn, IN • 68 fatalities • Aileron hinge moment reversal with ridge of ice beyond the deicing boots Glenn Research Center at Lewis Field

Ice Protection Systems

• Thermal (evaporative and running wet) • Heated air • Electrothermal • Mechanical • Pneumatic • Ultrasonic • Other • Freezing-point depressants Glenn Research Center at Lewis Field

Engine Icing

• Ice crystal ingestion is a high priority area of research • High ice water content occurs at high altitudes around large convective storms • Over 200 power loss events since • Characterize the environment and develop capabilities to simulate and predict engine core ice accretion Glenn Research Center at Lewis Field

Rotorcraft Icing

• Research objective is

validated coupling of a rotor

performance code with an ice

accretion code

• Typically cannot fly fast enough (M > 0.6) to prevent icing by kinetic energy heating (except near the blade tips) • Usually cannot gain enough altitude to fly above weather • Helicopter operations often require remaining in an area for long periods of time • Potential for severe vibration or damage due to ice shedding • Smaller chord lengths Glenn Research Center at Lewis Field

Icing Research Tunnel

Capabilities:

• Develop and test aircraft de-icing

and anti-icing systems

• MVD:15-50 μ

• LWC: 0.2 to 3.0 g/m

• 6’ x 9’ Test Section

• Temperatures: -25 C to 5 C

• Airspeeds: 50 to 350 kts

TU R N IN G V A N E S FLO W 5 0 0 0hp FA N 2 1 0 0TO N B A LA N C E C O O LE R C H A M B E R V A R IC H R O ND R IV E C O N TR O L R O O M S E C O N D A R Y C O N TR O L R O O M M a xS pe e d: 1 7 9m /s o T =-30 C m in IC IN G Te s t S e c tion: 1 .8x2 .7m S P R A Y S

Glenn Research Center at Lewis Field

Propulsion Systems Lab

Capabilities: • Altitude testing of mid-size engines • Ice particle generation (MVD:40-60 μ) • IWC: 0.5 to 9.0 gm/m • Altitude simulation: 4000 to 40000 ft • Temperatures: -60 F to 15 F • Altitude simulation: 4000 to 40000 ft • Airspeeds: M=0.15 to 0.8 Glenn Research Center at Lewis Field

Vertical Icing StudiesTunnel

Capabilities • Planar stagnation point flow • Test section 64-in x 30-in • Airspeed at contraction: – Max = 25 m/s – Design point V = 17 m/s • Air Temperature: ambient to -15°C • LWC: 0.1 – 1.5 g/m (design spec.)

• MVD: 20 – 2000 μm (design spec.)

13’

Glenn Research Center at Lewis Field

Droplet Imaging Flow Tunnel

Capabilities • 6” x 6” Test Section • 175 mph (empty tunnel) • Phantom High Speed Camera • Sheet Laser and Intensified Camera Glenn Research Center at Lewis Field

Flight Simulation and Training

Ice Contamination Effects Flight Training Device: for familiarizing pilots with possible effects of ice contamination Glenn Research Center at Lewis Field

Icing Remote Sensing

Remote Sensing Ground Site: for developing and assessing remote icing condition detection algorithms NASA Narrowbeam Multi-frequency Microwave Radiometer (NNMMR): for terminal area icing detection and warning Glenn Research Center at Lewis Field

Benefits of Using Simulation • Identify critical conditions for icing test campaigns • Incorporate icing issues earlier into the design cycle • Explore a larger portion of the icing envelope than can be examined by tunnel or flight testing • Provide critical information for certification efforts along with tunnel and flight test information • Provide a faster, cheaper and equally accurate assessment of icing effects for purposes of design and certification Icing Data Method Data Points Time Cost Obtained Requirements Flight Testing 10 - 50 2-3 months Over $1 million Icing Tunnel Testing 100 - 150 2-3 weeks Approx. $500 thousand LEWICE Over 1000 1 day One days salary Glenn Research Center at Lewis Field

LEWICE

Ice Accretion Prediction

LEWICE is a software package the predicts the size, shape, and location

of ice growth on aircraft surfaces exposed to a wide range of icing

conditions.

LEWICE also models the

behavior of thermal ice

 Flow solution using potential flow or structured viscous solver

protection systems while

 Particle trajectory calculation, including

exposed to the same range

impingement limit search for collection efficiency of icing conditions.

and multiple drop size distributions  Integral boundary layer routine calculates heat transfer coefficient  Quasi-steady analysis of control volume mass and energy balance in time stepping routine  Geometry modification using density correlations to convert ice growth mass into volume allows multiple time-step solutions  All physical effects modeled, including turbulence, bouyancy, droplet deformation, breakup and splashing  Extensive validation against experimental data Glenn Research Center at Lewis Field

LEWICE: Ice Growth Simulation Software

INPUT: • Flow Coordinates of a body surface • Flight conditions (free stream velocity, temperature, angle of attack) • Icing conditions (water droplet diameter, liquid water content of the cloud, water droplet size distribution) OUTPUT: • Ice shape geometry • Collection efficiency on the surface • Freezing fraction along ice surfaces • Heat transfer values along the surface • Temperatures along the surface Glenn Research Center at Lewis Field

LEWICE User Base

US Government US Aerospace Industry Universities

• NASA • Learjet • Boeing • UIUC • NCAR • FAA • Gulfstream • Lockheed • WSU • Iowa Sate • CRREL • Raytheon • ALPA • MIT • Ohio State • NOAA • Cessna • Sikorsky • MSU • Penn Sate • NTSB • Cox & Co. • Embraer • CWRU • GT • AMCOM • Goodrich • GEAE • Toledo • WVU • USAF • P & W • Honeywell • Others… • Wyoming • NAVAIR • Bell • Boeing Helicopters • Beech • Hamilton Sundstrand • Nordham • Engineering Services • Northrop • New Piper • Ice Management Systems • Many Others…

International Distribution Non-Aerospace

• American Kestrel • Bridge cables • Lake Erie wind turbine project Glenn Research Center at Lewis Field

LEWICE3D

Three-Dimensional Ice Accretion Software

LEWICE3D is a suite of codes used to determine the amount and

location of ice accretion on an aircraft.

Generation of a full ice

accretion for 3D surfaces

 Based on the Messinger model and Monte Carlo analysis  Monte Carlo-based collection efficiency calculation using droplet impact counts  Integral boundary layer technique used to generate heat transfer coefficients  Ice growth calculated using a modified LEWICE scheme  Supports both structured and unstructured grids  Calculation off-body concentration factors  Determination of shadow zones Glenn Research Center at Lewis Field

SMAGGICE

Surface Modeling and Grid Generation for Iced Airfoils

The SMAGGICE software suite is an interactive toolkit used to prepare

2D cross-sections of iced airfoils for computational fluid dynamic

analysis.

 geometry preparation  block creation and grid generation  grid quality checks  flow solver interface  convenience capabilities  both single and multi-element airfoils Glenn Research Center at Lewis Field

Summary

• NASA research provides tools, methods and databases for industry, academia, other government agencies • NASA’s icing codes are the gold standard in the U.S. and the world • NASA’s icing tunnel remains highly utilized and continues to expand its envelope of calibrated conditions • NASA’s Propulsion Systems Lab will greatly expand the envelope for engine icing research with its new icing capability • Few organizations conduct basic icing research in-house • Pilot and dispatcher education and training, modifications to aircraft, improvements in detection, etc. have all contributed to saving lives • Flight into known icing conditions will remain important as airspace capacity continues to grow Glenn Research Center at Lewis Field