Document
The NASA A i r c r a f t I c i n g Research Program R o b e r t J . Shaw and John J . Reinmann ABSTRACT The objective of the NASA aircraft icing research program is to develop and make available to industry icing technology to support the needs and requirements for all weather aircraft designs. Research is being done for both fixed and rotary wing The NASA program emphasizes technology development in two key areas: applications.
advanced ice protection concepts and icing simulation (analytical and experimental).
This paper reviews the computer code development/validation, icing wind tunnel testing, and icing flight testing efforts which have been conducted to support the icing technology development.
5-59 AIRCRAFT ICING TECHNOLOGY PROGRAM The icing research program can be viewed to have a generic portion which is devoted to developing fundamental technology. This basic technology is applied with appropriate alterations and modifications to fixed wing and rotorcraft applications to develop more vehicle specific icing technology.
AIRCRAFT ICING TECHNOLOGY PROGRAM
ICING EFFECTS SIMULATIONS ICING FLIGHT TESTS ICE PROTECTION CONCEPTS TEST TECHNIQUES ANALYSIS CODES FIXED WING PHYSICS OF ICING ICING INSTRUMENTATION GENERIC TEST TECHNIQUES ICE PREVENTlONlREMOVAL ROTARY WING CONCEPTS ICING EFFECTS SIMULATIONS ICING FLIGHT TESTS ROTOR ICE PROTECTION CONCEPTS ROTOR ICING TEST TECHNIQUES CD-07-20729 5-60 The icing research program is a balanced effort in that it contains analysis code development/validation, wind tunnel testing, and icing flight research activities.
ICING RESEARCH
SEPARATED FLOW ZBWE -
WIND TUNNEL
TESTING
FLIGHT RESEARCH
CD-87-28730 5-6 1 ICE PROTECTION CONCEPTS
ICE PROTECTION CONCEPTS
LIGHTER, MORE EFFICIENT SYSTEMS FOR ADVANCED
MILITARY AND CIVILIAN AIRCRAFT
CD-87-30307 5-62 NASA ELECTROMAGNETIC IMPULSE DEICER PROGRAM The major steps i n the multi-year NASA/industry/university program to develop the required technology data base for the electromagnetic impulse deicer (EIDI) are shown. This EIDI technology now available allows manufacturers of both general aviation and commercial transport aircraft to consider EIDI for future aircraft designs.
NASA ELECTROMAGNETIC IMPULSE DEICER PROGRAM
ANALYTICAL MODELING
-yJJ
LABORATORY WIND TUNNEL TESTING - c _ GENERAL AVli COMMERCIAL TRANSPORT CD-07-20731 5-63 NASA/ARMY/INDUSTRY ROTOR PNEUMATIC BOOT PROGRAM A multi-year NASA/Army/industry program has demonstrated that a conventional pneumatic boot design can be used to protect the main rotor of the UHlH helicopter.
The main steps of the program are shown.
ORIGINAL PAGE IS
OE POOR QUALITY
NASAIARMYIINDUSTRY ROTOR PNEUMATIC BOOT PROGRAM
EJECTOR FLOW CONTROL VALVE -
RELIEF VALVE ~ CHECK VALVE - TURBINE BLEED LOW VACUUM U H l H INSTALLATION OTTAWA SPRAY RIG D EM 0 N STRATED ROTOR DEICING CAPABILITY c~-a7-28732 5-64 ~ ANALYTICAL AND EXPERIMENTAL ICING SIMULATION
ANALYTICAL AND EXPERIMENTAL ICING SIMULATION
DEVELOPNALIDATE CODES TO PREDICT AIRCRAFT PERFORMANCE,
STABILITY AND CONTROL IN ICING
IMPROVENALIDATE ICING SIMULATION FACILITIES
CONDUCT NATURAUARTIFICIAL ICING FLIGHT TESTS
IMPROVE ICING INSTRUMENTATION
CD-07-20733 5-65 AIRCRAFT ICING ANALYSIS METHODOLOGY The large number of computer codes and some of the required interfaces to form a comprehensive icing analysis methodology are shown.
AIRCRAFT ICING ANALYSIS METHODOLOGY
FLOW FIELD AERODYNAMIC 1 1
-
_ _ _ _ _ _ _ _ _ _ _ _ _ J
I I \ HOT GAS SYSTEM I ~ C H A R . I N C L U D I N G 1 - 1 MECHANICAL INDICATES AREA OF CURRENT COMPUTER CODE DEVELOPMENT BY NASA LeRC CD-07-20735 5-66 COMPUTER CODES BEING DEVELOPED/VALIDATED The individual computer codes currently being developed and validated are shown.
This set of codes forms a core analysis capability which can be used to build the more comprehensive icing analysis capability which is desired.
COMPUTER CODES BEING DEVELOPEDNALIDATED
TRAJECTORY ANALYSES
- TWO DIMENSIONAL
- THREE DIMENSIONAL
AIRFOIL ICE ACCRETION
AERODYNAMIC PERFORMANCE-IN-ICING
- AIRFOIL
- PROPELLER, ROTOR (APPROXIMATE)
- COMPLETE AIRCRAFT (APPROXIMATE)
ICE PROTECTION SYSTEMS
- ELECTROTHERMAL
- ELECTROIMPULSE
- FLUID FREEZING POINT DEPRESSANT
- PNEUMATIC BOOT
c~-a7-2a734 5-6 7 NASA/FAA WATER DROPLET IMPINGEMENT RESEARCH PROGRAM The major steps of the NASA/FAA program to acquire a validation data base for water droplet trajectory codes are shown.
OMGINAE PAGE r s
OF POOR QUALITY
PROGRAM
NASAlFAA WATER DROPLET IMPINGEMENT RESEARC
OBJECTIVE - ACQUIRE A DATA BASE TO VALIDATE TRAJECTORY CODES
INLET MODEL WITH
BLOTTER STRIPS
EXPERIMENT __ THEORY
LOCAL COLLECTION
CD-87-28736 EFFICIENCY DISTRIBUTION
5-68 TWIN OTTER TRAJECTORY ANALYSIS A computer graphics representation of the NASA icing research aircraft, a deHavilland DHC6 Twin Otter, is shown. This computer model is being used to calculate three-dimensional trajectories of water droplets about the aircraft to help in interpreting icing cloud instrument data.
TWIN OTTER TRAJECTORY ANALYSIS
5-6 9 TRAJECTORY ANALYSIS FOR LASER SPECTROMETER Selected results for trajectory analysis studies of the laser spectrometer droplet sizing instrument are shown. The results show that significant error can occur when the instrument is mounted beneath the main wing of the aircraft. This error is attributed to the three-dimensional flowfield effects on the trajectories of the water droplets. The curves indicate that, for the droplet sizes of interest (-10 to 100 pm), the instrument will sense that fewer droplets/m3 exist than actually do exist in the "freestream" icing cloud.
TRAJECTORY ANALYSIS FOR LASER SPECTROMETER
1 .o
---
ISOLATED ,/)e INSTRUMENT 8 6- INSTALLED .9 ERROR / ' / ---Cr(' DROPLET CONCENTRATION .8 FACTOR .7 .6 10' 102 103 WATER DROP DIAMETER, pm CD-07-20730
ORIGINAL' PAGE I S
OF POOR QUALITY 5-70 NASA AIRFOIL ICE ACCRETION CODE (LEWICE) An indication of the capability of the NASA ice accretion code (LEWICE) to predict the growth of ice on an airfoil is shown.
NASA AIRFOIL ICE ACCRETION CODE (LEWICE)
C O M P A R I S O N OF GLAZE ICE SHAPES N A C A 0012 AIRFOIL, 21 in. CHORD THEORETICAL EX PER I MENTAL
VELOCITY, m/sec ............. 89. 40
TEMPERATURE, ' C . . . . . . . . . . . -10.65
PRESSURE, kPa ............... 94.20
LWC, g l m 5 ........................ 1 . 20
5-71 CLOSE UP FLASH PICTURE OF DROPLET IMPINGEMENT These A close up flash picture of droplet impingement o n a surface is shown.
photographic studies are being done to better understand the physics of the ice accretion process. An improved understanding of the basic physics will result in improved ice accretion prediction capabilities.
0NGmA.L PAGE I S
OE POOR QUALITY
CLOSE UP FLASH PICTURE OF DROPLET IMPINGEMENT
CD-87-28740 5-72 ADHESIVE SHEAR STRESS VERSUS INTERFACE TEMPERATURE Improved values f o r impact ice structural properties as well as adhesion strengths are required inputs to computer models of mechanical and thermal deicing systems.
Fundamental experiments are being conducted to acquire such data and a representative sample of the data being acquired is shown.
ADHESIVE SHEAR STRESS VERSUS INTERFACE TEMPERATURE
o
r
AVERAGE SCATTER, +42% 0 130-MIHR WIND SPEED A 100-MIHR WIND SPEED SHEAR STRESS.
PSI n U
- 10 - 4 - 2 8 14 20 26 32 38
TEMPERATURE, O F CD-07-20741 5-73 CODE VALIDATION STUDIES - ICED AIRFOIL ANALYSIS Detailed data are required to evaluate the various codes being developed to predict airfoil aerodynamic performance degradation due to leading edge ice accretions. A summary of the data being acquired for a NACA 0012 model with an idealized leading edge ice accretion is shown.
CODE VALIDATION STUDIES-ICED AIRFOIL ANALYSIS
I
I - I - - P ‘ ‘1
0 5 1 0 NACA 0012 MODEL FORCE AND MOMENT DATA - 2 I I I I I 0 UPPER SURFACE V LOWER SURFACE C P L . .. . . . .
BOUNDARY LAYER FLOW VISUALIZATION PROFILES CD-87-28742 5-74 ICED AIRFOIL ANALYSIS The "iced" airfoil predictions of the Navier-Stokes and interactive boundary layer codes are compared to the code validation data shown in the previous figure. The agreement is judged to be generally good for both codes.
.
ICED AIRFOIL ANALYSIS
INTERACTIVE BOUNDARY LAYER NAVIER-STOKES .16 EXPERIMENT
B
DRAG .12 COEFFICIENT COEFFICIENT .08 .04 0 2 4 6 8 10 0 2 4 6 8 10 ANGLE OF ATTACK, deg C D-87-29472 5-75 COMPARISON OF LASER SPECTROMETER DROP SIZE INDICATIONS TO OLD IRT CALIBRATION Droplet size measurements made in the Icing Research Tunnel (IRT) using various laser spectrometer probes are compared to the group of cloud droplet sizes using the facility calibration developed by NACA. The wide spread of the data away from the line of perfect agreement suggests the need for improvements in the accuracy of droplet sizing instrumentation. The data taken in this test program suggested current instrumentation accuracies of no better than +4 pm (on a volume median diameter (VMD) basis).
COMPARISON OF LASER SPECTROMETER DROP SIZE
INDICATIONS TO OLD IRT CALIBRATION
RANGE O F CONDITIONS: 10 < DVM < 30 pM; 0 . 3 -= LWG < 3 G/M3; 80 -= V -= 460 K M / H R M E A N OF - + 1 STD.
A S S P DATA DEV. OF - ' A S S P DATA -.
p ' LINE OF
A 'I +20% / PERFECT
e , 'I / /' * , ' A G R E E M E N T
' - _ _ I N D I C ATE D ' 20 M V D, 'ECTROMETER S F Clm A S S P A S S P 2 A S S P 3 , A S S P 4 I e F S S P 1
- //-/ -
I '5, ou v A S S P 1979
-
5 10 15 20 . 25 30 IRT MVD, pm CD-87-28743 5-76 EFFECTS OF DROP SIZE MEASUREMENT ERRORS The effect of a 24 pm variation of volume median diameter (VMD) on ice accretion shape and resulting airfoil drag increase are shown. The figure suggests the effects can be significant and that the accuracy of droplet sizing instrumentation must be improved.
EFFECTS OF DROP SIZE MEASUREMENT ERRORS
DRAG DROP SIZE, COEFFICIENT C L m Cd 25 0.074
---
21 .039
- --
17 .015 DRY .0085
f
0012 AIRFOIL I , 21 in. CHORD V CD-87-28744 5-77 PARTICLE SIZING INSTRUMENTATION RESEARCH The current activities to improve the accuracy of existing droplet sizing instrumentation are shown.
Cl3XXNS PAGE I S OF POOR QUALITY
RESEARCH
PARTICLE SI Z I N G INSTRU M E NTAT
C O R R E C T E D , .. R 4 W
DATA CORRECTION
~ CALIBRATION DEVICES
ALGORITHMS
THEORETICAL MODEL1 N G
FUNDAMENTAL INSTRUMENT
CD-07-20745 RESEARCH
COMPARISONS
5-78 ICING RESEARCH TUNNEL The NASA Icing Research Tunnel (IRT), the largest refrigerated icing wind tunnel in the world, recently underwent a $3.6M upgrade to modernize the facility which began operation in 1944. The key features of the "new" IRT are shown.
ORIGINAL PAGE I S IOE: POOR QUALITY;
ICING RESEARCH TUNNEL
CONTROLS B U I L D I M
6- BY 9-FT
SPRAY BAR SYSTEM CONTROL ROOM TEST SECTION
CD-07-20746 5-79 TWIN OTTER WING ICING/AEROPERFORMANCE The major objective of the icing flight research portion of the program is to acquire a data base which can be used to validate experimental and analytical of icing. The key components of the data base being acquired are shown.
simulations ORIGINAL PAGE I S
OX W R QUUm
TWIN OTTER WING IClNGlAERO PERFORMANCE
ICING CLOUD INSTRUMENTS STEREO PHOTOGRAPHY SYSTEM .8 I - O 5 10 15 20 25 TIME, min L POS ICING SI M ULATlON CLEAN’ I VALIDATION CD-07-20747 DATA BASE 5-80 AIRCRAFT PERFORMANCE IN NATURAL ICING The aircraft is also being used to acquire aircraft performance/stability control Representative samples of data acquired are shown.
changes due to icing.
AIRCRAFT PERFORMANCE IN NATURAL ICING
db EXPERIMENTAL DATA BASE IS BEING
-
ACQUIRED, RELATING AIRCRAFT PERFORMANCE
DEGRADATION TO A MATRIX OF MEASURED
NATURAL ICING CONDITIONS
NASA DHC-6 TWIN OTTER
GLAZE ICING ENCOUNTER
ICING RESEARCH AIRCRAFT
ICING TIME - 26 min
MVD - 13p.m
LWC - 0.31 g/m3 STATIC TEMP. -4 O C
PERFORMANCE PERFORMANCE
DECREMENT
CD-87-28748 5-81 REDUCTION OF AIRCRAFT STATIC LONGITUDINAL STABILITY DUE TO ICING
REDUCTION OF AIRCRAFT STATIC LONGITUDINAL STABILITY DUE TO ICING
OBJECTIVE: EMPLOY STATIC LONGITUDINAL FLIGHT TEST METHODS TO A DHC-6 AIRCRAFT WITH A N ARTIFICIAL ICE SHAPE ATTACHED TO THE HORIZONTAL TAIL PLANE TO MEASURE THE CHANGE I N STATIC M A R G I N A REDUCTION I N STATIC M A R G I N WAS MEASURED THROUGHOUT RESULTS: THE N O R M A L FLAPS-UP CRUISE ENVELOPE STANDARD WEIGHT . I 1 IXQ Ib c g . 3 Z t l % M A C PULL -0 8 NORMALIZE0 MODERATE STICK-FORCE, -0 4 F S h P U S H 4 0 2 4 6 8 1 0 1 2 1 4 C l V A R I A T I O N I N NORMALIZED CONTROL FORCE ARTIFICIAL MODERATE GLAZE ICE SHAPE ATTACHED TO HORIZONTAL TAIL FOR THE "ICED" VERSUS BASELINE TAIL
70 r
STICK-FREE NEUTRAL 50 POIM.
9L M A C
1 - 0 BASELINE IN0 ICE1
40 -- 0 WITH ARTIFICIAL ICE SHAPE NOMINAL CRUISE POWER 275 shpIENGINE I I I I CD-87-28749 5-82 MODEL ROTOR ICING PROGRAM The evaluation of the technique of testing model helicopter rotors in the IRT is the current focus of the helicopter related icing research. This effort is a joint NASA/industry/university program, and the key elements of the initial phases of the multi-year program are shown.
.SHGINA.L PAGE I S
OE POOR QUALITY
MODEL ROTOR ICING PROGRAM
BOEING-VERTOL McDONN ELL-DOUG LA TEXAS A&M UNIV.
BELL TEST PLANNING MODEL PREPARATION SIKORSKY DATA ACQUISITION SYSTEM TEST TECHNIQUES RIG DRY WIND TUNNEL (OH58 TAIL ROTOR) THOROUGH EVALUATION OF MODEL ROTOR ICING FU L TEST TECHNIQUE (SIKORSKY PFM) CD-87-28750 HELICOPTER ICING FLIGHT TEST PROGRAM The NASA/Army/industry/university helicopter icing flight test program was a multi-phase effort to acquire unprotected helicopter rotor ice accretion and aerodynamic performance data for both hover and forward flight conditions. The test techniques developed will be used in a proposed future program to acquire flight data for comparison with scale model rotor data which will be acquired.
HELICOPTER ICING FLIGHT TEST PROGRAM
OTTAWA SPRAY RIG TEST (PHASE I) DETAILED ICE SHAPE DOCUMENTATION
)*C
HISS TESTING (PHASE 1 1 ) ___ --
- -
- -~
%
-
/ Mo
L M .- ~ --
WIND TUNNEL TESTS OF ROTOR PERFORMANCE “EQUIVALENT” TWO-DIMENSIONAL MEASUREMENTS MODELS CI, cd, Cm (HP REQUIRED) ROTOR PERFORMANCE CALCULATIONS (HP REQUIRED) CD-87-28751 5-84 AIRCRAFT ICING TECHNOLOGY PROGRAM The areas of future emphasis in the program are shown in this figure. The basic or generic icing research activities will be continued and this technology will be applied to the fixed wing aircraft to develop icing effects simulations. These simulations will be computer based and validated through appropriate wind tunnel and flight test programs. In the longer term, the emphasis will switch toward rotorcraft applications where again icing effects simulations will be developed and validated.
In addition, rotor icing test techniques will be developed and validated and alternate concepts for rotor ice protection will be sought.
AIRCRAFT ICING TECHNOLOGY PROGRAM
ICING EFFECTS SIMULATIONS ICING FLIGHT TESTS ICE PROTECTION CONCEPTS TEST TECHNIQUES ANALYSIS CODES PHYSICS OF ICING FIXED WING ICING INSTRUMENTATION GENERIC TEST TECHNIOUES ICE PREVENTION/REMOVAL ROTARY WING CONCEPTS ICING EFFECTS SIMULATIONS ICING FLIGHT TESTS ROTOR ICE PROTECTION CONCEPTS ROTOR ICING TEST TECHNIQUES CD-07-20729 5-85