Document
N92-22534
THE NASA AIRCRAFT ICING RESEARCH PROGRAM Robert J. Shaw and John J. Reinmann SUMMARY 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 applications. The NASA program emphasizes tech- nology development in two key areas: advanced ice protection concepts and icing simulation (analytical and experimental). This paper reviews the com- puter code development validation, icing wind tunnel testing, and icing flight testing efforts which have been conducted to support the icing technology development.
PROGRAM OVERVIEW The major areas of emphasis of the NASA icing research program are shown in figure I. The program has a generic portion which is devoted to developing the required fundamental technology. The basic technology is applied with appro- priate modifications and alterations to fixed- and rotary-wing specific icing problems. The icing research program is a balanced effort (fig. 2) in that it contains analysis code development/validation, wind tunnel testing, and icing flight research activities. These elements of the program are closely coordi- nated since all are conducted within the icing rsearch group. In addition, close coordination exists with industry and universities through formal con- tracts and grants as well as through collaborative and cooperative programs.
Some recent accomplishments of the icing research program will be reviewed by looking at some past activities in two technology areas: ice protection concepts, and analytical and experimental icing simulation. The first area to be reviewed will be ice protection concepts, where the goal is to develop con- cepts which will result in lighter, more efficient ice protection systems for advanced military and civilian aircraft.
In fiscal year 1987, a 5-year NASA/industry/university program was com- pleted to develop the technology data base for the electromagnetic impulse deicer concept (or EIDI) which shows great promise for providing highly effi- cient deicing with low power requirements. The major phases of this program are shown in figure 3.
The technology was developed through many different Icing Research Tunnel (IRT) tests of various general aviation and commercial transport components which require ice protection. The hardware was provided by the many aerospace companies that were part of the consortium. Complimentary analytical modeling PRECED;?;G MAG£ _LAi'_K NOT FILMED (structural and electrodynamic) and laboratory tests were conducted at Wichita State University to better understand the key physics associated with EIDI.
Natural icing flight tests were conducted with the NASA icing research aircraft to which was affixed a leading edge glove or cuff with the EIDI system installed. Excellent deicing performance was documented in natural icing con- ditions. As a result of this program, the technology is now in hand for both the general aviation and transport manufacturers to consider EIDI for main wing/tail deicing for future applications.
The electrothermal deicing system has become the de facto standard for the helicopter industry, but the weight, power requirements, and complexity of electrothermal deicing systems has caused the industry to seek alternative con- cepts. In a joint program with the Army and industry (Bell Helicopter Textron and B.F. Goodrich), a pneumatic boot deicer was applied to the UHIH rotor and highly acceptable deicing capability was demonstrated (fig. 4). Deicing per- formance was demonstrated in both forward flight conditions behind the Army's spray tanker and near hover conditions at the Canadian NRC's Ottawa Spray rig.
Prior to the icing flight tests, tests were conducted in the IRT on a full- scale, fixed-position UHIH rotor section. These tests were used to screen various pneumatic boot configurations and led to the selection of the configu- ration shown. Two of the attractive features of the pneumatic boot deicer system is that it had relatively few components and the UHIH system weight was only about 40 lb.
As a result of this program, the Army has qualified the UHIH helicopter with pneumatic deicers to fly into forecast icing conditions up to the "moderate" level. Future activities are being conducted by the Army and B.F. Goodrich to acquire the needed field experience especially as related to rain and sand erosion characteristics and the frequency of field repair/ replacement required.
The second icing technology area to be reviewed will be analytical and experimental icing simulation. The following activities are included in this technology area: (I) Developing/validating codes to predict aircraft performance, stability, and control in icing (2) Improving/validating icing simulation facilities (3) Conducting natural/artificial icing flight tests (4) Improving icing instrumentation First, the development and validation of icing analysis computer codes will be discussed. Figure 5 attempts to show the many codes required to form a comprehensive icing analysis methodology as well as some of the many inter- faces required. The individual computer codes currently being developed and validated are as follows: (I) Trajectory analyses, both two dimensional and three dimensional (2) Airfoil ice accretion
(3) Aerodynamic performance-in-icing, including airfoil, propeller, rotor
(approximate), and complete aircraft (approximate)
(4) Ice protection systems, including electrothermal, electroimpulse, fluid freezing point depressant, and pneumatic boot.
This set of codes forms a core analysis capability which can be used to build
a more comprehensive icing analysis capability. Someexamples of the various
codes being developed and the supporting fundamental and validation
experiments being conducted will be given.
A number of two- and three-dimensional trajectory analysis codes have been
developed which can calculate water droplet paths around bodies ranging from
simple, single-element airfoils to complete aircraft configurations. Appropri-
ate data are required to validate the code accuracies, and one aspect of this
experimental research as shown in figure 6. This is a joint NASA/FAA program
to measure local water impingement rates (often called local collection effi-
ciencies) on various airfoil, wing, and inlet configurations.
These curves are determined by collecting water mixed with a known concen-
tration of blue dye on blotter strips affixed to the models like the Boeing
737-300 I/4-scale inlet shown. A He-Ne laser system measures the local
reflectance of the blotter paper which can be converted to local collection
efficiency. The first phase of this joint program has been completed, and
additional tests are planned in order to acquire a comprehensive data base for
code validation.
Figure 7 shows a computer graphics representation of the NASA icing
research aircraft, a deHavilland DHC6 Twin Otter. 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. Selected results of trajectory analysis studies of the laser spectrometer droplet sizing instru- ment are shown in figure 8. The results show that significant errors can occur when the instrument is mounted beneath the main wing of the NASA icing research 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 (i0 to i00 _an), the instrument will sense that fewer droplets per cubic meter exist than actually do exist in the "free stream" icing cloud. Similar results would be expected for any other aircraft configu- ration which had icing instruments located in close proximity to the aircraft surface.
A first-generation code has been developed to predict the growth of ice on a single-element airfoil. A typical comparison of the predictions of this code (called LEWICE) with data taken in the IRT on a 21 in. chord NACA 0012 airfoil is shown in figure 9. Currently evaluation studies of LEWICE are being conducted by NASA, FAA, and several companies under cooperative programs.
The LEWICE code uses a simple control volume approach for calculating local mass and energy balances which lead to local ice growth rate predictions.
Such a global approach is necessary because the fundamental physics of aircraft icing are not that well understood. Fundamental in-house and university research efforts are under way to improve the basic physics understanding and incorporate this knowledge into later versions of LEWICE to improve the ice shape predictions. One example of this research is shown in figure i0.
Closeup flash pictures were taken of droplet impingement in the stagnation region of a circular cylinder. Individual cloud droplet streaks can be seen as well as water coalescence into much larger droplets and resulting movement on the surface prior to freezing.
Improved values for 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 in fig- ure II. The figure shows adhesive shear stress as a function of airstream temperature. One important point to be gained from the figure is the consider- able amount of scatter which exists with this type of data. Similar levels of data scatter have been observed by other researchers.
The current emphasis in predicting aerodynamic performance degradation due to icing is to extend and validate state-of-the-art airfoil analysis codes to predict "iced airfoil" performance. Detailed flowfield data are required to evaluate these codes, and the current approach being taken is shown in fig- ure 12. A 21-1n. NACA 0012 airfoil model was fabricated with an idealized leading edge ice accretion as shown. This initial ice accretion shape tested was meant to be generally like an ice accretion but to have well-defined cross-sectional characteristics and smooth continuous coordinates. This model was tested in the Ohio State University 4- by 5-ft low-speed wind tunnel. As the figure indicates, force and moment data were acquired as well as detailed surface pressure distributions, boundary layer profiles on both surfaces, con- centrating in the vicinity of the separation reattachment zones, and flow visu- alization data. These data were used to compare with two state-of the-art analysis codes - the ARC two-dimensional Navier-Stokes analysis code of NASA Ames and the Interactive Boundary Layer (IBL) code of Cebeci (California State, Long Beach). The lift and drag coefficient variations with angle of attack as predicted by the codes are compared in figure 13 to the data previously shown. Generally, the agreement is judged to be good for both codes although the IBL code tends to underpredict drag at the higher angles of attack. The activity is continuing, and, in particular, measurements and comparisons are being made with more realistic ice shape geometries.
Icing instrument research is an important part of the NASA icing research program. Figure 14 shows droplet size measurements made in the Icing Research Tunnel (IRT) using various laser spectrometer probes compared with the volume median droplet sizes determined from the facility calibration developed by NACA. The wide spread of the data away from the line of perfect agreement sug- gests the need for improvements in the accuracy of droplet sizing instrumenta- tion. The data taken in this test program suggested current instrumentation accuracies of no better than ±4 _un (on a volume median diameter (VMD) basis). The effect of a ±4 _m variation of VMD on ice accretion shape and resulting airfoil drag increase are shown in figure 15. The figure suggests that the effects can be significant and that the accuracy of droplet sizing instrumenta- tion must be improved.
A more accurate measurement of icing cloud properties (i.e., liquid water content and droplet size distribution) is necessary for many icing R&D pur- poses. Currently it is felt that the most severe problems exist for those instruments that measure droplet sizes. As indicated, the accuracy of current optical systems appears to be no better than ±4 _um out of 20 (on a VMD basis).
The current research activities to improve current drop sizing instruments (fig. 16) include the following: (I) Improved calibration devices (2) Theoretical modeling of the optical characteristics of the instruments and complimentary fundamental research (3) Comparisons of available instruments in a simple, well-documented spray The NASA Icing Research Tunnel (IRT) is the largest refrigerated icing wind tunnel in the world (fig. 17). It has played a key role in developing technology to solve aircraft icing problems since it became operational in June of 1944. As an indication of its importance and contributions, the American Society of Mechanical Engineers (ASME) recently designated the IRT to be an international mechanical engineering landmark facility, one of only 21 such facilities in the world. A _3.6 million upgrade to the facility was recently completed to ensure that the IRT will continue to play a key role in the future in developing aircraft icing technology. Some of the key features of the new IRT are shown here. Of particular interest to the research community is the new spray bar system, which will allow a wider range of icing conditions to be provided to users. The final goal is to be able to provide complete coverage of the FAA/Icing envelopes.
Natural icing flight testing is also a key part of the aircraft icing research program. Currently, the aircraft being used for these tests is a deHavilland DHC6 Twin Otter. The prime emphasis of the flight tests has been to acquire an icing simulation data base, as indicated in figure 18. The pri- mary parts of this data base are (i) the icing cloud properties (liquid water content (LWC) and droplet size spectra) measured by using the vast array of instruments on the aircraft, (2) main wing ice accretion shapes documented with a stereo photography system, and (3) wing section drag measured with a heated wake survey probe. This data being acquired over a wide range of natural icing conditions will be compared with IRT results from tests of a full-scale Twin Otter wing section and with icing analysis code predictions.
Studies of aircraft performance/stability and control changes due to icing are also being conducted with the Twin Otter. Representative performance and stability and control data are shown in figures 19 and 20. These data are also being compared with computer predictions.
Emphasis in the aircraft icing research program will eventually shift from the fixed wing to the rotary wing since some of the most difficult icing prob- lems are faced by the rotorcraft community. Currently, the rotorcraft icing activities are focused on evaluating the model rotor icing test technique, that is, determining what use can be made of testing scale-model rotors in a large icing wind tunnel such as the IRT. To date, no such tests have been conducted in the U.S., and U.S. manufacturers must rely primarily on artificial/natural icing flight testing which is extremely costly and time consuming. In order to evaluate the model rotor test technique, NASA has teamed with the four major U.S. helicopter manufacturers and Texas A&M University to carry out all the activities required to test in the IRT a fully instrumented, powered-force model provided by Sikorsky and shown in figure 21. Prior to this test, several
supporting test techniques must be developed, and for these preliminary activi-
ties, an 0H58 tail rotor rig shown here will be used. The 0H58 is a much
sturdier rig and therefore should be more forgiving to any unexpected surprises
which might be encountered during the initial IRT test.
Once this initial evaluation is completed, it is envisioned that follow-on
tests will be conducted, especially for comparison with full-scale, natural
icing flight test results. Initial full-scale rotor icing test results were
acquired in the recent NASA/Army Helicopter Icing Flight Test Program. The
various activities in this multiphase program are shown in figure 22. This
test program was a multiphase effort to acquire unprotected helicopter rotor
ice accretion and aerodynamic performance data for both hover and forward
flight conditions. The techniques developed will be used in proposed future
programs to acquire flight data for comparison with the scale-model rotor data
which will be acquired in follow-on IRT Tests.
Nowthat somehighlights of the NASA aircraft icing research program have
been reviewed, it is appropriate to consider figure I and indicate the future
directions of the program.
The generic activities will continue as indicated:
(I) The icing analysis codes will becomemore robust and sophisticated as
to the problems which can be analyzed.
(2) New instrumentation concepts will be investigated which will offer improved accuracy levels over current instruments.
(3) Research will continue to look for alternate ice protection concepts which look attractive from weight, power requirement, and efficiency standpoints.
Future emphasis as related to fixed-wing aircraft will be to couple the codes together to form more comprehensive icing-effects-simulation computer models. Such models, once validated against icing flight data, could be used in pilot training simulators, for preliminary design studies, and possibly as part of certification/qualification programs.
(I) Investigations will be conducted of potential icing problems for unique military aircraft configurations of the future with emphasis on the ice protection design requirements for such aircraft.
(2) NASA is also developing jointly with the major U.S. airframe and engine manufacturers a proposed research program to investigate the ice protec- tion requirements for the advanced propfan engine configurations which will be flying in the early 1990's. A major component of this proposed program would be natural icing flight tests of a propfan configuration, and it is felt that the so-called PTA aircraft would be the ideal research aircraft to conduct these studies.
The longer term emphasis of the NASA icing research program will shift to the helicopter, with the areas of emphasis shown in figure I. In the shorter term, the majority of activities will be to evaluate the model rotor icing test technique.
A bibliography of icing reports generated by the NASA Aircraft Icing Research Program is included in the appendix.
APPENDIX - AIRCRAFT ICING RESEARCH PROGRAM BIBLIOGRAPHY Norment, H.G.: Calculation of Water Drop Trajectories To and About Arbitrary Three-Dimensional Bodies in Potential Airflow. NASA CR-3291, 1980.
Bragg, M.B.; Gregorek, G.M.; and Shaw, R.J.: An Analytical Approach to Airfoil Icing. AIAA Paper 81-0403, Jan. 1981.
Breeze, R.K.; and Clark, G.M.: Light Transport and General Aviation Aircraft Icing Research Requirements. (NA-81-110, Rockwell International Corp.; NASA Contract NAS3-22186) NASA CR-165290, 1981.
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Kohlmann, D.L.; Schweikhard, W.G.; and Evanlch, P.: Icing Tunnel Tests of a Glycol-Exuding Porous Leading Edge Ice Protection System on a General Aviation Airfoil. AIAA Paper 81-0405, Jan. 1981.
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Reinmann, J.J.; Shaw, R.J.; and Olsen, W.A., Jr.: Aircraft Icing Research at NASA. Proceedings of the First International Workshop on Atmospheric Icing of Structures, CRREL SR-83-17, L.D. Minsk, ed., Electric Power Research Institute, 1982, pp. 103-116. (Avail. NTIS, AD-AI31869 and AD-E850387). (NASA TM-82919.)
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Marano, J.J.: Numerical Simulation of an Electrothermal Deicer Pad. NASA
CR-168097, 1983.
Miller, T.L.; Korkan, K.D.; and Shaw, R.J.: Statistical Study of an Airfoil
Glaze Ice Drag Correlation. SAEPaper 830753, 1983.
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(MRI-82-FR-1862, Meteorology Research Inc.; NASA Contract NAS3-22760) NASA CR-168008, 1983.
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1984.
Arimilli, R.V.; Keshock, E.G.; and Smith, M.E.: Measurements of Local Convective Heat Transfer Coefficients on Ice Accretion Shapes. AIAA Paper 84-0018, Jan. 1984.
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Shapes. AIAA Paper 84-0184, Jan. 1984.
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a Model Helicopter Main Rotor in Hover and Forward Flight With a Generic Ice
Shape. AIAA Paper 84-0609, Mar. 1984.
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Accretion in Hover. AIAA Paper 84-0608, Mar. 1984.
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Main Rotor of a UH-IH Helicopter in Hover. NASA CR-168332, 1984.
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Drag Increase for a NACA 0012 Airfoil. AIAA Paper 84-0109, Jan. 1984.
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Potapczuk, M.G., et al.: Evaluation of Iced Airfoil Performance Using a Navier-Stokes Equation Solver With a Body-Fitted Curvilinear Coordinate System. AIAA Paper 84-0107, Jan. 1984.
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Schrag, R.L.; and Zumwalt, G.W.: Electro-lmpulse Deicing: Concept and Electrodynamic Studies. AIAA Paper 84-0021, Jan. 1984.
Shaw, R.J.: Experimental Determination of Airfoil Performance Degradation Due to Icing. AIAA Paper 84-0607, Mar. 1984.
Shaw, R.J.: Progress Toward the Development of an Aircraft Icing Analysis Capability. AIAA Paper 84-0105, Jan. 1984. (NASA TM-83562.)
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Zaguli, R.J.; Bragg, M.B.; and Gregorek, G.M.: Results of an Experimental Program Investigating the Effects of Simulated Ice on the Performance of the NACA-63A415 Airfoil With Flap. (AARL-TR-83-2, Ohio State Univ.; NASA Grant NAG3-28) NASA CR-168288, 1984.
Zumwalt, G.W.; and Mueller, A.A.: Flight and Wind Tunnel Tests of an Electro-Impulse De-lclng System. AIAA Paper 84-2234, July 1984.
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Bragg, M.B.; and Coirier, W.J.: Detailed Measurements of the Flowfield in the Vicinity of an Airfoil with Glaze Ice. AIAA Paper 85-0409, Jan. 1985.
Flemming, R.J.; and Lednicer, D.A.: Correlation of Airfoil Icing Relationships with Two-Dimensional Model and Full Scale Rotorcraft Icing Test Data. AIAA Paper 85-0337, Jan. 1985.
Flemmlng, R.J.; Shaw, R.J.; and Lee, J.D.: The Performance Characteristics of Simulated Ice on Rotorcraft Airfoils. Proceedings, 41st Annual Forum, American Helicopter Society, 1985, pp. 743-757.
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Hansman, R.J., Jr.; and Kirby, M.S.: Measurement of Ice Accretion Using Ultrasonic Pulse-Echo Techniques. AIAA Paper 85-0471, Jan. 1985.
Haworth, L.A.; and Graham, M.S.: Flight Tests of the Helicopter Pneumatic Deicing System. Proceedings, American Helicopter Society, 41st Annual Forum, 1985, pp. 725-733.
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Kim, J.J.: Computational Particle Trajectory Analysis on a Three-Dimensional Engine Inlet. AIAA Paper 85-0411, Jan, 1985.
Korkan, K.D.; Dadone, L.; and Shaw, R.J.: Performance Degradation of Heli- copters Due to Icing - A Review. Proceedings, 41st Annual Forum, American Helicopter Society, 1985.
Lee, J.D.; and Shaw, R.J.: The Aerodynamics of Rotor Blades with Ice Shapes Accreted in Hover and in Level Flight. Proceedings, 41st Annual Forum, American Helicopter Society, 1985, pp. 735-742.
Masiulaniec, K.K., et al.: Full Two-Dimensional Transient Solutions of Electrothermal Aircraft Blade Deicing. AIAA Paper 85-0413, Jan. 1985.
Mikkelsen, K.L., et al.: Icing Flight Research: Aerodynamic Effects of Ice, and Ice Shape Documentation with Stereo Photography. AIAA Paper 85-0468, Jan.
1985.
Miller, T.L.; Korkan, K.D.; and Shaw, R.J.: Analytical Determination of Propeller Performance Degradation Due to Ice Accretion. AIAA Paper 85-0339, Jan. 1985.
Norment, H.G.: Calculation of Water Drop Trajectories To and About Arbitrary Three-Dimensional Lifting and Nonllfting Bodies in Potential Airflow. NASA CR-3935, 1985.
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Potapczuk, M.G.; and Gerhart, P.M.: Progress in Development of a Navier-Stokes Solver for Evaluation of Iced Airfoil Performance. AIAA Paper 85-0410, Jan.
1985.
Shaw, R.J.; and Richter, G.P.: The UH-IH Helicopter Icing Flight Test Program: An Overview. AIAA Paper 85-0338, Jan. 1985.
Zumwalt, G.W.: Icing Tunnel Tests of Electro-Impulse De-Icing of an Engine Inlet and High Speed Wings. AIAA Paper 85-0466, Jan. 1985.
Bernhart, W.D.; Glen, P.H.; and Wilson, B.K.: A Structural Dynamics Investi- gation Related to EIDI Application. AIAA Paper 86-0550, Jan. 1986.
Bragg, M.B.; and Coirler, W.J.: Aerodynamic Measurements of an Airfoil With Simulated Glaze Ice. AIAA Paper 86-0484, Jan. 1986.
Hansman, R.J., Jr.; and Kirby, M.S.: Real-Time Measurement of Ice Growth During Simulated and Natural Icing Conditions Using Ultrasonic Pulse-Echo Techniques. AIAA Paper 86-0410, Jan. 1986.
Hovenac, E.A.: Calibration of Droplet Sizing and Liquid Water Content Instruments: Survey and Analysis. (FAA-CT-86-19, Sverdrup Technology Inc., NASA Contract NAS3 24105) NASA CR 175099, 1986.
Hovenac, E.A.: Use of Rotating Reticles for Calibration of Single Particle Counters. LIA, vol. 58, 1987, pp. 129-134.
Ingebo, R.D.: Formation and Characterization of Simulated Small-Droplet Icing Clouds. AIAA Paper 86-0409, Jan. 1986. (NASA TM-87180.)
Jordan, J.L.; Platz, S.J.; and Schinstock, W.C.: Flight Test Report of the NASA Icing Research Airplane: Performance, Stability, and Control After Flight Through Natural Icing Conditions. (KSR-86-OI, Kohlman Systems Research; NASA Contract NAS3-24547) NASA CR-179515, 1986.
Kim, J.J.: Particle Trajectory Computation on a 3-Dimensional Engine Inlet.
(DOT-FAA-CT-86-1, Wichita State Univ.; NASA Grant NAG3-566) NASA CR-175023, 1986.
Kim, J.J.; and Elangovan, R.: An Efficient Numerical Computation Scheme for Stiff Equations of Droplet Trajectories. AIAA Paper 86-0407, Jan. 1986.
McKnight, R.C.; Palko, R.L.; and Humes, R.L.: In-Flight Photogra_etric Measurement of Wing Ice Accretions. AIAA Paper 86-0483, Jan. 1986. (NASA TM-87191.)
Mikkelsen, K., et al.: In-Flight Measurements of Wing Ice Shapes and Wing Section Drag Increases Caused by Natural Icing Conditions. NASA TM-87301, 1986.
Nelepovitz, D.0.; and Rosenthal, H.A.: Electro-Impulse De-Icing of Aircraft Engine Inlets. AIAA Paper 86-0546, Jan. 1986.
Olsen, W.: Experimental Evaluation of Icing Scaling Laws: A Progress Report.
AIAA Paper 86-0482, Jan. 1986.
Olsen, W.; and Walker, E.: Experimental Evidence for Modifying the Current Physical Model for Ice Accretion on Aircraft Surfaces. NASA TM-87184, 1986.
Papadakis, M., et al.: An Experimental Method for Measuring Droplet Impinge- ment Efficiency on Two- and Three-Dimensional Bodies. AIAA Paper 86-0406, Jan. 1986.
Ranaudo, R.J., et al.: The Measurement of Aircraft Performance and Stability and Control After Flight Through Natural Icing Conditions. AIAA Paper 86-9758, Apr. 1986. (NASA TM 87265.)
Ross, R.: Application of Electro-Impulse De-lcing to the NASA Lewis Altitude Wind Tunnel (AWT) Turning Vanes. AIAA Paper 86-0548, Jan. 1986.
Ruff, G.A.: Verification and Application of the Icing Scaling Equations.
AIAA Paper 86-0481, Jan. 1986.
Shaw, R.J.: NASA's Aircraft Icing Analysis Program. NASA TM-88791, 1986.
Shaw, R.J., et al.: The Use of a Three Dimensional Water Droplet Trajectory Analysis to Aid in Interpreting Icing Cloud Data, AIAA Paper 86-0405, Jan.
1986.
Zumwalt, G.W.; and Friedberg, R.A.: Designing an Electro-lmpulse De-lcing System. AIAA Paper 86-0545, Jan. 1986.
Alexander, D.R.: Comparison of UNL Laser Imaging and Sizing System and a Phase/Doppler System for Analyzing Sprays from a NASA Nozzle. NASA CR-182437, 1987.
Bragg, M.B.: An Experimental Study of the Aerodynamics of a NACA 0012 Airfoil with a Simulated Glaze Ice Accretion. NASA CR-179897, 1987.
Cebeci, T.: Effects of Environmentally Imposed Roughness on Airfoil Perform- ance. NASA CR-179639, 1987.
Henderson, R.A.; and Schrag, R.L.: Theoretical Analysis of the Electrical Aspects of the Basic Electro-Impulse Problem in Aircraft De-Icing Applications.
NASA CR-180845, 1987.
Hovenac, E.A.: Fresnel Diffraction by Spherical Obstacles. Am. J. Phys., vol. 57, no. I, Jan. 1989, pp. 79-84.
Hovenac, E.A.: Performance and Operating Envelope of Imaging and Scattering Particle Sizing Instruments. NASA CR-180859, 1987.
Miller, T.L.; Shaw, R.J.; and Korkan, K.D.: Evaluation of Icing Drag Coefficient Correlations Applied to Iced Propeller Performance Prediction.
SAE Paper 871033, Apr. 1987.
Miller, T.L.; Korkan, K.D.; and Shaw, R.J.: Analytical Determination of Propeller Performance Degradation Due to Ice Accretion. J. Aircraft, vol. 24, no. II, Nov. 1987, pp. 768-775.
Newton, J.E.: Icing of Flow Conditioners in a Closed-Loop Wind Tunnel. NASA TM-89824, 1987.
Oldenburg, J.R.: Analysis of Counting Errors in the Phase/Doppler Particle Analyzer. NASA TM-IO0231, 1987.
Olsen, W.; Van Fossen, J.; and Nussle, R.: Measured Performance of the Heat Exchanger in the NASA Icing Research Tunnel Under Severe Icing and Dry Air Conditions. NASA TM-IO0116, 1987.
Potapczuk, M.G.: Numerical Analysis of a NACA 0012 Airfoil with Leading-Edge
Ice Accretions. AIAA Paper 87-0101, Jan. 1987. (J. Aircraft, vol. 25, no. 3, Mar. 1988, pp. 193-194).
Reehorst, A.L.; and Richter, G.P.: NewMethods and Materials for Molding and
Casting Ice Formations. NASA TM-IO0126, 1987.
Scavuzzo, R.J.; and Chu, M.L.: Structural Properties of Impact Ices Accreted
on Aircraft Structures. NASA CR-179580, 1987.
Shaw, R.J.; and Reinmann,J.J.: NASA'sRotorcraft Icing Research Program.
NASA/Army Rotorcraft Technology, Vol. 2, NASA CP-2495-VOL-2, 1987, pp. 802-832.
Khatkhate, A.A.; Scavuzzo, R.J.; and Chu, M.L.: A Finite Element Study of the
EIDI System. AIAA Paper 88-0022, Jan. 1988.
VanFossen,J.G., et al.: Measurementof Local Convective Heat Transfer
Coefficients from a Smoothand RoughenedNACA-0012 Airfoil: Flight Test
Data. AIAA Paper 88-0287, Jan. 1988. (NASATM-100284).
i, • ICINGEFFECTS SIMULAI"IONS • ICINGFLIGHTTESTS • ICE PROTECTION CONCEPTS • TESTTECHNIQUES • ANALYSIS CODES FIXED WINQ_WL_ • PHYSICSOF ICING • ICINGINSTRUMENTATION GENERIC • TESTTECHNIQUES • ICEPREVENTION/REMOVAL ROTARY WING CONCEPTS • ICINGEFFECTS SIMULATIONS • ICINGFLIGHTTESTS • ROTORICEPROTECTION CONCEPTS • ROTORICINGTESTTECHNIQUES CD-87-28729 Figure i. - Aircraft icing technology program.
FLOW RE,ATTACHMNT _ SEPARATED FLOW ZONE .+.+_ ANALYSIS WIND TUNNEL TESTING FLIGHT RESEARCH CD-87-28730 Figure 2. - Icing research.
ORIGINAL PAGE BLACK AND WHITE PHOTOGRAPH LABORATORY TECHNOLOGY DATA BASE TWIN OTTE_ _, FLIGHT TE_ WIND TUNNEL TESTING _J__ cD-87-2873_ GENERAL AVIATI_ COMMERCIAL TRANSPORT Figure 3. - NASA electromagnetic impulse deicer program.
IRT TES1 UH_H INSTALLATION OTTAWA SPRAY RIG _-t,l_l er_ TU|(- 3 ?$ _m TAP|RED _CHOROWI|| ITYP) [OQ! {lYel _ _, DEMONSTRATED ROTOR DEICING ARMY HISS TANKER CAPABILITY CD-87-28732 Figure 4. - NASA/Army/industry rotor pneumatic boot program.
FLIGHT, /
, ]!', _,E:RODYN,_M,C
............................................. : PERFORMANCE CONDITIONS i ::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::: /1:::" PENALTIES =Jii PARTICLE iiL.,J;i;::i ICE ::i:.i_/ ...................................... " ........
FLOW RELD ENVIRONMENTAL IX _ rliI!TRAJECTORYiiI-IIi!i!!ACCRETIONi!IiF"x I ' " ::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::: ::::::::::::::::::::::::::::::::::::: _1 AEROOYNAMIC .... - "_l LOADS GEOMETRY BODY t ON ICE HOT GAS li::il THERMAL i'::,iii:l
l
i ICE SHEDDING I :CHAR.INCLUDING I
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_, , _ I TRAJECTORIES J VIBRATION [;i;;:;i IMPULSE i:';;i;;; I I;;; BOOT ;;;;I I MECHANICAL SYSTEM
li:,ili:;:s_s_:_,:,:,ii_iiii!l [;::, SYSTEM ::;,_]
I I i i !ELEcTRO" i::i::iiiill [ '
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NOTE: l_:i-:\:i ] INDICATES AREA OF CURRENT COMPUTER CODE DEVELOPMENT BY NASA LeRC ICEPHOBICS Ii:,DEPRESSANT ] li;::,: ;: SY_TE:M:::: :: 1 CD-87-28735 Figure 5. - Aircraft icing analysis methodology.
OBJECTIVE - ACQUIRE A DATA BASE TO VALIDATE TRAJECTORY CODES
INLET MODEL WITH
BLOTTER STRIPS
IRT NOZZLE SYSTEM
A EXPERIMENT j___= THEORY
DATA
I
S
REDUCTION
SYSTEM
LOCAL COLLECTION
EFFICIENCY DISTRIBUTION
CD-B7--2B736 Figure 6. - NASA/FAA water droplet impingement research program.
ORIGINAL PAGE' BLACK AND WHITE PHOTOGRAPH CD-87-28737 Figure 7. - Twin Otter trajectory analysis.
1,0-- .9 DROPLET CONCENTRATION .8 FACTOR .7--
I
.8 ! I
100 101 102 103 CD-87-28738 WATER DROP DIAMETER, _m Figure 8. - Trajectory analysis for laser spectrometer.
EXPERIMENTAL THEORETICAL VELOCITY,m/sec............. 89.40 TEMPERATURE, °C ........... -10.65 PRESSURE,kPa............... 94.20 LWC, g/m_ ........................ 1.20 CD-87-28739 Figure 9. - NASA airfoil ice accretion code (LEWICE) comparison of glaze ice shapes (NACA 0012 airfoil, 21-in. chord).
STAGNATION _LI CD-87-28740 impingement.
Figure i0. - Closeup flash picture of droplet ORIGINAL PAGE BLACK AND WHITE PHOTOGRAPH 150 _ r7 I'1 AVERAGE SCATTER, +_420/0 130-M/HR WIND SPEED IO0-M/HR WIND SPEED SHEAR -_ STRESS, PSI 60 E] A
I
-10 -4 -2 8 14 20 26 32 38 TEMPERATURE, OF CD-87-28741 Figure ii. - Adhesive shear stress versus interface temperature.
,r .... --T-- l t I t I (XPERJ_NL linT. TR_S, T5 0 CLI'M I [ _ { '-7 t o OF, [_l_nl_lzl, [ILM '° /n o C t TO It_ -U_[ t k_OWn -- ¢%.., i s '_ Io 15 2O i_ 5 to 1_ 2o o ,, io _,, o D NACA 0012 MODEL FORCE AND MOMENT DATA I 1 I I 1 0 UPPIER SJ_qFACE -I -- __ C_ F D]VIDI_ STRF_I_ | NE 1 I I 1 I -.2 o .2 ._ .6 .B 1.o xlC BOUNDARY LAYER DETAILED SURFACE PRESSURES FLOW VISUALIZATION PROFILES CD-87-28742 Figure 12. - Code validation studies - iced airfoil analysis.
m o 1"IF'-. _ OAo EXPERIMENTNAVIER'STOKEsINTERACTIVE BOUNDARYLAYER .20.16 DRAG .12 LIFT COEFFICIENT .4 .08 .2 .04 _ COEFFICIENT
J
2 4 6 8 10 0 2 4 6 8 10 ANGLE OF ATTACK, deq CD-87-29472 Figure 13. - Iced airfoil analysis.
MEAN OF +I STD. ASSP DATA 35 -- ASSPDATA-_ DEV. OF _## '_ LINEOF , +205, / ,_¢PERFECT AGREEMENT 30-- e ',/ / / INDICATED VMD, 20 -- _, SPECTROMETER _m 15 -- [3 <> ASSP2 (3 ASSP 3 /_/_O O ASSP ] 10 • FSSP !
V ASSP 1979 /_S O " _ ASSP 4
,5 I I I
5 lO D 20 2,5 30 IRT VMD, pm C:D-87-28743 Figure IA. - Comparison of laser spectrometer drop size indications to old IRT calibration (range of conditions: VMI), I0 to 30 mm; LWC, 0.3 to 3 g/m3; velocity, 80 to _60 km/hr; ASSP and ISSP denote axial scattering and forward scattering spectrometer probes, respectively).
DRAG COEFFICIENT DROP SIZE, /,,.m Cd 25 0.074 21 .039 17 .015 DRY .0085 0012 AIRFOIL V 21 In. CHORD CD-87-28744 Figure 15. - Effects of drop size measurement errors.
RRECTEO /_" //, • i
DATA CORRECTION
CALIBRATION DEVICES
ALGORITHMS
F
SCATTERED _- LIGHT ENERGY PARTICLE DIAMETER
THEORETICAL MODELING
FUNDAMENTAL
INSTRUMENT
CD-87-28745
RESEARCH
COMPARISONS
Figure 16. - Particle sizing instrumentation research.
URIGI[4AL PAGE BLACK AND WHITE Pi.,IOTOGtliIAPh
5000-HP
SYSTEM
VARICHRON SYSTEM
\
SPRAY BAR
CONTROLS BUILDINQ
\
6- BY 9-FT
TEST SECTION
SPRAY BAR SYSTEM CONTROL ROOM
CD-87-28746 Figure 17. - Icing Research Tunnel.
ICING CLOUDINSTRUMENTS
STEREO PHOTOGRAPHY SYSTEM
WAKESURVEYPROBE
glm 3 .4 0 5 10 15 20 25 ' l- i_t,_.,. _ ...........
TIME, rain
%
SIMULATION
VALIDATION
ICED _"_J CD-87-28747
DATABASE
Figure 18 - Twin Otter wing icing/aeroperformance.
.,'- ,_,.._ V¢L,lit._ i..t,IOt-OG_A'PH EXPERIMENTAL DATA BASEIS BEING ACQUIRED, RELATINGAIRCRAFTPERFORMANCE DEGRADATION TO A MATRIX OF MEASURED NATURALICINGCONDITIONS GLAZE ICING ENCOUNTER NASA DHC-6 TWIN OTTER ICING RESEARCH AIRCRAFT VMD - 13 p.m ICINGTIME - 26 min LWC - 0.31 g/m 3 STATIC TEMP. •-4 'C PERFORMANCE PERFORMANCE .14 DECREMENT 1.4 -- DECREMENT .10 1.0 ....o..- ALL ICED CL Cd .,.s WINGSDEICED _o,. WINGSAND EMPENNAGE DEICED BASELINE
"°el. I .6
[ [ I
.02 [ .2_ 0 .4 .8 1.2 0 4 8 12 a, deg co-87-2s?,8 CL2 Figure 19. - Aircraft performance in natural icing.
0 BJECTIVE: EMPLOY STATIC LONGITUDINAL FLIGHTTESTMETHODS TO A DHC-6 AIRCRAFT WITH AN ARTIFICIAL ICESHAPE All'ACHED TO THE HORIZONTAL TAILPLANE TO MEASURE THE CHANGE IN STATIC MARGIN RESULTS: A REDUCTION IN STATICMARGIN WAS MEASURED THROUGHOUT THE NORMAL FLAPS-UP CRUISE ENVELOPE -1.6 -- $1APQbARD _IGH1 • I). O_Otb / -l.2 C.9. • 32 ±1%MAC J NORMALIZED PULL -O,! 1_TJ STICK,,-FOIIC,E, ..0, 4 /f_ MOOERAT( F$1q _ GLAZE PUSH
/
.s "1 I I l I I ] .2 .4 .6 .6 LO J.2 ].4 C L ARTIFICIAL MODERATEGLAZE ICE SHAPE VARIATION IN NORMALIZEDCONTROL FORCE ATTACHED TO HORIZONTAL TAIL FOR THE "ICED" VERSUS BASELINE TAIL 6o __ STICK-FREE "_", - _0 -- o wiT, ART,F_C_A_CES_P_ N_'N_ C_U_Se _W1_ 21S ,h_H_NE I I ] ] I ,l .4 ,6 .I 1,0 I,Z CL REDUCTION IN STICK'FREESTATIC MARGIN DUETO TAIL ICE CD-87-26749 Figure 20. - Reduction of aircraft static longitudinal stability due to icing.
OIR1GINAI: PA C_E" agL.ACK AND WHITE PHO1-OGRAmH BOEING-VERTOL McDONNELL-DOUGLAS NASA TEXAS A&M UNIV.
• TEST PLANNING BELL • MODEL PREPARATION • DATA ACQUISITION SYSTEM SIKORSKY • DRY WIND TUNNEL TEST TECHNIQUES RIG (0H58 TAIL ROTOR) THOROUGH EVALUATION OF MODEL ROTOR ICING FULLY INSTRUMENTED MODEL TEST TECHNIQUE (SIKORSKY PFM) C0-87-28750 Figure 21. - Model rotor icing program.
OTTAWA SPRAY RIG TEST (PHASE I) _'_DETAILED ICE SHAPE CUMENTATION
>
HISS TESTING (PHASE II) Mo WIND TUNNEL TESTS OF "EQUIVALENT" TWO-DIMENSIONAL MODELS CI, Cd, Cm (HP REQUIRED) ROTOR PERFORMANCE ROTOR PERFORMANCE MEASUREMENTS CALCULATIONS (HP REQUIRED) 0D-87-28751 Figure 22. - Helicopter icing flight test program.
ORICt_'JA(. PA_._ 8LACK AND WHITE PHOTOG_'ApH