SAE AIR 1168 4B-2016 SAE Aerospace Applied Thermodynamics Manual Ice Rain Fog and Frost Protection.pdf

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1、_SAE Technical Standards Board Rules provide that: “This report is published by SAE to advance the state of technical and engineering sciences. The use of this report is entirely voluntary, and its applicability and suitability for any particular use, including any patent infringement arising theref

2、rom, is the sole responsibility of the user.”SAE reviews each technical report at least every five years at which time it may be revised, reaffirmed, stabilized, or cancelled. SAE invites your written comments and suggestions.Copyright 2016 SAE InternationalAll rights reserved. No part of this publi

3、cation may be reproduced, stored in a retrieval system or transmitted, in any form or by any means, electronic, mechanical, photocopying, recording, or otherwise, without the prior written permission of SAE.TO PLACE A DOCUMENT ORDER: Tel: 877-606-7323 (inside USA and Canada)Tel: +1 724-776-4970 (out

4、side USA)Fax: 724-776-0790Email: CustomerServicesae.orgSAE WEB ADDRESS: http:/www.sae.orgSAE values your input. To provide feedbackon this Technical Report, please visithttp:/www.sae.org/technical/standards/AIR1168/4BAEROSPACEINFORMATION REPORTAIR1168/4 REV. BIssued 1990-07Reaffirmed 2004-06Revised

5、2016-08Superseding AIR1168/4ASAE Aerospace Applied Thermodynamics ManualIce, Rain, Fog, and Frost ProtectionRATIONALEAn improved method for calculating vapor pressure in defog calculations is available that was not available when original document was prepared.PREFACEThis document is one of 14 Aeros

6、pace Information Reports (AIR) of the SAE Aerospace Applied Thermodynamics Manual. The manual was originally published in one volume as ARP1168. The manual provides a reference source for thermodynamics, aerodynamics, fluid dynamics, heat transfer, and properties of materials for the aerospace indus

7、try. Procedures and equations commonly used for aerospace applications of these technologies are included.To maintain consistency with the other 13 reports, unit abbreviations were retained from the previous document, although they may not be the currently recommended abbreviation. An exception is t

8、hat the current SAE guideline of using “lb” to refer pound mass has been followed. When the Thermodynamics Manual was originally written, most calculations were performed based on pound force and not pound mass. Since most of the equations in this document are more familiar using pound mass, pound m

9、ass is used. If using one of the other 13 reports, be aware that “lb” likely represents pound force.The SAE Aerospace Applied Thermodynamics Manual comprises the following AIR documents. AIR1168/1 Thermodynamics of Incompressible and Compressible Fluid FlowAIR1168/2 Heat and Mass Transfer and Air-Wa

10、ter MixturesAIR1168/3 Aerothermodynamic Systems Engineering and DesignAIR1168/4 Ice, Rain, Fog, and Frost ProtectionAIR1168/5 Aerothermodynamic Test Instrumentation and MeasurementAIR1168/6 Aircraft Fuel Weight Penalty Due to Air ConditioningSAE INTERNATIONAL AIR1168/4B Page 2 of 73AIR1168/7 Aerospa

11、ce Pressurization System DesignAIR1168/8 Aircraft Fuel Weight Penalty Due to Air ConditioningAIR1168/9 Thermophysical Properties of the Natural Environment, Gases, Liquids, and SolidsAIR1168/10 Thermophysical Characteristics of Working Fluids and Heat Transfer FluidsAIR1168/11 Spacecraft Boost and E

12、ntry Heat TransferAIR1168/12 Spacecraft Thermal BalanceAIR1168/13 Spacecraft Equipment Environmental ControlAIR1168/14 Spacecraft Life Support SystemsF. R. Weiner, formerly of Rockwell International and past chairman of the SAE AC-9B Subcommittee, is commended for his dedication and effort in prepar

13、ing the errata lists that were used in creating the original 14 documents that comprise AIR1168.SAE INTERNATIONAL AIR1168/4B Page 3 of 73TABLE OF CONTENTS1. INTRODUCTION. 61.1 Scope 61.2 Nomenclature 61.3 Common Abbreviations. 81.4 Definition of Terms 92. ICE PROTECTION OF NONTRANSPARENT SURFACES. 1

14、03. METHODS OF THERMAL ICE PROTECTION 103.1 Fully Evaporative Anti-Icing 103.2 Running Wet Anti-Icing . 113.3 Cyclic Deicing 114. EXTERNAL FACTORS AFFECTING HEAT REQUIREMENTS. 114.1 Water Catch and Impingement Limits. 114.1.1 Methods of Determination. 114.1.2 Airfoils 114.1.3 Bodies of Revolution .

15、204.2 External Heat Transfer Coefficients 224.2.1 Airfoils 224.2.2 Bodies of Revolution . 245. AIRFOIL EVAPORATIVE ANTI-ICING . 265.1 Wet Surface Temperature. 265.1.1 Wettedness Factor 265.1.2 Evaporation Rate 265.2 Anti-Icing Heat Load 275.3 Determination of Air Flow Requirements 285.3.1 Passage De

16、sign 285.3.2 Internal Heat Transfer Coefficient . 295.3.3 Passage Heat Balance 295.3.4 Piccolo Tubes 316. RUNNING WET ANTI-ICING 347. ELECTROTHERMAL CYCLIC DEICING 347.1 Description 347.2 Heater Construction 357.3 Parting Strip Power Requirements 367.4 Cyclic Requirements . 378. DETERMINATION OF THE

17、 NEED FOR ICE PROTECTION. 378.1 Design Point 378.2 Government Regulations 398.2.1 Commercial Airplanes and Rotorcraft. 398.2.2 Military Aircraft 418.3 Unheated Equilibrium Temperature of an Iced Surface 418.3.1 Surface Temperature Below Freezing 418.3.2 Surface Temperature Above Freezing 419. ILLUST

18、RATIVE EXAMPLES 429.1 Airfoil Hot Air Evaporative Anti-Icing . 429.2 Airfoil Hot Air Evaporative Anti-Icing with Piccolo Type Heat Exchanger. 449.3 Engine Inlet Electrothermal Running Wet Anti-Icing. 44SAE INTERNATIONAL AIR1168/4B Page 4 of 7310. WINDSHIELD ICE PROTECTION 4610.1 Introduction . 4610.

19、2 Methods of Protection . 4610.2.1 Electrical Anti-Icing 4610.2.2 Hot Air Anti-Icing . 4810.2.3 Fluid Anti-Icing 4910.3 Analysis of System Requirements 4910.3.1 Electrical Anti-Icing 4910.3.2 Hot Air Anti-Icing . 5410.3.3 Fluid Anti-Icing 5411. WINDSHIELD AND CANOPY FOG AND FROST PROTECTION . 5611.1

20、 Introduction . 5611.2 Methods of Fog Protection 5611.2.1 Electrical Heating 5611.2.2 Free Jet Air Blast. 5711.2.3 Double Pane Hot Air . 5811.2.4 Dehydration of Defogging Air 5811.2.5 Infrared Heating 5811.2.6 Fog Preventive Coating. 5911.3 Analysis of System Requirements 5911.3.1 Protected Areas an

21、d Design Conditions. 5911.3.2 Cabin Dew Point . 6111.3.3 Steady-State Heat Requirements . 6311.3.4 Transient Performance of the Free Jet System 6812. WINDSHIELD RAIN REMOVAL . 6812.1 Introduction . 6812.2 Design Conditions . 6912.3 Methods of Rain Removal. 6912.3.1 Jet Blast 6912.3.2 Windshield Wipe

22、rs 6912.3.3 Windshield Rain Repellents 6913. REFERENCES 7014. NOTES 7314.1 Revision Indicator 73FIGURE 1 WATER CATCH EFFICIENCIES FOR VARIOUS AIRFOILS AND GEOMETRIC SHAPES (J REFERS TO JOUKOWSKI 0015 AIRFOIL, SUBSCRIPT C MEANS CAMBERED; REFERENCES 6 AND 7) 13FIGURE 2 GRAPHICAL SOLUTION OF KO FOR 15

23、F AMBIENT AIR TEMPERATURE (REFERENCES 6 AND 7). 14FIGURE 3 AIRFOIL TOTAL CATCH TYPICAL FOR 6 TO 16% THICK AIRFOILS AT D = 4 DEGREES 20 m VOLUME MEDIAN DROPS (ALL ALTITUDES: STRICTLY TRUE FOR 10000 FEET AND APPROXIMATELY, WITHIN 10%, TRUE BETWEEN SEA LEVEL AND 20000 FEET) . 15FIGURE 4 MAXIMUM WATER C

24、ATCH EFFICIENCIES AT THE STAGNATION LINE, D = 0 DEGREES. 16FIGURE 5 AIRFOIL IMPINGEMENT LIMITS FOR 40 m MAXIMUM (20 m VOLUME MEDIAN) DROPS(ALL ALTITUDES: STRICTLY TRUE FOR A PARTICULAR ALTITUDE AND APPROXIMATELY,WITHIN 10%, TRUE BETWEEN SEA LEVEL AND 20000 FEET). 17FIGURE 6 WATER DROP TANGENT TRAJEC

25、TORIES ON UPPER SURFACE NOTE: SU 0.80 FOR CONES (D = 0 DEGREES, ANY VERTEX ANGLE) FOR KO 0.04 . 18FIGURE 7 WATER DROP TANGENT TRAJECTORIES ON LOWER SURFACE NOTE: SL 0.80 FOR CONES (D = 0 DEGREES, ANY VERTEX ANGLE) FOR KO 0.04 . 19SAE INTERNATIONAL AIR1168/4B Page 5 of 73FIGURE 8 CATCH EFFICIENCY ON

26、CONES FOR 20 m VOLUME MEDIAN DROPS (A) - TOTAL, (B) - STAGNATION POINT (ALL ALTITUDES: STRICTLY TRUE FOR 10000 FEET ALTITUDE AND APPROXIMATELY, WITHIN 10%, TRUE BETWEEN SEA LEVEL AND 20000 FEET) . 20FIGURE 9 LOCAL CATCH DISTRIBUTION (BOTTOM) AND IMPINGEMENT LIMITS (TOP) ON CONES FOR 20 m VOLUME MEDI

27、AN DROP DIAMETER. NOTE: IMPINGEMENT LIMITS ARE FAIRLY INSENSITIVE TO CHANGES IN ALTITUDE AND VELOCITY. 21FIGURE 10 CONE GEOMETRY 21FIGURE 11 AVERAGE EXTERNAL FILM CONDUCTANCE FOR FULLY TURBULENT FLOW OVER AIRFOILS (V = VELOCITY, KNOTS TAS) 23FIGURE 12 LAMINAR HEAT TRANSFER COEFFICIENTS OVER CONES 25

28、FIGURE 13 TURBULENT HEAT TRANSFER COEFFICIENTS OVER CONES. 26FIGURE 14 SKIN TEMPERATURE REQUIRED FOR EVAPORATIVE ANTI-ICING 27FIGURE 15 AIRFOIL EVAPORATIVE ANTI-ICING ENERGY REQUIREMENTS. 28FIGURE 16 TYPICAL PASSAGE DESIGNS 28FIGURE 17 AIR FLOW REQUIRED FOR EVAPORATIVE ANTI-ICING. 30FIGURE 18 CORREC

29、TION FACTOR FOR PASSAGE ASPECT RATIO, Z = (1+D/B)0.2 . 31FIGURE 19 PICCOLO TUBE IN A LEADING EDGE . 31FIGURE 20 FLOW SPLIT ON A HEATED AIRFOIL LEADING EDGE 32FIGURE 21 ENERGY REQUIREMENTS FOR RUNNING WET ANTI-ICING. SURFACE TEMPERATURE = 40 F, 10000 FEET AT 0 F AMBIENT. TO OBTAIN VALUES FOR OTHER AL

30、TITUDES: SUBTRACT 11.0 FOR SEA LEVEL, ADD 15.0 FOR 22000 FEET 34FIGURE 22 HALF WING HEATER LAYOUT . 35FIGURE 23 EXAMPLE HEATER CONSTRUCTION . 36FIGURE 24 CONTINUOUS MAXIMUM ICING CONDITION. ALTITUDE: SEA LEVEL TO 22000 FEET; MAXIMUM VERTICAL EXTENT, 6500 FEET; HORIZONTAL EXTENT, 17.4 NMI.(A) LIQUID

31、WATER CONTENT, (B) ENVELOPE OF ICING TEMPERATURE. 38FIGURE 25 UNHEATED EQUILIBRIUM TEMPERATURE OF AN ICED SURFACE, ALL ALTITUDES 39FIGURE 26 VARIATION OF LIQUID WATER CONTENT WITH CLOUD HORIZONTAL EXTENT 40FIGURE 27 INTERMITTENT MAXIMUM ICING CONDITION. ALTITUDE: 4000 TO 22000 FEET; HORIZONTAL EXTEN

32、T: 2.6 NMI, (A) LIQUID WATER CONTENT, (B) ENVELOPE OF ICING TEMPERATURE 40FIGURE 28 VELOCITY ABOVE WHICH ICE PROTECTION IS NOT REQUIRED. 41FIGURE 29 TYPICAL WINDSHIELD PANELS HEATED ELECTRICALLY. 47FIGURE 30 DOUBLE PANE HOT AIR WINDSHIELD ANTI-ICING SYSTEM. 48FIGURE 31 EXTERNAL AIR BLAST WINDSHIELD

33、ANTI-ICING AND RAIN REMOVAL SYSTEM. 49FIGURE 32 GRAPHICAL SOLUTION OF KO FOR 15 F AMBIENT AIR TEMPERATURE (REFERENCES 6 AND 7). 51FIGURE 33 COLLECTION EFFICIENCY OF WINDSHIELDS (BASED ON SEMI-INFINITE RECTANGLE). 52FIGURE 34 VARIATION OF WINDSHIELD SURFACE HEAT REQUIREMENT WITH AMBIENT TEMPERATURE (

34、CALCULATED FOR 7000 FEET CRUISE AT 205 MPH TRUE AIR SPEED) 52FIGURE 35 WINDSHIELD SURFACE TEMPERATURE IN ICING FOR EXTERNAL AIR BLAST ANTI-ICING SYSTEM. FLIGHT VELOCITY, 225 KNOTS; LIQUID CONTENT, 1.0 G/M3;NOZZLE VELOCITY, MACH 1; DROP SIZE 20 M, CONTINUOUS SLOT NOZZLE. 54FIGURE 36 DATUM TEMPERATURE

35、 VERSUS FLIGHT VELOCITY (VALUES SHOWN AT 10000 FEET AND ARE APPROXIMATELY CORRECT FOR 0 TO 20000 FEET; SEE REFERENCE 8) 55FIGURE 37 FREEZING POINTS FOR AQUEOUS SOLUTIONS OF SEVERAL FLUIDS 55FIGURE 38 ANTIFOG COATING AND BUS BAR ARRANGEMENT FOR ELECTRICAL ANTIFOGON PLASTIC CANOPY (OR WINDSHIELD) PANE

36、L . 57FIGURE 39 FREE JET AIR BLAST ANTIFOG OR DEFOG SYSTEM USING MIXED COMPRESSOR BLEED AND CABIN AIR. 58FIGURE 40 AMBIENT TEMPERATURE VERSUS ALTITUDE FOR DEFOGGING DESIGN CONDITIONS . 60FIGURE 41 VAPOR PRESSURE OF WATER (ICE BELOW 32 F). SOURCE: MECHANICAL ENGINEERING HANDBOOK, LIONEL G. MARKS, 195

37、7 EDITION, P. 357 (REFERENCE 59). 62FIGURE 42 TEMPERATURE DECAY RATIO OF FREE JET DISCHARGING PARALLEL TO FLAT PLATE (SLOT TYPE OF NOZZLE). SOURCE: REFERENCE 26, AVERAGE FOR NOZZLE DEPTH 0.1 TO 0.5 INCH. 66FIGURE 43 VELOCITY DECAY RATIO OF FREE JET DISCHARGING PARALLEL TO FLAT PLATE (SLOT TYPE OF NO

38、ZZLE). DATA ARE AN AVERAGE FROM REFERENCE 27 67TABLE 1 AIRFOIL GEOMETRY. 42TABLE 2 HEAT REQUIREMENTS AT VARIOUS CRUISE SPEEDS . 50SAE INTERNATIONAL AIR1168/4B Page 6 of 731. INTRODUCTIONThe ability of aircraft to fly in adverse weather conditions is a requirement for most military and commercial air

39、craft. Ice buildups in critical areas can affect flight safety by adding drag and weight and thus adversely affecting stability.Supercooled water drops may exist in clouds at ambient temperatures far below the freezing point. When the drops are disturbed by an aircraft flying through them, the drops

40、 will impinge and may freeze on airfoil surfaces, radomes, engine inlets, windshields, and other areas, resulting in weight and drag penalties or obstruction of vision through transparent surfaces. Some means, therefore, must be provided to prevent large ice buildups in critical areas.The inner surf

41、aces of most cockpit transparencies are susceptible to condensation in the form of fog or frost during most normal aircraft operation, particularly when descending from high altitude flight, unless fog and frost protection systems areprovided. Fog will form on the inside surface of the windshield wh

42、enever that surface is below the cockpit air dew point. If the surface temperature is below 32 F, frost will form.Removal of rain from the windshields to maintain pilot visibility is accomplished by hot air jet blast or by windshield wipers. A rain repellent fluid is sometimes used in conjunction wi

43、th either system for increased rain removal efficiency.1.1 ScopeThis section presents the basic equations for computing ice protection requirements for nontransparent and transparent surfaces and for fog and frost protection of windshields. Simplified graphical presentations suitable for preliminary

44、 design and a description of various types of ice, fog, frost, and rain protection systems are also presented.1.2 NomenclatureA/B = Semi-length/maximum radius ratio of ellipsoid, dimensionlessAc = Area of cold side, ft2Af = Body frontal area, ft2AF = Windshield projected area (along line of flight),

45、 ft2Ah = Area of hot side, ft2Apa = Airfoil passage cross-sectional area, ft2/ft of span-surfaceAw = Wetted surface area, ft2a = Nozzle depth, feetB = Airfoil maximum thickness, feetb = Passage width, feetC = Airfoil chord length, or characteristic length, feetCmin = Minimum heat capacity between ho

46、t and cold side, Btu/h-F cw = Specific heat of water = 1.0 Btu/lb-FDh = Passage hydraulic diameter, feetdmed = Volume-median drop diameter, m (3.94 x 10-5 inches)d = Passage depth, feete = Base of the Napierian (natural) logarithm, 2.718exp = ExponentEm = Total water catch efficiency, dimensionlessF

47、 = Wettedness factor, dimensionlessGf = Percent freeze point depressant by weight in final mixture, %Gi = Percent freeze point depressant by weight in initial mixture, %hc = Hot side heat transfer coefficient, Btu/h-ft2-Fhi = Internal (or passage) heat transfer coefficient, Btu/h-ft2-Fho = External

48、heat transfer coefficient, Btu/h-ft2-FhoSo = External film conductance, Btu/h-F-ft of span per surfacek = Thermal conductivity, Btu-in/h-ft2-Fka = Thermal conductivity of air at nozzle, Btu/h-ft-Fkg = Thermal conductivity of glass, 6 Btu-in/h-ft2-Fkp = Thermal conductivity of plastic 1.5 Btu-in/h-ft

49、2-Fko = Thermal conductivity of air at freestream static temperature, Btu/h-ft-FKo = Modified inertia parameter, dimensionlessK1 = Pressure correction (see Figure 11), dimensionlessSAE INTERNATIONAL AIR1168/4B Page 7 of 73Ka = Average power/power at control point (Equation 48), dimensionlessKh = Power at hot spot/power at control point (Equation 49), dimensionlessKm = Average power/power at hot spot (Equation 50)