1、 AEROSPACE INFORMATION REPORT (R) Cooling of Military Avionic Equipment Issued 1976-05 Revised 2005-02 Superseding AIR1277A AIR1277 REV.B TABLE OF CONTENTS 1. SCOPE 5 1.1 Purpose5 1.2 Field of Application.5 2. REFERENCES.5 2.1 Applicable Documents .5 2.1.1 SAE Publications5 2.1.2 U.S. Government Pub
2、lications .6 2.1.3 U.S. Army Publications 72.1.4 NATO Publications.7 2.2 Related Publications 82.3 Definitions 12 2.4 Abbreviations .14 3. INTRODUCTION154. DESIGN REQUIREMENTS .15 4.1 General Requirements.15 4.1.1 Contract Specification 154.1.2 Military or Government Specifications16 4.1.3 System De
3、sign Process.16 4.2 Avionic Thermal Design Considerations 16 4.2.1 Reliability16 4.2.2 Temperature Effect on Avionic Performance .21 4.2.3 Environmental Requirements.21 4.2.4 Avionic Thermal Control.23 4.2.5 Avionic Integrity Requirements 23 Reaffirmed 2010-05SAE Technical Standards Board Rules prov
4、ide 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 therefrom, is the sole responsibility of the us
5、er.” SAE reviews each technical report at least every five years at which time it may be reaffirmed, revised, or cancelled. SAE invites your written comments and suggestions. Copyright 2010 SAE International All rights reserved. No part of this publication may be reproduced, stored in a retrieval sy
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7、ae.org SAE WEB ADDRESS: http:/www.sae.orgSAE values your input. To provide feedbackon this Technical Report, please visit http:/www.sae.org/technical/standards/AIR1277BCopyright SAE International Provided by IHS under license with SAENot for ResaleNo reproduction or networking permitted without lice
8、nse from IHS-,-,-SAE AIR1277 Revision B - 2 - 4.3 Airframe Systems.244.3.1 Thermal Control Requirements 24 4.3.2 Trade-off Studies24 4.3.3 Environmental Requirements.24 4.3.4 Moisture Condensation 24 5. INTERFACE BETWEEN AVIONICS, ECS, AND AIRCRAFT25 5.1 Interface Cooling Requirements.26 5.2 Life Cy
9、cle Cost.29 5.3 Ram and Compartment Cooling Air .30 5.4 Air and Liquid Cooled Systems30 5.4.1 Forced Air Cooling .305.4.2 Liquid Cooling Systems32 5.5 Fuel Heat Sink35 5.6 Installation36 5.7 Weight36 5.8 Commercial-off-the-shelf (COTS) Avionics 38 6. AVIONIC THERMAL CONTROL HARDWARE DESIGN/SELECTION
10、38 6.1 Line-Replaceable-Unit (Weapon Replaceable Assembly) Thermal Design.38 6.1.1 Passively Cooled (Natural Convection/Radiation) LRUs .40 6.1.2 Actively Cooled (Forced Convection) LRUs.44 6.1.3 Cold Wall-Cooled LRU Thermal Design.50 6.2 Cold Plate Design 556.2.1 Basic Cold Wall Configurations57 6.
11、3 Heat Exchanger Design .59 6.3.1 Plate Fin Heat Exchangers 59 6.3.2 Weight and Other Considerations62 6.4 Specialized Thermal Control Technologies62 6.4.1 Thermoelectric Coolers62 6.4.2 Heat Pipes64 6.4.3 Immersion Cooling .696.4.4 Expendable Liquid Coolants 70 6.4.5 Liquid Coolant Within Board.70
12、6.5 Thermal Analysis Methods.71 6.5.1 Thermal Modeling Techniques.71 6.5.2 Finite-Difference Modeling Techniques72 6.5.3 Finite-Element Modeling Techniques.73 6.5.4 Computational-Fluid-Dynamics (CFD) Simulation .74 6.5.5 ECS Simulation74 7. AIRFRAME THERMAL CONTROL HARDWARE74 7.1 Heat Sink Hardware.
13、75 7.1.1 Ram Air 75 7.1.2 Fuel 75 7.1.3 Expendable Liquid Heat Sinks .76 Copyright SAE International Provided by IHS under license with SAENot for ResaleNo reproduction or networking permitted without license from IHS-,-,-SAE AIR1277 Revision B - 3 - 7.1.4 Thermal Storage 767.2 ECS Hardware .777.2.1
14、 Transport Loops.77 7.2.2 Fluid Refrigeration78 7.3 Thermal Analysis Methods.80 8. THERMAL TESTING .81 8.1 Thermal Testing of Avionics.82 8.2 Thermal Testing of Cooling Systems and ECS82 9. AVIONIC THERMAL MANAGEMENT CASE STUDIES 83 9.1 FLIR Turret Thermal Control 83 9.1.1 Design for Operation at Hi
15、gh Altitude.85 9.1.2 Design Verification Testing 87 9.1.3 Problems Associated With Forced Convection Cooled Avionics .87 9.2 Liquid-Cooled, Phased Array Radar System .88 9.2.1 Critical Design Issues.899.2.2 Temperature Gradient from Module-to-Module Across the Array 89 9.2.3 Absolute Temperature of
16、Module Components .90 9.2.4 Temperature Cycling909.2.5 Module/Cold Plate Thermal Resistance.91 10. NOTES.91 FIGURE 1 Integrated Circuit Failure Rate as a Function of Junction Temperature.19 FIGURE 2 Relative Performance of CMOS Devices as a Function of Temperature .22 FIGURE 3 Direct Liquid Cooling
17、with Integral Cold Plate 33 FIGURE 4 Indirect Liquid Cooling with Integral Cold Plate34 FIGURE 5 Difference Between Integrated Circuit Junction Temperature and Cooling Air Supply Temperature as a Function of Dissipated Power.39 FIGURE 6 Values of Heat Transfer Coefficient for Different Modes of Heat
18、 Transfer.43 FIGURE 7 Direct Air-Cooled Chassis (PWB Card Rack).45 FIGURE 8 Combined Direct and Indirect Cooled System .45 FIGURE 9 Cold Wall/Thermal Plane Interface for Edge-Cooled PWB 47 FIGURE 10 PWB Chassis with PWBs Edge-Cooled by Conduction to Air-Cooled Cold Wall 47 FIGURE 11 PWB Populated wi
19、th Dual-In-Line (DIP) Packages Mounted in Thermal Plane Card Rail with Interface to Cold Wall .48 FIGURE 12 Leadless Ceramic Chip Carrier (LCCC) and Metal Core Substrate .48 FIGURE 13 Chassis Populated with Air-Cooled Flow-Through Modules 49 FIGURE 14 Cross Section of Flow-Through Module .50 FIGURE
20、15 Three Common Cold Wall Configurations51 FIGURE 16 Liquid-Cooled Cold Wall with Machined, Rectangular-Section Channels 53 FIGURE 17 Isometric Cross Section of Plate Fin Heat Exchanger Construction 60 FIGURE 18 Thermoelectric Cooler 64 FIGURE 19 Basic Construction of Heat Pipes.65 FIGURE 20 Operati
21、ng Temperature Ranges for Various Heat Pipe Working Fluids.66 Copyright SAE International Provided by IHS under license with SAENot for ResaleNo reproduction or networking permitted without license from IHS-,-,-SAE AIR1277 Revision B - 4 - FIGURE 21 Basic Heat Pipe Configurations66 FIGURE 22 ISEM-2A
22、 Heat Pipe Module .68 FIGURE 23 Heat Pipe Application to Standard Electronics Module (SEM).68 FIGURE 24 SEM-E Temperature Profile With and Without Heat Pipe 69 TABLE 1 Failure Mechanisms Accelerated by Increased Temperature 17 TABLE 2 Temperature Effects on Military Electronic Equipment Reliability
23、21 TABLE 3 Cabin, Avionics and Total ECS Heat Load Trends 27 TABLE 4 Typical Coolant Temperatures .28 TABLE 5 Typical Avionic Mass/Weight37 TABLE 6 Helicopter Cooling Capacities and ECS Mass/Weight .37 TABLE 7 Comparison of Methods of Cooling Electronic Modules.40 TABLE 8 Typical Card Guide Thermal
24、Resistance Values55 TABLE 9 Thermal Testing for Avionic Systems and Aircraft ECS and Cooling Systems 81 Copyright SAE International Provided by IHS under license with SAENot for ResaleNo reproduction or networking permitted without license from IHS-,-,-SAE AIR1277 Revision B - 5 - 1. SCOPE: This SAE
25、 Aerospace Information Report (AIR) contains information on the thermal design requirements of airborne avionic systems used in military airborne applications. Methods are explored which are commonly used to provide thermal control of avionic systems. Both air and liquid cooled systems are discussed
26、. 1.1 Purpose: This document describes guidelines for the configuration and design of military aircraft subsystems that provide cooling to airborne avionic systems and recommendations for the basic cooling concepts, analytical methods and design practices used for the thermal design of those airborn
27、e avionic systems. The efficient design of the interface between the airframe system and the avionic system is considered. 1.2 Field of Application: This document is intended to apply to both designers of airborne avionic equipment and of airborne environmental control systems. 2. REFERENCES: 2.1 Ap
28、plicable Documents: The following publications form a part of this document to the extent specified herein. The latest issue of SAE publication shall apply. The applicable issue of other publications shall be the issue in effect on the date of the purchase order. In the event of conflict between the
29、 text of this document and references cited herein, the text of this document takes precedence. Nothing in this document however, supersedes applicable laws and regulations unless a specific exemption has been obtained. 2.1.1 SAE Publications: Available from SAE, 400 Commonwealth Drive, Warrendale,
30、PA 15096-0001.ARP217 Testing of Commercial Airplane Environmental Control Systems AIR1168/10 Thermophysical Characteristics of Working Fluids and Heat Transfer Fluids AIR1706 The Advanced Environmental Control System (AECS) Computer Program for Steady State Analysis and Preliminary System Sizing AIR
31、1811 Liquid Cooling Systems Copyright SAE International Provided by IHS under license with SAENot for ResaleNo reproduction or networking permitted without license from IHS-,-,-SAE AIR1277 Revision B - 6 - 2.1.1 (Continued): AIR1812 Environmental Control Systems Life Cycle Cost AIR1823 Environmental
32、 Control System Transient Analysis Computer Program (EASY) AIR1957 Heat Sink Thermal Management 2.1.2 U.S. Government Publications: Available from DODSSP, Subscription Services Desk, Building 4D, 700 Robbins Avenue, Philadelphia, PA 19111-5094 or at http:/assist.daps.dla.mil/online/start/.AFGS-87145
33、A Environmental Control, Airborne, Department of Defense, Washington, DC, October 1, 1992. Note: This is a controlled distribution document. JSSG-2009 Joint Service Specification Guide, Air Vehicle Subsystems, Department of Defense, Washington, DC, October 30, 1998 MIL-E-18927E Environmental Control
34、 Systems, Aircraft, General Requirements For, Department of Defense, Washington, DC, August 18, 1983, (currently Amendment 2 dated December 19, 1986) MIL-HDBK-175 Microelectronic Device Data Handbook, Department of Defense, Washington, DC, May 1, 1968 MIL-HDBK-217F Reliability Prediction of Electron
35、ic Equipment, Department of Defense, Washington, DC, December 2, 1991 MIL-HDBK-251 Reliability/Design, Thermal Applications, Department of Defense, Washington, DC, January 19, 1978 MIL-HDBK-310 Global Climatic Data for Developing Military Products, Department of Defense, Washington, DC, June 23, 199
36、7, (supersedes MIL-STD-210)MIL-HDBK-454 General Guidelines For Electronic Equipment, Department of Defense, Washington, DC, April 28, 1995, Notice 1, May 28, 1997 (supersedes MIL-STD-454M) MIL-HDBK-781A Reliability Test Methods, Plans, and Environments for Engineering Development, Qualification, and
37、 Production, Department of Defense, Washington, DC, July 14, 1987 Copyright SAE International Provided by IHS under license with SAENot for ResaleNo reproduction or networking permitted without license from IHS-,-,-SAE AIR1277 Revision B - 7 - 2.1.2 (Continued): MIL-HDBK-5400 Electronic Equipment, A
38、irborne, General Guidelines For, Department of Defense, Washington, DC, Amendment 1, November 30, 1995 MIL-HDBK-87244 Avionics/Eletronics Integrity, Department of Defense, Washington, (USAF)DC, January 30, 1995 MIL-STD-810F Environmental Engineering Consideration and Laboratory Test, Department of D
39、efense, Washington, DC, January 1, 2000 MIL-STD-883E Test Method Standard, Microcircuits, Notice 4, Department of Defense, Washington, DC, December 18, 2000 MIL-STD-2218 Thermal Design, Analysis, and Test Procedures for Airborne Electronic Equipment, supersedes MIL-T-23103A (AS) dated April 29, 1971
40、, Department of the Navy, Washington, DC, May 20, 1992 MIL-T-5842B Transparent Areas on Aircraft Surfaces (Windshields and Canopies), Rain Removing and Washing Systems for, De-Frosting, De-Icing, Defogging, General Specification for, Department of Defense, Washington, DC, March 29, 1985 MIL-T-18606
41、Test Procedures for Aircraft Environmental Systems, Department of Defense, Washington, DC, March 31, 1955, (currently Amendment 1 dated October 31, 1969) 2.1.3 U. S. Army Publications: Available from www.usapa.army.mil/USAPA_PUB_search_P.asp. AR 70-38 Research, Development, Test, and Evaluation of M
42、aterial for Extreme Climatic Conditions, US Army Regulation, Department of the Army, Washington, DC, August 1, 1979 2.1.4 NATO Publications: Available from Global Engineering Documents, 15 Inverness Way, East Englewood, CO 80112. STANAG 2895 Extreme Climate Conditions and Derived Conditions for Use
43、in Defining Design/Test Criteria for NATO Forces Material, February 15, 1990 Copyright SAE International Provided by IHS under license with SAENot for ResaleNo reproduction or networking permitted without license from IHS-,-,-SAE AIR1277 Revision B - 8 - 2.2 Related Publications: The following publi
44、cations are provided for information purposes only and are not a required part of this SAE Aerospace Technical Report. Altoz, F., Brach, J.P., and Rosen, D. 1982, “Reliability Optimization-A Method for Thermal Design“, Proceedings Annual Reliability and Maintainability Symposium, 1982, pp. 303-308.
45、Anderson, R.T., 1976, Reliability Design Handbook, RDH-376, Reliability Analysis Center, Rome Air Development Center, Griffiss Air Force Base, New York, March, 1976 ANSYS 1988, ANSYS Finite Element Modeler, Swanson Analysis Systems Inc., 1988. Berger, R.L., 1983, A Systems Approach - Minimizing Avio
46、nics Life Cycle Cost, SAE 831107, 13th ICES, July 1983. Birtcher Catalog, (1986), Card Guide and Retainer Selector Tables, E.G. ground, fixed (GF); and ground, benign (GB). The prediction assumes that each part operates at the same electrical stress ratio and temperature.No two electronic assemblies
47、 are alike and therefore these figures should be used only for a qualitative estimate of the effect of temperature on failure rate. Copyright SAE International Provided by IHS under license with SAENot for ResaleNo reproduction or networking permitted without license from IHS-,-,-SAE AIR1277 Revisio
48、n B - 20 - 4.2.1.4 (Continued): The predicted dependence of failure rate on temperature has been observed in the field. For avionic equipment, studies by the US Air Force concluded that temperature effects cause 20% of field failures. A recent study of avionic equipment concluded that, while the rel
49、iability of equipment cooled by free convection is sensitive to temperature, the reliability of more complex equipment cooled by forced-convection is more sensitive to temperature. While Figure 1 relates component reliability to junction temperature, it is also possible to relate the overall system reliability to the temperature and flow
