1、SAE Technical Standards Board Rules provide that: “This report is published by SAE to advance the state of technical and enginee ring sciences. The use of this report is entirelyvoluntary, and its applicability and suitability for any particular use, including any patent infringement arising therefr
2、om, is the sole responsibility of the user.”SAE reviews each technical report at least every five years at which time it may be reaffirmed, revised, or cancelled. SAE invit es your written comments and suggestions.Copyright 1997 Society of Automotive Engineers, Inc.All rights reserved. Printed in U.
3、S.A.QUESTIONS REGARDING THIS DOCUMENT: (412) 772-8510 FAX: (412) 776-0243TO PLACE A DOCUMENT ORDER: (412) 776-4970 FAX: (412) 776-0790400 Commonwealth Drive, Warrendale, PA 15096-0001AEROS PACE INFORM ATION REPORTSubmitted for recognition as an American National StandardAIR1900 RE V. AIssued 1991-02
4、Revised 1997-11Superseding AIR1900(R) G uide to T emperature M onitoring in A ircraft G as T urbine E nginesTABLE OF CONTENTS1. SCOPE . 41.1 Purpose . 42. REFERENCES . 42.1 Definitions/Glossary . 43. BACKGROUND 83.1 Need 83.2 Airframe Measurements 83.3 Heat Transfer . 84. CURRENT USAGE . 84.1 Functi
5、ons . 84.2 Media . 94.3 Sensor Types . 134.4 Measurement Locations 205. SYSTEM CONSIDERATIONS 215.1 Signal Source Location 225.2 Mounting Considerations . 225.3 Signal Transmission 245.4 Signal Processing 315.5 Shared Signals 34COPYRIGHT SAE International (Society of Automotive Engineers, Inc)Licens
6、ed by Information Handling ServicesSAE AIR1900 Revision A- 2 -TABLE OF CONTENTS (Continued)6. SELECTION CRITERIA 366.1 Measurement Type 366.2 Performance 366.3 Costs 376.4 Reliability/Maintainability 386.5 Interface Considerations 387. ACCURACY 397.1 Error Types 397.2 Minimizing Errors . 498. POTENT
7、IAL PROBLEMS IN MEASUREMENT . 538.1 Shared Signals . 538.2 Thermocouple Drift 548.3 EMI/EMP 549. NOTES 5410. CONCLUSIONS 54APPENDIX A BIBLIOGRAPHY . 55FIGURE 1 Thermodynamic Stations for Twin-Spool Turbofan . 10FIGURE 2 R Versus T Two Nickel Sensors 16FIGURE 3 Output (mV) Versus Temperature for Vari
8、ous Thermocouples 18FIGURE 4 Means of Attachment to Engine Mounting Surface . 23FIGURE 5 RTD Shielded Cable-Grounding Options 27FIGURE 6 Transmission of Radiant Energy . 30FIGURE 7 Floating Reference Junction for Thermocouples 32FIGURE 8 Typical Radiation Pattern From Optical Pyrometers . 33FIGURE 9
9、 Locations of Signal Bifurcation 35FIGURE 10 Total Temperature as Function of Mach Number 42FIGURE 11 Conduction Error as Function of Mass Flow for Various Immersion Depths . 43FIGURE 12 Deicing Heat Error as Function of Inlet Mass Flows . 45FIGURE 13 Repeatability and Thermal Hysteresis Errors in R
10、TDs 46COPYRIGHT SAE International (Society of Automotive Engineers, Inc)Licensed by Information Handling ServicesSAE AIR1900 Revision A- 3 -TABLE OF CONTENTS (Continued)TABLE 1 Thermocouple Wire Combinations . 7TABLE 2 Normal Operating Temperature Ranges 11TABLE 3 Accuracy Requirements . 12TABLE 4 S
11、elected Thermocouples and Their Characteristics 17TABLE 5 Media Applications of Each Sensor Type . 20TABLE 6 Maximum Resistance of Selected Lead Wires . 25TABLE 7 Extension Wires for Thermocouples 28COPYRIGHT SAE International (Society of Automotive Engineers, Inc)Licensed by Information Handling Se
12、rvicesSAE AIR1900 Revision A- 4 -1. :This SAE Aerospace Information Report (AIR) provides an overview of temperature measurement for engine monitoring systems in various areas of aircraft gas turbine engines while focusing on current usage and methods, systems, selection criteria, and types of hardw
13、are. This document emphasizes temperature monitoring for diagnostics and condition monitoring purposes.1.1 Purpose:The purpose of this document is to provide information and guidance on the selection and use of aircraft turbine engine temperature monitoring systems and elements.2. REFERENCES:See App
14、endix A - Bibliography.2.1 Definitions/Glossary:For further detail, consult ARP485.BIMETALLIC ELEMENT: A temperature sensitive device composed of two materials having different thermal coefficients of expansion resulting in a proportional movement of the free segment of the device with changes in te
15、mperature.COCKPIT INDICATOR : An instrument used to translate the EMF from a temperature measurement system into a visual indication of measuring junction temperature.CONDUCTION ERROR : The difference between the gas temperature and the sensed temperature caused by conduction of heat along the therm
16、ocouple assembly support tubes and leads.ELECTRICAL CONNECTOR : Self-explanatory.MEASURING JUNCTION : That junction of a thermocouple sensing system immersed or in contact with the medium whose temperature is to be observed.RADIATION ERROR : The difference between the gas temperature and the sensed
17、temperature caused by radiant heat transfer between the sensing element and surrounding areas.RADIATION PYROMETER TEMPERATURE MEASUREMENT SYSTEM : A system located remotely from the medium whose temperature is to be measured and depending for its indication on the wavelength and intensity of radiati
18、on from the medium to the measuring element of the pyrometer.RECOVERY FACTOR : That ratio of the difference in indicated temperature and static temperature to the difference in total temperature and static temperature.COPYRIGHT SAE International (Society of Automotive Engineers, Inc)Licensed by Info
19、rmation Handling ServicesSAE AIR1900 Revision A- 5 -2.1 (Continued):RECOVERY RATIO : Recovery ratio is the ratio of the measured temperature versus true air temperature as performed in a wind tunnel or open jet facility.(Eq. 1)REFERENCE JUNCTION : That union of the two dissimilar metal wires that is
20、 maintained at a known signal level.RESISTANCE BULB : A temperature sensitive device composed of a material whose resistance increases in a reproducible manner as the temperature increases with negligible hysteresis.STAGNATION TEMPERATURE : This term is sometimes used as an alternative to total temp
21、erature. Thermodynamically they are different in concept, but numerically the same for an ideal gas.STATIC TEMPERATURE (GAS AND THERMAL EQUILIBRIUM) : A measurable property that is directly proportional to the mean kinetic energy of the particles. In a moving gas, the static temperature would be ind
22、icated by a conventional error free instrument moving in the same direction and at the same velocity as the gas.TEMPERATURE : The thermal state of a body considered with reference to its ability to communicate heat to other bodies.TEMPERATURE INDICATING SYSTEM : That part of the temperature measurem
23、ent system extending physically from the engine-airframe interface up to and including the aircraft cockpit indicator.TEMPERATURE INDICATOR : A device that responds to a signal from a temperature measuring system to provide a reproducible indication of the signal level.TEMPERATURE MEASUREMENT : The
24、observation of the relative heat energy present as it affects engine performance and/or life, i.e., bearing, compressor inlet, turbine in or out, blade temperature, and any other pertinent material or gas temperature.TEMPERATURE MEASUREMENT SYSTEM : A system consisting of one or more measuring ele-m
25、ents to quantitatively measure temperature by heat transfer including a means of transmitting the resultant single output to and including the indicator, and if applicable, to the engine control device.TEMPERATURE MEASURING ELEMENT : That element or portion of a temperature measuring system that yie
26、lds a measurable signal that is reproducible as a function of temperature.a. Probe - A probe is an immersion type temperature measuring element.b. Contact Element - A contact element is a temperature measuring element used in intimate contact with the solid state body to be measured.c. Remote Measur
27、ing Element - A remote measuring element is a temperature measuring device removed from the medium to be measured.R T indicatedTT-=COPYRIGHT SAE International (Society of Automotive Engineers, Inc)Licensed by Information Handling ServicesSAE AIR1900 Revision A- 6 -2.1 (Continued):TEMPERATURE SENSING
28、 SYSTEM : That part of the temperature measurement system extending physically from and including the temperature measuring element to the engine-airframe interface and, if applicable, to the engine control.THE COMPENSATED REFERENCE JUNCTION : A junction maintained at a known signal output level by
29、circuitry designed to compensate for changes in ambient temperatures.THE INDICATING LEAD : That portion of the thermocouple indicating system from the engine-air-frame disconnect to the reference junction.THERMISTOR : A temperature sensitive device composed of a material whose resistance decreases i
30、n a reproducible manner as the temperature increases with negligible hysteresis.THERMOCOUPLE ASSEMBLY : That part of the thermocouple sensing system including all components from the measuring junction to the electrical connector or to the harness junction box as is the case with the integral harnes
31、s.THERMOCOUPLE CALIBRATION : The plot of the EMF output of a temperature measuring junction versus known temperatures.THERMOCOUPLE CALIBRATION ACCURACY : The ratio, expressed in percentage, of the difference between the EMF output of a temperature measuring junction at a given temperature and the sp
32、ecified EMF for that temperature, to that specified EMF.(Eq. 2)THERMOCOUPLE HARNESS : An assembly that physically supports, protects, and insulates the conductors extending from the thermocouple assemblies to the thermocouple output harness connector.THERMOCOUPLE HARNESS EXTENSION LEAD : An assembly
33、 that physically supports, protects, and insulates the conductors extending from the thermocouple harness output connector to the engine-airframe disconnect and/or engine control.THERMOCOUPLE INDICATING SYSTEM : That part of the thermocouple type measurement system extending physically from the engi
34、ne-airframe disconnect to and including the cockpit indicator.THERMOCOUPLE LEAD : That portion of the thermoelements from the electrical connector to the measuring junction.THERMOCOUPLE SENSING SYSTEM : That part of the thermocouple type measurement system extending physically from and including the
35、 thermocouple assembly to the engine-airframe disconnect, and if applicable to the engine control.Accuracy (%)EMFtestEMFref()EMFref-100=COPYRIGHT SAE International (Society of Automotive Engineers, Inc)Licensed by Information Handling ServicesSAE AIR1900 Revision A- 7 -2.1 (Continued):THERMOCOUPLE-T
36、YPE TEMPERATURE MEASUREMENT SYSTEM : A thermocouple and associated supporting structure, electrical insulation up to and including the indicator and if applicable, to the control device. This system as applied to exhaust gas temperature measurement may include one or more thermocouple assemblies, a
37、thermocouple harness, thermocouple harness lead, reference junction, resistance spool, and indicator.THERMOCOUPLES : A pair of dissimilar electrically conducting materials joined together so that a difference in temperature at the junction generates an EMF across the ends not joined. Typical combina
38、tion of wire are as follows:THERMOMETER : An immersion or contact type device whose operation is based on thermal equilibrium between the sensitive measuring element and the medium to be measured. Types of thermometers include thermocouples, resistance bulbs, thermistors, bimetallic elements, vapor
39、pressure elements, etc.TOTAL TEMPERATURE (GAS AND THERMAL EQUILIBRIUM) : The temperature indicated by an error free instrument having a fixed position in the gas stream and is the sum of the static temperature and the temperature rise due to the conversion of kinetic energy to heat, as the compressi
40、on occurs at the sensing element.VAPOR PRESSURE ELEMENT : A temperature sensitive device with a signal proportional to pressure of vapor in coexistence with its liquid phase and independent of the specific volume.TABLE 1 - Thermocouple Wire CombinationsType + (positive polarity) - (negative polarity
41、)E Chromel ConstantanJ Iron ConstantanT Copper ConstantanK Chromel AlumelR, S, B Platinum/Rhodium PlatinumIridium/Rhodium IridiumCOPYRIGHT SAE International (Society of Automotive Engineers, Inc)Licensed by Information Handling ServicesSAE AIR1900 Revision A- 8 -3. BACKGROUND:3.1 Need:Temperature is
42、 one of the most critical and widely measured variables in the monitoring of aircraft gas turbine engines. The measurement of temperature is accomplished by a variety of sensor types used in a number of locations (i.e., thermodynamic stations) in an engine. Furthermore, signal processing is often ac
43、complished differently and used for a number of purposes by different engine manufacturers. This document will attempt to provide a common reference point for considerations of:a. Sensor typeb. Locationc. Signal transmissiond. Signal processinge. Signal usesf. Selection criteriag. Accuracyh. Potenti
44、al problems3.2 Airframe Measurements:It is possible to make certain temperature measurements on the aircraft physically apart from the engine. For example, it is possible to make a total temperature measurement on the fuselage and to have this represent the engine inlet total temperature. However, t
45、here is an increasing tendency to make engine temperature measurements independent of those made on the airframe. This document will, therefore, concern itself primarily with measurements made on the engine.3.3 Heat Transfer:The measurement of temperature depends upon the balance of three physical p
46、henomena: convection, conduction, and radiation. This document will not address the theory of these phenomena. The reader is referred to Reference 18 for more in-depth information.4. CURRENT USAGE:The measurement of temperature is dependent on the state of both the current technology available to th
47、e user and the purpose for which it is intended.4.1 Functions:Temperature measurements on the engine are used for three basic functions: control, diagnostics and condition monitoring, and performance measurement.COPYRIGHT SAE International (Society of Automotive Engineers, Inc)Licensed by Informatio
48、n Handling ServicesSAE AIR1900 Revision A- 9 -4.1.1 Control: The signal is used, in an active sense, in a feedback control loop to correct a number of physical variables. For example, temperature is used to limit fuel flow in order to prevent turbine blades from overheating. Furthermore, temperature
49、 is used to correct a number of physical variables such as rotor speeds; scheduling variable geometry; surge schedules; and acceleration and deceleration schedules.4.1.2 Diagnostics and Condition Monitoring: Temperature signals from one location can be used to compute the temperature of other locations in an engine. This means the signal is used, in a passive sense, to measure thermal behavior in various parts of the engine. The time history of the thermal behavior is usually recorded for later examinati
