1、Designation: D 6812 04aAn American National StandardStandard Practice forGround-Based Octane Rating Procedures for Turbocharged/Supercharged Spark Ignition Aircraft Engines1This standard is issued under the fixed designation D 6812; the number immediately following the designation indicates the year
2、 oforiginal adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon (e) indicates an editorial change since the last revision or reapproval.1. Scope*1.1 This practice covers ground-based octane rating proce-
3、dures for turbocharged/supercharged spark ignition aircraftengines. This practice has been developed to allow the widestrange of applicability possible but may not be appropriate forall engine types. This practice is specifically directed toground-based testing and actual in-flight octane ratings ma
4、yproduce significantly different results.1.2 This standard does not purport to address all of thesafety concerns, if any, associated with its use. It is theresponsibility of the user of this standard to establish appro-priate safety and health practices and determine the applica-bility of regulatory
5、 limitations prior to use.2. Referenced Documents2.1 ASTM Standards:2D 2700 Test Method for Motor Octane Number of Spark-Ignition Engine Fuel3. Terminology3.1 Definitions:3.1.1 amine number of reference fuels above 100, ANdetermined in terms of the weight percent of3-methylphenylamine in reference g
6、rade isooctane (2,2,4-trimethylpentane). For example, 5 % of 3-methylphenylaminein reference grade isooctane has an amine number if 105 (AN105). No attempt has been made to correlate performancenumber of leaded reference fuels to the amine number ofunleaded reference fuels, and none is implied.3.1.2
7、 engine octane requirementone full number greaterthan the maximum number that results in knock (graphic knocklevel descriptions can be seen in Annex A1). For example, atest engine knocks on primary reference fuels with 98 and 99motor octane numbers. The test engine does not knock on aprimary referen
8、ce fuel with a 100 motor octane number. Themaximum motor octane number that results in knock is 99 sothe motor octane requirement is 100. If a test engine knocks ona reference fuel with a 3-amine number and does not knock ona fuel with a 4-amine number, then the engine requirement is a4-amine number
9、.3.1.3 full richcondition where the mixture control is at thefull-rich stop position with the fuel flow within the manufac-turers recommended settings.3.1.4 house fuel, nfor engine operation, a fuel that doesnot contain metallic additives used for engine warm-up and allnon-octane rating engine opera
10、tion.3.1.5 knock, nin an aircraft spark ignition engine, abnor-mal combustion caused by autoignition of the air/fuel mixture.3.1.6 knock condition, nfor octane rating, where theknock intensity in any cylinder is light knock or greater, asdescribed in Annex A1.3.1.7 knock number, nfor octane rating,
11、a numericalquantification of knock intensity.3.1.8 motor octane number of primary reference fuels from0to100the volume % of isooctane (equals 100.0) in a blendwith n-heptane (equals 0.0).3.1.9 no-knock condition, nfor octane rating, where theknock intensity in all cylinders is less than light knock.
12、 Referto Annex A1 for description of knock intensity.3.1.10 peak EGT, nfor octane rating, as the mixture ismanually leaned from a state rich of stoichiometric, the exhaustgas temperature will increase with the removal of excess fuel.As the mixture is continually leaned, a peak temperature willbe att
13、ained, after which continued leaning will result in lowerexhaust gas temperatures.3.1.11 primary reference fuels, nfor octane rating,blended fuels of reference grade isooctane and n-heptane.3.1.12 reference fuels above 100, nfor octane rating,blended fuels of reference grade isooctane and3-methylphe
14、nylamine.3.1.12.1 DiscussionThis practice describes reference fu-els above 100 MON in terms of isooctane/3-methylphenylamine. Alternate reference fuels may be used ifappropriate, for example, MON in Test Method D 2700,1This practice is under the jurisdiction of ASTM Committee D02 on PetroleumProduct
15、s and Lubricants and is the direct responsibility of Subcommittee D02.J0 onAviation Fuels.Current edition approved Nov. 1, 2004. Published November 2004. Originallyapproved in 2002. Last previous edition approved in 2004 as D 6812 04.2For referenced ASTM standards, visit the ASTM website, www.astm.o
16、rg, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.1*A Summary of Changes section appears at the end of this standard.Copyright ASTM International, 100 Barr Harbor Drive, PO Box
17、C700, West Conshohocken, PA 19428-2959, United States.Section 8, mixtures of tetraethyl lead and reference gradeisooctane. Care should be exercised to ensure the reference fueldoes not adversely contaminate the engine and influence theresults.3.1.13 stable engine conditions, nfor octane rating, cyl-
18、inder head temperatures change less than 5C (9F) during a1-min period. Any changes or minor adjustments to throttle,mixture, or engine conditions mandate restarting the clock fordetermining stable conditions.3.1.14 takeoff power, nfor octane rating, normal or maxi-mum rated power with the engine spe
19、ed at maximum rated.3.1.15 turbocharged/supercharged aircraft engine,naircraft piston engine that breathes with forced means fromeither turbochargers or superchargers.3.2 Acronyms:3-MPA = 3-methylphenylamineAN = amine numberCHT = cylinder head temperatureEGT = exhaust gas temperatureinHg = inches of
20、 mercuryMAP = manifold absolute pressureMAT = manifold absolute temperaturemmHg = millimetres of mercuryMON = motor octane numberPRF = primary reference fuelpsig = pounds per square inch gageRF = reference fuel above 100rpm = revolutions per minuteTDC = top dead centerTIT = turbine inlet temperature
21、4. Summary of Practice4.1 A recently overhauled, remanufactured, or new,turbocharged/supercharged aircraft engine is octane rated todetermine the minimum ground-based octane requirement.Minimum octane requirement is defined as one number abovethe highest MON orAN where knock was detected. The engine
22、is tested at three or more of the worst power points subject toknock behavior while operating under harsh and repeatableenvironmental conditions. These points usually involve highmanifold pressures. At the very least, takeoff power, a maxi-mum continuous or climb power, and a cruise configurationsha
23、ll be tested. Takeoff power and climb power are tested underfull-rich mixture conditions, and cruise power is tested underfull-rich and lean mixture configurations in 5 % incrementreductions from full-rich fuel flow to peak exhaust gas tem-perature. Engine operating temperatures and oil temperatures
24、are kept at maximum allowable limits.4.2 Octane ratings are determined under stable engineconditions using known PRFs and RFs.4.3 Knock sensor installation and knock quantification aredescribed in Annex A1.5. Significance and Use5.1 This practice is used as a basis for determining theminimum ground-
25、based octane requirement of turbocharged/supercharged aircraft engines by use of PRFs and RFs.5.2 Results from standardized octane ratings will play animportant role in defining the octane requirement of a givenaircraft engine, which can be applied in an effort to determinea fleet requirement.6. App
26、aratus6.1 Instrumentation:6.1.1 The engine shall be equipped with the followinginstrumentation, which shall be accurate to within 62 % of fullscale unless noted otherwise.6.1.1.1 Absolute Manifold Pressure TransducerThe loca-tion of the MAP sensor shall conform to engine manufacturersspecified locat
27、ion. Manifold pressures shall be measured withan accuracy of less than 2.5 mmHg and recorded to ensureproper engine behavior and repeatability.6.1.1.2 Cooling Air Pressure Transducer, located so as todetermine the pressure within the cowling.6.1.1.3 Cooling Air Temperature Sensor, located eitherwith
28、in the cowling or at the entrance to the cowling. If athermocouple is utilized, it should extend at least a third of theway across the measured area.6.1.1.4 Crankshaft Angle Encoder, if required for knockdetection. The encoder shall have a sample resolution of atleast 0.4 of crankshaft rotation. The
29、 encoder TDC pulse shallbe aligned with the TDC of cylinder number one prior tooctane rating.6.1.1.5 Cylinder Head Temperature Sensors, installed ineach cylinder. The sensing locations and types of thermo-couples shall conform to the engine manufacturers recommen-dations. The CHT measurements shall
30、be accurate to within1 % of full scale.6.1.1.6 Exhaust Gas Temperature Sensors, on all cylinders.Installation shall conform to the manufacturers recommendedlocation and proper material selection. EGT probes are usuallyinstalled within 5 cm (2 in.) of the exhaust stack flange. TheEGT probes shall be
31、accurate to within 1 % of full scale.6.1.1.7 Turbine Inlet Temperature Sensors, for each turbine.Installation shall conform to the manufacturers recommendedlocation and proper material selection. The TIT probes shall beaccurate to within 1 % of full scale.6.1.1.8 Manifold Absolute Temperature Sensor
32、Installation shall conform to the manufacturers recommendedlocation and proper material selection. The MAT probe shall beaccurate to within 1 % of full scale.6.1.1.9 Engine Speed SensorThe dynamometer or propel-ler stand shall measure the engine shaft speed to determinepower development. The engine
33、speed sensor shall be accurateto within 65 rpm.6.1.1.10 Fuel Flow MeterIf the device is calibrated for aparticular fuel, then the device shall be recalibrated for eachdifferent and subsequent fuel. Data should be reported in massflow units. If applicable, vapor return flow rate shall also bemeasured
34、 to obtain the actual engine fuel consumption rate.6.1.1.11 Fuel Pressure TransducersLocations of fuelpressure transducers shall conform with that recommended bythe engine manufacturer. One transducer is required for themetered fuel pressure, if necessary, and another is required forthe pump outlet
35、pressure. The fuel inlet pressure shall not fallD 6812 04a2below the minimum specified by the engine manufacturerduring the rating process.6.1.1.12 Induction Air Pressure Transducer, located so as tomeasure the pressure of the induction stream prior to thethrottle plate.6.1.1.13 Induction Air Temper
36、ature Sensor, located so as tomeasure the temperature of the induction stream prior to thethrottle plate.6.1.1.14 Knock SensorsThe referee method for knockdetection is described in Annex A1. This method requires flushmounting piezoelectric transducers. All cylinders shall bemonitored. These transduc
37、ers are connected to charge ampli-fiers and shall be capable of measuring combustion pressuresunder a high temperature environment.6.1.1.15 Oil Pressure TransducerLocation of pressuremeasurement shall conform to the engine manufacturersspecified location.6.1.1.16 Oil Temperature SensorLocation of te
38、mperaturemeasurement shall conform to the manufacturers specifiedlocation.6.1.1.17 Torque MeterThe dynamometer or propellerstand shall measure the torque to determine power develop-ment. The torque measurement shall be accurate to within 1 %of full scale.6.1.2 The engine should be equipped with the
39、followinginstrumentation, which shall be accurate to within 62 % of fullscale unless noted otherwise.6.1.2.1 Induction Air Flow MeterData should be pre-sented in mass flow units.6.1.2.2 Induction Air Humidity Sensor, located in either theinduction air plenum or induction air duct. Data should bepres
40、ented in absolute, rather than relative, quantities.6.1.2.3 Outside Air Temperature Sensor, capable of measur-ing the ambient dry bulb temperature.6.2 Data Acquisition:6.2.1 The instrumentation listed in 6.1 shall be scanned andthe data recorded at least once every 10 s by an automatic dataacquisiti
41、on system. The data shall be stored in a universalformat (for example, comma separated values (CSV) for IBMcompatible machines) that can be retrieved at a later date.6.2.2 If in-cylinder pressures are recorded to determineknock intensity, the pressure data shall be sampled at a rate ofat least 1800
42、samples per pressure cycle per cylinder for 100consecutive engine cycles.6.3 Power AbsorptionThe testing is to be performed in aground-based test cell using either a dynamometer or propellertest stand that shall be capable of maintaining a constant speedto within 65 rpm.6.3.1 The power absorber shal
43、l be capable of providingloads for given engine speeds covering the entire range of theengines operating envelope.6.4 Fuel System:6.4.1 The fuel supply shall have a disposable or cleanablefilter. The filter shall allow the proper minimum fuel flow.6.4.2 The fuel selection valve shall be capable of s
44、electingat least two different fuel sources without the possibility ofcross contamination of either source.6.4.3 The fuel supply system shall comply with federal,state, and local regulations related with fire, hazards, and healthissues.7. Reagents and Materials7.1 The MON of PRFs is confirmed by usi
45、ng Test MethodD 2700. All PRFs used for the engine octane ratings consist ofblends of reference grade isooctane and n-heptane. The PRFswill be prepared in increments of one MON. All RFs used forengine octane rating consist of blends of reference gradeisooctane and 3-MPA. The reference fuels will be
46、prepared inincrements of one weight % 3-MPA. (WarningPRF and RFare flammable and the vapors are harmful. Vapors may causeflash fire.)7.1.1 Isooctane (2,2,4-trimethylpentane) shall be no lessthan 99.75 % by volume pure, contain no more than 0.10 % byvolume n-heptane, and contain no more than 0.5 mg/L
47、 (0.002g/U.S. gal) of lead. (WarningIsooctane is flammable and itsvapor is harmful. Vapors may cause flash fire.)7.1.2 n-Heptane shall be no less than 99.75 % by volumepure, contain no more than 0.10 % by volume isooctane, andcontain no more than 0.5 mg/L (0.002 g/U.S. gal) of lead.(Warningn-heptane
48、 is flammable and its vapor is harmful.Vapors may cause flash fire.)7.1.3 MPA shall be no less than 99 % by volume pure,contain no more than 0.10 % by volume isooctane, and containno more than 0.5 mg/L (0.002 g/U.S. gal) of lead. (Warning3-MPA is flammable and its vapor is harmful. 3-MPA is toxicby
49、inhalation, in contact with skin, and if swallowed. Danger ofcumulative effects. Vapors may cause flash fire.)7.1.4 A sample shall be taken of each PRF and subjected toTest Method D 2700 for motor octane verification.7.1.5 A sample shall be taken of each RF and the aminecontent verified. Ensure reference fuel is a homogenous mix-ture under test conditions.7.2 Fuels used for operations other than octane rating (forexample, warm-up) shall not contain metallic additives andshould be capable of satisfying the test engines octanerequirement unde
