1、Designation: D6812 04a (Reapproved 2014) An American National StandardStandard Practice forGround-Based Octane Rating Procedures for Turbocharged/Supercharged Spark Ignition Aircraft Engines1This standard is issued under the fixed designation D6812; the number immediately following the designation i
2、ndicates the year 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 () indicates an editorial change since the last revision or reapproval.1. Scope1.1 This practice covers ground-based octan
3、e rating proce-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 oc
4、tane ratings mayproduce 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-bilit
5、y of regulatory limitations prior to use.2. Referenced Documents2.1 ASTM Standards:2D2700 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
6、in reference grade 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
7、 implied.3.1.2 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 ap
8、rimary reference 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 a
9、4-amine number.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 ratin
10、g engine operation.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, n for
11、octane rating, a numericalquantification of knock intensity.3.1.8 motor octane number of primary reference fuels from0 to 100the 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
12、than light knock. 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 tempe
13、rature willbe attained, 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 isoocta
14、ne and3-methylphenylamine.3.1.12.1 DiscussionThis practice describes reference fuelsabove 100 MON in terms of isooctane/3-methylphenylamine.1This practice is under the jurisdiction of ASTM Committee D02 on PetroleumProducts, Liquid Fuels, and Lubricantsand is the direct responsibility of Subcom-mitt
15、ee D02.J0.02 on Spark and Compression Ignition Aviation Engine Fuels.Current edition approved Dec. 15, 2014. Published February 2015. Originallyapproved in 2002. Last previous edition approved in 2010 as D6812 04a (2010).DOI: 10.1520/D6812-04AR14.2For referenced ASTM standards, visit the ASTM websit
16、e, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States1
17、Alternate reference fuels may be used if appropriate, forexample, MON in Test Method D2700, Section 8, mixtures oftetraethyl lead and reference grade isooctane. Care should beexercised to ensure the reference fuel does not adverselycontaminate the engine and influence the results.3.1.13 stable engin
18、e conditions, nfor octane rating, cyl-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 ma
19、xi-mum rated power with the engine speed 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 = e
20、xhaust gas temperatureinHg = inches of 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
21、 centerTIT = turbine inlet temperature4. 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 orA
22、N where knock was detected. The engineis 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 clim
23、b power, and a cruise configurationshall 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 opera
24、ting temperatures and oil temperaturesare 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 ba
25、sis for determining theminimum ground-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
26、to determinea fleet requirement.6. Apparatus6.1 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
27、to engine manufacturersspecified location. 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
28、Temperature Sensor, located eitherwithin 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 a
29、tleast 0.4 of crankshaft rotation. The 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 recomme
30、n-dations. The CHT measurements shall 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
31、 stack flange. TheEGT probes shall be 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.
32、8 Manifold Absolute Temperature SensorInstallationshall conform to the manufacturers recommended location andproper material selection. The MAT probe shall be accurate towithin 1 % of full scale.6.1.1.9 Engine Speed SensorThe dynamometer or propel-ler stand shall measure the engine shaft speed to de
33、terminepower development. The engine 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 r
34、eturn flow rate shall also bemeasured 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 an
35、other is required forthe pump outlet pressure. The fuel inlet pressure shall not fallD6812 04a (2014)2below 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 thet
36、hrottle plate.6.1.1.13 Induction Air Temperature 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
37、cylinders shall bemonitored. These transducers 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.
38、1.1.16 Oil Temperature SensorLocation of temperaturemeasurement 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.
39、1.2 The engine should be equipped with the 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 plenu
40、m or induction air duct. Data should bepresented 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 on
41、ce every 10 s by an automatic dataacquisition 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
42、shall be sampled at a rate ofat least 1800 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
43、within 65 rpm.6.3.1 The power absorber shall 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
44、 fuel selection valve shall be capable of selectingat 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 Mater
45、ials7.1 The MON of PRFs is confirmed by using Test MethodD2700. 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 gradeisoocta
46、ne and 3-MPA. The reference fuels will be 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-
47、heptane, and contain no more than 0.5 mg/L (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
48、.002 g/U.S. gal) of lead.(Warningn-heptane 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 a
49、nd its vapor is harmful. 3-MPA is toxicby 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 D2700 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 satisfyin
