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 entirelyvoluntary, and its applicability and suitability for any particular use, including any patent infringement arising therefro
2、m, 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 invites your written comments and suggestions.QUESTIONS REGARDING THIS DOCUMENT: (412) 772-8512 FAX: (412) 776-0243TO PLACE A DOCUMENT
3、 ORDER; (412) 776-4970 FAX: (412) 776-0790SAE WEB ADDRESS http:/www.sae.orgCopyright 1995 Society of Automotive Engineers, Inc.All rights reserved. Printed in U.S.A.SURFACEVEHICLE400 Commonwealth Drive, Warrendale, PA 15096-0001RECOMMENDEDPRACTICESubmitted for recognition as an American National Sta
4、ndardJ228REAF.APR95Issued 1971-03Reaffirmed 1995-04Superseding J228 JUN90AIRFLOW REFERENCE STANDARDSForewordThis reaffirmed document has been changed only to reflect the new SAE Technical Standards Boardformat.1. ScopeThe purpose of this SAE Recommended Practice is to establish reference standards f
5、or airflowmeasurements in the ranges required for testing automotive engine induction systems and to describeequipment that will facilitate the use of such standards to check the accuracy of various equipment andmethods.2. ReferencesThere are no referenced publications specified herein.3. Airflow No
6、zzle DefinitionThe airflow reference system consists of a series of 10 nozzles called CalibrationTransfer Nozzles, which are designed for operation at sonic flow velocities. Each nozzle is identified by aparticular serial number and its nominal airflow, expressed in grams per second, at standard flo
7、w conditions.For this document, standard conditions are defined as:a. Air Pressure100 kPa ABSb. Exit Pressureless than 45 kPa ABSc. Air Temperature25 Cd. Ambient Relative Humidity35%3.1 The nominal flow values established for the series of nozzles that should be used are: 1, 5, 10, 15, 20, 25, 50,10
8、0, 150, and 200 g/s.Typical outline dimensions and nozzle shape of an approved calibration transfer nozzle are shown in Figure 1.Nozzles produced for use in accordance with this document must be calibrated by a procedure whichestablishes an overall uncertainty (possible bias plus three standard erro
9、rs) with 0.2% of a primary standardtraceable to the National Institute of Standards and Technology (NIST).SAE J228 Reaffirmed APR95-2-FIGURE 1TYPICAL OUTLINES OF AIRFLOW CALIBRATION TRANSFER NOZZLE4. Accessory Hardware and InstrumentationFigure 2 shows the nozzle holder which provides theadaptation
10、necessary to fit the users test equipment. The construction details of the holder are optional, butthe dimensions of the air section must be retained. During use, there shall be no obstruction upstream of thenozzle inlet face for a distance of 5 Dmax in a direction parallel to the flow and for a dis
11、tance of 3 Dmax in adirection perpendicular to the flow, where Dmax is the throat diameter of the largest nozzle. Although the kindof temperature and pressure measuring instruments are not specified in this document, their accuracy must betraceable to the NIST and the overall uncertainty of their re
12、adings must be within 0.1% of actual. Theseinstruments should be placed upstream of the nozzle entrance, preferably at a distance equal to theobstruction limits (see Figure 3). When calibration transfer nozzles are used for correlation between flowlocations, a single set of temperature and pressure
13、measuring instruments shall be used.SAE J228 Reaffirmed APR95-3-FIGURE 2NOZZLE HOLDERFIGURE 3NOZZLE ENTRANCE OBSTRUCTION LIMITSSAE J228 Reaffirmed APR95-4-5. Airflow Correction FactorsWhen the actual inlet conditions existing during use of calibration of a nozzleare not identical to the standard con
14、ditions, the calibrated mass flow rate, Ws, may be corrected to actual flowrate, W, at actual flowing conditions by Equation 1:(Eq. 1)where:Subscript s refers to standard conditionsW = Mass flow rateP = Absolute pressure at inletT = Absolute stagnation temperature at inletR = Gas constant for moist
15、air = Specific heat ratio for moist airValues of F(,R)/(F(s,Rs) may be obtained from Figure 4 and are valid for actual operating conditions over thefollowing ranges:a. Inlet Pressure, P96 to 103 kPa ABSb. Inlet Temperature, T293 to 303 Kc. Ambient Relative Humidity0 to 50%d. Nozzle Exit Pressureless
16、 than 45 kPa ABSWhen the use conditions are not within the limits given previously, special nozzle calculations or calibrationsmust be obtained from the nozzle manufacturer.WWs TsT- PPs-F R,()F s Rs,()-=F R,()R- 2 1+- 1+ 1-=SAE J228 Reaffirmed APR95-5-FIGURE 4CORRECTION FACTOR FOR FLOW THROUGH CRITI
17、CAL FLOW NOZZLES WITH MOIST AIRPREPARED BY THE SAE POWER TEST CODE STANDARDS COMMITTEESAE J228 Reaffirmed APR95RationaleThe English Units were removed from 3.1.Relationship of SAE Standard to ISO StandardNot applicable.ApplicationThe purpose of this SAE Recommended Practice is to establish reference
18、 standards for airflowmeasurements in the ranges required for testing automotive engine induction systems and to describeequipment that will facilitate the use of such standards to check the accuracy of various equipment andmethods.Reference SectionThere are no referenced publications specified herein.Developed by the SAE Power Test Code Standards Committee
