SAE J244-1992 MEASUREMENT OF INTAKE AIR OR EXHAUST GAS FLOW OF DIESEL ENGINES.pdf
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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 entirely voluntary, 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 invites your written comments and suggestions. QUESTIONS REGARDING THIS DOCUMENT: (724) 772-8512 FAX: (724) 776-0243 TO PLACE A DOCU
3、MENT ORDER; (724) 776-4970 FAX: (724) 776-0790 SAE WEB ADDRESS http:/www.sae.org Copyright 1992 Society of Automotive Engineers, Inc. All rights reserved.Printed in U.S.A. SURFACE VEHICLE 400 Commonwealth Drive, Warrendale, PA 15096-0001 RECOMMENDED PRACTICE An American National Standard J244 REV. A
4、UG92 Issued1971-05 Revised1992-08 Superseding J244 JUN83 (R) MEASUREMENT OF INTAKE AIR OR EXHAUST GAS FLOW OF DIESEL ENGINES 1.ScopeThis procedure establishes recommendations on the measurement of diesel engine intake air flow under steady-state test conditions. The measurement methods discussed hav
5、e been limited to metering systems and associated equipment found in common usage in the industry, specifically, nozzles, laminar flow devices, and vortex shedding. The procedure establishes accuracy goals as well as explains proper usage of equipment. The recommendations concerning diesel engine ex
6、haust mass flow measurements are minimal in scope. 1.1PurposeThis SAE Recommended Practice is intended to provide guidance for the proper measurement of combustion air flow into diesel engines as utilized in engine test cell environments. 2.References 2.1Applicable PublicationsThe following publicat
7、ions form a part of the specification to the extent specified herein. Unless otherwise indicated the lastest revision of SAE publications shall apply. 1.SAE J177Measurement of Carbon Dioxide, Carbon Monoxide, and Oxides of Nitrogen in Diesel Exhaust. 2.ASME PTC 19.5:4-1959“Flow Measurement.“ 3.“Flui
8、d Meters, Their Theory and Application,“ ASME, Sixth Edition, New York, 1971. 4.ISA 1979, ISBN 87664-453-3, Tutorial, “Test Measurement Accuracy.“ 5.Voss, L. R., and Hollyer, R. N., “GMR True Radius Nozzles,“ General Motors Research Laboratories, Warren, MI, January 1961. 6.“Tables of Thermal Proper
9、ties of Gases,“ National Bureau of Standards Circular 564, 1960. SAE J244 Revised AUG92 -2- 3.DefinitionsSymbols and Abbreviations 3.1Abbreviations absAbsolute calCalibration exhExhaust rpmRevolutions per minute volVolume moMoist 3.2SymbolsSI Units (English Units) BBarometric pressure, kPa (in Hg);
10、abs CCoefficient of discharge DUpstream pipe diameter, mm (in) EVelocity of approach factor FaArea thermal expansion factor MWMolecular weight, kg/kg-mole (lbm/lbm-mole) NHHodgsons number NRReynolds number PPressure, kPa (in Hg) QVolume flow rate, m3/s (ft3/s) RUUniversal gas constant, 8314.4 J/kg-K
11、 (1545.3 ft-lb/lbm mole R) RGas constant, specific gas, J/kg-K (ft-lbf/lbm-R) SWSwept volume, m3 (ft3) TTemperature, Kelvin (Rankine) UUncertainty VVelocity, m/s (ft/s) YExpansion factor ZCompressibility factor bBias error dNozzle throat diameter, mm (in) eVapor pressure, kPa (in Hg, abs) fFrequency
12、, Hz kRatio of specific heats mMass flow per unit time, kg/s (lbm/s) tAmbient temperature, Celsius (Fahrenheit) Viscosity, absolute, centipoise Ratio of nozzle throat diameters (throat or orifice to pipe diameter) Density, kg/m3 (lbm/ft3) Precision error YRatio of specific heats, 1.40 for air PPress
13、ure differential, kPa (in H2O) SAE J244 Revised AUG92 -3- 3.3Subscripts Aabsolute dDry dtDry at test conditions tTest moMoist (test)Test conditions (cal)Calibration conditions LLeakage vVapor 1Location point at meter inlet 2Location point at meter outlet 4.Principal Equipment 4.1Component Descriptio
14、nComponents necessary for measurements are as described as follows and as in Figure 1: a.Filter Only as required by flow meter. b.Flow meter As described in Section 5. c.Nonpulsating blower Optional, to restore pressure loss due to flow meter and temperature control. d.Temperature control Optional.
15、e.Restriction valve To control engine inlet air pressure. f.Plenum See 4.2. g.Engine. h.Pressure sensors, P1, P2, P3, and P4. i.Temperature sensors, T1, T2, T3, and T4. j.Chamber to engine line may be flexible. Should be minimum length; diameter selected on basis of maximum velocity not to exceed 90
16、 m/s. k.Restriction valve Optional, to control engine back pressure. Locate the valve at usual muffler position. However, if muffler location is unknown, it is recommended that the valve be located 20 diameters of exhaust pipe from the engine exhaust flange. 4.2Plenum Chamber VolumeDue to the nature
17、 of diesel engines, pressure pulsations in the air measurement system may be present. In general, pulsations in the systems have adverse effects on most air flow metering devices and must be controlled for proper air flow measurements. A plenum chamber between the meter and the engine air intake can
18、 help isolate the meter by attenuating the pulsations. 4.2.1The minimum recommended plenum chamber volume should conform to Equation 1: (Eq. 1)vol KSW rpmStroke Rev - -= SAE J244 Revised AUG92 -4- FIGURE 1COMPONENT FIGURATION SAE J244 Revised AUG92 -5- where: 4.2.2The plenum may be excluded if test
19、data show that the engine and flow meter are insensitive to the plenum chamber volume. The check, as follows, may help determine the effect of the pressure pulsations. a.The frequency of the pulsations should be determined at a point between the flow meter and the plenum chamber. b.Low-pressure tran
20、sducers or microphones can be used to sense the pulsations with their output fed into a narrow-band frequency analyzer or FFT (Fast Fourier Transform analyzer). c.Determine the effect of the pulsations by Equation 2: (Eq. 2) where: MetricEnglish NH=Hodgson Numberm3ft3 Vol =Volume of the flow system
21、(piping between the pulsation source and the meter) f=Frequency of the pulsationsHZHZ Q=Average volume rate of flowm3/sft3/min P =Average pressure drop in the system from pulsation sources to the meter PA=Average absolute pressure atkPain Hg the meter KH=Units conversion1.04.42 d.The Hodgson Number(
22、NH should be larger than 2 to minimize the errors due to pulsations. For air flow measurement systems the effects of pulsations must be minimized by isolating the meter from the source, since there is no known correction factor. e.With vortex-shedding meters it is important that the pulsation freque
23、ncies near the meter shedding frequencies be minimized in amplitude. 5.Measurement SystemsWhenever possible, a flow measuring system per 4.1 should be used. The flow meter, nonpulsating blower, plenum, temperature control, and restriction valve may be combined in a single unit. vol=Volume of plenum
24、chamber m3in3 SW=Swept volume of one cylinderL in3 rpm=Lowest engine speed at which air flow measurements are to be made rpmrpm Stroke/Rev=Number of intake strokes per engine revolution K=Dimensionless constant. Suggested values are: Naturally aspirated diesel w/nozzle180180 000 Naturally aspirated
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