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 ther
2、efrom, is the sole responsibility of the user.” SAE reviews each technical report at least every five years at which time it may be revised, reaffirmed, stabilized, or cancelled. SAE invites your written comments and suggestions. Copyright 2016 SAE International All rights reserved. No part of this
3、publication may be reproduced, stored in a retrieval system or transmitted, in any form or by any means, electronic, mechanical, photocopying, recording, or otherwise, without the prior written permission of SAE. TO PLACE A DOCUMENT ORDER: Tel: 877-606-7323 (inside USA and Canada) Tel: +1 724-776-49
4、70 (outside USA) Fax: 724-776-0790 Email: CustomerServicesae.org SAE WEB ADDRESS: http:/www.sae.org SAE values your input. To provide feedback on this Technical Report, please visit http:/www.sae.org/technical/standards/J2777_201601 SURFACE VEHICLE RECOMMENDED PRACTICE J2777 JAN2016 Issued 2007-01 R
5、evised 2016-01 Superseding J2777 JAN2007 Recommended Best Practice for Climatic Wind Tunnel Correlation RATIONALE This document has been declared “Stabilized“ by the SAE Interior Climate Control Steering Committee and will no longer be subjected to periodic reviews for currency. Certain references a
6、re being deleted as they are not publicly available. It has been determined by the committee that there is no longer any customer pull for further maintenance, review or revision to the standard. TABLE OF CONTENTS 1. SCOPE 2 1.1 Background . 2 2. REFERENCES 3 2.1 Applicable Documents 3 3. FACILITY C
7、APABILITIES . 3 4. DYNAMOMETER LOAD SIMULATIONS . 4 4.1 Vehicle Target Road Load Simulation Force 4 4.2 Matching the Target Road Load Force on a Chassis Dynamometer . 5 4.3 Trailer Road Load Simulation . 6 4.4 Grade Load Simulation Force . 7 4.5 Vehicle, Trailer and Grade Load Simulation Force . 7 4
8、.6 Simulated Mass . 7 4.7 Simulated Mass Used for Trailer . 7 5. WIND SPEED SETTING AND TUNNEL BLOCKAGE CORRECTIONS 8 5.1 Wind Speed Considerations . 8 5.2 Wind Speed Calibration Considerations . 8 5.3 Wind Tunnel Blockage Considerations . 9 6. SOLAR SIMULATION . 10 6.1 Solar Spectrum . 10 6.2 Solar
9、 Intensity and Distribution . 11 6.3 Solar Lamp Height 12 6.4 Side Banks 12 6.5 Measurement 12 6.6 Considerations 13 7. IDLES AND SOAKS 14 7.1 Idle and Soak Configurations 14 SAE INTERNATIONAL J2777 JAN2016 Page 2 of 23 7.2 Test Section Temperature During Idle 15 7.3 Vehicle Soak . 16 8. WIND TUNNEL
10、 COMPARISON TEST SCHEDULES 16 8.1 Heater Test . 17 8.2 AC Test . 17 8.3 Powertrain Cooling Test #1 . 18 8.4 Powertrain Cooling Test #2 . 18 8.5 Powertrain Cooling Test #3 . 19 9. TEST CRITERIA AND INSTRUMENTATION . 19 9.1 A/C Test Comparison Criteria . 19 9.2 PTC Comparison Criteria 20 10. NOTES 22
11、10.1 Revision Indicator 22 FIGURE 1 TARGET ROAD LOAD FORCES EXPERIENCED ON A PASSNEGER VEHICLE 5 FIGURE 2 MEASURABLE FORCES IN A CLIMATIC WIND TUNNEL . 6 FIGURE 3 VARIABILITY IN TRAILER ROAD LOAD FORCES WITH THE SAME TRAILER WEIGHT . 8 FIGURE 4 ON ROAD WIND VELOCITY MEASUREMENT USING BOOM ANNEMOMETE
12、R . 9 FIGURE 5 WIND TUNNEL VELOCITY PROFILE 10 FIGURE 6 GLOBAL AND SIMULATED SOLAR RADIATION SPECTRUM 11 FIGURE 7 RECOMMENDED SOLAR SIMULATION DISTRIBUTION 12 FIGURE 8 SIMULATED SOLAR MEASUREMENT . 13 FIGURE 9 SOLAR TRANSMISSION AS A FUNCTION OF GLASS TYPE . 13 FIGURE 10 TEMPERATURE EFFECTS OF SOLAR
13、 SOURCES TO DIFFERENT COLORS 14 FIGURE 11 VEHICLE IN WIND TUNNEL SHOWING BYPASS AIR CONFIGURATION . 15 FIGURE 12 VEHICLE IN WIND TUNNEL WITH AIR BYPASSAIR USING IDLE BOARD 15 TABLE 1 WIND TUNNEL CORRELATION VEHICLE INSTRUMENTATION LIST . 21 TABLE A1 PRETEST CHECK LIST . 23 TABLE B1 CLIMATIC WIND TUN
14、NEL CORRELATION PARTICIPANTS . 23 1. SCOPE With many corporations and suppliers conducting development and validation tests at different Climatic Wind Tunnel sites, there is an increasing need for a recommended best practice that defines a process by which climatic wind tunnels can be correlated. Th
15、is document addresses the test methods and metrics used to obtain similar results, independent of location, for Heating Ventilation and Air Conditioning (HVAC) and Powertrain Cooling (PTC) development. This document should be used as a guideline to make sure key aspects of tunnel testing are covered
16、 when comparing various climatic wind tunnel facilities. The depth of the correlation program is ultimately influenced by program objectives. Therefore a correlation program, for the intent and purposes of this document, can range from just a few tests to a full analysis that involves multiple vehic
17、le tests identifying limitations and statistical boundaries. Using recommendations in this document will eliminate most of the items that effect facility mismatch in a correlation program. 1.1 Background With manufacturers and OEMs conducting development and validation tests at different Climatic Wi
18、nd Tunnel sites, there is an increasing need to establish correlation between test facilities. Several climatic wind tunnel organizations and affiliations assembled to discuss a plan to determine what was necessary to complete a successful correlation program. It became obvious that first and foremo
19、st all groups involved must understand the variations in climatic wind tunnel design. As a result, attention was diverted to a series of meetings dedicated to special topics, presented by experts in the climatic wind tunnel industry. The information collected throughout these discussions is the foun
20、dation used in publishing this document. SAE INTERNATIONAL J2777 JAN2016 Page 3 of 23 2. REFERENCES 2.1 Applicable Documents The following publications form a part of this specification to the extent specified herein. Unless otherwise indicated, the latest issue of SAE publications shall apply. 2.1.
21、1 SAE Publications Available from SAE International, 400 Commonwealth Drive, Warrendale, PA 15096-0001, Tel: 877-606-7323 (inside USA and Canada) or +1 724-776-4970 (outside USA), www.sae.org. SAE J2263 Road Load Measurements Using Onboard Anemometry and Coastdown Techniques SAE J2264 Chassis Dynamo
22、meter Simulation of Road Load Using Coastdown Techniques U.S. EPA SC03 driving schedule representing vehicle operation with air conditioning, as set forth in Appendix I of 40 CFR Part 86 Rout, R. K., “Unique Correlation Technique for Real-World Flow Simulation in the Wind Tunnel,” SAE 980033 Yen, J.
23、 C. et al., “Determining Blockage Corrections in Climatic Wind Tunnels Using CFD,” SAE 2003-01-0936 Yen, J. C. et al., “The Plenum Method versus Blockage Corrected Nozzle Method for Determining Climatic Wind Tunnel Airspeed,” SAE 2004-01-0668 Hucho, W.-H., Aerodynamics of Road Vehicles, 4th Ed., 199
24、8, SAE 3. FACILITY CAPABILITIES With environmental and vehicle load simulation being the primary function of climatic wind tunnels, it is imperative that all facility parameters are captured in the effort of reproducing “real world” conditions that exist within the test environment. The accuracy of
25、the instruments used in the measurement of these parameters is detrimental to the outcome of the test. Although calibration methods and processes are not included in scope of this document, demonstration of compliance of calibration should be included in the final correlation report. Its recommended
26、 that the instrumentation used throughout the correlation effort is calibrated and traceable to the National Institute of Standards and Technology. 3.1 Air Temperature Air temperature is also referred to as dry bulb temperature. It is the temperature the test vehicle will experience while in the tes
27、t section and is set for specific condition. Its point of measurement should be before the test vehicle and after the heat exchanger that is used by the test cell for conditioning and in maintaining dry bulb temperature. A preferred location would be in the exit air stream prior to leaving the exit
28、nozzle. A precision probe or RTD, (Resistive Thermal Device) should be used for measuring this parameter. The range of operation for the purpose of this practice is -15 C to +38 C. 3.2 Humidity Humidity can be measured by obtaining wet bulb temperature, using a chilled mirror, or other forms of humi
29、dity analyzers. This measurement should be in close proximity of the location in which dry bulb temperature is measured and follows the same criteria for location. The range of operation for the purpose of this practice is 40 to 90 % RH. 3.3 Vehicle Speed Generally dynamometer roll speed is measured
30、 and reflects the actual vehicle wheel speed. The speed measured by the vehicle is not necessarily the same as the target speed measured at the roll dynamometer. Therefore speed set point, for the purpose of this correlation effort, is dynamometer roll speed (both target and measured). The range of
31、accuracy for the purpose of this practice is 0 to 110 kph. SAE INTERNATIONAL J2777 JAN2016 Page 4 of 23 3.4 Tractive Effort This also requires a chassis dynamometer and is the measurement of the net force applied to the vehicle power train after vehicle and dynamometer losses are accounted for. The
32、tractive effort target force as it relates to speed is the measurement that should be used throughout the correlation program and carried from facility to facility. In doing so, variation in dynamometer roll size, load cell orientation, etc remain specific to a given facility and not the vehicle und
33、er test. The range of accuracy for the purpose of this practice will be determined by the capability of the vehicle under test. 3.5 Solar Simulation Solar (Sun) simulation is required for HVAC / PTC development and validation. There are a number of different solar simulation arrays currently in use,
34、 the most common being IR and near full spectrum. The variation in solar simulators must be well documented and understood at each facility used. The effects of a few solar simulators currently in use are illustrated in Section 6 of this document. The maximum range of accuracy for the purpose of thi
35、s practice should be a uniform distribution of 1000 W/m2. 3.6 Wind Speed and Blockage Correction Typically the wind speed measurement is upstream of the vehicle under test. Facility instrumentation is used to infer the wind speed based on previous calibration tests. It is important that wind speed (
36、as corrected for blockage) matches the dynamometer roll speed in a steady state mode and follows as close as possible to transient conditions. The range of accuracy for the purpose of this practice should be at least 0 to 110 kph. Aerodynamic interferences due to discrepancies in boundary conditions
37、 in a wind tunnel simulation compared to the open road are collectively referred to as “blockage”. Blockage depends not only on the wind tunnel boundary conditions, but also the size and shape of the vehicle under test and the method used to measure the facilitys wind speed. Corrections for blockage
38、 are therefore desirable for the best possible wind speed simulation. This is discussed in more detail in Section 5. 3.7 Nozzle Size Exit nozzle size used at each facility involved in the correlation effort needs to be documented and referenced as necessary when comparing results. Facilities that ha
39、ve extendable nozzles should use the nozzle to vehicle front end distance typically used for HVAC and PTC tests. Facilities that can vary their exit nozzle size (nozzle inserts or flaps) should use the maximum nozzle size possible to meet the wind speed requirement of 0 to 110 kph. 4. DYNAMOMETER LO
40、AD SIMULATIONS Regardless of individual climatic wind tunnel capabilities, dynamometer load simulation needs to result in good correlation between facilities. While most groups have their own process for duplicating real world force loads, the method necessary to correlate wind tunnel facilities can
41、 be simplified into a 2nd order polynomial equation that includes vehicle, trailer, and grade simulation forces. Identifying the vehicle and trailer load equation and making sure the loads are applied at the vehicle powertrain will result in exceptional load correlation between facilities. Otherwise
42、 its one of the biggest causes of correlation mismatch. 4.1 Vehicle Target Road Load Simulation Force The target road load simulation force is the force that must be overcome by the vehicle powertrain to maintain steady speed on a flat road. The illustration below demonstrates the origin of these fo
43、rces. By conducting an on road coastdown per SAE J2263 Road Load Measurements Using Onboard Anemometry and Coastdown Techniques, these forces can be identified at predetermined speeds. At which point a best fit 2ndorder polynomial equation can be derived. Since the purpose of this paper is to provid
44、e recommendations that result in optimum correlation, only the Target Road Load Simulation Force equation will be discussed. How the equation is obtained is covered in SAE J2263. SAE INTERNATIONAL J2777 JAN2016 Page 5 of 23 Figure 1 - Target road load forces experienced on a passneger vehicle Target
45、 Road Load Simulation Force (Vehicle) = (AV + BV*V + CV*V2+ MV dV/dt) Newtons (Eq. 1) where: AV = Mostly Constant Friction (approximated by Crr*WV) Units = N BV = Mostly Variable Friction (proportional to speed) Units = N/kph CV = Mostly Aero Resistance (approximated by 1/2CdAFV2) Units = N/kph2WV =
46、 Weight of Vehicle Units = N MV = Mass of Vehicle or Weight / 9.81 Units = kg V = Vehicle Speed Units = kph t = Time Units = Seconds Crr = Coefficient of Rolling Resistance Units = None = Air Density Units = kg/m3AF = Frontal Area Units = Meters2 4.2 Matching the Target Road Load Force on a Chassis
47、Dynamometer While the Target Road Load Simulation Force equation is common to all facilities involved in the correlation effort, the method of applying the target force becomes specific to the facility conducting the correlation test. The reason for this is that climatic wind tunnels will have sligh
48、t differences in chassis dynamometer configurations. Tire to dynamometer roll interface and load cell locations are just a few examples. In addition the vehicle itself exhibits retarding forces when installed in the climatic wind tunnel test section. A good example of this would be the vehicle tie d
49、own restraint forces exhibited in all three axes. These types of vehicle and dynamometer (loss) forces are not included in the Target Road Load Force Equation obtained on road, making it necessary for adjustment when installed on a chassis dynamometer. 4.2.1 Vehicle Coast down Determination - Preferred Method The preferred method for assuring target road load forces are seen by the vehicle powertrain is performing a vehicle coa
