SAE AIR 6297-2017 Method to Calculate Behind Start of Takeoff Roll Noise Level Adjustments.pdf

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5、 Takeoff Roll Noise Level Adjustments RATIONALE This AIR describes a method to calculate noise level adjustments at locations behind an airplane at the start of takeoff roll (SOTR) for the purposes of aircraft noise prediction modeling. This method replaces the methods found in paragraph 3.3.1 (Soun

6、d Exposure Level Behind the Start-of-Takeoff Roll) of AIR1845A “Procedure for the Calculation of Airplane Noise in the Vicinity of Airports“. Specifically, the calculations presented in 3.1 and 3.2 of this document replace the calculations in Step 3 of paragraph 3.3.1 of AIR1845A. It adheres to the

7、basic approach described in AIR1845A and is based on measurements from modern jet and turboprop aircraft (circa 2004). The behind start of takeoff roll noise directivity method found in AIR1845A is based on measurements of older-generation (circa 1980), low by-pass ratio aircraft, primarily configur

8、ed with fuselage-mounted engines. The new method described herein for modeling the noise directivity behind start of takeoff roll is derived from empirical data from modern jet aircraft, most of which are configured with wing-mounted engines that tend to have higher by-pass ratios as well as operate

9、 at higher thrust levels. Additionally, this AIR version includes a separate directivity adjustment for propeller-driven aircraft. Comparison of directivity adjustments computed from the method described herein and the AIR1845A method are presented in Appendix A. FOREWORD The SAE Aircraft Noise Comm

10、ittee (A-21) initiated an activity to update the behind start of takeoff roll algorithm in AIR1845A. This update was preceded by a study conducted at Dulles International Airport (IAD) in October 2004 by the National Aeronautics and Space Administration (NASA), Langley Research Center, with support

11、provided by the Volpe National Transportation Systems Center (Volpe). Analysis of the data collected at IAD showed that the directivity patterns of modern aircraft have only marginal similarities with the AIR1845A directivity pattern. The updated algorithms will benefit current aircraft noise predic

12、tion models, as the adjustments better represent the current aircraft fleet and allow for the directivity associated with jet and turboprop aircraft to be represented separately in the models. SAE INTERNATIONAL AIR6297 Page 2 of 12 TABLE OF CONTENTS 1. SCOPE 3 2. REFERENCES 3 2.1 Applicable Document

13、s 3 2.1.1 SAE Publications . 3 2.1.2 ANSI Publications 3 2.1.3 NASA Publications 3 2.2 Related Publications 3 2.2.1 SAE Publications . 3 2.2.2 ECAC Publications 4 2.2.3 ICAO Publications . 4 2.2.4 Volpe Publications . 4 2.3 Definitions 4 3. TAKEOFF ROLL NOISE MODELING . 5 3.1 Behind the Start of Tak

14、eoff Roll Directivity Adjustment for Jet Aircraft . 6 3.2 Behind the Start of Takeoff Roll Directivity Adjustment for Turboprop Powered Aircraft 7 4. SUMMARY OF APPLICATIONS . 8 4.1 Categories of Aircraft 8 4.2 Operations . 9 4.3 Distance Limitations 9 5. NOTES 9 5.1 Revision Indicator 9 APPENDIX A

15、COMPARISON WITH AIR1845A METHOD . 10 APPENDIX B DESCRIPTION OF AIRCRAFT REPRESENTED IN MEASURED FLEET 12 Figure 1 Illustration of azimuth angle . 4 Figure 2 Directivity adjustment (DIRADJ) for jet aircraft 6 Figure 3 Directivity adjustment for turboprop aircraft 8 Table 1 Representative set of direc

16、tivity adjustment values for jet aircraft 7 Table 2 Representative set of directivity adjustment values for turboprop aircraft. 8 SAE INTERNATIONAL AIR6297 Page 3 of 12 1. SCOPE This document describes a method to calculate noise level adjustments at locations behind an airplane (described by an ang

17、ular offset or directivity) at the start of takeoff roll (SOTR). This method is derived from empirical data from jet aircraft (circa 2004), most of which are configured with wing-mounted engines with high by-pass ratios (Lau, et al., 2012). Methods are also described which apply to modern turboprop

18、aricraft. Calculations of other propagation-related adjustments required for aircraft noise prediction models are described in AIR1845A, ARP5534, ARP866A, and AIR5662. 2. REFERENCES 2.1 Applicable Documents The following publications form a part of this document to the extent specified herein. The l

19、atest issue of SAE publications shall apply. The applicable issue of other publications shall be the issue in effect on the date of the purchase order. In the event of conflict between the text of this document and references cited herein, the text of this document takes precedence. Nothing in this

20、document, however, supersedes applicable laws and regulations unless a specific exemption has been obtained. 2.1.1 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

21、.org. AIR1845A Procedure for the Calculation of Airplane Noise in the Vicinity of Airports 2.1.2 ANSI Publications Copies of these documents are available online at http:/webstore.ansi.org/. ANSI/S1.1-1994 Acoustical Terminology, American National Standard 2.1.3 NASA Publications NASA Technical Serv

22、ices, NASA STI Program STI Support Services, Mail Stop 148, NASA Langley Research Center, Hampton, VA 23681-2199, 757-864-9658, Fax: 757-864-6500, http:/ntrs.nasa.gov/. Lau, Michael C., Roof, C.J., Fleming, G.G., Rapoza, A.S., Boeker, E.B., McCurdy, D.A., and Shepherd, K.P., “Behind Start of Take-of

23、f Roll Aircraft Sound Level Directivity Study Revision 1,” NASA Technical Memorandum 217783, NASA Report No. NASA/TM-2012-217783, Volpe Report No. DOT-VNTSC-NASA-12-01, 2015. 2.2 Related Publications The following publications are provided for information purposes only and are not a required part of

24、 this SAE Aerospace Technical Report. 2.2.1 SAE Publications Available from SAE International, 400 Commonwealth Drive, Warrendale, PA 15096-0001, Telephone: 877-606-7323 (inside USA and Canada) or +1 724-776-4970 (outside USA), www.sae.org. AIR5662 Method for Predicting Lateral Attenuation of Airpla

25、ne Noise ARP5534 Application of Pure-Tone Atmospheric Absorption Losses to One-Third Octave-Band Data ARP866A Standard Values of Atmospheric Absorption as a Function of Temperature and Humidity SAE INTERNATIONAL AIR6297 Page 4 of 12 2.2.2 ECAC Publications Available from the European Civil Aviation

26、Conference website at https:/www.ecac-ceac.org/. ECAC Doc 29 Standard Method of Computing Noise Contours Around Civil Airports 2.2.3 ICAO Publications Available from International Civil Aviation Organization, 999 University Street, Montreal, Quebec H3C 5H7, Canada, Tel: +1 514-954-8219, http:/www.ic

27、ao.int/. ICAO Doc9911 Recommended Method for Computing Noise Contours around Airports 2.2.4 Volpe Publications Available from the U.S. Department of Commerce, Technology Administration, National Technical Information Service (NTIS), Alexandria, VA, http:/www.ntis.gov. Koopman, et al., Aviation Envir

28、onmental Design Tool (AEDT) 2A Technical Manual, Report No. DOT-VNTSC-FAA-12-09, Cambridge, MA, John A Volpe National Transportation Systems Center, April 2014. 2.3 Definitions 2.3.1 AZIMUTH ANGLE () The angle, with vertex at the nominal location of airplane engines, measured between a line along th

29、e center of an airplane from nose to tail and the radial line to the sound receiver. A 0 angle represents positions directly in front of the airplane, and a 180 angle represents positions directly behind the airplane. Also, may be referred to as directivity angle. Figure 1 - Illustration of azimuth

30、angle SAE INTERNATIONAL AIR6297 Page 5 of 12 2.3.2 BASELINE NOISE DATA Referred to as noise-power-distance (NPD) data. A set of aircraft source noise levels expressed as a function of engine power, usually the corrected net thrust per engine, and distance. NPD data account for sound propagation over

31、 distance, taking into account the spreading of sound and atmospheric absorption through a standard atmosphere, as defined in AIR1845A. NPD data typically represent specific aircraft (airframe and engine) and a range of engine power settings that represent typical aircraft operating conditions (appr

32、oach, departure and level flight). 2.3.3 DIRECTIVITY ADJUSTMENT (DIRADJ) Adjustment applied to the baseline NPD data, measured during overflight conditions, to predict noise levels behind an aircraft on the ground at the start of takeoff-roll (see 2.3.4). In AIR1845A, DIRADJ is presented as L. 2.3.4

33、 START OF TAKEOFF ROLL (SOTR) The initial, ground-based stage(s) of an aircraft takeoff maneuver, generally beginning as the aircraft is aligned with the center of the runway, the engines are brought up to a specific thrust level, and the aircraft begins to accelerate, and ending at liftoff (see Sum

34、mary of Applications). 3. TAKEOFF ROLL NOISE MODELING Aircraft noise prediction models compute takeoff roll noise using several paramenters including; (1) the baseline aircraft- and operation-specific noise (NPD) data; and (2) a behind start of takeoff roll (SOTR) directivity adjustment. The behind

35、SOTR directivity adjustment is applied to the baseline noise levels associated with the entire takeoff ground roll (the initial stage of an aircraft takeoff) according to the azimuth angle between the aircraft and receiver. This adjustment acounts for noise level differences due to the acoustical di

36、rectivity characteristics of the engines when the aircraft is on the ground. The baseline noise levels are most commonly described in terms of the A-weighted sound exposure level (SEL), denoted by the symbol LAE, but the adjustment may also be applied to other A-weighted metrics (such as equivalent

37、sound level (denoted by the symbol LAeq) or maximum sound level (denoted by the symbol LAmx) and metrics based on alternate weighting schemes (i.e., C-weighting, tone-corrected percieved noise level) (ANSI/S1.1-1994). Paragraphs 3.1 and 3.2 (Equations 1 and 2) describe the SOTR directivity adjustmen

38、ts for jet (turbofan) and turboprop airplanes, respectively. These equations were empirically derived from data measured at Dulles International Airport in 2004 (Lau, et al., 2012). Further information on the aircraft fleet represented in the measured data are described in Appendix B. The sound expo

39、sure level at an observer point (P), in decibels, is calculated according to Equation 1, corresponding to Equation 3.4.1 of AIR1845A: (Eq. 1) where: LAE(P,d) is the sound exposure level derived from the reference data base, corresponding to takeoff power setting and distance d = r, from the aircraft

40、 to the observer point. V is the speed adjustment for the difference between the minimum takeoff airspeed (generally 1 knot or the minimum model airspeed) and the normalization airspeed (generally 160 knots)1. (0,r) is the lateral attenuation adjustment for the elevation angle of 0 and distance r (A

41、IR5662). DIRADJ is the directivity adjustment defined in 3.1 and 3.2. 1 In AIR1845A, V is equal to 10log10(160/V), and a minimum airspeed of 32 knots was specified. This minimum airspeed limitation has been removed to reflect current modeling practices, which incorporate a minimum airspeed of 1 knot

42、. SAE INTERNATIONAL AIR6297 Page 6 of 12 3.1 Behind the Start of Takeoff Roll Directivity Adjustment for Jet Aircraft The behind SOTR directivity adjustment (DIRADJ), in decibels, for turbofan-powered jet aircraft is calculated according to the following: 0900 ADJDI RFor 18090 For (Eq. 2) where : is

43、 the azimuth angle in degrees (see 2.3.1). The directivity pattern is symmetric about the aircraft longitudinal axis. Figure 2 illustrates the directivity adjustment for jet aircraft. Table 1 presents a representative set of values computed from Equation 2 at specific angles between 90 and 180. In p

44、ractice, Equation 2 must be used to compute values at other angles. Figure 2 - Directivity adjustment (DIRADJ) for jet aircraft SAE INTERNATIONAL AIR6297 Page 7 of 12 Table 1 - Representative set of directivity adjustment values for jet aircraft Azimuth Angle (, degrees) Directivity Adjustment (DIRA

45、DJ, dB) 90 -0.20 100 -0.90 110 -0.03 120 0.93 130 0.56 140 -1.56 150 -5.07 160 -9.09 170 -12.39 180 -13.48 3.2 Behind the Start of Takeoff Roll Directivity Adjustment for Turboprop Powered Aircraft The behind SOTR directivity adjustment (DIRADJ), in decibels, for turboprop-powered aircraft is calcul

46、ated according to the folowing: 0900 ADJDI RFor 18090 For (Eq. 3) where: is the azimuth angle in degrees (see 2.3.1). The directivity pattern is symmetric about the aircraft longitudinal axis. Figure 3 illustrates this directivity pattern. Table 2 presents a representative set of values computed fro

47、m Equation 3 at specific angular offsets between 90 and 180. In practice, Equation 3 must be used to compute values at other angles. SAE INTERNATIONAL AIR6297 Page 8 of 12 Figure 3 - Directivity adjustment for turboprop aircraft Table 2 - Representative set of directivity adjustment values for turbo

48、prop aircraft Azimuth Angle (, degrees) Directivity Adjustment (DIRADJ, dB) 90 -0.16 100 -0.98 110 0.30 120 1.94 130 0.62 140 -3.10 150 -6.93 160 -9.24 170 -9.91 180 -10.14 4. SUMMARY OF APPLICATIONS This section summarizes considerations for the practical application of the methods described in the

49、 previous sections. 4.1 Categories of Aircraft The methods described herein by Equations 2 and 3 for calculating the behind SOTR directivity adjustment apply to turbofan, turboprop, and piston-prop powered airplanes, regardless of engine position, mounting configuration or number of engines. In the absence of corresponding empirical data and methods for military aircra