A comparing overview on ECAC Doc.29 3 rd Edition and the new German AzB Dr. Ullrich Isermann German Aerospace Center DLR Institute of Aerodynamics und Flow Technology JRC Workshop on Aircraft Noise, Brussels, 19./20. January 2010, Sheet 1
Doc.29 Vol.3 vs. AzB 2008 Model Type Emission Data Directivity Aircraft Categories Performance Data Doc.29 3 rd Edition Segmentation model with specific improvements NPDdata and spectral classes Semiempirical dipole model with correction for installation effects Airframe/engine combinations Procedural profiles Octave spectra AzB2008 Segmentation depending on receiver location Spectral 2dimensional directivity function Limited number of aircraft groups Predefined fixedpoint profiles Lateral Spreading Receiver Height Topography Reverse Thrust Ground Noise Field of Application 7 subtracks (recommended) Civil airports / Flexible 15 subtracks (prescribed) Solid angle correction (ISO 96132) Only altitude effect on propagation distance AzB adapted the Doc.29 model Taxiiing and APU All airports / Primarily Forecast JRC Workshop on Aircraft Noise, Brussels, 19./20. January 2010, Sheet 2
Doc.29 Vol.3 vs. AzB2008 Segmentation model AzB: 2step segmentation with additional segmentation step depending on aircraftobservergeometry Doc.29: Classical 2step flight path segmentation with specific improvements JRC Workshop on Aircraft Noise, Brussels, 19./20. January 2010, Sheet 3
Principle of Segmentation Original flight track Segmented arc Point of closest approach E 4 E 1 E 2 E 3 Observer Total exposition E = E i JRC Workshop on Aircraft Noise, Brussels, 19./20. January 2010, Sheet 4
Flight path segmentation: 1. Step 1. step identical for AzB an Doc.29 /2 R Flight track (horizontal plane) with track segments s s Path segments from 1 st segmentation step Altitude profile (vertical plane) with profile segments s s JRC Workshop on Aircraft Noise, Brussels, 19./20. January 2010, Sheet 5
Flight path segmentation: 2. Step (Doc.29) T/ORoll segment : Segmentation in fixed time intervals (const. acceleration) Improved comparability to simulation s TO = 1600 m s [m] 25 100 225 400 625 900 1225 1600 Airborne segments: Removal of points located close to each other Segmentation of long segments with great changes in aircraft speed Transition segments adjacent to curved flight tracks Removal of discontinuities due to effects of bank angle JRC Workshop on Aircraft Noise, Brussels, 19./20. January 2010, Sheet 6
Flight path segmentation: 2. Step (AzB) or L WAE > 1 db L WA > 1 db Origin: flight path segments L WAE ' L WA V 10 lg V ref l 1m 0 and L WAE 1 db L WA 1 db Result: flight path subsegments by adaption of specific emissions JRC Workshop on Aircraft Noise, Brussels, 19./20. January 2010, Sheet 7
Flight path segmentation: 3. Step (AzB) Flight path subsegment of length is subdivided in final segments of length l i Subdivision starts at point of closest approach Q 0 Final segments are represented by point sources Q i l 1 l 0 l 1 l 2 Q1 Q 2 Q 2 Q 1 Q 3 Q 0 s 2 s 1 s 1 s 2 s 3 Condition: l r i i 0.1 s 0 =r 0 r 1 r 1 r 2 Segmentation depends on observer location! Observer JRC Workshop on Aircraft Noise, Brussels, 19./20. January 2010, Sheet 8
Doc.29 Vol.3 vs. AzB2008 Source model AzB: Octave spectra Spectral 2D directivitiy (directivity factors) Doc.29: NPD data based on spectral classes Semiempirical 2D dipole model Lateral directivity from installation effects JRC Workshop on Aircraft Noise, Brussels, 19./20. January 2010, Sheet 9
Example of AzB2008 approach data set Acoustical data JRC Workshop on Aircraft Noise, Brussels, 19./20. January 2010, Sheet 10
Directivity according to AzB2008 Directivity diagram L WA () for departure of aircraft category S5.2 R n = { 1, 1, 1 } Representation of spectral directivity by series expansion in cosine of radiation angle D I, n( ) 3 a1 cos( ) a2 cos(2) a3 cos(3) 130 db 140 db 150 db JRC Workshop on Aircraft Noise, Brussels, 19./20. January 2010, Sheet 11
Source model of Doc.29 Segment Flight path E seg E E seg = F E F Energy fraction Observer E seg E Segment contribution to exposure Exposure from infinite segment Noise Level NPDData Parameter: Power Distance Approach: 4thpower90 dipolemodel p 2 ~ sin 2 /d 2 ~ d 4 JRC Workshop on Aircraft Noise, Brussels, 19./20. January 2010, Sheet 12
The principle of the scaled distance Problem: The energy fraction is derived from the analytical dipolemodel. The NPDdata are derived from measurements (i.e. from real directivities). The differences L L E, (V) L max are not the same: L Dipole L NPD Solution: A scaled distance d is introduced: L Dipole (d ) L NPD (d ) The energy fraction is calculated for the scaled distance, not for the slantdistance. The real directivity is modelled by a modified propagation distance. The analytical model changes to a semiempirical one! JRC Workshop on Aircraft Noise, Brussels, 19./20. January 2010, Sheet 13
Installation effect (lateral directivity, only Doc.29) 5 db Fuselage mounted jet Wing mounted jet Prop JRC Workshop on Aircraft Noise, Brussels, 19./20. January 2010, Sheet 14
Doc.29 Vol.3 vs. AzB2008 Propagation models Both models account for geometrical spreading, atmospheric absorption and ground effect. AzB: Explicit modelling of propagation effects Doc.29: Geometrical spreading and atmospheric absorption implicit modelled by NPD Changed atmospheric conditions require recalculation of NPD data JRC Workshop on Aircraft Noise, Brussels, 19./20. January 2010, Sheet 15
Doc.29 Vol.3 vs. AzB2008 Excess attenuation AzB: Ground effect correction Solid angle correction Allowance for receiver height Doc.29: Ground effect correction Engine installation correction Receiver on the ground JRC Workshop on Aircraft Noise, Brussels, 19./20. January 2010, Sheet 16
Ground effect correction (AzB2008) Ground effect correction: D Z,n = f() g(s) (spectral) Solid angle correction: D =f(s,h s,h r ) : Angle of incidence Receiver s h s h r Horizontal plane JRC Workshop on Aircraft Noise, Brussels, 19./20. January 2010, Sheet 17
Ground effect correction (Doc.29) Ground effect correction: = f() g() : Angle of incidence Receiver Horizontal plane JRC Workshop on Aircraft Noise, Brussels, 19./20. January 2010, Sheet 18
Ground effect and installation correction (Doc.29) Ground effect correction: = f() g() (propagation effect) Installation correction: Inst = Inst () (source property) : Angle of incidence : Bank angle : Depression angle Wing plane Receiver Horizontal plane JRC Workshop on Aircraft Noise, Brussels, 19./20. January 2010, Sheet 19
Doc.29 Vol.3 vs. AzB2008 Aircraft categories and flight profiles AzB: Limited number of aircraft groups (23 civil, 8 military, 5 helicopter) Unambiguous rules for grouping Fixed flight profiles Grouping according to acoustic equivalence Doc.29: Large number of airframe/engine combinations (123+ civil commercial, extensible) Procedural flight profiles Substitution rules for aircraft not in database JRC Workshop on Aircraft Noise, Brussels, 19./20. January 2010, Sheet 20
Flight path definition Flight track segments Flight profile segments Flight path segments Standard profiles (AzB): Fixed Profile segments Performance parameters as function of distance from brake release / landing threshold simple but not flexible Procedural profiles (Doc.29): Variable profile segments Performance parameters as function of procedural step of flight procedure and aircraft mass flexible but complex JRC Workshop on Aircraft Noise, Brussels, 19./20. January 2010, Sheet 21
Example of AzB2008 approach data set Performance data (fixed point profile) JRC Workshop on Aircraft Noise, Brussels, 19./20. January 2010, Sheet 22
Procedural profiles: mass point model L F L Z D W Climb W Turn L : Lift W : Weight D : Drag F : Thrust : Climb angle Z : Centrifugal force : Bank angle Lift and drag are estimated from the coefficients c L and c D. JRC Workshop on Aircraft Noise, Brussels, 19./20. January 2010, Sheet 23
Example for procedural flight profiles 10000 9000 Departure profile B737400, 48.5 t (calculated with INM 6.1) Engine thrust (arbitrary units) Altitude [ft] 8000 7000 6000 5000 4000 3000 2000 1000 0 Madrid: 27 C, 580 m above SL Stockholm: 13 C, 15 m above SL 0 10000 20000 30000 40000 50000 60000 70000 Distance from brake release [ft] JRC Workshop on Aircraft Noise, Brussels, 19./20. January 2010, Sheet 24
Grouping criteria for AzB database Acoustic equivalence: Two aircraft are acoustic equivalent in case that they produce similar noise footprints along the noiserelevant part of the flight path. They can be assigned to the same aircraft group. Noise significance: A noise significant aircraft codetermines considerably the noise situation in the vicinity of an airport (i.e. considerable changes in number of movements induce considerable noise changes). A noise significant aircraft must be modelled as precise as possible. A separate group has to be created for it in case that there are no acoustic equivalent aircraft. Noise insignificant aircraft can be grouped disregarding acoustic equivalence. JRC Workshop on Aircraft Noise, Brussels, 19./20. January 2010, Sheet 25
Example of acoustic equivalence: AzBGroup S6.1 Departure profiles for ICAOAprocedure (calculation with INM 6.2) 3500 3000 A310 (150 t) A300 (170 t) A330 (212 t) B767 (191 t) B777 (289 t) 2500 Altitude [m] 2000 1500 1000 500 Calculated standard deviation of SEL under flight path in db 1.4 1.4 1.3 1.2 1.2 1.6 0 0 5 10 15 20 25 30 35 40 45 Distance from brake release [km] JRC Workshop on Aircraft Noise, Brussels, 19./20. January 2010, Sheet 26
Comparison of type mix for the main AzBgroups AzBGroup Aircraft Germany 2005 (5 airports) Zurich 2007 Avro RJ, Bae146 27% 51% S5.1 Canadair RJ Fokker 70/100 48% 13% 8% 14% other 12% 27% A318..A321 48% 76% S5.2 B737 48% 21% other 4% 3% A300 37% > 1% A310 8% 1% S6.1 A330 24% 59% B767 22% 33% B777 9% 7% JRC Workshop on Aircraft Noise, Brussels, 19./20. January 2010, Sheet 27
Summary Both models use a segmentation algorithm, whereas the AzB implements an additional step depending on observer location. From an acoustical view the AzB uses a more detailled algorithm (spectral calculation, nongeneralised directivity) that is flexible with respect to a future expansion. Doc.29 provides much more flexibility in generating flight paths. The AzB is primarily designed for forecasts (grouping). Doc.29 provides more functionality, e.g. for whatifstudies (noise mitigation studies, effects of noise abatement flight procedures). The AzB covers additionally military and general aviation as well as helicopters and some ground operations. However both models are in principle easily extensible (AzB with respect to operational aspects, Doc.29 with respect to other fields of application). JRC Workshop on Aircraft Noise, Brussels, 19./20. January 2010, Sheet 28
The next step: DIN 45689 AzB 2008 DIN 45684 Doc. 29 3 rd ed. +??? DIN 45689 Work starts in 2010 (1 st special meeting on radar data January 26). 3 5 years of development expected JRC Workshop on Aircraft Noise, Brussels, 19./20. January 2010, Sheet 29
Problems to be discussed propagation modelling for aircraft noise JRC Workshop on Aircraft Noise, Brussels, 19./20. January 2010, Sheet 30
Workpackage 4 of DLR project Quiet Air Traffic II Problem: Conventional noise calculation procedures account only for standardised weather conditions (isotropic atmosphere, no wind) Reality temperature decrease with altitude upward refraction for a or for Wind temperature increase with altitude downward refraction shadow zone Question: What is the error introduced by this simplifying assumption? JRC Workshop on Aircraft Noise, Brussels, 19./20. January 2010, Sheet 31
Analysis of meteorological data (Hahn Airport, 2001) Classification used by the DLRIPA sound propagation model stability class stable neutral unstable SC 1 2 3 4 5 6 7 8 9 10 11 12 v W,10m [m/s] 0 1 2 0 1 2 5 10 20 0 1 2 Prandtl [K/m] +0.1 0.01 0.02 Ekman [K/m] +0.05 0.01 0.01 Distribution on wind direction and stability class wind direction 1 percentage of occurrence during daytime in stability class 2 3 4 5 6 7 8 9 10 11 12 30 120 0.8 2.1 1.3 7.6 0.0 0.3 2.3 120 210 1.2 3.3 2.2 12.0 0.6 0.3 2.5 210 300 0.6 2.5 2.6 34.1 4.0 0.4 2.4 300 30 0.7 1.8 1.5 9.5 0.7 0.4 2.4 JRC Workshop on Aircraft Noise, Brussels, 19./20. January 2010, Sheet 32
Calculation of noise contours using DLR model SIMUL Influence of meteorology on SEL contours (runway direction 21) stable, v w = 2 m/s (SC 3) neutral, v w = 5 m/s (SC 7) unstable, v w = 2 m/s (SC 12) JRC Workshop on Aircraft Noise, Brussels, 19./20. January 2010, Sheet 33
Calculation of noise contours using DLR model SIMUL Influence of meteorology on SEL contours (runway direction 03) stable, v w = 2 m/s (SC 3) neutral, v w = 5 m/s (SC 7) unstable, v w = 2 m/s (SC 12) JRC Workshop on Aircraft Noise, Brussels, 19./20. January 2010, Sheet 34
Comparison with isotropic atmosphere Contours SEL = 70, 80, 90 db (weighted yearly average) day SEL met night SEL iso SEL iso SEL met 2 db. 0 db. 2 db. 4 db. JRC Workshop on Aircraft Noise, Brussels, 19./20. January 2010, Sheet 35
Problems to be discussed measuring directivities JRC Workshop on Aircraft Noise, Brussels, 19./20. January 2010, Sheet 36
Example: A380800 Jet noise generation 60 m Angle of radiation? 1.2 m microphones on 60 m radius JRC Workshop on Aircraft Noise, Brussels, 19./20. January 2010, Sheet 37
Thank you! JRC Workshop on Aircraft Noise, Brussels, 19./20. January 2010, Sheet 38