applications

3. Workshop “Strömungsschall in Luftfahrt, Fahrzeug- und Anlagentechnik”
future applications for scientific
aircraft noise simulation tools
Presentation contents:
1. background
2. motivation
3. applications
… discussion …
Lothar Bertsch,
Institute of Aerodynamics
and Flow Technology,
DLR Göttingen
www.DLR.de • Chart 2
L. Bertsch
background
- aircraft noise: dominating
contribution to community
noise annoyance
- measures for noise reduction (ICAO):
(1) reduction at the source
(2) flight operational concepts
- most effective only if accounted for simultaneously
 system level assessment
- assessment of new / future technology
 advanced simulation capabilities
www.DLR.de • Chart 3
L. Bertsch
background
available methodologies (system level): fast prediction methods
(1) best current practice
- simplified source modeling
(aircraft = 1 overall source)
- empirical: based on measured
noise impact  high result
accuracy
- comprehensive data base
(2) scientific
- physics-based noise emission
modeling (semi-empirical)
- componential and parametrical
- modeling of individual noise
contributions / mechanisms
- limited data base
application to ICAO
measure
(1) current practice
modifications noise
source
flight procedures
very limited
very limited
(e.g. INM, Soundplan,
IMMI, CadnA …)
(modification of existing vehicle
database)
(simplified procedures, approach is
questionable)
(2) scientific
yes
yes
(e.g. PANAM, ANOPP …)
(parametric approach, limited to
modeled technology)
(3D flight procedures)
www.DLR.de • Chart 4
L. Bertsch
background
scientific tool outputs:
emission spectra (broadband & tonal)
… per time step / operational condition
… per individual noise source
… per emission angle
“status quo”: focus on standard immission metrics
- time-level history, max. or integrated levels (SPL, EPNL …)
- certification points, contour plots …
www.DLR.de • Chart 5
L. Bertsch
motivation
go beyond status quo
 exploit output data
exemplary future
applications:
identify and assess most effective
technologies
- source measures: radical concepts
- flight procedures: go beyond “ 3.2° ”
assist decision making &
increase awareness
1) noise-to-design
2) real-time analysis
(here: awareness through
professional training / education)
assist communication among
involved players
3) auralization
www.DLR.de • Chart 6
L. Bertsch
applications
1) noise-to-design
- status quo: design-to-noise
simulation process*
- TU BS: PrADO
- DLR: PANAM
- problem: identification of
optimal geometry & flight
procedure
 iterative process (!)
- new concept: noise-to-design**
1. select “noise goals (impact)”  identify required modifications
2. modify underlying geometry and / or flight operation
3. assess result
*) L. Bertsch: Noise prediction within conceptual aircraft design, DLR-FB-2013-20
**) PhD dissertation topic, J. Blinstrub, 2014-2016
www.DLR.de • Chart 7
L. Bertsch
applications
1) noise-to-design: status-quo
derive
emission limit
per source
„noise goal“:
reduction by
5 EPNdB at
each observer
transfer to vehicle / flight path modification is difficult
 simple source models = trivial correlations (“the bigger, the louder“)
© PhD dissertation topic – J. Blinstrub, 2014-2016
www.DLR.de • Chart 8
L. Bertsch
applications
1) noise-to-design: status-quo
derive
emission limit
per source
„noise goal“:
allowable increase by
0.1 EPNdB due to
additional (unknown)
source!
© PhD dissertation topic – J. Blinstrub, 2014-2016
DLR.de • Folie 9
L. Bertsch
applications
ATC workstation © DFS
2) real-time analysis
assist decision making in real-time
- airtraffic routing (ATC):
display current “noise” status & support
low-noise routing / traffic distribution
- pilot: weather dependent flight
procedure*, e.g. cockpit noise display
increase noise awareness
- pilot and ATC: ground-based simulator
training  moving “noise contour”
- PC version  gaming application
Ground-based simulator © DLR
*) small impact on noise propagation BUT huge impact on flight
operation, i.e. thrust setting, runway operating direction …
DLR.de • Folie 10
L. Bertsch
applications
2) real-time analysis
- contour on moving map: low computational costs
- fix movable “observer array” to aircraft x-y-position
- move and rotate array along with a/c flight position
and direction
- adapt “observer” height (and population density) to current x-y-position
t1
t2
 for each time step: sub-grid with different alt. profile (and population density)
DLR.de • Folie 11
L. Bertsch
applications
2) real-time analysis
computational effort  is a real-time
application feasible?
• selected time step: ∆𝑡 = 1.0 𝑠
• relevant sub-grid area:
2000 x 4000 m  flight points N ≈ 50
• typical grid: 150 x 150 m
 observers M ≈ 400
• requirement: ∆𝑡𝑠𝑠𝑠 < 1.0 𝑠
• status quo 2015*: single core cpu cost
• quad-core: ∆𝑡𝑠𝑠𝑠 ≈ 1 𝑠
• code speed optimization yet to be implemented
real-time application
can be realized !
*) Fujitsu Celsius W510, 4 Cores, 3.3 GHz, 2010
DLR.de • Folie 12
L. Bertsch
applications
3) auralization
available:
auralization:
spectral data per source / flight point / emission angle
translate simulation result into audible sound files
(ongoing activities at NASA, NLR, EMPA, and RWTH Aachen)
auralization goal: assist communication among involved players
- compare old vs. new technology (e.g. new vehicles @ NASA ...)
- identify preferable / acceptable ground noise signature (e.g. NASA)
- assess new flight procedures (e.g. spacial routing @ NLR …)
new concept: identify low-noise concepts by perception
- combination of auralization and noise-to-design
define
„noise goal“
(impact @ observer)
Fig. left © DLR sound machine
DLR.de • Folie 13
L. Bertsch
applications
3) auralization
status quo: (automated) post-process
for conceptual aircraft design:
PrADO
Aircraft
design
Novel configuration PANAM
Acoustic
evaluation
Source noise
PASTA
Auralization
& Propagation
Audible
impression
© M. Arntzen et al.: “Auralization of novel aircraft configurations”, CEAS Conference Sept. 2015
www.DLR.de • Chart 14 L. Bertsch
applications
3) auralization
- approach simulation
(observer location: -2400 m prior touch-down)
© M. Arntzen et al.: “Auralization of novel aircraft configurations”, CEAS Conference Sept. 2015
DLR.de • Folie 15
L. Bertsch
discussion
Thank you!
Your questions?