ABSTRACT: Technologies for Aircraft Noise Reduction
By Dennis Huff NASA Glenn Research Center
Technologies for aircraft noise reduction have been developed by NASA over the past 15 years through the Advanced Subsonic Technology (AST) Noise Reduction Program and the Quiet Aircraft Technology (QAT) project. This presentation summarizes highlights from these programs and anticipated noise reduction benefits for communities surrounding airports. Historical progress in noise reduction and technologies available for future aircraft/engine development are identified. Technologies address aircraft/engine components including fans, exhaust nozzles, landing gear, and flap systems. New “chevron” nozzles have been developed and implemented on several aircraft in production today that provide significant jet noise reduction. New engines using Ultra-High Bypass (UHB) ratios are projected to provide about 10 EPNdB (Effective Perceived Noise Level in decibels) engine noise reduction relative to the average fleet that was flying in 1997. Audio files are embedded in the presentation that estimate the sound levels for a 35,000 pound thrust engine for takeoff and approach power conditions. The predictions are based on actual model scale data that was obtained by NASA. Finally, conceptual pictures are shown that look toward future aircraft/propulsion systems that might be used to obtain further noise reduction.
1
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13
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15
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16
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to G
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17
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maj
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thru
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tech
nolo
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und
er d
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hat a
re
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d no
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r a n
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vels
for a
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ed ta
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bas
ed o
nac
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’s w
ind
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et A
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of th
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cous
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Qui
et A
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nes
of th
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d En
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eds
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cous
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plitt
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lat C
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ound
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ecte
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vel r
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for
obje
ctio
nabl
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ise
to b
e co
ntai
ned
with
in a
irpor
t bo
unda
ry.
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icte
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urce
Noi
se R
educ
tion
Rela
tive
to C
urre
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leet
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rage
Ta
ke-O
ff C
ondi
tion
-24
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rent
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etA
dvan
ced
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nes
&A
irfr
ame
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port
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dary
EPNdB
Clic
k on
pic
ture
to
play
sou
nd d
emo:
Inle
t A
ft
Aud
io S
eque
nce
12
3
19
Nat
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Qui
et A
irpla
nes
of th
e Fu
ture
Adv
ance
d En
gine
s &
Airf
ram
e•L
ower
Fan
Tip
Spe
eds
•Low
er J
et E
xit V
eloc
ities
•Var
iabl
e A
rea
Noz
zle
•“So
ft”Fa
n St
ator
Van
es•F
an T
raili
ng E
dge
Blo
win
g•B
ypas
s A
cous
tic S
plitt
er•“
Tobo
ggan
”La
ndin
g G
ear
Fairi
ngs
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tinuo
us M
old
Line
Fla
p•S
lat C
ove
Fille
r
Airp
ort B
ound
ary
Proj
ecte
d le
vel r
equi
red
for
obje
ctio
nabl
e no
ise
to b
e co
ntai
ned
with
in a
irpor
t bo
unda
ry.
Pred
icte
d So
urce
Noi
se R
educ
tion
Rela
tive
to C
urre
nt F
leet
Ave
rage
A
ppro
ach
Con
ditio
ns
-24
-20
-16
-12-8-40
Cur
rent
Fle
etA
dvan
ced
Engi
nes
& A
irfr
ame
Air
port
Boun
dary
EPNdB
Clic
k on
pic
ture
to
play
sou
nd d
emo:
Inle
t A
ft
Aud
io S
eque
nce
12
3
20
Nat
iona
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154.
2”Fa
n D
iam
eter
Sing
le F
an O
n B
lend
ed W
ing
Bod
y (B
WB
)
21
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iona
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istra
tion
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105.
1”Fa
n D
iam
eter
Dua
l Fan
On
Ble
nded
Win
g B
ody
(BW
B)
22
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iona
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Dua
l Fan
–C
once
ptua
l App
licat
ions
23
Nat
iona
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istra
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Sum
mar
y•C
onsi
dera
ble
prog
ress
has
bee
n m
ade
over
the
past
15
year
sde
velo
ping
tech
nolo
gies
for a
ircra
ft no
ise
redu
ctio
n.
•NA
SA h
as b
een
wor
king
clo
sely
with
aer
ospa
ce c
ompa
nies
toid
entif
y op
port
uniti
es to
intr
oduc
e ne
w te
chno
logi
es in
toen
gine
s an
d ai
rcra
ft.
•Lim
ited
tech
nolo
gies
are
retr
ofit-
able
, mos
t will
requ
irede
velo
pmen
t with
new
veh
icle
s.
•Ben
efits
nea
r airp
orts
are
incr
emen
tal d
ue to
slo
w tu
rnov
erfr
om e
xist
ing
airc
raft
to n
ewer
airc
raft
with
bet
ter n
oise
redu
ctio
n te
chno
logi
es.
•Tec
hnol
ogie
s ex
ist t
oday
to p
rodu
ce a
ircra
ft/en
gine
com
bina
tions
that
can
mov
e th
e av
erag
e 65
LD
N n
oise
con
tour
near
the
airp
ort b
ound
arie
s if
the
entir
e fle
et w
ere
repl
aced
.