Engine noise in diffuser section reduction method and composite sound absorbing panel usage and material survey and testing methods

1. REDUCTION OF NOISE IN COMP
RESSOR USING ACOUSTIC LINE
R
GUIDE:
MR.ARAVINDHAN
(ASSISTANT PROFESS0R)
REC
BY:
SAMEER M (211613101033)
Final year

2. ACOUSTIC
DEFINITION:
 It is the interdisciplinary science that deals with the study of all mechanic
al waves in gases,liquids, and solids such as vibration, sound, ultrasound,
and infrasound.
NOISE FROM AIRCRAFT:
The noise originates from three main sources
 Aerodynamics noise
 Engine and other mechanical noise
 Noise from aircraft system

3. NOISE INSIDE ENGINE COMPONENTS
 Aircraft jet enigines are responsible for much of the aircraft noise, such as
the buzzsaw noise generated when the tips of the fan blades reach supers
onic speeds.
 Noise also produced from exhaust. The high velocity jet leaving the back o
f the engine has an shear layer instability, ring vortex formation.Eventually
leads to breakdown into turbulence.
PROJECT AREA:
 We are concentrating on reducing
the noise on compressor

4. AIM
Reducing the noise which was produced from compressor region using Acoust
ic liner.
ACOUSTIC LINER:
 It is a composite panel
Which has the ability to
Absorb or weakens the
Sound waves produced on
The compressor region and
Diffuser duct.
(stator and rotar blades)
 It is placed on the
Nacelle cowling in the
Compressor region.

5. ACOUSTIC LINER REQUIRE
MENTS
Acoustic Liners are fundamental in ensuring jet aircraft ar
e quiet, but they must also satisfy many other requirement
s:
Must be effective over a wide range of engine operating c
onditions and frequencies (reducing both tones and broad
band noise)
 Must fit into the restricted space available (liner depth a
nd area)
Must be light to ensure that fuel burn is not penalised
 Must be cost effective to buy their way onto the aircraft
 Must be specified when many details of the airframe a
nd engine design have not been finalised, so the liner desi
gn must be robust
 Must be integrated with other engine design requireme
nts
 Must survive rain, ice, oil leaks, maintenance staff ...
 Must satisfy manufacturability and maintainability requ
irements, for decades of in-service life in the exacting aer
o-engine environment

6. RECENT DEVELOPMENT OF USI
NG ACOUSTIC LINER
 Recently there was huge demand for using Acoustic liner in Aircraft
various positions such as Engine Inlet and even in exhaust .
 There was a recent development and testing of using acoustic liner in wing
inside casing to reduce airframe noise produced inside the wing section.
 Application of Acoustic liner in fuselage section is developing right now in
order to act as a barear for preventing outside noise from entering
fuselage section.

7. •Material survey
•JT 3D-3=glass fibre reinforced epoxy
Composite in back plate, core material
Nomex honeycomb.
•CFM 56 -3= kevlar 49,aramid fibr
e reinforced composite in back pl
ate, thermoplastic elastomer core
material.
•V2500=carbon panel in back plate, d
ouble nomex honeycomb core with se
ptum
•A/c muffler=ceramic foams are used, p
orous material like metal rubber could b
e applied as facing sheet materials of h
oneycomb liners.

8. ACOUSTIC LINER:
 Aircraft engine typically turbofans use acoustic Liner to damp engine noise.
Liners are applied on the internal walls of the engine nacelle in the intake and use
Helmholtz resonance principle for the dissipation of incident acoustic energy.
HOW TO MAKE AN ACOUSTIC LINER?
 A porous top layer called Face Sheet.
 A honeycomb structure providing internal partition
 An impervious layer called Back Sheet or Back Skin.
 Acoustic liners can be distinguished by their internal configuration on the
base of the number of honeycomb cell layer.
 porous layer ( e.g. the septum and the face sheet) can be for example a
perforate plate, a wire mesh or a felt- metal.
 The honey comb can be of alumunium or glass fiber and the cells size is selected
small enough to ensure an acoustic plane wave in the cell for the whole frequency
of interset.The face sheet and back-skin can be either metalic or in natural fiber or
synthetic fiber.

9. MATERIAL GOING TO USE
 In acoustical liner, the material should be good enough for sound absorption
coefficient, noise reduction coefficient, acoustic impedance, and reflection
coeffecient.
LINER CONSTRUCTION & MATERIAL GOING TO
USE.
 we made an acoustic liner by using sandwach construction of composite materials.
 A sandwhich consists of face material, core and the back sheet.
 In which we are using a perforated alumunium face sheet .
 In the core we are placing a nomex honey comb material.
 In between the honeycomb and back sheet we are placing an septum material,
which is an wire meshing of alumunium material.
 In the back panel, we are using an natural fiber(JUTE) reinforced polymer
material,in which natural fiber has more sound absorption than synthetic fiber.

10. MATERIAL SURVEY FROM JO
URNAL
Material comparison chart Frequency vs ISR

11. INSTRUMENTS REQUIRED
TO TEST ACOUSTIC LINER PANEL
 We are going to make use of jet compressor from the nozzle jet noise. We
are
going to set a rectangular tunnel like section.
 So that we can compress the jet flow and make an artifical noise inside the
tunnel section instrument , without acoustic liner for different frequency we
are going to find sound inside the section.
 After that we are going to use Acoustic liner in that section so that we
calculate the noise reduced in tunnel section by using microphone and
parameters to calculate like NR,TR , graph for SL VS Frequency can be
calculated.

12. LECTURER SURVEY
 Evaluation of Ceramic Matrix Composite Technology for Aircraft Turbine Engine Applications
Michael C. Halbig1, Martha H. Jaskowiak2, James D. Kiser3, and Dongming Zhu4,N
ASA Glenn Research Center, Cleveland, OH 44135
 Using Acoustic Liner for Fan Noise Reduction in Modern Turbofan Engines
Mohammadreza Azimi and Fathollah Ommi Faculty of Mechanical Engineering, T
arbiat Modares University, Tehran, Iran
 Noise pollution of air compressor and its noise reduction procedures by using an
enclosure
Farhad Forouharmajd1,2, Parvin Nassiriz, Mohammad Reza Monazzam
 APPLICATION STATUS OF COMPOSITE ACOUSTIC LINER INAERO-ENGINE Dongbi
ng Geng , Kai Yi†, Chengyuan Shang Jian Yan , Yehong He

13.  The role of absorptive silencer in reduction of low-frequency noise produced by
a fan
Hossein Ali Yousefi, Farhad Forouharmajd, Leila Maghsudian1
 Predicted sound absorption coefficients of absorber materials lined in a chambe
r
Farhad Forouharmajd1,2, Parvin Nassiri2, Mohammad Reza Monazzam2, Mohamm
adreza Yazdchi3

14. THANK
YOU