Adaptive and Passive Flow Control for Fan Broadband Noise ... · 15.11.2015 16 Work Package 4: Flow...

Adaptive and Passive Flow Control for Fan Broadband Noise Reduction

Selected final results

Lars Enghardt, DLR BerlinFLOCON project coordinator

September 2008 – August 2012

15.11.2015Author: Lars Enghardt, DLR Berlin19th CEAS Workshop, La Rochelle 2

Motivation• Air traffic is predicted to grow by 5% per year in the short and medium term.

• Technology advances are required to achieve his growth with acceptable levels of noise in particular at airport surroundings.

• Fan broadband noise is one of the most important aircraft noise sources at aircraft start and landing conditions.

Objectives• Design noise reduction concepts and associated devices able to reduce fan broadband noise

at source.

• Assess the noise reduction concepts by conducting lab-scale experiments (to TRL 4).

• Complement the experiments by numerical simulations that are assessing the capability ofcurrently available numerical tools to design low broadband noise treatments and configurations.

• Develop understanding of the mechanisms involved and extrapolate the results to the aero-engine environment using state-of-the-art numerical methods.

• Select the best concepts by balancing noise benefit and integration impact.

Introduction

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Research centers:DLR - Deutsches Zentrum für Luft und Raumfahrt (DE)ONERA - Office National d’Études et Recherches Aérospatiales (FR)ISVR - Institute of Sound and Vibration Research (UK)NLR - Nationaal Lucht- en Ruimtevaart Laboratorium (NL)

Industrial partners:Snecma Moteurs (FR)Rolls-Royce plc (UK)EADS Innovation Works (DE)MTU Aero Engines (DE)VOLVO Aero Corporation (SW)AVIO SpA (IT)

Universities:Ecole Centrale de Lyon (FR)Universität Siegen (DE)Chalmers University of Technology (SW)Technische Universität Berlin (DE)

SME:Fluorem SAS (FR)Microflown Technologies BV (NL)Sandu M. Constantin PF (RO)

• Budget: 5.3 M€ (EU funding 3.5 M€)• Project start: 1. September 2008 • Duration: 4 years (12 months extension at no costs)• Coordination: DLR Berlin

EU FP7, 1st Call, Level 1 ProjectConsortium

Author: Lars Enghardt, DLR Berlin19th CEAS Workshop, La Rochelle

15.11.2015 4

Work Package 2:Airfoil treatments for low-noise

Objective• Development of leading edge and trailing edge treatments for reducing

airfoil self-noise and interaction noise and for reducing the turbulence in the wake.

Workplan• Demonstration and validation of these treatments in an open jet wind

tunnel facility (TRL 2)• Down-selection of the best trailing edge treatments for testing in a

cascade rig (TRL 3) and of the best leading edge treatments for testing in a fan rig in WP3(TRL 4).

• Modelling of these treatments using RANS and LES CFD simulations.


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ISVR open jet wind tunnel

Airfoil to be investigated


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2040

60

05

1015

-1-0.500.511.522.533.54

OA

SW

L re

duct

ion

[dB

A]

Geometrical AoA [degree]U [m/s]

LE1

LE2

LE3

05

1015

-100.0%

-80.0%

-60.0%

-40.0%

-20.0%

0.0%

20.0%

CL reduction

Treatments

Geometrical angle of attack [degree]

ONERA LE

CL

redu

ctio

n

AoA [degree]TEDown select of best LE treatment:

ONERA wavy pattern

Leading edge treatment


Acoustic pressure field (Pa)

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Calculation : V. Clair

3D multi-bloc grid with 1 motif of 2S wing

ONERA Euler computations on wavy-edge case


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20

40

60

05

1015

-1-0.500.51

1.5

2

2.5

3

3.5

4

OA

SW

L re

duct

ion

[dB

A]

Geometrical AoA [degree]U [m/s]

TE15

TE17

05

1015

-2.0%

0.0%

2.0%

4.0%

6.0%

8.0%

10.0%

CL reduction

Treatments

Geometrical angle of attack [degree]

ISVR TE

CL

redu

ctio

n

AoA [degree]TE

Down select of best TE treatment:ISVR serrated edge

Trailing edge treatment


15.11.2015 9Slide 9

AVIO3D LES on Treated airfoils


Velocity on a plane normal to the serration plate

ROOT MID TIP

ROOT

MID

TIP

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ISVR tandem experiment


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Work Package 3: Casing and airfoil treatments for low noise in a fan stage

Objective Development of new and innovative technologies for fan broadband noise

reduction focusing on airfoil treatments and the interaction between blade tip and fan casing.

Workplan• Demonstration and validation of these technologies (selected best concept

from WP2, special overtip treatment) on a low speed laboratory rotating rig • Demonstration of vane trailing edge treatment technology for fan

broadband noise reduction under rotating rig flow conditions


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EADS low speed fan rig


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Tuneable Overtip Acoustic Treatment

EADS - Overtip acoustic treatment


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OGV Treatment

Porous Trailing EdgeSinter metal spheres

CFD / CAA

OGV treatments


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SN / FLU: Cavity Treatment


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Work Package 4: Flow Control in a Fan Stage

Objective• To develop and assess several broadband noise reduction concepts by

means of flow control in a fan-OGV stage.• To understand the physical influence of the flow control concepts on

broadband noise.

Workplan• Support the assessment of each concept with numerical and experimental

investigations. • Achieve broadband noise reductions in experiments performed under

representative conditions of a fan-stage.


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mass flow meter

radial blower

microphone array

duct section for suction

DAQ system

continous circumferential slit at rotor LE

DLR laboratory scale fan rig


15.11.2015Author: Lars Enghardt, DLR BerlinX-Noise EV FC Meeting, Lausanne 18

NLR: Source localization and azimuthal mode decomposition


DLR: Stator with variable vane stagger angle

TUB: Instantaneous spanwise vorticity and pressure time derivative

TUB: Noise impact of Gurney flaps

Adaptation of stator vane loading


Trailing edge blowing

MTU: Simulation of wake filling (different slit counts)

USI: Rotor blade with internal channels

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Experimental assessment of the wake filling

Wake filling

5 slots in the rotor trailing edge

Supply of pressurized air


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Axial Velocity:

no wake filling with wake filling (blowing 142 g/s)

Turbulence intensity:

Wake filling


15.11.2015 23Author: Lars Enghardt, DLR Berlin19th CEAS Workshop, La Rochelle

ONERA: LES computation resultscomparison of baseline and blowing case

ONERA: LES computation resultscomparison of baseline and blowing case

Average relative velocity amplitude and streamlines near the trailing edge of the rotor

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Wake filling (post FLOCON)


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Wake filling (post FLOCON)


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Technology Evaluation

• Virtual platforms used for the in-flight noise transposition:

The FLOCON technology is assessed on the Short-Medium Range (SMR) and Long-Range (LR) OPENAIR virtual aircraft platforms

The SMR engine platform AP2-EP1b - is a turbofan BPR 9 engine - engine modelling provided by SN- The technology level of this engine is coherent with an initial EIS date in

year 2012


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-0.35

-0.3

-0.25

-0.2

-0.15

-0.1

-0.05

0

Del

ta E

PNL

tota

l

(e

ngin

e+ai

rfra

me)

FLOCON technologies impactsEPNL total (engine + airframe) WP2

Wavy LE

Microfiber LE

Porous LE

Porous TE

Saw-tooth serrations

Butterfly TE


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-0.25

-0.2

-0.15

-0.1

-0.05

0

0.05

0.1

0.15

Del

ta E

PNL

tota

l

(e

ngin

e+ai

rfra

me)

FLOCON technologies impactsEPNL total (engine + airframe) WP4

Gurney flaps T4.1

Suction of rotor vortex T4.2

Wake-filling T4.3


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• A wide range of concepts was considered and developed to Technology Readiness Level 4 (laboratory scale validation): Rotor trailing edge blowing Rotor tip vortex suction Rotor overtip treatments Rotor and Stator leading and trailing edge treatments Partly lined stator vanes

• Experiments were performed on 4 rigs: two rotating rigs, supported by more detailed measurements on a single airfoil and on a cascade.

• Numerical methods were used to optimize the concepts for experimental validation and to extrapolate the results from laboratory scale to real engine application.

• The potential benefit of each concept was assessed, including any associated penalties (weight, complexity, aerodynamic performance).

• Recommendations were made as to which concepts could be integrated into new engine designs or will require further validation at industrial rig or full engine-scale.

Summary: Final results


Adaptive and Passive Flow Control for Fan Broadband Noise ... · 15.11.2015 16 Work Package 4: Flow...

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