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FANPAC

Title: Aeroacoustics Methods for Fan-Noise Prediction and Control

General information:

The objective of this programme is to provide European air-frame and nacelle manufacturers with the technology required to control fan tone noise on future civil transport aircraft equipped with advanced high-bypass-ratio (HBR, typically 6:1), very-high-bypass-ratio (VHBR, typically 9:1) or ultra-high-bypass-ratio (UHBR, typically 12:1-15:1), turbofans. Fan noise is predicted to be one of the most important noise sources on HBR, VHBR and UHBR engines and must be controlled if aircraft are to meet future community noise regulations.

Research in this field is required to keep European aircraft, aero-engine and nacelle manufacturers competitive with regard to the US. The objectives of the work are:

i) To establish the physical mechanisms responsible for the generation of fan tones, and to validate aero-acoustic models for predicting fan tone levels,
ii) To explore novel methods for controlling fan tone generation at source (in particular buzz-saw tones),
iii) To develop codes to predict noise attenuations by non-locally-reacting liners and non-axisymmetric liners,
iv) To develop a semi-empirical/theoretical model of wake propagation,
v) To design and test novel 500-5000 Hz acoustic liners for fan noise control, and to validate models for predicting liner performance,
vi) To perform tests using a model fan rig to validate community and cabin noise prediction methods,
vii) To improve community and cabin fan tone noise prediction methods and to assess various techniques to control fan noise, aiming to reduce community noise levels by typically 4dB and cabin buzz-saw noise levels by typically 5-10dB.

Achievements:

The FANPAC programme has addressed the opportunities for noise reduction at source by first developing an improved understanding of the noise source generation mechanisms. A considered and focused approach to noise reduction follows from this understanding. Similarly the optimisation of noise reduction by conventional and novel acoustic liners follows from both a microscopic understanding of the internal liner behaviour and a macroscopic understanding of the propagation of sound over complex impedance structures.

The development of understanding of the noise generation mechanisms in this programme has resulted principally from the testing of the model fan at a range of conditions in several different configurations and equipped with advanced acoustic and aerodynamic instrumentation.

To assess the potential benefit from novel, non-locally reacting, acoustic liners, a two step approach was taken by first analytically modelling the liner behaviour in response to an applied sound field to determine impedances or characteristic properties and validating the model with laboratory impedance tests and second by developing attenuation prediction models for lined ducts.

Considerable progress has been made over the last 3 1/2 years towards the targets originally set. Studies into the human sensitivity to buzzsaw noise have helped identify the problems for controlling cabin noise. There is potential to reduce fan noise by up to 5dB at some conditions through source noise control and the use of acoustic liners. Other technologies such as active noise control may offer further benefits.

Start Date : 1993-01-01

End Date : 1996-06-30

Duration : 42 months

Project Status : Completed

Programme Type : 3rd FWP (Third Framework Programme)

Prime Contractor :

Organisation : Rolls Royce plc

Address : Elton Road PO Box 31

Postcode : DE2 8BJ

City : Derby

Region : EAST MIDLANDS DERBYSHIRE, NOTTINGHAMSHIRE Derbyshire

Country : UNITED KINGDOM

Contact Person : Andrew KEMPTON

Email : andrew.j.kempton@rolls-royce.com

Project Partners :

University of Southampton (UK)

University of Salford (UK)

SNECMA (FR)

Aérospatiale (FR)

University College Galway (IRL)

Danmarks Tekniske Universitet (DK)

Nationaal Lucht- en Ruimtevaart Laboratorium (NL)

Alenia (IT)

Deutsche Aerospace Airbus GmbH (DE)

Université du Maine (FR)

Short Brothers (UK)

SNAAP

Title: Study of Noise and Aerodynamics of Advanced
Propellers

General Information:

Recent progress in aerodynamics, aeroelasticity, materials
and structures has enabled the design of innovative propeller
configurations which operate at the same cruise speeds as
jet-propelled aircraft. The inherently high propulsive efficiency
of these advanced propellers and propfans allows fuel savings
with a corresponding reduction in exhaust emissions. The
major drawback is the level of noise emitted by propellers
operating at high rotational speeds. This is partly due to a lack of detailed information on the understanding of the physical phenomena involved so that commensurate progress in the aeroacoustics of advanced propellers is now essential.

Achievements :

The project SNAAP has provided a complete data base from propeller wind tunnel basic test, i.e. without installation effect. Sophisticated techniques like blade fitted and inflow sensors adapted to acoustic measurements have been used .
In addition aerodynamic and acoustic prediction codes have been developed and their validity investigated.
The work program performed was addressed to: the definition of the parameters and the conditions to be tested in the wind tunnel, to the design and manufacturing of the propeller blade models, to the preparation and realisation of the tests, to the preparation and validation of the theoretical aero-acoustic prediction tools.

Two types of aircraft flight conditions have been simulated to define the condition at which the propellers have been tested: take-off (low Mach number, high angle of attack) and cruise (high Mach number, low angle of attack). The design and manufacturing of the composite instrumented blades was a really challenge. Manufacturing of such instrumented propeller blade was new in Europe. All the activity was completed in 10 months, two sets of 8 blades delivered for wind tunnel tests. The two instrumented models are two 6-bladed propellers. The first one a Low Speed Propeller (LSP) is an advanced subsonic propeller for a cruise Mach number of 0.7 and helical tip Mach number of 0.88; the second one an High Speed Propeller (HSP) is a transonic one with a cruise Mach number of 0.78 and helical tip Mach number of 1.1. Both the propeller models have a diameter of 90 cm. The propeller assemblies have been completed and tested with success.

Although actual work started with one year delay, the wind tunnel testing activity met its targets beyond expectations. Two wind tunnel facilities have been used: ARA transonic wind tunnel, to simulate the cruise condition of the aircraft (high flight Mach numbers), and DNW low speed wind tunnel to simulate take-off, climb and approach conditions (low Mach numbers). Both wind tunnel tests have been safely conducted to a successful end. The amount of data accumulated is unique on European scene and meets the 99% of the project objectives, which is a very impressive result for such a challenging experimental exercise. Those data have been used to validate computer codes developed within the project.

An aeroacoustic code is now available to predict the aerodynamics and the acoustics of such advanced propellers. This is the most important result of the research programme. The code consists of several computer programs which are linked together by a simple procedure. The aerodynamic module of this code works within limits clearly investigated along the project: it cannot include non-axial inflow angles, and it is unable to converge below Mach 0.2.Two acoustic modules developed and validated within the project, are included in the code. Those modules use two different approach one in the time domain, the other in the frequency domain, both use the input from the unique aerodynamic module.

Also the acoustic modules work within some limits: when “classical noise terms” are computed (thickness, loading, ...) the aero input does not influence so much the noise output. So that in take-off condition the predictions are very satisfactory but only with no in-flow angle of attack. In cruise conditions, the prediction tool can provide very helpful results for a large range of “not-too-high” flight Mach number. While when higher Mach number causes helical tip speed to be significantly supersonic, some numerical problems may arise in the loading and quadrupole noise terms calculations.

Furthermore other acoustic tools have been developed within the project and are now available: one to predict the installation effect, due to the aircraft fuselage; another to identify the noise source using fluctuating pressure records.
In addition some empirical methods or simplified models to account the scattering effect of the fuselage and of the angle of attack on the noise, have been developed.

Start Date : 1993-01-01

End Date : 1996-06-30

Duration : 36 + 6 months

Project Status : Completed

Programme Type : 3th FWP (Third Framework Programme)

Prime Contractor :

Organisation : ALENIA Aerospazio

Department : Acoustics

Address : Viale dell’Aeronautica

Postcode : 80038

City : Pomigliano d’Arco

Region : Campania

Country : ITALY

Contact Person : Antonio PAONESSA

Email : apaonessa@aeronautica.alenia.it

Project partners:
Aerospatiale (FR)
Dornier (DE)
Fokker (NL)
NLR (NL)
Dowty (UK)
Ratier-Figeac (FR)
ONERA (FR)
University of Galway (IE)
CIRA (IT)
University of Galway (IE)
IBK (Ingenieurburo Dr.Kretzschmar ) (DE)
TCD (Trinity College Dublino) (IE)
IST (Istituto Superiore Tecnico) (P)

APIAN

Title : Advanced propulsion integration aerodynamics
and noise

General Information:
The need to cope with rapidly evolving requirements for
economically   viable   and   environmentally   acceptable
propulsion   systems has forced   airframers   to explore
revolutionary systems   such as ultra-high by-pass ratio
engines especially open rotors. The development (and
exploitation)   of   these    novel    powerplants     requires
technology to integrate then with the airframe to produce
efficient performance and reduced noise for operational
configurations. The ultimate goal is a competitive new
generation of commuter aircraft with the same operational
capacity and comfort as regional jets yet with reduced
emission and noise. It is first proposed to investigate in
wind tunnels advanced propeller driven aircraft equipped with high-speed propellers (Mach 0.7-0.8). The test rig will primarily consist of an advanced powered wind tunnel model developed in IMT3"GEMINI II" programme. This includes an internal six components balance, a set of two air driven high-power turbines (290 SHP Engine Simulators), a set of typical high-speed propellers (Mach 0.78) with rotating balances and instrumentation such as dynamic pressure sensors or microphones.

Wings, nacelles and propellers are original design from GEMINI and SNAAP CEC funded research programmes. The powered model will be tested in ONERA S1 transonic wind tunnel and in DNW low speed tunnel to investigate aerodynamics and acoustics of "propeller-to-airframe interactions". The same propellers will be tested on an isolated rig in the same conditions to identify the effect of the airframe. In addition, this isolated rig will be adapted to NLR-HST for transonic regime (up to 2 bars generative pressure) to identify Reynolds effects on the propellers (scale effect). Forces, moments, pressures, radiated noise will be measured together with flow field velocities by mean of techniques such as Particle Image Velocimetry (P.I.V.). Second goal is to develop the capability of propeller noise prediction in transonic regime when scattered by an airframe (boundary layer, wing, fuselage effects), SMEs, Universities and Research Centers will cooperate to generate such a computational tool. This will be a development and a first application of the codes initiated under the IMT3 "SNAAP" CEC funded research programme. Predictions will allow an optimisation of the test matrix and experimental data will later on be compared to the theoretical ones to ensure quality of the industrial exploitation policy.

Start Date : 1996-06-01

End Date : 2001-01-31

Duration : 56 months

Project Status : Completed

Programme Type : 4th FWP (Fourth Framework Programme)

Prime Contractor :

Organisation : AIRBUS FRANCE SAS

Adress : Route de Bayonne 316

Postcode : 31060

City : TOULOUSE

Région : Haute-Garonne

Country : FRANCE

Contact Person : Pierre LEMPEREUR

E-mail : pierre.lempereur@airbus.com

Project partners :

Fluid Gravity Engineering Ltd

Trinity College Dublin (IE)

Office National d'Études et de Recherches Aérospatiales (ONERA) (FR)

Ratier-Figeac SA (FR)

University College Galway (IE)

German Aerospace Centre (DE)

IBK Ingenieur Buero - DR Guenter Kretzschmar (DE)

Instituto Superior Técnico (PT)

German - Dutch Tunnel (DE)

Nationaal Lucht- en Ruimtevaart Laboratorium (NL)

Centro Italiano Ricerche Aerospaziali ScpA (IT)

Construcciones Aeronauticas SA (ES)

Airtechnologies SA

Dornier GmbH (DE)

Alenia Aerospazio - Un'Azienda Finmeccanica SpA (IT)

AEROCERT

Title : Aircraft Environmental Impacts and Certification Criteria

General information : AEROCERT describes the research items to provide options for improvement of the certification standards, and recommendations for preferred options related to aircraft environmental impact.

The key objectives and principal tasks are :

I. To identify necessary revisions and/or extensions of the emission certification procedures.

a) To identify the known and possible impacts of aircraft emissions on the environment and to identify the data needed to quantify these impacts.
b) To define possible indices showing the actual impact of aircraft emissions on the environment or usable to quantify the actual impact on the environment.
c) To identify whether the existing certification procedures reflect the impact on the environment, considering different influences such as flight procedures.
d) To define options for possible improvements by changing standards and procedures or by extending them, considering the technical feasibility, effectiveness and economic impact of the proposed improvements.

II. To identify the effect of operational and maintenance procedures on the certified emission levels.

e) To identify the influence of the deterioration in the emission levels of engine and aircraft and to characterise the deterioration in noise and emission levels.
f) To make recommendations on operational and maintenance procedures to keep near to the certification levels.

Start Date : 1997-07-01

End Date : 2000-06-30

Duration : 36 months

Project Status : Completed

Programme Type : 4th FWP (Fourth Framework Programme)

Prime Contractor :

Organisation : STICHTING NATIONAAL LUCHT- EN RUIMTEVAARTLABORATORIUM

Adress : Anthony Fokkerweg 2 90502 1006BM

Postcode : 1059 CM

City : Amsterdam

Country : WEST-NEDERLAND NOORD-HOLLAND Groot-Amsterdam

Pays : NETHERLANDS

Contact person : Name: TEN HAVE, Helmut (Mr)

E-mail : havehbg@nlr.nl

Project partners :

Loughborough University of Technology (UK)

Secretery of State for Defence, Acting Through Defence Evaluation and Reserarch Agency (UK)

The Aeronautical Research Institute of Sweden (SE)

Deutsche Forschungsanstal Für Luft - Und Raumfarhrt E.V. (DE)

AEROCERT Website

ROSAS

Title : Research on Silent Aircraft Concepts

General information :

As a complement to the on-going research and
development efforts deployed by the European
aeronautical community towards the reduction of
civil aircraft noise, efforts which focus on reducing
noise emitted at the source by the engine and the
airframe   like   in   RAIN   and   SILENCE(R)
programmes, the ROSAS project aims   at
developing the necessary capabilities for   the
evaluation and selection of innovative silent aircraft
concepts, characterized by the shielding of the
engine noise sources by the airframe components
(wing/fuselage/empennage).

ROSAS tackles the main critical issues of alternative
installations of advanced turbofan engines through
acoustic experimental and theoretical investigations,
including a wind tunnel test campaign, and CFD-based aerodynamic work to identify the key phenomena and related risks and achieve an efficient shape design in the power plant area. This will be completed with a multi-disciplinary evaluation of the innovative concepts in order to achieve a fair comparison with the conventional under-wing engine installation.

Start Date : 2002-01-01

End Date : 22004-12-31

Duration : 36 months

Project Status : Execution

Programme Type : 5th FWP (Fifth Framework Programme)

Prime Contractor :

Organisation : AIRBUS FRANCE SAS

Department : FUTURE PROJECT OFFICE

Adress : Route de Bayonne 316

Postcode : 31060

City : TOULOUSE

Région : SUD-OUEST MIDI-PYRÉNÉES Haute-Garonne

Country : FRANCE

Contact Person : Pierre Lempereur

E-mail : pierre.lempereur@airbus.com

Project partners :

Centro Italiano Ricerche Aerospaziali S.C.P.A. (I) (IT)

Instituto Superior Tecnico (PT)

Trinity College Dublin (IE)

Analysis Systems Research High -Tech LTD (UK)

Rolls Royce PLC (UK)

Airbus Deutschland GMBH (DE)

Stichting Nationaal Lucht - En Ruimtevaart Laboratorium (NL)

Rolls-Royce Deutscthland LTD&CO KG (DE)

Airbus UK Limited (UK)

Office National d'Etudes et de Recherches Aérospatiales (FR)

Snecma Moteurs SA (FR)

Hurel-Hispano Le Havre (FR)

German Aerospace Centre (DE)

AROMA

Title : Acoustic radiation of small turbomachines

General information :

Predicting the noise produced by turbomachines requires three essential modelling components :

(1) an accurate description of the flow through the turbomachine (WP1);

(2) a model predicting the amplitude of the acoustic source from the results of the CFD calculation (WP2);

(3) a prediction of the propagation of the source in a lined duct taking into account the flow field in the duct (WP3);

The different components must then be seamlessly integrated and connected to an optimisation tool (WP4).

Finally each component of the loop and the integrated system must be validated against experimental results (WP5).

In order to be successful the project must be managed and its results disseminated and exploited (WP6).

The proposal is a result of the SCRATCH initiative and give therefore a leading role to SME. The focus is also on the development of a product / methodology that can be exploited by the SMEs at the end of the project.