Objective 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.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 process has been made over the last 3 1/2 years towards the targets originally set. Studies into the human sensitivity to buzz saw 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.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. Fields of science engineering and technologymechanical engineeringvehicle engineeringaerospace engineeringaircraftnatural sciencesphysical sciencesacoustics Programme(s) FP3-AERO 1C - Specific programme of research and technological development in the field of industrial and materials technologies - Aeronautics research -, 1990-1994 Topic(s) Data not available Call for proposal Data not available Funding Scheme CSC - Cost-sharing contracts Coordinator ROLLS-ROYCE PLC EU contribution No data Address 65 BUCKINGHAM GATE SW1E 6AT LONDON United Kingdom See on map Total cost No data Participants (11) Sort alphabetically Sort by EU Contribution Expand all Collapse all Alenia Un'Azienda Finmeccanica SpA Italy EU contribution No data Address Corso Marche 41 10146 Torino See on map Total cost No data Aérospatiale Société Nationale Industrielle SA France EU contribution No data Address 316 route de Bayonne 31060 Toulouse See on map Total cost No data CENTRE NATIONAL DE LA RECHERCHE SCIENTIFIQUE France EU contribution No data Address Centre d'Affaires Oberthur, 74E rue de Paris 35069 RENNES See on map Total cost No data Danmarks Tekniske Universitet Denmark EU contribution No data Address 2800 Lyngby See on map Total cost No data Deutsche Aerospace Airbus GmbH Germany EU contribution No data Address Kreetslag 10 21111 Hamburg See on map Total cost No data STICHTING NATIONAAL LUCHT- EN RUIMTEVAARTLABORATORIUM Netherlands EU contribution No data Address Anthony Fokkerweg 2 1006 AMSTERDAM See on map Links Website Opens in new window Total cost No data Short Brothers Plc United Kingdom EU contribution No data Address Airport Road BT3 9DZ Belfast See on map Total cost No data Société Nationale d'Études et de Construction de Moteurs d'Aviation (SNECMA) France EU contribution No data Address 2 boulevard du Général Martial Valin 75724 Paris See on map Total cost No data UNIVERSITY OF SOUTHAMPTON United Kingdom EU contribution No data Address Highfield SOUTHAMPTON See on map Links Website Opens in new window Total cost No data University College Galway Ireland EU contribution No data Address 90 Galway See on map Total cost No data University of Salford United Kingdom EU contribution No data Address The Crescent M5 4WT Salford See on map Total cost No data