Speaking about FlowAirS

FlowAirS Calendar

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FlowAirS in the medias

  • Radio Alpa live from Le Mans European Researchers' Night, 25 Septembre 2015 - interview P. Raséra (min 50:30)
  • F. Sanna has been nominated as “Fellow of the week” on the MSCA Facebook page (26th June 2015)
  • Marie Curie Alumni Magazine "IRRADIUM", n°1, February 2015 - interviews F. Sanna, Y. Aurégan and J. Golliard: Discover a Marie Curie project – FlowAirS (access restricted to MCAA members)
  • Radio Alpa, "Le Labo des savoirs" live from Le Mans European Researchers' Night, 26 September 2014 - interview A. Alomar
  • Magazine "Innovation & Industrie", n°71, December 2013, p. 61 - article
  • Magazine "Chercheurs européens", l'UNAM, n°7, October 2013, p. 13 - interview Y. Aurégan

6th European Transport Research Conference - Warsaw, Poland

Francesco Sanna presented his research work within FlowAirS during the 6th European Transport Research Conference that took place in Warsaw (Poland).

More information: http://www.traconference.eu/

ESR 11 - Maaz Farooqui PhD Defense

Topic: "Innovative noise control in ducts"

Jury:
Opponent:
Ih, Jeong-Guon, Professor

Supervisors:

Åbom, Mats, Professor 

Bodén, Hans, Professor 

Elnady, Tamer, Professor

 

Abstract :

The objective of this doctoral thesis is to study three different innovative noise control techniques in ducts namely: acoustic metamaterials, porous absorbers and microperforates. There has been a lot of research done on all these three topics in the context of duct acoustics. This research will assess the potential of the acoustic metamaterial technique and compare to the use of conventional methods using microperforated plates and/or porous materials. 

The objective of the metamaterials part is to develop a physical approach to model and synthesize bulk moduli and densities to feasibly control the wave propagation pattern, creating quiet zones in the targeted fluid domain. This is achieved using an array of locally resonant metallic patches. In addition to this, a novel thin slow sound material is also proposed in the acoustic metamaterial part of this thesis. This slow sound material is a quasi-labyrinthine structure flush mounted to a duct, comprising of coplanar quarter wavelength resonators that aims to slow the speed of sound at selective resonance frequencies. A good agreement between theoretical analysis and experimental measurements is demonstrated.

The second technique is based on acoustic porous foam and it is about modeling and characterization of a novel porous metallic foam absorber inside ducts. This material proved to be a similar or better sound absorber compared to the conventional porous absorbers, but with robust and less degradable properties. Material characterization of this porous absorber from a simple transfer matrix measurement is proposed.The last part of this research is focused on impedance of perforates with grazing flow on both sides. Modeling of the double sided grazing flow impedance is done using a modified version of an inverse semi-analytical technique. A minimization scheme is used to find the liner impedance value in the complex plane to match the calculated sound field to the measured one at the microphone positions.

 

More information here.


ESR 2 - Francesco Sanna PhD Defense

Topic: "Interraction between flow induced pulsations and multiphase flows in gas liquid systems"

Jury:
Rapporteurs:
Avraham HIRSCHBERG Professeur, Technische Universiteit Eindhoven
Christophe SCHRAM Professeur, the von Karman Institute for Fluid Dynamics
Examinateurs: Yves GERVAIS Professeur, Université de Poitiers
Invité(s): Stefan P.C. BELFROID Chercheur, TNO, Pays-Bas
Directeur de thèse: Yves AUREGAN DR CNRS, LAUM, Univ. du Maine
Co-encadrant de thèse: Joachim GOLLIARD Docteur, TNO, Pays-Bas

Abstract :
Coupling between flow instabilities and acoustic resonances in ducts with closed side branches leads to Flow Induced Pulsations (FIPs). This is a typical phenomenon in engineering applications (gas transport systems, compressor installations, and chemical plants). The objective of this work is to extend the knowledge about FIPs when the transported medium is not uniquely gas but a combination of gas and (a small quantity of) liquid. For two configurations of double side branches (in tandem and in quasi-cross), the amplitude of pressure pulsations in the side branches was measured for different liquid injection rates. This was repeated with the liquid injection point located at different places to allow different flow regimes at the pipe connections. The results show a strong effect of the water content on the pulsations.
On basis of these results and additional measurements, the following hypotheses for the effect of liquid were made : (1) interaction of the liquid with the flow instability and (2) increase of the acoustical damping in the ducts in presence of liquid. The effect of liquid on damping was measured with a dedicated test setup designed to have a stratified flow. It was found that the liquid always increases the acoustical damping, mainly due to the reduction of the effective cross section by the liquid, and because of the increased turbulent friction at the interface between gas and liquid.

ESR1 - Lei Xiong PhD Defense

Topic: "Use of mode coupling to enhance sound attenuation in acoustic ducts : Effects of exceptional points"

Jury:
Rapporteurs: Jean-François MERCIER DR CNRS, POems (UMR 7231), ENSTA
Michel ROGER Professeur, LMFA, Ecole Centrale de Lyon
Examinateurs: Emmanuel PERREY-DEBAIN Professeur, Laboratoire Roberval, UTC
Hélène POSSON, Docteur Airbus Operations S. A. S.
Directeur de thèse: Yves AUREGAN DR CNRS, LAUM, Univ. du Maine
Co-encadrant de thèse: Wenping BI Maitre de Conférences, LAUM,Univ. du Maine

Abstract :
The central theme of this thesis is to use the mode coupling effects to enhance sound attenuation in acoustic ducts for potential applications, e.g. silencers for ventilation systems and wall treatments for aircraft engines. Two different strategies are presented. The idea of the first strategy is to couple the incoming propagative mode in the duct with the mode localized in the scattering region. This strategy is first presented in an acoustic duct-cavity system and then applied in a partially lined waveguide. It is shown that a zero in the transmission is present when a real resonance frequency of the open system is equal to the incident frequency. This transmission zero with a transmission peak occurs as a Fano resonance - due to the excitation of a trapped mode in the open system. This trapped mode is formed by the interferences of two neighboured modes with complex resonance frequencies. It is also linked to the avoided crossing of the eigenvalues and exceptional point (a point in a 2D parameter space, where not only the eigenvalues but also the eigenfunctions of a non-Hermitian operator coalesce). The scattering matrix is expressed in terms of a matrix Heff which describes the complex resonances in the scattering region. With the aid of the eigenvalues and eigenfunctions of matrix Heff , the traditional acoustic resonance scattering formula can be extended to describe the coupling effects between the scattering region and the rigid parts of the waveguide.
In the second strategy, a set of periodic rigid inclusions are embedded in a porous lining to enhance sound attenuation at low frequencies. The mode coupling is due to the presence of the embedded inclusions. Floquet-Bloch theorem is proposed to investigate the attenuation in a 2D periodic waveguide. Crossing is observed between the mode attenuations of two lower Bloch modes. The most important and interesting figure is that near the frequency where the crossing appears, an attenuation peak is observed for the least attenuated mode. This phenomenon can be used to explain the transmission loss peak observed numerically and experimentally in a 3D waveguide with a portion of its wall lined by a porous material embedded with periodic inclusions.
Finally, the acoustical behaviours of a purely reacting liner in a rectangular duct in both absence and presence of flow are investigated. The results exhibit an unusual acoustical behaviour : for a certain range of frequencies, no wave can propagate against the flow. A negative group velocity is found in a certain range of frequencies, and it is demonstrated that the sound can be slowed down and even stopped.

Presentations and Seminars by FlowAirS fellows

28 and 30/04/2015 - ESR8 Deepesh K. Singh presented his work within the FlowAirS project at the Department of Aerospace Engineering of the Indian Institute of Technology (IIT) Kharagpur  and at the ITT Delhi (India).

14/04/2015 - ER1 Antoni Alomar presented his research activities within the FlowAirS project during a Seminar on "Liner impedance determination from PIV measurements / Investigation into bluff body roughness noise" in the LAUM.

13/03/2015 - ESR6 Gabriele Grasso presented his research on "A rotor wake – rotor tonal interaction noise computation procedure for contra-rotating fans" at the IFAR virtual Conference on "PhD research in Aviation Fluid Dynamics" that took place during the 6th VKI PhD Symposium. The aim of this virtual conference was to stimulate technical and scientific interaction between young researchers of the IFAR partner organisations and associated universities.

17/04/2013 and 9/04/2014 - ESR8 Deepesh K. Singh presented his work during the CASA Days 2013 and 2014 at TU/e. CASA days are the opportunity for PhD students to explain their research of the past six months and discuss their plans for the next six months.

European Researchers' Night 2015: 10th Anniversary - Science is Wonder-ful!

The European Researchers' Night is a mega event which takes place every year simultaneously in several hundred cities all over Europe and beyond. The events offer a wide variety of fun-learning activities, frombehind-the-scenes guided tours of research labs that are normally closed to the public, through interactive science shows, to hands-on experiments or workshops. The European Researchers' Night is supported by the European Commission through the Marie SkÅ‚odowska-Curie Actions. You can find an event in your region here.

On the occasion of the 10th Anniversary of the European Researchers' Night, a big event has been organised in Brussels. "Science is Wonder-ful" was the opportunity for the public to discover projects from Marie SkÅ‚odowska-Curie researchers, aiming at getting people, especially young people, interested and engaged in science and research. Francesco Sanna, ESR2 at TNO, was there with a stand to present his activities within FlowAirS.

 

Euronoise 2015

Various FlowAirS fellows presented their work during the Euronoise 2015 congress in Maastricht (session on Fans, ducts and mufflers).

In this occasion, ESR11 Maaz Farooqui won the EAA Best paper awards for young researchers.

Forum Jeunes Recherche 2014 - Université du Maine

Lei Xiong and Francesco Sanna presented their work on posters during the 12th Forum Jeunes Recherche that was held in Le Mans.

Click here to see Lei Xiong's poster

Click here to see Francesco Sanna's poster

European Researchers' Night 2014

The European Researchers' Night 2014 edition took place on 26th September simultaneously in several hundred cities all over Europe and beyond.

This is a unique opportunity for the public to explore science in engaging ways and discover what researchers really do and why it matters for everyone's daily life.

In Le Mans, Antoni Alomar has been interviewed about his experience as a FlowAirS fellow during the "On Air" live radio broadcast.

Official launch of Horizon 2020 in the Mediterranean

FlowAirS has been invited to participate in the exhibition of success stories (poster) during the official launch of HORIZON 2020 in the Mediterranean region Conference organised by the European Commission in Cairo.  

The conference brought together around 400 policy makers, researchers, representatives from academia and industry and research institutes, technology transfer centers, incubators, technology platforms from the EuroMed region and all research and innovation community in the EuroMed region.

More information: www.euromedh2020.com

 

Séminaire EUROPE - L'UNAM

The coordinator presented FlowAirS as an example of an on-going ITN project during the Séminaire EUROPE "Du 7e PCRD à HORIZON 2020", organised by the service Europe et recherche of the UNAM held on 17th October 2013 in Nantes.

Program (in French)