Hereafter the summaries of the short and long projects now closed and selected in the frame of the 2012 Call of LabEx EMC3:
Characterisation in line of Polycyclic Aromatic Hydrocarbons (HAPs) by soot Axis 2: Clean combustion – CIMAP/CORIA Polycyclic Aromatic Hydrocarbons (PAH) are hydrocarbons molecules generated from incomplete combustion processes of fossil material (oil, fuel, coal…) at high temperature. These molecules are created in low-oxygen conditions during the combustion process of automotive (diesel), domestic (wood) or industrial fuel. Many studies are led on HAPs because their aromatic characteristics give them a biological activity which can contribute to cellular dysfunction with carcinogenic and mutagenic effects on the organisms. Then, PAHs are listed among the pollutants by the World Health Organisation or the EU. Besides, PAHs play a significant role in the generation of soot particles. But the diagnostics allowing to characterize them are not easily measurable and cannot detect the capacity of these molecules to fix on soot during their growth within the combustion flames. The CAHAPS project (Characterisation in line of the adsorption of Polycyclic Aromatic Hydrocarbons by soot) led by Dr Jérôme Yon from CORIA proposes the implementation of a device allowing to generate and measure the adsorption of PAHs by soot aggregates. This project lies on the cooperation of 2 laboratories, one specialised in the generation and characterization of soot (CORIA – INSA Rouen / University of Rouen), the other working on the control of the generation and characterization of PAHs (CIMAP – ENSICAEN / University of Caen). Within a year, the joint team led engineering work by adapting different devices to generate controlled-sized soot and soaked it with PAHs in a depressurized environment. Afterwards, analysis works have been undertaken in order to characterize different hydrocarbons molecules adsorbed on soot thanks to mass spectroscopy (TOF-MS). In this new approach, the works led to enhance the specific adsorption of some PAHs on soot and generate soot aggregates covered with PAHs perfectly identified. Other studies must be carried out to measure the rate of adsorbed PAHs. These exploratory results let see the opportunity to identify quantitatively the pollutants derived from the combustion of organic matter (biofuel as traditional fuel) in a few years in order to improve the systems of energy production.
Dynamics of Görtler vortices and their impact on heat transfer Axis 2 : Clean Combustion – CORIA/LOMC This project aims to model the heat transfer phenomena that occur in turbulent flow dominated by longitudinal vortices induced by the centrifugal force, typically caused by the curvature of a concave wall. The two partners share their research experiences between physical physical modeling undertaken by the LOMC laboratory and high-performance numerical simulation performed by the CORIA laboratory. These fundamental studies are part of efforts undertaken to understand and improve the – thermal behavior of materials subjected to high temperatures such as those encountered in the automotive and aerospace sectors but also in energy production (solar, wind, tidal, geothermal…). This work laid the groundwork in numerical modeling to understand these complex phenomena and should serve as state-of-the-art for the scientific community. The study opens the way to new investigations, for a fine prediction of heat process at walls, and their control in industrial systems, such as micro-mixers, heat exchangers, gas turbine blades, or aeronautical injectors.
Schematic of Görtler vortices and numerical simulations
Influence of the Nanostructure on the evolution under irradiation of the microstructure and on the properties of austenitic stainless steel Axis 1: Materials for energy – GPM/CIMAP/CRISMAT In nuclear power stations, the interior structures of the pressurized water reactors are composed of austenitic stainless steel. The functioning conditions (temperature, neutron irradiation, environment, mechanical constraints) to which these structures are subject bring a deterioration of the properties of the steel which compose them. This evolution can lead to the rupture of some parts by a mechanism of corrosion under constraint caused by the irradiation and thus limit the life of these reactors. The irradiation sustained by the steel provokes modifications at the microstructural level by creating several punctual shortcomings. They are formed by ballistic collisions between the neutrons from the fission reactions and the atoms of the structure materials. This project aimed at elaborating an austenitic stainless steel with fine grains (from 10 to 100 nm), by severe plastic deformation of a 316-type steel. Then, studying its behavior under ion irradiation would help determine to which extent nanostructuration improve the resistance to irradiation. According to several studies on ultra-fine grain materials, nano-austenitic stainless steel developed in laboratory are more resistant to irradiation and corrosion during irradiation better than conventional steel. Thus, this proves the potential of nanostructuration to improve the resistance of irradiated steel in a corrosive environment. Besides, this project allowed to enhance the existing collaborations between the GPM laboratory in Rouen and the IPAM (Russia) resulting in a European project (ERA.NET-RUS). Leader : Bertrand Radiguet (GPM) TEM microscope and diffraction pictures related to “micro-structured” (a), nanostructured (b) and nanostructured galvanneal 316-type steel (c).
White light emission based on ZnO doped with rare earth ions and metals Axis 1: Materials for energy – CIMAP/CRISMAT/GPM This project is part of the research axis “Materials for light emission” and aimed at develop an original and simple electroluminescent material with a very good thermic stability and no toxic elements for health. Nowadays, the more expanded LED structures to produce white light are P-N junctions based on GaN emitting in the blue specter or UV and whose radiation excites phosphorescent elements located in the superior part of the diode. The innovation of this work stands in the creation of a monolithic electroluminescent device from LED-type based on ZnO doped with a smaller quantity of rare earth ions like Terbium and Europium as used in current LED devices, decreasing the cost of the device and the impact on nature. Respective concentrations on rare earth help control the color rendering index (CRI). In 18 months, the teams involved in the project managed to undo the technological locks by realizing effective tools but with smaller intensities than current standards. In spite of it and even if the doped zinc oxide with magnesium could not be obtained, the coupling of the effects of Erbium and Europium was proven and really promising results have been gained on one of the synthesized material. Following this project and from those encouraging results, the realization of structures is planned for semi-conductor lasers used in telecommunications for instance. The teams of CIMAP are currently working on the optimization of this technique. (a) schematic view of the electroluminescent device, (b) electroluminescent signal showing the performance of the proposed device. Leader : Xavier Portier (CIMAP)
Structures Organic Inorganic Eletro-optic hybrid materials Axis 1: Materials for energy – CRISMAT/CIMAP/LCMT The HELIOS project (Electro-optic inorganic-organic (2013-2017) is a research project which had two main goals. First, the synthesis of organic-inorganic hybride films which are original, self-assembled with electro-optic properties. The second aim was the elaboration of photoconductive and light-emitting devices from the developed films for applications in LEDs and photovoltaic cells. The objective of such materials is to combine the assets of all-inorganic devices with the properties of organic materials, which are respectively, solid with strong electric and optic properties at a low cost of production. The HELIOS project was composed of 3 work packages :
- The synthesis of new organic molecules light-emitting or light-absorbinng which could be used in hybrid films and devices.
- The set up of new hybrid films via electroplatin from a water solution, a lesser expensive and ecological technique.
- The elaboration of devices from hybrid films which could be used in light-emitting apparels or in photovoltaic cells (process through coating, printing and metallization).
Fig. 1: Elaboration of a hybrid device composed of a hybrid film synthesized from luminescent molecules and ZnO zinc oxide This project allowed the set up of new molecules, lighting in the visible region and with photoluminescence properties. From this process, new semi-conductive and photoluminescent hybrid films and devices have been created. Precisions on several information of these films have been made along the project’s life (chemical compositions, thermal stabilities, micro-structures, crystal structure, electric conductivity, photoluminescence and photoconduction). Alle these fundamental characterizations are an essential step to set up new perfoming hybrid devices, affordable and lesser toxic for photovoltaic or LEDs applications. These new materials could then become a promising alternative to hybrid devices based on perovskites, materials often studied in the scientific literature due to their properties and their affordability, but with a high toxicity. The HELIOS project initiated new national and international collaborations (Hanoi University, ICMCB in Bordeaux, INSA Rennes) and more especially in the field of synthesis and physical characterizations. New skills on the elaboration of hybrid films and devices and their study have all also been brought within LabEx EMC3. Leader : Sophie Boudin (CRISMAT)
Development of 3D optic methods for complex fluids Axis 3 : Multidisciplinary research – CORIA/LOMC The 3D project (2013-2017) aimed at developing interferometric techniques for the 3D characterisation of flows. .3 different techniques have been elaborated in the frame of this project. On the one hand, the digital holography has been transferred to LOMC lab and adapted to the tudy of vortex dynamics created by the wave-structure interaction. The use of holography in multi-shot exposition enablmes the monitoring of the bubbles successive positions over time and deduce the 3D velocity field in a volume of several cm3. Besides, the team has set up digital holography with two recording wavelengths. This new and innovative technique can solve the issues linked to the measurement of different velocity scales used during particle velocimetry measurements in the frame of a vortex flow. An on-board system composed of 2 fiber laser diode linked to a coupler allowed to measure various velocity ladders and to characterize the heart of the vortex as accurately as the periphery of the system. On the other hand, the out-of-focus interferometric imaging has been extended to configurations allowing a 3D localisation of bubbles in a flow, as well as the measurement of their size. This method has also been extended to irregular particles, which enables the study of triphasic systems (liquid flow with the presence of air bubbles and solid particles). Fig.1: Characterisation of 3D vortex dynamics of Digital Holography (Lebon et. al., Exp. Fluids 57(6), 2016) Then, the 3D project, which allowed to confront theorical model calculations of CORIA lab to experiments in the wide-wave flume in LOMC lab reinforced the relations between both laboratories, the digital holography, developed in CORIA, being from now on operational in LOMC. Besides, this digital holography method is particularly well adapted to 3D monitoring of particles paths, which offers significant prospects for the study of complex flows (marine environment and dynamic behaviour of viscoelastic filaments). Then, the CORIA/LOMC collaboration initiated though “3D” will be pursued in the frame of the CPER-ERDF project “NEPTUNE”, with the recruitment of a post-doctoral contract on the study of sediment-fluid flows via digital holography. At the end of the 3D project, the “RainbowVision” start-up has been created in 2017 by the researcher hired in CORIA. An impressive scientific production comes form these works with no less than 17 multi-partner publications, 15 communications in international conferences as well as a patent and a software. Leader : Gérard Gréhan (CORIA)