Numerical Study of the Thermal Behaviour of a Thermo-Structural Aeronautical Composite under Fire Stress

International audienceThe use of composite materials for aeronautical applications has been growing since several years because of the opportunity to produce lightweight structures reducing the fuel bills and emissions. The need for fireproof certification imposes costly and time consuming experiments that might be replaced or complemented in the years to come by numerical calculations. The present work creates a CFD numerical model of a fireproof test. As an example, a composite part (plenum) located in an aircraft APU (auxiliary power unit) which provides power to the aircraft is investigated. A numerical calibration of the flame is conducted according to the fireproof standards. The results of fireproof tests demonstrate a good evaluation of the plenum temperature (discrepancies lower than 19%). The influence of an internal air jet within the studied part is also evaluated observed to evaluate how this could lower the requirements of certification rules. A thermal decrease as high as 38 % is found for a velocity of 10 m/s. Proceedings of the 2 nd IAFSS European Symposium of Fire Safety Science 1. Introduction The use of composite materials for aeronautical applications has been growing since several years because of the opportunity to produce lightweight structures reducing the fuel bills and emissions. The growing use of these materials leads to technical and design challenges to comply with safety standards and certifications, especially when fire safety requirements are concerned. Aircraft parts dedicated to firewall applications or located in a designated fire zone, should meet a fireproof requirement. Therefore the composite parts have to pass fire tests according to ISO 2685 [1] or FAA-AC20-135 (FAR-25) [2] standards. Both standards use an oil burner to heat the part with a minimum temperature of 1100°C for 15 minutes. In this work, a 3D numerical model of a fireproof test using a CFD code is created to investigate the predictivity of a numerical fireproof test. This numerical step is expected to replace experimentation during the development phases of the composite part before the certification test to reduce development cost. This numerical tool would help designers to choose between different composite materials and designs options to avoid critical temperature increases at certain areas and perforation in this composite part during fireproof tests. The second section is dedicated to the presentation of the experimental setup and the third one will present the physical and numerical modelling approaches. In the fourth section the computed temperatures are compared to the experimental ones to validate the presented numerical approach and the results are discussed. The influence of an internal air jet within the studied part is also evaluated The feasibility of replacing a thermal protection by an internal air jet is also presented in this paper as a first design variable case. 2. Experimental setup To be labelled " fireproof " as it is requested in most of the APU (Auxiliary power unit) part specifications and according to the related standards, the concerned part (here a composite plenum) has to resist 15 minutes to a calibrated flame. Criteria to establish the test is passed include no burn through of the part structure, as well as no ignition of the emitted smokes (backside part inner surface self-ignition). This second criteria is here investigated by measuring the part material temperature increase. The Figures 1 and 2 present respectively a picture and an overview of the experimental setup. The composite part is located at 100 mm from the outlet of the cone burner above a vibrating table (sinusoidal vibration of 0.4 mm amplitude and 50 Hz frequency). The oil burner (kerosene-air) operates with a kerosene flow rate o

Experimental investigation on the concentration and voltage effects on the characteristics of deposited magnesium–lanthanum powder

International audiencePhone: +33 248 484 065 Highlights x We synthetize Mg-La powders by means of an electrodeposition process. x We characterize Mg-La powders using EDS, SEM, XRD and FTIR techniques

Challenges in coupled on-line-on-mine-real time mineralogical and chemical analyses on drill cores

The SOLSA project aims to develop an innovative on-line-on-mine-real-time expert system, combining sonic drilling, mineralogical and chemical characterization and data treatment. Ideally, this combination, highly demanded by mining and metallurgical companies, will speed up exploration, mining and processing. In order to evaluate the instrumental parameters for the SOLSA expert system, portable and laboratory analyses have been performed on four samples with contrasting lithologies: siliceous breccia, serpentinized harzburgite, sandstone and granite. More precisely, we evaluated the influence of the surface state of the sample on the signals obtained by portable X-Ray Fluorescence (pXRF) for chemistry and portable Infra-Red spectroscopy (pIR) for mineralogy. In addition, laboratory Raman spectroscopy, X-Ray Diffraction (XRD), XRF and ICP-OES laboratory analyses were performed to compare surface bulk mineralogical and chemical analyses. This presentation highlights (1) the importance of coupling chemical and mineralogical analytical technologies to obtain most complete information on samples, (2) the effect of the sample surface state on the XRF and IR signals from portable instruments. The last point is crucial for combined instrumental on-line sensor design and the calibration of the different instruments, especially in the case of pXRF

3D Imaging on heterogeneous surfaces on laterite drill core materials

The SOLSA project aims to construct an analytical expert system for on-line-on-mine-real-time mineralogical and geochemical analyses on sonic drilled cores. A profilometer is indispensable to obtain reliable and quantitative data from RGB and hyperspectral cameras, and to get 3D definition of close-to-surface objects such as rheology (grain shape, grain size, fractures and vein systems), material hardness and porosities. Optical properties of minerals can be analyzed by focusing on the reflectance. Preliminary analyses were performed with the commercial scan control profilometer MI-CRO-EPSILON equipped with a blue 405 nm laser on a conveyor belt (depth resolution: 10 μm; surface resolution: 30x30 μm2 (maximum resolution; 1m drill core/4 min). Drill core parts and rocks with 4 different surface roughness states: (1) sonic drilled, (2) diamond saw-cut, polished at (3) 6 mm and (4) 0.25 μm were measured (see also abstract Duée et al. this volume). The ΜICRO- EPSILON scanning does not detect such small differences of surface roughness states. Profilometer data can also be used to access rough mineralogical identification of some mineral groups like Fe-Mg silicates, quartz and feldspars). Drill core parts from a siliceous mineralized breccia and laterite with high and deep porosity and fractures were analyzed. The determination of holes’ convexity and fractures) is limited by the surface/depth ratio. Depending on end-user’s needs, parameters such as fracture densities and mineral content should be combined, and depth and surface resolutions should be optimized, to speed up “on-line-on-mine-real- time” mineral and chemical analyses in order to reach the target of about 80 m/day of drilled core

Efficient long-term open-access data archiving in mining industries

Efficient data collection, analysis and preservation are needed to accomplish adequate business decision making. Long-lasting and sustainable business operations, such as mining, add extra requirements to this process: data must be reliably preserved over periods that are longer than that of a typical software life-cycle. These concerns are of special importance for the combined on-line-on-mine-real-time expert system SOLSA (http://www.solsa-mining.eu/) that will produce data not only for immediate industrial utilization, but also for the possible scientific reuse. We thus applied the experience of scientific data publishing to provide efficient, reliable, long term archival data storage. Crystallography, a field covering one of the methods used in the SOLSA expert system, has long traditions of archiving and disseminating crystallographic data. To that end, the Crystallographic Interchange Framework (CIF, [1]) was developed and is maintained by the International Union of Crystallography (IUCr). This framework provides rich means for describing crystal structures and crystallographic experiments in an unambiguous, human- and machine- readable way, in a standard that is independent of the underlying data storage technology. The Crystallography Open Database (COD, [2]) has been successfully using the CIF framework to maintain its open-access crystallographic data collection for over a decade [3,4]. Since the CIF framework is extensible it is possible to use it for other branches of knowledge. The SOLSA system will generate data using different methods of material identification: XRF, XRD, Raman, IR and DRIFT spectroscopy. For XRD, the CIF is usable out-of-the-box, since we can rely on extensive data definition dictionaries (ontologies) developed by the IUCr and the crystallographic community. For spectroscopic techniques such dictionaries, to our best knowledge, do not exist; thus, the SOLSA team is developing CIF dictionaries for spectroscopic techniques to be used in the SOLSA expert system. All dictionaries will be published under liberal license and communities are encourage to join the development, reuse and extend the dictionaries where necessary. These dictionaries will enable access to open data generated by SOLSA by all interested parties. The use of the common CIF framework will ensure smooth data exchange among SOLSA partners and seamless data publication from the SOLSA project

Etude et mesure de paramètres pertinents dans un écoulement réactif

Manuscrit définitifTo ensure hypersonic flight in the coming years by use of SCRAMJET, regenerative cooling of the engine has to be done with endothermic fuel. Phenomena involved in the pyrolysis have been taken into account thanks to a detailed reaction mechanism (153 chemical species, 1185 reactions). Specific calculation methods have been employed to determine physical and chemical properties of multi-species mixtures, which are possibly diphasic or under supercritical state.Thanks to numerical hydro-thermo-chemical tools, developped especially for the present study, a steady-state then transient analysis has been conducted to investigate phenomena related to the overall system. An experimental test bench has been designed to confirm numerical knowledge and to test some "measuring methods" needed to characterize reactive flow, under conditions close to the in-flight ones (35 bars, 1500 K). The dynamic of heat and mass transfer has been studied.Pour assurer, dans les décennies à venir, le vol hypersonique par super-statoréacteur, il est nécessaire d'en gérer le refroidissement actif par injection de carburant endothermique. Les phénomènes de pyrolyse ont été pris en compte grâce à un mécanisme cinétique détaillé (153 espèces, 1185 réactions). Des méthodes de calcul spécifiques aux mélanges multi-espèces potentiellement diphasiques ou à l'état supercritique ont été employées pour la détermination des propriétés physico-chimiques. Grâce aux outils numériques d'hydro-thermo-cinétique développés spécialement pour cette étude, une analyse en régime stationnaire, puis transitoire, a été menée afin de comprendre les phénomènes interagissant sur le système complet identifié. Une expérimentation a également été conçue afin de confirmer les connaissances numériques acquises et tester des méthodes de mesure utiles à la caractérisation de l'écoulement réactif, dans des conditions proches de celles attendues en vol (35 bars, 1500 K). La dynamique des transferts thermiques et de matière a été étudiée