Analyse comparative de modèles d'endommagement de composite soumis à impact

Ce rapport présente une étude du modèle méso d’endommagement des composites stratifiés, qui a été développé au LMT de Cachan depuis de nombreuses années. Il y a près de 10 ans, ce modèle a fait l’objet d’une implémentation dans le code de dynamique explicite PAM-CRASH pour un pli unidirectionnel. Malgré cela, il reste très peu utilisé par manque de connaissance et de recul des éventuels utilisateurs.Les pré-imprégnés suivants sont concernés : tissé carbone 977-2A-44-3kHTA-PW-193-1270 et uni-directionnel carbone 977-2-35-12kHTA-PW-134-30

Exergo-technological explicit methodology for gas-turbine system optimization for series hybrid electric vehicles

International audienceSignificant research efforts have been invested in the automotive industry on hybrid-electrified powertrains in order to reduce the passenger cars’ dependence on oil. Powertrains electrification resulted in a wide range of hybrid vehicle architectures. Fuel consumption of these powertrains strongly relies on the energy converter performance, as well as on the energy management strategy deployed on-board. This paper investigates the potential of fuel consumption savings of a series hybrid electric vehicle (SHEV) using a gas turbine (GT) as energy converter instead of the conventional internal combustion engine (ICE). An exergo-technological explicit analysis is conducted to identify the best GT-system configuration. An intercooled regenerative reheat cycle is prioritized, offering higher efficiency and power density compared to other investigated GT-systems. A SHEV model is developed and powertrain components are sized considering vehicle performance criteria. Energy consumption simulations are performed on the worldwide-harmonized light vehicles test procedure (WLTP) driving cycle using dynamic programing as global optimal energy management strategy. A sensitivity analysis is also carried out in order to evaluate the impact of the battery size on the fuel consumption, for self-sustaining and plug-in hybrid SHEV configurations. Results show 22% to 25% improved fuel consumption with GT as auxiliary power unit (APU) compared to ICE. Consequently,the studied GT-APU presents a potential for implementation on SHEVs

Methodology for Fuel Saving Optimization of a Serial Hybrid Electric Vehicle using Gas Turbine as Energy Converter

International audienceSignificant research efforts have been invested in the automotive industry on hybrid-electrified powertrains inorder to reduce the passenger cars’ dependence on oil. Powertrains electrification resulted in a wide rangeof hybrid vehicle architectures. Fuel consumption of these powertrains strongly relies on the energyconverter performance, as well as on the energy management strategy deployed on-board. This paperinvestigates the potential of fuel consumption savings of a serial hybrid electric vehicle (SHEV) using a gasturbine (GT) as energy converter instead of the conventional internal combustion engine (ICE). An exergotechnoexplicit analysis is conducted to identify the best GT-system configuration. An intercooledregenerative reheat cycle is prioritized, offering higher efficiency and power density compared to otherinvestigated GT-systems. A SHEV model is developed and powertrain components are sized consideringvehicle performance criteria. Energy consumption simulations are performed on WLTP cycle using dynamicprograming as global optimal energy management strategy. A sensitivity analysis is also carried out in orderto evaluate the effect of the battery size on the fuel consumption. Results show improved fuel consumptionwith GT as auxiliary power unit (APU) compared to ICE. Moreover, GT offers other intrinsic advantages suchas reduced mass, suitable vehicle integration as well as a multi-fuel use capability. Consequently, thestudied GT-APU presents a potential for implementation on SHEVs

Production of a methyl ester from the microalgae Nannochloropsis grown in raceways on the French west coast

International audienceThe present article describes the production of oil from autotrophic microalgae grown in raceways in France, and presents the bench test results of a Diesel monocylinder engine with the derived biodiesel (methyl ester).The cultivation of Nannochloropsis has been performed under nitrogen limitation in order to increase the lipid content of the microalgae. After harvesting, a drying operation has been carried out so as to obtain a dry microalgae powder with controlled water content. Neutral lipids were then recovered using supercritical carbon dioxide extraction technology applied to the dry powder. One hundred kilograms of dry microalgae has been treated leading to about five kilograms of algal oil, free of polar lipids, that has been transesterified with methanol. The fuel obtained has been blended with a standard biofuel-free Diesel fuel (10% algal fuel/90% standard Diesel fuel B0) and engine tests have been carried out with the resulting blend (B10). In order to compare with well-known fuels similar engine tests were performed with B0 and with a B10 fuel made of ten percent vegetable oil methyl ester complying with the European 14214 fuel standard (B10 EU-type). The B10 quality was rather close to Diesel fuel except for oxidation stability, which was well below the minimum limit for Diesel fuel. The behavior of the B10 fuel appears to be very similar in terms of combustion efficiency and pollutant emissions to the one of the standard Diesel fuel B0

Experimental characterization of combustion regimes for micron-sized aluminum powders

International audienceThis work presents an experimental study of combustion characteristics of micron-sized aluminum particles in the transition regime under constant volume combustion experiments. Burning velocities were estimated from the measured pressure traces using both a simplified model for aerosol combustion on closed spherical bombs and a semi-empirical correlation, and compared to previous literature. Flame temperatures were measured by bi-color pyrometry and indicate that for particles smaller than 12 m, the flame moves closer to the particle's surface, since flame temperatures were close to aluminum boiling point. For 17:9 µm particles, flame temperatures were close to predicted adiabatic flame temperature and alumina vaporization-dissociation temperature, indicating a classical vapor phase flame under a diffusion-controlled mechanism. However, spectroscopy measurements did not detect significant reductions on molecular AlO emissions for ner particles. This indicates a still very significant presence of vapor phase reaction for powders with a Sauter mean diameter at least as large as 7 µm, which is further supported by the presence of nanometric spheres in the combustion residues, since alumina formed under a vapor phase reaction is expected to condensate into nanometric droplets

Comparison of Combustion Characteristics of Magnesium and Aluminum Powders

International audienceThis work presents an experimental study of the combustion characteristics of micron-sized aluminum andmagnesium powders under constant volume combustion experiments. Burning velocities were estimated from the measured pressure traces using both a simplified model for combustion on closed spherical bombs and a semi-empirical correlation for dust explosions, and compared to previous literature. Flame temperatures were measured by bi-color pyrometry and indicate that, for aluminum powders with a mean particle diameter smaller than 12 μm, the flame moves closer to the particle’s surface. However, emission spectra obtained during combustion indicate that vapor-phase oxidation exists for all studied powders. Analysis of the combustion products further supported the presence of a vapor-phase reaction. For aluminum, the residue is composed by partially crystallized nanometric spheres as fine as 200 nm. MgO was found in crystallized cubic structures of different sizes, the finest ones also about 200 nm