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Laurent François Joël Dupays Dmitry Davidenko Marc Massot 《Combustion Theory and Modelling》2020,24(5):775-809
We investigate a model of solid propellant combustion involving surface pyrolysis coupled to finite activation energy gas-phase combustion. Existence and uniqueness of a travelling wave solution are established by extending dynamical system tools classically used for premixed flames, dealing with the additional difficulty arising from the surface regression and pyrolysis. An efficient shooting method allows to solve the problem in phase space without resorting to space discretisation nor fixed-point Newton iterations. The results are compared to solutions from a CFD code developed at ONERA, assessing the efficiency and potential of the method, and the impact of the modelling assumptions is evaluated through parametric studies. 相似文献
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In this Note, we first present a model for droplet secondary breakup, in liquid sprays. This model is based on the kinetic theory formalism and uses experimental correlations found in the literature (L.-P. Hsiang, G.M. Faeth, Int. J. Multiphase Flow 19 (5) (1993) 721–735; R. Maxey, J. Riley, Phys. Fluids 26 (4) (1983) 883–889; M. Pilch, C.A. Erdman, Int. J. Multiphase Flow 13 (6) (1987) 741–757) to determine the fragmentation rate and its outcome. We then conduct a mathematical study of the resulting kinetic equation. We prove, under some physically reasonable assumptions, an existence and uniqueness theorem and characterize the long-time behaviour of the solution. To cite this article: G. Dufour et al., C. R. Acad. Sci. Paris, Ser. I 336 (2003). 相似文献
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S. Chitra P. Kalyani T. Mohan M. Massot S. Ziolkiewicz R. Gangandharan M. Eddrief C. Julien 《Ionics》1998,4(1-2):8-15
A moderate-temperature method of preparation of the spinel LiMn2O4 was developed around 500 °C. Physical features of the products were identified by X-ray photoelectron spectroscopy, X-ray
diffractometry, Raman scattering and FTIR spectroscopy. The electronic conductivity of LiMn2O4 has been studied as a function of annealing temperature. The product LiMn2O4 is identified as a micron-sized powder and analysis of the local environment is in good accordance with the classical structural
model of Fd3m space group. LiMn2O4 exhibits an electrical conductivity of 1.9×10−5 S/cm at room temperature with an activation energy of 0.16 eV which corresponds to an electron hopping mechanism between
the two charge states of Mn3+ and Mn4+ ions. A first-order phase transition is observed at 292 K. 相似文献
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This paper presents a study of the coupling between a source and a fibre bundle. A ray trace numerical simulation was used to examine the effects of geometrical and optical parameters of the concentrator and the fibre bundle. We compare the results of the computer program with measurements obtained in the case of a light emitting diode and a single lens. 相似文献
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This paper presents a theoretical and experimental study of the application of the near field technique to the measure of radiance of light emitting diodes and laser diodes. We have shown the possibilities and the limitations of this technique. 相似文献
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A numerical method, using the Ritz-Galerkin approach has been applied to the problem of determining the propagation characteristics of inhomogeneous planar optical waveguides. It is shown that very accurate results are obtained for mode spectra and field distributions when compared with the predictions of other exact or approximate methods. 相似文献
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Nanoscopic scale studies of LiFePO4 as cathode material in lithium-ion batteries for HEV application
We present a review of the structural properties of LiFePO4. Depending on the mode of preparation, different impurities can poison this material. These impurities are identified and
a quantitative estimate of their concentrations is deduced from the combination of X-ray diffraction analysis, Fourier transform
infrared spectroscopy, Raman spectroscopy, and magnetic measurements. An optimized preparation provides samples with carbon-coated
particles free of any impurity phase, insuring structural stability and electrochemical performance that justify the use of
this material as a cathode element a new generation of lithium secondary batteries. 相似文献
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Original mass spectra of uracil and thymine derivatives are presented with the corresponding fragmentation schemes. In the first series of spectra, the fragmentations of thymine derivatives, including 14C-2-thymine, dimers, and bromo thymines, confirm the basic retro Diels-Alder mechanism. The second series includes dihydro 5,6-derivatives of uracil (hydroxy and bromo substituents). The behaviour of these molecules is quite different; they are more sensitive to the substituents and a part of the fragmentation is often explained by protonated molecular ions. 相似文献