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The topic of this study is the numerical simulation of a turbulent non-premixed hydrogen flame with different micromixing models in order to investigate their predictive capability. The two micromixing models are compared. Comparisons with experimental data demonstrate that predictions based on the EMST model are slightly better. The EMST improves largely the precision of the results to the detriment of the RAM and the CPU performances. Overall, profile predictions of mixture fraction, flame temperature and major species are in reasonable agreement with experimental data.

Nowadays, the exhaust emissions of vehicle become very dangerous. Low temperature combustion in automotive engines becomes more and more important and it is achieved by high rates of Exhaust Gas Recirculation (EGR). EGR gases are used to dilute the fuel/air mixture in the engine and to control ignition delay times. In this paper we will present a numerical study of the impact of various additives on the oxidation of a typical automotive surrogate fuel blend, i.e. n-heptane/toluene mixture. It examines the impact of EGR compounds on the operating parameters of homogeneous charge compression ignition (HCCI) engine combustion -fueled by a mixture of heptane and toluene-and on the formation of emissions pollutant and how to reduce it. We used the CHEMKIN software and the combined chemical kinetics mechanism of the heptane and toluene to determine the exhausts gases composition. The numerical simulation is based on the code PSR (perfectly-Stirred Reactor). The influence of various additives, namely nitric oxide (NO) and ethylene (C2H4) on the oxidation of n-heptane/toluene blend was studied with a different concentrations of NO and C2H4. First, the NO addition guided to an inhibition, more or less important with added quantities, of cool flame, but an important promotion of main combustion. Second, C2H4 had no impact on the cool flame ignition, but promoted the main combustion. Indeed, some components of the EGR gas species had a very significant effect on initiation of combustion, which gives a general idea about the control of combustion in HCCI mode.

A x-dynamic factor of amplification for the longitudinal deformation; A θ:-dynamic factor of amplification for the radial deformation; [C]-matrix of rigidity; [D]-matrix of the compression forces; E-Young modulus; h-oil film thickness; H(x)-heaviside distribution; P(x,t)-hydrodynamic pressure; R-average radius of the bearing; t-time; U(x;t)-longitudinal displacement; V-linear speed; Vb-speed propagation of the longitudinal wave; Vp-speed propagation of the radial wave; W(x,t)-radial displacement; x-axial coordinate; []-deformation vector;  x-longitudinal deformation;  -radial deformation; -Poisson's ratio; -rod-bearing frequency; -density;  x-longitudinal constraint;  -transversal constraint; -angular position.

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