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Escot Bocanegra P.,Icare Institute Of Combustion | Davidenko D.,Icare Institute Of Combustion | Sarou-Kanian V.,Icare Institute Of Combustion | Chauveau C.,Icare Institute Of Combustion | Gokalp I.,Icare Institute Of Combustion
Experimental Thermal and Fluid Science | Year: 2010

An experimental study has been conducted to determine flame propagation velocities in clouds of micro- (4.8 μm) and nano- (187 nm) aluminum particles in air at various concentrations. The experimental results show faster flame propagation in nanoparticle cloud with respect to the case of microparticles. Maximum flame temperature has been measured using a high-resolution spectrometer operating in the visible range. Analysis of combustion residual shows that nanoparticles combustion is realized via the gas-phase mechanism. A three-stage particle combustion model has been proposed based on these observations. Model parameters have been fitted to match the experimental results on the flame velocity and maximum temperature. Particle burning time is estimated from the flame simulations. © 2009 Elsevier Inc. All rights reserved.

Garrigues L.,CNRS LAPLACE Lab | Mazouffre S.,Icare Institute Of Combustion | Bourgeois G.,Icare Institute Of Combustion
Journal of Applied Physics | Year: 2012

We compare time-averaged and time-varying measured and computed ion velocity distribution functions in a Hall effect thruster for typical operating conditions. The ion properties are measured by means of laser induced fluorescence spectroscopy. Simulations of the plasma properties are performed with a two-dimensional hybrid model. In the electron fluid description of the hybrid model, the anomalous transport responsible for the electron diffusion across the magnetic field barrier is deduced from the experimental profile of the time-averaged electric field. The use of a steady state anomalous mobility profile allows the hybrid model to capture some properties like the time-averaged ion mean velocity. Yet, the model fails at reproducing the time evolution of the ion velocity. This fact reveals a complex underlying physics that necessitates to account for the electron dynamics over a short time-scale. This study also shows the necessity for electron temperature measurements. Moreover, the strength of the self-magnetic field due to the rotating Hall current is found negligible. © 2012 American Institute of Physics.

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