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Diffusion raman spontanée pour la combustion turbulente et les plasmas

Abstract : Because of its low efficiency, spontaneous Raman scattering is still a rarely used method for analysis of reacting flows, especially if they are unsteady as turbulent combustion or pulse discharges. For this purpose, an experimental setup was developed, associated with specific analytical procedures. This setup was evaluated in two cases : a premixed flame and nanosecond discharge as a new ignition method. Measurements demonstrate the originality and the novelty of the results that can bring the spontaneous Raman scattering to the analysis of complex reacting flows. The discharge is generated in a point-plan gap of air and lean propane-air mixture by an application of a positive high voltage pulse of 25 KV and 25 ns to the point electrode at the repetition rate of 10 Hz. Comparisons between experimental Raman spectra with synthetic spectra calculated taking into account the vibrational non-equilibrium and rotation-vibration couplings, yielded vibrational and rotational temperatures of N2 and O2 in the afterglow of air and propane-air mixtures. The study of energy deposition made from measurements of temperatures and densities of major species was used to characterize the different processes of energy transfers occurred during ignition by nanosecond discharge. The feasibility of single-shot temperature measurements by spontaneous Raman scattering for turbulent combustion was then explored on laminar flames of methane-air obtained with a Bunsen burner. In the flame burnt gases, single-shot temperature measurements are obtained with very good accuracy. In both cases studied, the quality of temperature measurement is obtained thanks to an in-situ determination of the instrumental function and uncertainties are evaluated. The results make possible to consider simultaneous single-shot temperature and density of major species measurements with the same experimental set-up opening interesting perspectives for the analysis of other reacting flows.
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https://tel.archives-ouvertes.fr/tel-01059053
Contributor : Amath Lo <>
Submitted on : Friday, August 29, 2014 - 11:18:19 AM
Last modification on : Tuesday, February 5, 2019 - 11:44:13 AM
Long-term archiving on: : Sunday, November 30, 2014 - 10:25:13 AM

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  • HAL Id : tel-01059053, version 1

Citation

Amath Lo. Diffusion raman spontanée pour la combustion turbulente et les plasmas. Milieux fluides et réactifs. Université de Rouen, 2012. Français. ⟨tel-01059053⟩

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