Séminaire D2 : Conditioned Structure Approach for Premixed Turbulent Flames

Andrei Lipatnikov, Université de Chalmers
Lieu Evenemement: 
SP2MI, bâtiment H2, salle 175/177
Tuesday, 18 December, 2018 - 14:00



The second-order structure functions of velocity field, which characterize velocity difference in two points, are widely used in research into non-reacting turbulent flows. In the present paper, the approach is extended and a new method for analyzing Direct Numerical Simulation (DNS) or experimental data is developed in order to study the influence of combustion-induced thermal expansion on turbulent flow within a premixed flame brush. For this purpose, structure functions conditioned to various combinations of mixture states in two different points (reactant-reactant, reactant-product, product-product, etc.) are introduced. Subsequently, in order to demonstrate opportunities offered by the newly developed method, the conditioned structure functions are extracted from 3D DNS data obtained from two statistically 1D, planar, fully-developed, weakly turbulent, premixed, single-step-chemistry flames characterized by significantly different (7.53 and 2.50) density ratios, with all other things being approximately equal. Obtained results show that the conditioned structure functions differ significantly from standard mean structure functions and convey a large amount of important information on various local phenomena that stem from the influence of combustion-induced thermal expansion on turbulent flow. In particular, the conditioned structure functions not only (i) indicate a number of already known local phenomena, but also (ii) reveal less recognized phenomena such as substantial influence of combustion-induced thermal expansion on turbulence in constant-density unburned reactants, and even (iii) allow us to detect a new phenomenon such as appearance of strong local velocity perturbations (shear layers) within flamelets.


Short bio:


Andrei Lipatnikov received his Ph.D. in Molecular and Chemical Physics from Moscow Institute of Physics and Technology in 1987. Subsequently, he was employed by that Institute until he was invited to join Internal Combustion Engine Group at Chalmers University of Technology as a guest scientist in 1996. In May 1998, he was permanently employed as a researcher at the same department. In August 2000, the School of Mechanical and Vehicular Engineering accepted Dr. Lipatnikov as a docent. In July 2017, he got appointment of a research professor. His academic activities have been concerned with modeling of burning of gaseous mixtures in turbulent and laminar flows, pollutant formation in flames, autoignition of premixed reactants, thermo-acoustic instabilities, fuel sprays, as well as numerical simulations of turbulent flames in laboratory burners and internal combustion engines. He has authored a monograph and about 270 scientific contributions, including 99 journal papers.


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