Chalmers University, Sweden
Professor 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 Department of Thermo- and Fluid Dynamics 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 280 scientific contributions, including 104 original journal papers and five review articles published by Progress in Energy and Combustion Science and Annual Review of Fluid Mechanics.
Direct Numerical Simulation (DNS) data obtained from two statistically stationary, 1D, planar, weakly turbulent premixed flames are analyzed in order to examine the influence of flame-generated vorticity on the area of the reaction surface. The two flames are associated with the flamelet combustion regime and are characterized by significantly different density ratios, i.e. σ=7.53 and 2.5, with all other things being roughly equal. Results indicate that generation of vorticity due to baroclinic torque within flamelets can impede wrinkling the reaction surface, reduce its area, and, hence, decrease burning rate. Thus, these results call for revisiting the widely-accepted concept of combustion acceleration due to flame-generated turbulence. In particular, in the case of σ=7.53, the local stretch rate, which quantifies the local rate of an increase or decrease in the surface area, is predominantly negative in regions characterized by a large magnitude of enstrophy or a large magnitude of baroclinic torque term in the transport equation for the enstrophy, with the effect being more pronounced at larger values of the mean combustion progress variable. If σ=2.5, baroclinic torque weakly effects vorticity field within the mean flame brush and the aforementioned effect is not pronounced.