A direct numerical simulation study of the influence of flame-generated vorticity on reaction-zone-surface area in weakly turbulent premixed combustion
Journal article, 2019

Direct numerical simulation data obtained from two statistically stationary, one-dimensional, planar, weakly turbulent, premixed flames are analyzed in order to examine the influence of flame-generated vorticity on the surface area of the reaction zone. The two flames are associated with the flamelet combustion regime and are characterized by two significantly different density ratios  sigma= 7.53 and 2.5, with all other things being roughly equal. The obtained results indicate that generation of vorticity due to baroclinic torque within flamelets can impede wrinkling of the reaction surface, reduce its area, and, hence, decrease the 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  sigma= 7.53, the local stretch rate, which quantifies the local rate of increase or decrease in the surface area, is predominantly negative in regions characterized by a large magnitude of enstrophy or a large magnitude of the baroclinic torque term in the enstrophy transport equation, with the effect being more pronounced at larger values of the mean combustion progress variable. If the density ratio is low, e.g.,  sigma= 2.5, the baroclinic torque weakly affects the vorticity field within the mean flame brush and the aforementioned effect is not pronounced.

DNS

flame-generated turbulence

stretch rate

premixed turbulentcombustion

flame-surface area

vorticity

Author

Andrei Lipatnikov

Chalmers, Mechanics and Maritime Sciences, Combustion

Vladimir Sabelnikov

ONERA Centre de Palaiseau

Shinnosuke Nishiki

Kagoshima University

Tatsuya Hasegawa

Nagoya University

Physics of Fluids

1070-6631 (ISSN) 1089-7666 (eISSN)

Vol. 31 1-16 055101

Driving Forces

Sustainable development

Subject Categories

Applied Mechanics

Other Physics Topics

Fluid Mechanics and Acoustics

Roots

Basic sciences

DOI

10.1063/1.5094976

More information

Latest update

7/1/2019 1