Conditioned moments in premixed turbulent reacting flows
Artikel i vetenskaplig tidskrift, 2011

Although the rms turbulent velocity u′ is commonly considered to be the key characteristic of turbulence when studying premixed combustion, the definition of u′ in a flame is impeded by the intermittency of unburned and burned mixtures due to the random advection of the flame front by turbulent eddies. To resolve the problem, rms velocities conditioned either on unburned or burned mixture are often invoked to characterize turbulence. The goal of the present paper is to dispute this solution. To do so, balance equations for the conditioned velocities and Reynolds stresses are numerically solved in the case of a statistically planar and one-dimensional, constant-density, premixed, turbulent, reacting flow, with the turbulence being assumed to be homogeneous, isotropic, and statistically stationary. The obtained results show that the conditioned rms velocities differ substantially from u′ in such a "flame", i.e. the above conditioned quantities are controlled not only by turbulence, but also by the aforementioned unburned-burned intermittency. Therefore, the use of the conditioned rms velocities for characterizing turbulence is not justified in premixed turbulent flames. Behaviour of various conditioned second and third moments is shown to differ substantially from the behaviour of counterpart unconditioned moments, thus calling for further research into conditioned characteristics of turbulent flames. © 2010 Published by Elsevier Inc. on behalf of The Combustion Institute. All rights reserved.

Conditioned quantities

Modeling

Reynolds stresses

Premixed turbulent combustion

Författare

Andrei Lipatnikov

Chalmers, Tillämpad mekanik, Förbränning

Proceedings of the Combustion Institute

1540-7489 (ISSN)

Vol. 33 1489-1496

Drivkrafter

Hållbar utveckling

Styrkeområden

Energi

Fundament

Grundläggande vetenskaper

Ämneskategorier

Strömningsmekanik och akustik

DOI

10.1016/j.proci.2010.06.138