Conditional statistics of inert droplet effects on turbulant combustion in reacting mixing layers


Xia, J. and Luo, Kai (2009) Conditional statistics of inert droplet effects on turbulant combustion in reacting mixing layers. Combustion Theory and Modelling, 13, (5), 901-920. (doi:10.1080/13647830903288381).

Download

Full text not available from this repository.

Description/Abstract

Direct numerical simulation (DNS) of turbulent reacting mixing layers laden with evaporating inert droplets is used to assess the droplet effects in the context of the conditional moment closure (CMC) for multiphase turbulent combustion. The temporally developing mixing layer has an initial Reynolds number of 1000 based on the vorticity thickness with more than 16 million Lagrangian droplets traced. An equivalent mixture fraction incorporating the inert vapour mass fractions clearly demonstrates the effects of vapour dilution on the mixture. Instantaneous fields and conditional statistics, such as the singly conditioned scalar dissipation rate, the gas temperature 〈 Tg|η 〉, conditional variance of the gas temperature 〈 Tg”2|η 〉 and conditional covariance between the fuel mass fraction and gas temperature 〈 Yf” Tg”|η 〉 show considerable droplet effects. Comparison between the droplet-free and droplet-laden reacting mixing layer cases suggests significant extinction in the latter case. The resulting large conditional fluctuations around the conditional means contradict the basic assumption behind the first-order singly conditioned CMC. More sophisticated CMC approaches, such as doubly conditioned or second-order CMCs are, in principle, better able to incorporate the effects of evaporating droplets, but significant modelling challenges exist. The scalar dissipation rate doubly conditioned on the mixture fraction and a normalized gas temperature 〈 χ | η, ζ 〉 exemplifies the modelling complexity in the CMC of multiphase combustion.

Item Type: Article
Keywords: multiphase combustion, conditional moment closure, droplets, reacting mixing layer, DNS
Subjects: T Technology > T Technology (General)
Divisions: University Structure - Pre August 2011 > School of Engineering Sciences
ePrint ID: 147317
Date Deposited: 23 Apr 2010 13:48
Last Modified: 28 Mar 2014 15:18
Research Funder: EPSRC
Projects:
Study of Vitiated Turbulent Combustion for Low-Emission High-Efficiency Hybrid Energy Systems
Funded by: EPSRC (EP/E011640/1)
Led by: Kai Hong Luo
1 March 2007 to 28 February 2010
URI: http://eprints.soton.ac.uk/id/eprint/147317

Actions (login required)

View Item View Item