Imperial College London
Portrait Picture

Dr Lu Tian

Faculty of Engineering, Department of Mechanical Engineering

Honorary Lecturer
 
 
 
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Contact

 

l.tian14 CV

 
 
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Location

 

674City and Guilds BuildingSouth Kensington Campus

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Summary

 

Publications

Citation

BibTex format

@article{Tian:2019:10.1016/j.combustflame.2019.04.039,
author = {Tian, L and Lindstedt, RP},
doi = {10.1016/j.combustflame.2019.04.039},
journal = {Combustion and Flame},
pages = {51--67},
title = {Impact of molecular mixing and scalar dissipation rate closures on turbulent bluff-body flames with increasing local extinction},
url = {http://dx.doi.org/10.1016/j.combustflame.2019.04.039},
volume = {206},
year = {2019}
}
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RIS format (EndNote, RefMan)

TY  - JOUR
AB  - The Combustion Institute  Bluff-body turbulent CH 4 : H 2 (1:1) flames at 50% (HM1), 75% (HM2) and 91% (HM3) of the blow-off velocity (235 m s−1) were studied experimentally by Masri and co-workers and found to exhibit gradually increasing periodic and shear layer instabilities. The latter are coupled with increasing levels of local extinction with subsequent re-ignition further downstream. This study provides a systematic evaluation of the sensitivity of predictions to molecular mixing and scalar dissipation rate closures. The latter include extended forms of the Euclidean Minimum Spanning Tree (EMST) and modified Curl's (MC) models, applicable to premixed turbulent flames via a closure that accounts for local Damköhler number effects (EEMST and EMC), and a conceptually related blended scalar time-scale approach (BEMST and BMC). Computations are performed using a hybrid finite volume (FV) – transported Joint Probability Density Function (JPDF) algorithm featuring stochastic Lagrangian particles, a comprehensive 48-scalar systematically reduced C/H/N/O mechanism, and a second moment method based on the Generalised Langevin Model that provides a partial resolution of the unsteady fluid motion. The sensitivity to solution parameters affecting the temporal resolution is quantified using Fourier transforms of the time histories of velocity and scalar traces. Radial profiles, conditional means and scatter plots are compared to the experimental data along with burning indices based on the conditional mean temperature. Vortex related instabilities ∼ 1 kHz in the outer shear layer appear for all closures with EMC showing periodic local extinction and re-ignition in the neck region for HM3 and flame turbules (i.e., discrete pockets of hot gas) separating periodically at frequencies ∼ 85 Hz. Results are similar to well–resolved JPDF/LES simulations for HM1. It is shown that the EMC and (E)EMST models essentially enclose the experimental data for
AU  - Tian,L
AU  - Lindstedt,RP
DO  - 10.1016/j.combustflame.2019.04.039
EP  - 67
PY  - 2019///
SN  - 0010-2180
SP  - 51
TI  - Impact of molecular mixing and scalar dissipation rate closures on turbulent bluff-body flames with increasing local extinction
T2  - Combustion and Flame
UR  - http://dx.doi.org/10.1016/j.combustflame.2019.04.039
UR  - http://hdl.handle.net/10044/1/70152
VL  - 206
ER  -
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