Thesis-2007-RangaDinesh.pdf (14.43 MB)
Large eddy simulation of turbulent swirling flames
thesis
posted on 2016-04-27, 13:04 authored by K.K.J. Ranga-DineshLarge eddy simulation (LES) is attractive as it provides a reasonable compromise
between accuracy and cost, and is rapidly evolving as a practical approach
for many engineering applications. This thesis is concerned with the application
of large eddy simulation to unconfined swirl in turbulent non-premixed flames
and isothermal flows. The LES methodology has been applied for the prediction
of turbulent swirling reacting and non-reacting flows based on laboratory scale
swirl burner known as the Sydney swirl burner, which has been a target flame of
the workshop series of turbulent non-premixed flames (TNF). For that purpose a
LES code was developed that can run wide range of applications. An algorithm
was developed for LES of variable density reacting flow calculations. Particular
attention was given to primitive conservation (mass, momentum and scalar) and
kinetic energy of the flow and mixing field. The algorithm uses the primitive
variables, which are staggered in both space and time. A steady laminar flamelet
model which includes the detailed chemical kinetics and multi component mass
diffusion, has been implemented in the LES code. An artificial inlet boundary
condition method was implemented to generate instantaneous turbulent velocity
fields that are imposed on the inflow boundary of the Cartesian grid. To improve
the applicability of the code, various approaches were developed to improve stability
and efficiency. LES calculations for isothermal turbulent swirling jets were
successful in predicting experimentally measured mean velocities, their rms fluctuations
and Reynolds shear stresses. The phenomenon of vortex breakdown
(VB) and recirculation flow structures at different swirl and Reynolds numbers
were successfully reproduced by the present large eddy simulations indicating
that LES is capable of predicting VB phenomena which occurs only at certain
conditions. For swirling flames, the LES predictions were able to capture the unsteady
flow field, flame dynamics and showed good agreement with experimental
measurements. The LES predictions for the mean temperature and major species
were also successful.
History
School
- Mechanical, Electrical and Manufacturing Engineering
Publisher
© K.K.J. Ranga DineshPublisher statement
This work is made available according to the conditions of the Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International (CC BY-NC-ND 4.0) licence. Full details of this licence are available at: https://creativecommons.org/licenses/by-nc-nd/4.0/Publication date
2007Notes
A Doctoral Thesis. Submitted in partial fulfilment of the requirements for the award of Doctor of Philosophy of Loughborough University.Language
- en