1,503
Views
76
CrossRef citations to date
0
Altmetric
Original Articles

Flame and Flow Topologies in an Annular Swirling Flow

, , , , , , , , , & show all
Pages 1041-1074 | Received 30 Jul 2013, Accepted 09 Jan 2014, Published online: 26 Jun 2014
 

Abstract

This article describes an investigation of flame shapes and flow configurations in a premixed, swirl-stabilized dump combustor. High swirl, annular nozzle flows of this nature enable a variety of different flame configurations and heat release distributions with their associated flow fields. These differences are significant, since each of these configurations, in turn, has different thermoacoustic sensitivities and influences on combustor emissions, nozzle lifetime, and liner heating. These different configurations arise because multiple flame stabilization locations are present, associated with the inner and outer shear layers of the annulus, and the stagnation point of the vortex breakdown region. We present results from high-speed luminosity imaging, particle image velocimetry (PIV), and OH-planar laser induced fluorescence (PLIF) to illustrate time-averaged and instantaneous flame shapes and flow fields associated with the different configuration “families.” Selected cases are compared with large eddy simulations (LES). Particular emphasis is given to the distinctly different flame and flow topologies that exist in these flows, and their sensitivity to geometric (such as centerbody size and shape, combustor diameter, exhaust contraction) and operational (e.g., bulkhead temperature, preheat temperature, fuel/air ratio) parameters. We particularly emphasize the importance of the centerbody shape, and its associated impact on the structure of the central recirculating flow, as differentiating between two different families of flame shapes.

CB=

centerbody

CIFS=

combustion induced flow separation

DCB=

centerbody diameter

DCOMB=

combustor diameter

fcutoff=

cutoff frequency for seeding particle dynamics

ISL=

inner shear layer

IRZ=

inner recirculation zone

LCOMB=

combustor length

m=

PIV seed particle mass

OSL=

outer shear layer

ORZ=

outer recirculation zone

PVC=

precessing vortex core

R=

PIV seed particle radius

Re=

Reynolds number

Sm=

momentum base swirl number

St=

Stokes number

Stcut-off=

cut-off Stokes number for seeding particle dynamics

Tad=

adiabatic flame temperature

Tbhd=

bulkhead corner temperature

TCB=

centerbody corner temperature

Tph=

preheat temperature of reactants

U=

flow velocity

Ur=

radial flow velocity component

Urms=

root-mean-square velocity

Uz=

axial flow velocity component

Uz,o=

average axial nozzle exit velocity

Uθ=

azimuthal flow velocity component

u=

seed particle velocity

ur=

seed particle radial velocity component

uz=

seed particle axial velocity component

uθ=

seed particle azimuthal velocity component

uterm=

seed particle terminal velocity (additional subscript refers to velocity component)

VBB=

vortex breakdown bubble

ϵannulus=

post-swirler annulus area contraction ratio

ϵexhaust=

exhaust nozzle area contraction ratio

=

dynamic viscosity

=

kinematic viscosity

ρ=

density

φ=

fuel/air equivalence ratio

Reprints and Corporate Permissions

Please note: Selecting permissions does not provide access to the full text of the article, please see our help page How do I view content?

To request a reprint or corporate permissions for this article, please click on the relevant link below:

Academic Permissions

Please note: Selecting permissions does not provide access to the full text of the article, please see our help page How do I view content?

Obtain permissions instantly via Rightslink by clicking on the button below:

If you are unable to obtain permissions via Rightslink, please complete and submit this Permissions form. For more information, please visit our Permissions help page.