Kallifronas, DP;
Ahmed, P;
Massey, JC;
Talibi, M;
Ducci, A;
Balachandran, R;
Swaminathan, N;
(2022)
Influences of heat release, blockage ratio and swirl on the recirculation zone behind a bluff body.
Combustion Science and Technology
10.1080/00102202.2022.2041616.
(In press).
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Abstract
The recirculation zone created through vortex breakdown mechanisms in swirling flows plays a vital role for aerodynamic stabilization of turbulent flames in practical combustion systems. This zone interacts with the central recirculation zone (CRZ) of an upstream bluff body and this leads to a complex flow behavior that depends on the blockage ratio and swirl number. It has been previously observed that the vortex breakdown bubble (VBB) merges with the CRZ at large swirl number or blockage ratio. In this study, the influences of heat release on this flow structure and their physical mechanisms are explored through a series of large eddy simulations and experiments of bluff body stabilized premixed flames with swirling flows. Comparisons of simulation results with measurements are good. It is observed that in isothermal flows, as the swirl number or blockage ratio is increased, the vortex breakdown bubble moves upstream and its mean structure changes. The effect of heat release leads to considerable differences in the flow characteristics as the vortex breakdown bubble is pushed downstream due to dilatation. The critical swirl number, at which the VBB and CRZ merge, is observed to be higher in reacting flows for the same blockage ratio.
| Type: | Article |
|---|---|
| Title: | Influences of heat release, blockage ratio and swirl on the recirculation zone behind a bluff body |
| Open access status: | An open access version is available from UCL Discovery |
| DOI: | 10.1080/00102202.2022.2041616 |
| Publisher version: | https://doi.org/10.1080/00102202.2022.2041616 |
| Language: | English |
| Additional information: | © 2022 The Author(s). Published with license by Taylor & Francis Group, LLC. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. |
| Keywords: | Swirling flows; premixed flames; turbulent reacting flows; bluff body flames; recirculation zone |
| UCL classification: | UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Engineering Science UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Engineering Science > Dept of Mechanical Engineering UCL > Provost and Vice Provost Offices > UCL BEAMS UCL |
| URI: | https://discovery.ucl.ac.uk/id/eprint/10145364 |
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