Large eddy simulation of vortex breakdown/flame interaction
2007 (English)In: Physics of fluids, ISSN 1070-6631, E-ISSN 1089-7666, Vol. 19, no 7Article in journal (Refereed) Published
The dynamics of a swirl-stabilized premixed flame is studied using large eddy simulation (LES). A filtered flamelet model is used to account for the subgrid combustion. The model provides a consistent and robust reaction-diffusion expression for simulating the propagation of turbulent premixed flames correctly. The numerical results were found to be relatively insensitive to small changes in the inflow boundary conditions and to the numerical mesh employed. Furthermore, the results were found to agree well with the available experimental data both for velocity and scalar fields. In addition, unsteady flame features [i.e., precessing vortex core (PVC)] were identified and compared with experimental data. The agreement between LES results and experimental data, in terms of flame dynamics, was also good. Increasing swirl did not affect the flame strongly but a decrease of swirl number was shown to change the flame shape and suppress the PVC. The PVC and flame dynamics were studied using proper orthogonal decomposition (POD) allowing us to identify and isolate the PVC from smaller-scale turbulence. The POD results indicate that the PVC corresponds to a helical wave consisting of two counter-rotating helices. A dynamical reduced model was also derived do describe the flame response to the PVC.
Place, publisher, year, edition, pages
2007. Vol. 19, no 7
proper orthogonal decomposition, premixed turbulent combustion, reynolds-number flows, coherent structures, flame, model, mechanisms, jet
IdentifiersURN: urn:nbn:se:kth:diva-16835DOI: 10.1063/1.2749812ISI: 000248486100033OAI: oai:DiVA.org:kth-16835DiVA: diva2:334878
QC 201005252010-08-052010-08-05Bibliographically approved