At present, the key element of lean low NOx combustors is a premixer where swirlers are often used for intensification of mixing processes and further formation of required flow pattern in combustor liner. Swirling flow leads to significant effect of some parts of hardware on stream features and mixing quality, emergence of flashback and flame blowout, formation of complex eddy structures causing flow perturbations. Therefore, at design phase, it is necessary to pay great attention to aerodynamics of premixers. The most effective method of swirling flow analysis in real combustor design is computational fluid dynamics (CFD). The present work is dedicated to study the effect of some computational model parameters, such as a turbulence model, grid size on calculation results as well as the analysis of the flow pattern in real swirler. Comparison between the analysis and experimental data showed that use of Detached Eddy Simulation (DES) allows to defining flow structure more accurately rather than use of RANS (URANS) with SST turbulence model also the size of computational grid elements influences stability of vortex structures. Analysis of swirling flow in production combustor swirler showed presence of large number of different eddy structures that can be conditionally divided into three types relative to its location of origin and a propagation path. Further, features of each eddy type were subsequently defined. Comparison of calculated and experimental pressure fluctuations spectrums verified correctness of computations. It was also noted that for the studied construction there is not even qualitative agreement between the steady and the time-averaged results of unsteady computations.

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