What is it about?

This study adopted the POD method to decompose the swirling flow field data,which is based on the LES of the combustor,while also carefully analyzing the energy of different modes.Additionally,a four decomposition method was employed to reconstruct the flow field. Then,detailed quantitative studies were conducted on the mean flow field,coherent flow field,transition flow field,and turbulent flow field. Consequently,the patterns of the swirler structure’s effect on the com bustor’s stability were systematized through the POD’s analysis of the multi-case and experimental verification.

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Why is it important?

At present,most academic studies prioritize the analysis of the PVC’s mobility and the decomposition of the swirling vortex core aimed at a swirling combustor,yet neglect to endorse the comprehen sion the influence regularity of the PVC on the combustor’s stability. Furthermore,efficient prediction methods for the combustor’s stability are yet to be developed,rendering prearrangement and selection of stability impossible from the design’s premature stages.In engineering implementations,the scalar used to evaluate the air flow’s swirling characteristics of the downstream flow field of the swirler is relatively limited,and the most widely accepted one is the swirl number.In the engineering design process,the optimized design of the swirler usually iterates the effective flow area of the swirler repeatedly through numer ous experiments,thus making flow pattern of the liner uniform.For a specific downstream flow field of the swirler,the design method can not be covered.

Perspectives

The pulsation outcomes of the unsteady simulation match the experimental data quite well,with case 1 having the highest pulsation quantity.The POD analysis reveals that the majority of pulsation energy is concentrated in the first two modes.The results of the motion state,regularity of the time coefficient,and frequency characteristics also demonstrate that the combustor’s PVC features are compatible with modes 1 and 2.There is an optimum value of swirl number,0.72,for which the flow field’s stability has the lowest degree of disturbance.Moreover,the airfoil vane’s stability is beyond that of the straight vane.The mean flow field and the coherent flow field in the pulsation flow field of case 3 are the most beneficial factors concerning combustion stability,and the unstable aspects of the transition flow field and the turbulent flow field are the least in shape and energy ratio.The data procured from the experiment certify that there is no characteristic frequency of pulsation within 5000 Hz that exists in case 3.

Li Xing

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This page is a summary of: Influence of dual-axial swirler configuration on hydrodynamic stability in combustor, Physics of Fluids, March 2023, American Institute of Physics,
DOI: 10.1063/5.0139259.
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