To reveal the relation between vortex structures and flow unsteadiness in the tip region of compressors, we calculated the flow fields in a subsonic compressor cascade at different incidences by solving URANS equations and extracted the tip-region vortex structures based on the Q-criterion. The results show that unsteady breakdown of the tip leakage vortex can indirectly influence the tip-region flow by inducing the formation of new vortex structures and therefore is the key factor leading to the instability of the tip-region flow. At incidences of -0.3ånd +0.7°, the spiral-type breakdown of the tip leakage vortex occurs, accompanied by the unsteady induced vortex. The effect of induced vortexes on the loading of the adjacent blade leads to the periodic fluctuation of the tip leakage vortex trajectory. At an incidence of +1.7°, the breakdown of the tip leakage vortex results in the formation of backflow vortexes. The transportation of backflow vortexes gives rise to the perturbations of blade loading and incidences, both of which, in turn, act on the vortex breakdown and backflow vortex formation. This periodic process leads to the self-sustained unsteady flow phenomenon.
WANG Bo
,
WU Yanhui
. Vortex-dynamics mechanism of tip-region unsteady flow in compressor cascade[J]. ACTA AERONAUTICAET ASTRONAUTICA SINICA, 2020
, 41(11)
: 123881
-123881
.
DOI: 10.7527/S1000-6893.2020.23881
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