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Transient separation and fluctuation of turbulent flow in an axisymmetric U-turn channel perturbed by periodically passing gust inflow.
- Source :
- Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science (Sage Publications, Ltd.); Jul2022, Vol. 236 Issue 14, p7745-7758, 14p
- Publication Year :
- 2022
-
Abstract
- The flow in the vane-less diffuser bend and return the channel of radial turbo-machines which is perturbed by the time-periodic and circumferentially passing jet-wake structure exited from the upstream impeller, and the transient characteristics of separation and fluctuation occurring in these stationary components determine the operational stability and performances of the turbo-machines especially for the next stage. In this work, we present a numerical investigation on the transient separation and fluctuation behaviors of turbulent flow in a sector of a 180° bended axisymmetric U-turn channel subjected to time-periodic gust inflow which passes in the circumferential direction. The objective is to explore the effect of period of gust inflow, in simulating the non-dimensional blade passing frequency (BPF*) in turbo-machines, on the characteristics of flow in the whole U-turn channel. Numerical results reveal that flow separation occurs in the curved section for about half the cycle at BPF* = 1 and 2, and earlier separation is observed for BPF* = 2, while there is no separation for BPF* = 5 and 10. There is a phase lag between the local skin friction coefficient in the channel and gust inflow, and the magnitude of the phase lag is related to BPF*. As BPF* increases, the thickness of the boundary layer on both walls decreases. [ABSTRACT FROM AUTHOR]
Details
- Language :
- English
- ISSN :
- 09544062
- Volume :
- 236
- Issue :
- 14
- Database :
- Complementary Index
- Journal :
- Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science (Sage Publications, Ltd.)
- Publication Type :
- Academic Journal
- Accession number :
- 158109485
- Full Text :
- https://doi.org/10.1177/09544062221081995