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Investigation of tip leakage flow unsteadiness and rotating instability in a centrifugal compressor impeller
- Source :
- Proceedings of the Institution of Mechanical Engineers, Part D: Journal of Automobile Engineering. 236:621-638
- Publication Year :
- 2021
- Publisher :
- SAGE Publications, 2021.
-
Abstract
- A phenomenon called rotating instability was rarely reported in a centrifugal compressor, although some associated discussions can be found in axial compressors. This paper presents a numerical investigation on the unsteadiness of the tip leakage flow and rotating instability in an isolated centrifugal compressor impeller. A three-dimensional, unsteady full annuls simulation is performed under three different operating conditions. The tip leakage flow unsteadiness at the impeller inlet and inside the impeller passage is detected by the pressure fluctuation. During the throttling process, the temporal and spatial propagation characteristic of the tip leakage flow unsteadiness under the near stall operating condition is revealed based on the wavelet analysis, Fourier transform, and dynamic mode decomposition. Furthermore, the relationship between the tip leakage flow unsteadiness and the rotating instability is also discussed. The results show that the pressure fluctuation mainly concentrates in the tip region at the near stall operating condition, which indicates the occurrence and circumferential propagation of tip leakage flow unsteadiness. The circumferential propagation of the tip leakage flow unsteadiness induces a significant circumferential rotating pressure wave with a wave number of 9 and approximately 48.2% of the rotational speed of the impeller. The characteristic frequency of the tip leakage flow unsteadiness agrees well with the dominant mode frequency of rotating instability. Therefore, the tip leakage flow unsteadiness is assumed to be responsible for the rotating instability. During the throttling process, the formation and development of the rotating instability at near stall operating condition can be divided into three stages based on signal analysis: prior to rotating instability, generation and development, and rotating instability.
- Subjects :
- Materials science
Mechanical Engineering
Centrifugal compressor
Aerospace Engineering
Leakage flow
02 engineering and technology
Mechanics
01 natural sciences
Instability
010305 fluids & plasmas
Impeller
020303 mechanical engineering & transports
Axial compressor
0203 mechanical engineering
0103 physical sciences
Subjects
Details
- ISSN :
- 20412991 and 09544070
- Volume :
- 236
- Database :
- OpenAIRE
- Journal :
- Proceedings of the Institution of Mechanical Engineers, Part D: Journal of Automobile Engineering
- Accession number :
- edsair.doi...........ecebfe2db89c750b31382fe826f3cc6d
- Full Text :
- https://doi.org/10.1177/09544070211025902