The Role of Tip Leakage Flow in Spike-Type Rotating Stall Inception
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Authors
Hewkin Smith, Max
Pullan, Graham
Grimshaw, Sam
Greitzer, EM
Spakovszky, ZS
Journal Title
ASME Turbo Expo 2017: Turbomachinery Technical Conference and Exposition
Conference Name
ASME Turbo Expo 2017: Turbomachinery Technical Conference and Exposition
Publisher
American Society of Mechanical Engineers
Volume
2D: Turbomachinery
Language
English
Type
Conference Object
This Version
AM
Metadata
Show full item recordCitation
Hewkin Smith, M., Pullan, G., Grimshaw, S., Greitzer, E., & Spakovszky, Z. (2017). The Role of Tip Leakage Flow in Spike-Type Rotating Stall Inception. ASME Turbo Expo 2017: Turbomachinery Technical Conference and Exposition, 2D: Turbomachinery https://doi.org/10.1115/GT2017-63655
Abstract
This paper describes the role of tip leakage flow in creating the leading edge separation necessary for the onset of spike-type compressor rotating stall. A series of unsteady multi-passage simulations, supported by experimental data, are used to define and illustrate the two competing mechanisms that cause the high incidence responsible for this separation: blockage from a casing-suction-surface corner separation and forward spillage of the tip leakage jet. The axial momentum flux in the tip leakage flow determines which mechanism dominates. At zero tip clearance, corner separation blockage dominates. As the clearance is increased, the leakage flow reduces the blockage, moving the stall flow coefficient to lower flow, i.e., giving a larger unstalled flow range. Increased clearance, however, means an increase in leakage jet momentum and the contribution to leakage jet spillage. There is thus a clearance above which jet spillage dominates in creating incidence, so the stall flow coefficient increases and the flow range decreases with clearance. As a consequence there is a $\textit{clearance for maximum flow range}$; for the two rotors in this study, the value was approximately 0.5% chord. The chord-wise distribution of the leakage axial momentum is also important in determining stall onset. Shifting the distribution towards the trailing edge increases the flow range of a leakage jet dominated geometry and reduces the flow range of a corner separation dominated geometry. Guidelines are developed for flow range enhancement through control of tip leakage flow axial momentum magnitude and distribution. An example is given of how this might be achieved.
Keywords
stall inception, leakage flows
Sponsorship
The authors gratefully acknowledge Mitsubishi Heavy Industries, Ltd. for providing the funding for this project. This work used the Wilkes GPU cluster at the University of Cambridge High Performance Computing Service, provided by Dell Inc., NVIDIA and Mellanox, and part funded by the STFC.
Identifiers
External DOI: https://doi.org/10.1115/GT2017-63655
This record's URL: https://www.repository.cam.ac.uk/handle/1810/264141
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