Three-dimensional rotating stall inception and effects of rotating tip clearance asymmetry in axial compressors

The effects of two types of flow nonuniformity on stall inception behavior were assessed with linearized stability analyses of two compressor flow models. Response to rotating tip clearance asymmetries induced by a whirling rotor shaft or rotor height variations were investigated with a two-dimensional flow model. A 3-D compressor model was also developed to study the stability of both full-span and part-span rotating stall modes in annular geometries with radial flow variations. The studies focussed on (1) understanding what compressor designs were sensitive to these types of circumferential and spanwise flow nonuniformities, and (2) situations where 2-D stability theories were inadequate because of 3-D flow effects. Rotating tip clearance nonuniformities caused the greatest performance loss for shafts whirling at the rotating stall frequency. A whirling shaft displacement of 1% chord caused the stalling mass flow to rise by as much as 10% and the peak pressure rise to decrease by 6%. These changes were an order of magnitude larger than for equivalent-sized stationary or rotor-locked clearance asymmetries. Spanwise flow nonuniformities always destabilized the compressor, so that 2-D models over-predicted the stall margin compared to 3-D theory. The difference increased for compressors with larger spanwise variations of characteristic slope and reduced characteristic curvature near the peak. Differences between 2-D and 3-D stall point predictions were generally unacceptable (2-4% of flow coefficient) for single-stage configurations, but were less than 1% for multistage compressors. 2-D analyses predicted the wrong stall mode for specific cases of radial inlet flow distortion, mismatching and annulus area contraction, where higher-order radial modes led to stall.

Department dc:contributor.department

Massachusetts Institute of Technology. Dept. of Aeronautics and Astronautics.

Grantor dc:publisher

Massachusetts Institute of Technology

Year dc:date.issued

1999

Author dc:creator

• Gordon, Kenneth A. (Kenneth Andrew), 1970-

Advisor dc:contributor.advisor

• Choon S. Tan.

• Aeronautics and Astronautics.

Statement dc:rights

• M.I.T. theses are protected by copyright. They may be viewed from this source for any purpose, but reproduction or distribution in any format is prohibited without written permission. See provided URL for inquiries about permission.

Licence dc:rights.uri

• http://dspace.mit.edu/handle/1721.1/7582

Language dc:language.iso

eng

Handle dc:identifier.uri

http://hdl.handle.net/1721.1/8183

OAI identifier oai:identifier

oai:dspace.mit.edu:1721.1/8183