Characterization of the flow field response to vaneless space reduction in centrifugal compressors

The unsteady three-dimensional flow field for two centrifugal compressors of nearly identical design (one with a marginally smaller impeller-diffuser gap) is interrogated to assess the difference in the time averaged performance and unsteady loading characteristics of the impeller blades. Computational calculations are conducted for three different operating points. Results show that the difference in the time-average performance of the two compressors is due to the change in the level of loss and blockage generated from a difference in the strength of the impeller-diffuser interaction between the two compressors. The unsteady component of loading on the impeller blade originates from pressure waves propagating with a phase difference on the suction and pressure surfaces of the blades. The frequency of the waves is set by the diffuser vanes passing frequency and the wavelength by the product of the diffuser vane passing period and the speed of the wave. It is demonstrated that the difference in static pressure from the pressure surface to the suction surface at the leading edge of the diffuser vanes sets the amplitude of unsteady loading on the blades of the impeller.

Department dc:contributor.department

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

Grantor dc:publisher

Massachusetts Institute of Technology

Year dc:date.issued

2006

Author dc:creator

• Villanueva V., Alfonso D. (Villanueva Villarreal)

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/1721.1/35559

OAI identifier oai:identifier

oai:dspace.mit.edu:1721.1/35559