Scaling of impeller response to impeller-diffuser interactions in centrifugal compressors

A numerical investigation has been conducted to quantify the effect of impeller-diffuser interaction on changes in impeller performance. An assessment is made of the hypothesis that the nondimensional parameter characterizing impeller performance change due to interaction is the ratio of the radial gap between the impeller trailing edge and the diffuser leading edge to the diffuser vane pitch. The time averaged results are found to show no measurable performance change with varying degrees of impeller-diffuser interaction, disproving the hypothesis. Analysis of the flow field shows that changes in loss and blockage due to interaction in the region of the blade leakage flow, which were expected to drive performance change, are negligible. The disproven hypothesis lacks parameters to relate the level of impeller passage unsteadiness to the level of performance change due to interaction, which are shown to be important. The ratio of the unsteady amplitude, of blade leakage velocity or blade loading, to the time average value appears to be a parameter capable of quantifying the impact of unsteadiness on impeller performance change.

Department dc:contributor.department

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

Grantor dc:publisher

Massachusetts Institute of Technology

Year dc:date.issued

2008

Author dc:creator

• Tarr, David Landon

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/1721.1/44924

OAI identifier oai:identifier

oai:dspace.mit.edu:1721.1/44924