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International Journal of Rotating Machinery
Volume 10, Issue 1, Pages 45-53

Multi-Control-Volume Analysis of the Compression Process in a High-Temperature Root's Type Compressor

1Padnos School of Engineering, Grand Valley State University, 301 W. Fulton St., Grand Rapids 49504-6431, MI, USA
2Mechanical and Aerospace Engineering Department, State University of New York at Buffalo, Buffalo, New York, USA

Copyright © 2004 Hindawi Publishing Corporation. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.


In this study we have modeled a high-temperature Root's type compressor and compared predicted results with measurements. Compression process is modeled using multiple control volumes. Initially, there are two control volumes connected by an “expansion nozzle” naturally formed by the rotor tip and the blower casing. The “nozzle” has time-varying geometry and is modeled to allow transition from choked to non-choked flow. The well-filling process is modeled via expansion of the compressed gas from the high-pressure reservoir into the well through this “nozzle.” When the pressures in the well and reservoir equalize, the “passive” part of the compression process is taken to be complete. At this point, the gas in the well is assumed to be fully-mixed and the two control volumes are subsequently considered as one. Then the “active” part of compression takes place. Numerical computations are shown to agree well with the experimental data.