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International Journal of Rotating Machinery
Volume 2006, Article ID 79084, 10 pages

Clearance Analysis and Leakage Flow CFD Model of a Two-Lobe Multi-Recompression Heater

1CD-adapco, 9401 General Drive, Plymouth, MI 48170, USA
2Department of Mechanical Engineering, School of Engineering, Grand Valley State University, Grand Rapids, MI 49504, USA
3Department of Mechanical and Aerospace Engineering, State University of New York at Buffalo, Buffalo, NY 14260, USA

Received 21 February 2006; Revised 5 May 2006; Accepted 4 June 2006

Copyright © 2006 Ashish M. Joshi et al. 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.


This paper reports the results of a study on multi-recompression heating. This process employs a Roots-type mechanism to heat gases to very high temperatures by compressive gas heating. A CFD model predicting the leakage flows in the machine was developed, and an excellent comparison with experimental data taken on a two-lobe Roots blower was obtained. A “clearance analysis” was performed to show that the clearance between the impellers remains constant for 96% of the angles of rotation. Assuming a quasi-steady state, the CFD simulation was performed for a single angle of rotation. A three-dimensional analysis showed that the flow field is identical along the rotor length, except for the leakage through the end plates. Hence, the model was further simplified to a two-dimensional analysis. This research may provide guidance in predicting the leakage flows in other blowers of the same kind with a different geometry.