The interaction between impeller and diffuser is considered to have strong influence on the flow in highly loaded centrifugal compressors. However, the knowledge about this influence is still not satisfying. This two-part paper presents an experimental investigation of the effect of impeller-diffuser interaction on the unsteady and the time averaged flow configuration in impeller and diffuser and the performance of these components. The flat wedge vaned diffuser of the investigated stage allows an independent adjustment of diffuser vane angle and radial gap between impeller exit and diffuser vane inlet. Attention is mainly directed to the radial gap, as it determines the intensity of the impeller-diffuser interaction. In part I it was shown that smaller radial gaps improve diffuser pressure recovery, whereas impeller efficiency is hardly affected. Part II focuses on the reasons for these effects. Measurements with a laser-2-focus velocimeter in the highly unsteady flow field between the impeller exit region and diffuser throat were performed at three different diffuser geometries allowing a detailed flow analysis. Especially the unsteady results show that for a smaller radial gap more impeller wake fluid is conveyed towards the highly loaded diffuser vane pressure side reducing its loading and leading to a better diffusion in the diffuser channel. Concerning the impeller flow, it was found that a smaller radial gap is leading to a noticeable reduction of the wake region at impeller exit. The experimental results are intended to be published as an open CFD testcase under the name “Radiver”.
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ASME Turbo Expo 2002: Power for Land, Sea, and Air
June 3–6, 2002
Amsterdam, The Netherlands
Conference Sponsors:
- International Gas Turbine Institute
ISBN:
0-7918-3610-X
PROCEEDINGS PAPER
A Study on Impeller-Diffuser Interaction: Part II — Detailed Flow Analysis
Kai U. Ziegler,
Kai U. Ziegler
RWTH – Aachen University of Technology, Aachen, Germany
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Heinz E. Gallus,
Heinz E. Gallus
RWTH – Aachen University of Technology, Aachen, Germany
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Reinhard Niehuis
Reinhard Niehuis
RWTH – Aachen University of Technology, Aachen, Germany
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Kai U. Ziegler
RWTH – Aachen University of Technology, Aachen, Germany
Heinz E. Gallus
RWTH – Aachen University of Technology, Aachen, Germany
Reinhard Niehuis
RWTH – Aachen University of Technology, Aachen, Germany
Paper No:
GT2002-30382, pp. 557-568; 12 pages
Published Online:
February 4, 2009
Citation
Ziegler, KU, Gallus, HE, & Niehuis, R. "A Study on Impeller-Diffuser Interaction: Part II — Detailed Flow Analysis." Proceedings of the ASME Turbo Expo 2002: Power for Land, Sea, and Air. Volume 5: Turbo Expo 2002, Parts A and B. Amsterdam, The Netherlands. June 3–6, 2002. pp. 557-568. ASME. https://doi.org/10.1115/GT2002-30382
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