Comparative Study of Unsteady Flows in a Transonic Centrifugal Compressor with Vaneless and Vaned Diffusers
To reduce vibration and noise level, the impeller and diffuser blade numbers inside an industrial compressor are typically chosen without common divisors. The shapes of volutes or collectors in these compressors are also not axis-symmetric. When impeller blades pass these asymmetric structures, the...
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| Main Author: | |
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| Format: | Article |
| Language: | English |
| Published: |
Wiley
2005-01-01
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| Series: | International Journal of Rotating Machinery |
| Subjects: | |
| Online Access: | http://dx.doi.org/10.1155/IJRM.2005.90 |
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| Summary: | To reduce vibration and noise level, the impeller and
diffuser blade numbers inside an industrial compressor are
typically chosen without common divisors. The shapes of volutes or
collectors in these compressors are also not axis-symmetric. When
impeller blades pass these asymmetric structures, the flow field
in the compressor is time-dependent and three-dimensional. To
obtain a fundamental physical understanding of these
three-dimensional unsteady flow fields and assess their impact on
the compressor performance, the flow field inside the compressors
needs to be studied as a whole to include asymmetric and unsteady
interaction between the compressor components. In the current
study, a unified three-dimensional numerical model was built for a
transonic centrifugal compressor including impeller, diffusers,
and volute. HFC 134a was used as the working fluid. The
thermodynamic and transport properties of the refrigerant gas were
modeled by the Martin-Hou equation of state and power laws,
respectively. The three-dimensional unsteady flow field was
simulated with a Navier-Stokes solver using the k−ε
turbulent model. The overall performance parameters are obtained
by integrating the field quantities. Both the unsteady flow field
and the overall performance are analyzed comparatively for each
component. The compressor was tested in a water chiller system
instrumented to obtain both the overall performance data and local
flow-field quantities. The experimental and numerical results
agree well. The correlation between the overall compressor
performance and local flow-field quantities is defined. The
methodology developed and data obtained in these studies can be
applied to the centrifugal compressor design and optimization. |
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| ISSN: | 1023-621X 1542-3034 |