Vaned diffusers in centrifugal compressor stages are used to achieve higher stage pressure ratios, higher stage efficiencies and more compact designs. The interaction of the stationary diffuser with the impeller can lead to resonant vibration with potentially devastating effects. This paper presents unsteady diffuser vane surface pressure measurements using in-house developed, flush mounted, fast response piezo-resistive pressure transducers. The unsteady pressures were recorded for 9 operating conditions, covering a wide range of the compressor map. Experimental work was complemented by 3D unsteady CFD simulations using ANSYS CFX V12.1 to detail the unsteady diffuser aerodynamics. Pressure fluctuations of up to 34.4% of the inlet pressure were found. High pressure variations are present all along the vane and are not restricted to the leading edge region. Frequency analysis of the measured vane surface pressures show that reduced impeller loading and the corresponding reduction of tip leakage fluid changes the characteristics of the fluctuations from a main blade count to a total blade count. The unsteady pressure fluctuations in the diffuser originate from three distinct locations. The impact of the jet wake flow leaving the impeller results in high variation close to the leading edge. It was observed that CFD results overpredicted the amplitude of the pressure fluctuation on average by 62%.
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ASME Turbo Expo 2014: Turbine Technical Conference and Exposition
June 16–20, 2014
Düsseldorf, Germany
Conference Sponsors:
- International Gas Turbine Institute
ISBN:
978-0-7918-4563-9
PROCEEDINGS PAPER
Experimental and Numerical Investigation of the Unsteady Flow Field in a Vaned Diffuser of a High-Speed Centrifugal Compressor
Klemens Vogel,
Klemens Vogel
ETH Zurich, Zurich, Switzerland
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Reza S. Abhari,
Reza S. Abhari
ETH Zurich, Zurich, Switzerland
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Armin Zemp
Armin Zemp
EMPA, Dübendorf, Switzerland
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Klemens Vogel
ETH Zurich, Zurich, Switzerland
Reza S. Abhari
ETH Zurich, Zurich, Switzerland
Armin Zemp
EMPA, Dübendorf, Switzerland
Paper No:
GT2014-25862, V02DT44A015; 12 pages
Published Online:
September 18, 2014
Citation
Vogel, K, Abhari, RS, & Zemp, A. "Experimental and Numerical Investigation of the Unsteady Flow Field in a Vaned Diffuser of a High-Speed Centrifugal Compressor." Proceedings of the ASME Turbo Expo 2014: Turbine Technical Conference and Exposition. Volume 2D: Turbomachinery. Düsseldorf, Germany. June 16–20, 2014. V02DT44A015. ASME. https://doi.org/10.1115/GT2014-25862
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