Rotating Stall in Centrifugal Compressor Vaneless Diffuser: Experimental Analysis of Geometrical Parameters Influence on Phenomenon Evolution

Ferrara, Giovanni; Ferrari, Lorenzo; Baldassarre, Leonardo

doi:10.1155/s1023621x04000430

Cited by 29 publications

(12 citation statements)

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“…They also affects the performance of the pump or the compressor. The behavior of vaneless diffusers of radial flow pumps, fans and compressors has been widely studied theoretically, experimentally and numerically [1][2][3][4][5]. Tsujimoto et al [6] have used a two-dimensional inviscid and incompressible flow analysis to study the rotating stall of vaneless diffuser.…”

Section: Introductionmentioning

confidence: 99%

Rotating instability in the vaneless diffuser of a radial flow pump

et al. 2008

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Section: Introductionmentioning

confidence: 99%

Rotating instability in the vaneless diffuser of a radial flow pump

et al. 2008

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“…From a perusal of the graph, one can readily notice that a wellmarked subsynchronous frequency appeared before surge running forward at a very low frequency (approximately 10% of the revolution frequency), which is typical of a rotating stall induced in a static component of the system [1,6,17].…”

Section: Resultsmentioning

confidence: 99%

“…1): in all sections, conventional measurements of pressure and temperature were performed (for further details on the standard instrumentation used in a similar test rig, please refer to Refs. [1,8,9,16]); in addition, in order to investigate the pressure fluctuations in aerodynamically unsteady regime, dynamic pressure measurements were also provided in Sections 20 and 40 of the tested configuration.…”

Section: Test-rig Experimental Measurementsmentioning

confidence: 99%

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A Systematic Approach to Estimate the Impact of the Aerodynamic Force Induced by Rotating Stall in a Vaneless Diffuser on the Rotordynamic Behavior of Centrifugal Compressors

Bianchini¹,

Biliotti²,

Ferrara

et al. 2013

Journal of Engineering for Gas Turbines and Power

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One of the main challenges of the present industrial research on centrifugal compressors is the need for extending the left margin of the operating range of ihe machines. As a result, interest is being paid to accurately evaluating the amplitude of the pressure fluctuations caused by rotating stall, which usually occurs prior to surge. The related aerodynamic force acting on the rotor can produce subsynchronous vibrations, which can prevent the machine's further operation, in case their amplitude is too high. These vibrations are often contained due to the stiffness of the oil journals. Centrifugal compressor design is, however, going towards alternative journal solutions having lower stiffness levels (e.g., active magnetic bearings or squeeze fllm dampers), which will be more sensitive to this kind of excitation: consequently, a more accurate estimation of the expected forces in the presence of dynamic external forces such as those connected to an aerodynamically unstable condition is needed to predict the vibration level and the compressor operability in similar conditions. Within this scenario, experimental tests were carried out on industrial impellers operating at high peripheral Mach numbers. The dedicated test rig was equipped with several dynamic pressure probes that were inserted in the gas flow path; moreover, the rotor vibrations were constantly monitored with typical vibration probes located near the journal bearings. The pressure fleld induced by the rotating stall in the vaneless diffuser was reconstructed by means of an ensemble average approach, thus deflning the amplitude and frequency of the external force acting on the impeller. The calculated force value was then included in the rotordynamic model of the test rig: the predicted vibrations on the bearings were compared with the measurements, showing satisfactory agreement. Moreover, the procedure was applied to two real multistage compressors, showing notable prediction capabilities in the description of rotating stall effects on the machine rotordynamics. Finally, the prospects of the proposed approach are discussed by investigating the response of a real machine in high-pressure functioning when different choices of journal bearings are made.

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“…The waterfalls signal presentation, based on the time-frequency analysis, was applied by Ferrara et al (2004) for a more in-depth study of the rotating stall inception and evolution. Even the most advanced time-frequency analysis by means of wavelet was applied by a few researchers in the field of turbomachinery.…”

Section: Introductionmentioning

confidence: 99%