Blade Vibration on Centrifugal Compressors - Fundamental Considerations and Initial Measurements

Haupt, U.; Bammert, K.; Rautenberg, M.

doi:10.1515/tjj.1987.4.1-2.107

Cited by 4 publications

(9 citation statements)

References 1 publication

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“…The flow enters through an axial suction pipe from a settling chamber and leaves downstream in an annular collecting chamber ended with a tangential outlet tube. Details of the testing system can be found in other publications in the past (Haupt, 1985a(Haupt, , 1986.…”

Section: Tested Compressormentioning

confidence: 99%

“…Therefore, designers of the compressor are no longer content with the conventional static stress analysis, and investigations on dynamic stress behaviors such as blade vibration are drawing more and more attentions. Apart from few early studies on the blade vibration in centrifugal compressor impellers (Nagub, 1977;Ellison, 1978), an extensive experimental programs have been carrying out for investigating blade vibration characteristics, sources of excitation, and mechanism of blade flow interactions (Haupt, 1982(Haupt, , 1985a(Haupt, , 1985b(Haupt, , 1986(Haupt, , 1988a(Haupt, , 1989b. These results have enabled a quantitative assessment of the danger of blade excitation and thus are very useful for the safety provision of compressor operation.…”

Section: Introductionmentioning

confidence: 99%

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Rotating Stall Flow and Dangerous Blade Excitation of Centrifugal Compressor Impeller: Part 2 — Case Study of Blade Failure

Hasemann

Haupt

Dai

et al. 1991

Volume 1: Turbomachinery

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Following a case of blade failure in running the test into unsteady rotating stall regime at 16000 rpm for a centrifugal compressor with backswept impeller, systematic unsteady flow investigation has been conducted, in order to clarify the cause of the failure, for the same compressor with a dublicated impeller. The doubled frequency of 2 cell rotating stall excitation, which is happened in the present case in the range of resonant frequencies, has been found to potentially impose the blade failure. Another source of dangerous excitation was found to be the excitation of large-number cell rotating stall. Some study has also been conducted to analyse the influencing parameters of the large-number stall cell phenomenon, which shows a trend of alleviating the dangerous excitation with increasing the diffuser inlet radius ratio or decreasing the diffuser vane inlet angle.

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Section: Tested Compressormentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Rotating Stall Flow and Dangerous Blade Excitation of Centrifugal Compressor Impeller: Part 2 — Case Study of Blade Failure

Hasemann

Haupt

Dai

et al. 1991

Volume 1: Turbomachinery

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“…2 were used to measure blade vibration. The fundamental calculations (Haupt et al 1985 a) and latter tests (Haupt et al 19856) indicated that this is the zone where the maximum stresses occur for the vibration in first and second blade modes. These modes were indeed the main modes excited when the compressor operates in the unsteady flow region.…”

Section: Compressor Test Facilitymentioning

confidence: 97%

“…2 and 3 were connected by thin wires to a 8-channel-FM-telemetry transmitter mounted on the bore of the hollow shaft at the impeller inlet. This transmitter is the rotating part of the telemetry system described in detail by Haupt et al (1985 a). The blade vibration signals transmitted by this system with trigger were recorded on a separate magnetic tape.…”

Section: Compressor Test Facilitymentioning

confidence: 99%

A Dangerous Blade Vibration Phenomenon due to Unsteady Flow in Centrifugal Compressors

Dai¹,

Hasemann²,

Haupt³

et al. 1993

Volume 3B: General

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Dangerous blade excitation caused by unsteady flow in a high pressure/high mass flow compressor running in a low mass flow region has been investigated. Experiments were carried out for compressors with two different types of vaned diffusers. Blade vibration was measured with strain gages while simultaneous unsteady pressure was measured with fast response dynamic transducers. All measured results were analysed in detail so that an in-depth understanding of blade excitation mechanism can be obtained. Firstly, the compressor with a straight-channel vane diffuser at reduced rotational speed of 12,300 rpm in an unstable operation region was considered. The analysis of blade vibration and unsteady pressure showed an unusual excitation phenomenon. Besides a strong blade vibration frequency component near the first blade mode frequency excited by the rotating stall cells existed another dangerous resonance excitation with first blade mode component which dominated the blade vibration spectrum. A detailed pressure signal analysis indicated that this blade vibration was excited by a broad band pressure fluctuation due to a strong reverse flow occurring simultaneously with the rotating stall. Further reducing the compressor mass flow to the operation point shortly before surge, the rotating stall was significantly weakened while the reverse flow kept its intensity until surge occurred. In this operation region blades suffered throughout a violent excitation of resonance because of the strong reverse flow. These blade excitation phenomena were also found in the next experiment for the compressor with a cambered vane diffuser at higher rotational speeds of nred = 13,500 and 14,000 rpm. The maximum strain values of blade vibration were obtained to quantitavely estimate the danger of blade vibration caused by this excitation.

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“…Experimental investigations by Haupt and coworkers (1982b,c;1985) have shown that in the case of highly-loaded centrifugal compressor impellers with small blade thicknesses and thin flexible impeller discs in the outlet region, coupled vibration behavior occurs which cannot be fully described interferometry. Further details of the finite element computations are given in Part II of the paper.…”

Section: Introductionmentioning

confidence: 99%

Coupled Vibration of Unshrouded Centrifugal CompressorImpellers. Part I: Experimental Investigation

Hasemann

Hagelstein

Rautenberg

1998

International Journal of Rotating Machinery

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The increased use of small gas turbines and turbochargers in different technical fields has led to the development of highly-loaded centrifugal compressors with extremely thin blades. Due to the high rotational speed and the corresponding centrifugal load, the shape of the impeller hub must also be optimized. This has led to a reduction of the thickness of the impeller disc in the outlet region. The thin parts of the impeller are very sensitive and may be damaged by the excitation of dangerous blade vibrations.Experimental investigations by means of holographic interferometry and telemetry were carried out for two different impeller types; one with radial-ending blades and the other with backswept blades. The results presented in Part I of the paper are able to explain the dominance of coupling effects between the blades and the disc in the middle and higher frequency range of the two tested impellers. Especially excitations caused by downstream sources such as vaned diffusers can endanger the blades and the impeller.The finite element (FE) code computations presented in Part II of the paper to investigate the coupled vibration behavior of the whole impeller were found to be in close agreement with the experimental results.

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Blade Vibration on Centrifugal Compressors - Fundamental Considerations and Initial Measurements

Cited by 4 publications

References 1 publication

Rotating Stall Flow and Dangerous Blade Excitation of Centrifugal Compressor Impeller: Part 2 — Case Study of Blade Failure

Rotating Stall Flow and Dangerous Blade Excitation of Centrifugal Compressor Impeller: Part 2 — Case Study of Blade Failure

A Dangerous Blade Vibration Phenomenon due to Unsteady Flow in Centrifugal Compressors

Coupled Vibration of Unshrouded Centrifugal CompressorImpellers. Part I: Experimental Investigation

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