The Influence of Blade Row Dynamics on Lateral and Torsional Shaft Vibrations in Steam Turbines

Bachschmid, N.; Salvini, G.; Tanzi, Elisabetta; Pesatori, Emanuel

doi:10.1007/978-3-319-06590-8_10

Cited by 3 publications

(3 citation statements)

References 2 publications

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“…The cepstrum calculation is the basic method of cepstral analysis. The so-called real cepstrum that is defined by Formula ( 6) is an inverse Fourier transform (IDFT) of a logarithm of an amplitude spectrum of the sampled signal Formula (6).…”

Section: Cepstral Liftering Of the Shaft Vibrationsmentioning

confidence: 99%

“…It turns out that the frequency spectrum of such a signal also contains information about blade vibrations. The physical principle of how the blade oscillations propagate to the measured signal is described in [6]. It states that the total moment of inertia given by the contribution from all blades must be large enough to be reflected on the shaft.…”

Section: Introductionmentioning

confidence: 99%

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A Novel Method of Impeller Blade Monitoring Using Shaft Vibration Signal Processing

Liška

Vasicek

Jakl

2022

Sensors

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The monitoring of impeller blade vibrations is an important task in the diagnosis of turbomachinery, especially in terms of steam turbines. Early detection of potential faults is the key to avoid the risk of turbine unexpected outages and to minimize profit loss. One of the ways to achieve this is long-term monitoring. However, existing monitoring systems for impeller blade long-term monitoring are quite expensive and also require special sensors to be installed. It is even common that the impeller blades are not monitored at all. In recent years, the authors of this paper developed a new method of impeller blade monitoring that is based on relative shaft vibration signal measurement and analysis. In this case, sensors that are already standardly installed in the bearing pedestal are used. This is a significant change in the accessibility of blade monitoring for a steam turbine operator in terms of expenditures. This article describes the developed algorithm for the relative shaft vibration signal analysis that is designed to run in a long-term perspective as a part of a remote monitoring system to track the natural blade frequency and its amplitude automatically.

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Section: Cepstral Liftering Of the Shaft Vibrationsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

A Novel Method of Impeller Blade Monitoring Using Shaft Vibration Signal Processing

Liška

Vasicek

Jakl

2022

Sensors

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“…The rotor blade dynamic frequency test is objectively complex. Therefore, the blade static frequency test can be used to check whether the actual assembly condition of the blade and the vibration characteristics of the individual blade itself are close to the resonance frequency, so that accidents of the unit equipment can be avoided in time [1]. Through the on-site tap test of the turbine frequency modulation blade to determine whether the blade meets the requirements of long-term safe operation.…”

Section: Introductionmentioning

confidence: 99%

Static Frequency Test and Leaf Fracture Analysis of Turbine Blades in a Power Plant

Chai

Zhang

2019

AMM

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During the overhaul of a steam turbine of a power station, the frequency of the last twostages of the low-pressure rotor is tested and high-pressure rotor-regulated stage broken blades weresubjected to macroscopic inspection and analysis, chemical composition analysis, hardness test andmetallographic microstructure observation and analysis.The results of blade frequency measurementshow that the two stages of the low-pressure rotor can be safely and stably operated at the workingspeed. The results of broken blade analysis show that: due to the surface damage in the innersurface of the blade root, the blade vibration is aggravated, and the lower step of the concavegroove of the blade root is the stress concentration zone, where the fatigue crack source is generatedand gradually expanded, resulting in fatigue fracture of the blade; The fracture fatigue source zoneand the fatigue crack growth zone occupy approximately two-thirds of the entire fracture area,indicating that the blade fracture is a high-cycle fatigue fracture.

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Rotating blades monitoring using standard turbine instrumentation

Liška

Jakl

Vasicek

2019

Proceedings of the Institution of Mechanical Engineers, Part C:

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Ensuring the reliability of the steam turbine is fundamental task for its proper operation. Early detection of any failure avoids material and financial losses. A very important task in turbomachinery diagnostics is monitoring of rotating blades vibration, especially in terms of the last stages of low-pressure turbine parts, where, in general, the vibration can reach the important level due the blades length. The commonly used methods are based on stress evaluation using strain gauges or on the non-contact measurement of blade tips – blade tip-timing (BTT) method. Rising demand for low-cost monitoring systems suitable for blade monitoring has led to development of a new approach based on signal processing of standard turbine instrumentation. The symptoms of blade vibration could be also visible in signals from relative shaft vibration (SV) sensors, which are standardly installed in turbine journal bearings. This paper illustrates the principles and possibilities of the approach based on processing of SV signals for monitoring of actual state of rotating blades. Finally, the comparison of parallel measurements using SV and BTT in operation of steam turbine reveals the properties and advantages of both methods.

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The Influence of Blade Row Dynamics on Lateral and Torsional Shaft Vibrations in Steam Turbines

Cited by 3 publications

References 2 publications

A Novel Method of Impeller Blade Monitoring Using Shaft Vibration Signal Processing

A Novel Method of Impeller Blade Monitoring Using Shaft Vibration Signal Processing

Static Frequency Test and Leaf Fracture Analysis of Turbine Blades in a Power Plant

Rotating blades monitoring using standard turbine instrumentation

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