Some Guidelines for the Experimental Characterization of Vaneless Diffuser Rotating Stall in Stages of Industrial Centrifugal Compressors

Bianchini, Alessandro; Biliotti, Davide; Giachi, Marco; Belardini, Elisabetta; Tapinassi, Libero; Ferrari, Lorenzo; Ferrara, Giovanni

doi:10.1115/gt2014-26401

Cited by 15 publications

(8 citation statements)

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“…This instability presents very interesting features and should be analyzed with different numerical experimental methods to provide a better understanding. The experiment should include at least two signals positioned at an angular spacing between 0 • and 60 • , or more pairs of points to assure correct stall recognition with larger number of lobes [42].…”

Section: Discussion Of Key Findingsmentioning

confidence: 99%

Unstable Flow Structures Present at Different Rotational Velocities of the Centrifugal Compressor

et al. 2020

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Unstable flow structures cause inevitable energy losses in all power energy systems, including turbomachines. In this study, a set of analyses was conducted with the use of spectral maps on the pressure signals obtained from an industrial centrifugal compressor. The spectral maps provide one a detailed visualization of the flow conditions present in the machine along the performance curve and to distinguish the flow phenomena present prior to the surge. The method accuracy is especially useful in detecting the inlet recirculation. The study was conducted at four impeller rotational speeds with varying loads imposed by a valve at the outlet. At each speed, the machine experienced different stages of unstable flow conditions prior to the surge. Five main frequency peaks that appeared in all cases were identified and discussed. The surge was observed at all impeller speeds. At lower ones, however, it appeared at higher valve closures. At higher speeds, the surge was much more intense. The study has also shown that the inlet recirculation appears also for the closed-type industrial impeller. The phenomenon was present in all conditions. The higher impeller speed, the faster onset of the inlet recirculation was. This structure has a strong potential for an early instability warning because it appears in various types of impellers, has a very particular spectral structure and its positioning is very predictable. This study gives another example of the inlet recirculation universality and potential for efficient anti-surge protection.

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Section: Discussion Of Key Findingsmentioning

confidence: 99%

Unstable Flow Structures Present at Different Rotational Velocities of the Centrifugal Compressor

et al. 2020

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“…If one relates these results with those displayed by Figure 9(b), it can be noticed that the microphone correctly only highlighted the stall frequency as that having the stronger amplitude, while the pressure probe sensed the first harmonic as that having the stronger amplitude. This can be probably due to the bi-cusp form of the stall, which is typical of patterns not completely rigid during their revolution [7]. Notwithstanding this, the procedure of [8] was able to correctly reconstruct the pattern anyway.…”

Section: Resultsmentioning

confidence: 97%

“…This aerodynamic phenomenon is characterized by the creation inside the diffuser of a non-axisymmetric pressure pattern, which rotates almost rigidly with a subsynchronous frequency generally lower than 20-30% of the revolution frequency [5,6]. This pattern is usually made of a small number (1-4) of stall cells or lobes [7]. The effect of this aerodynamic unbalance is the creation of a rotating force [8,9], which acts as a destabilizing external load on the rotordynamics of the compressor [10], possibly preventing the machine to operate in or beyond that operating condition.…”

Section: Introductionmentioning

confidence: 99%

Detection of vaneless diffuser rotating stall by means of dynamic pressure sensors and acoustic measurements

et al. 2021

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An accurate estimation of rotating stall is one of the key technologies for high-pressure centrifugal compressors. Several techniques have been proposed to detect the stall onset; inter alia, few dynamic pressure probes have been shown to not only properly detect the phenomenon, but also reconstruct the stall characteristics after an ensemble averaging approach. The massive use of this technique in the field is, however, not a common practice yet. In the present study, the use of dynamic pressure probes has been combined with that of an environmental microphone to evaluate the prospects of this latter for a possible stall onset detection. To this end, experimental tests have been carried out in the experimental test rig of the Department of Industrial Engineering (DIEF) of Università degli Studi di Firenze. Results show that the microphone was able to distinguish the onset of rotating stall accurately and promptly, even though – differently from dynamic pressure sensors - it does not provide sufficient information to determine the characteristics of the stall pattern. On this basis, the use of acoustic measurements could find room for automatic detection of rotating stall onset.

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“…In order to characterize the stall cell pattern during different quasi-steady operating conditions, the FFT spectrum combined with circumferential pressure distribution is first used for manual identification of the stall parameters since it is the most used and reliable method for industrial application [28]. Pressure pulsation signal spectrum is first analyzed to identify stall occurrences.…”

Section: Resultsmentioning

confidence: 99%

Rotating Stall Induced Non-Synchronous Blade Vibration Analysis for an Unshrouded Industrial Centrifugal Compressor

Zhao

Zhou

Yang³

et al. 2019

Sensors

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Rotating stall limits the operating range and stability of the centrifugal compressor and has a significant impact on the lifetime of the impeller blade. This paper investigates the relationship between stall pressure wave and its induced non-synchronous blade vibration, which will be meaningful for stall resonance avoidance at the early design phase. A rotating disc under a time-space varying load condition is first modeled to understand the physics behind stall-induced vibration. Then, experimental work is conducted to verify the model and reveal the mechanism of stall cells evolution process within flow passage and how blade vibrates when suffering such aerodynamic load. The casing mounted pressure sensors are used to capture the low-frequency pressure wave. Strain gauges and tip timing sensors are utilized to monitor the blade vibration. Based on circumferentially distributed pressure sensors and stall parameters identification method, a five stall cells mode is found in this compressor test rig and successfully correlates with the blade non-synchronous vibration. Furthermore, with the help of tip timing measurement, all blades vibration is also evaluated under different operating mass flow rate. Analysis results verify that the proposed model can show the blade forced vibration under stall flow condition. The overall approach presented in this paper is also important for stall vibration and resonance free design with effective experimental verification.

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Some Guidelines for the Experimental Characterization of Vaneless Diffuser Rotating Stall in Stages of Industrial Centrifugal Compressors

Cited by 15 publications

References 0 publications

Unstable Flow Structures Present at Different Rotational Velocities of the Centrifugal Compressor

Unstable Flow Structures Present at Different Rotational Velocities of the Centrifugal Compressor

Detection of vaneless diffuser rotating stall by means of dynamic pressure sensors and acoustic measurements

Rotating Stall Induced Non-Synchronous Blade Vibration Analysis for an Unshrouded Industrial Centrifugal Compressor

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