Unsteady processes in centrifugal compressors

Izmailov, R. A.; Seleznev, K. P.

doi:10.1007/bf01155744

Cited by 4 publications

(5 citation statements)

References 3 publications

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“…Signals obtained from different elements can serve as signs of a pre-surge state: the diaphragm of the flow meter in the method of Y.Z. Guzelbaeva [13] or a core in the Mackey R.J. method [14]. These methods are quite indirect and allow the compressor to enter the surge.…”

Section: Methodsmentioning

confidence: 99%

Improving the reliability of the compressor unit using the wavelet transform method

et al. 2019

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Centrifugal compressors are an integral part of modern production in such industries as gas transmission, oil refining, metallurgical, machine-building, mining, as well as in electric and heat power engineering. Interruptions in the operation or failures of compressors lead to decrease in profit or large material loss. Conditions should be created for the safe (stable) operation of centrifugal compressors. Surge is global (complete) loss of stability, an unacceptable phenomenon for a centrifugal compressor. Compressor surge protection must function during operation. The algorithms used to protect centrifugal compressors against surge have some drawbacks, which makes it impossible to reliably prevent surges. There are many methods for analyzing rapidly changing processes in the flow part of a centrifugal compressor. The wavelet theory is the most accurate and modern method. The use of the wavelet transform method for signal processing allows us to solve the problems of analyzing non-stationary processes of a centrifugal compressor to expand the acceptable range of work and build reliable operation of the anti-surge diagnostic system. In the future, it is possible to use other basic wavelet functions, for comparison and selection of the most suitable one, for the analysis of unsteady signals in a centrifugal compressor.

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Section: Methodsmentioning

confidence: 99%

Improving the reliability of the compressor unit using the wavelet transform method

et al. 2019

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“…As the compressor operational mass flow _ m becomes lower than the value of _ m crit (also known as 'stability margin') the first set of local flow instabilities appear. 3 These are typically referred to as rotating stall 4,5 or/and inlet recirculation [6][7][8] and appear respectively in radial diffuser and in impeller inducer; . Further mass flow decrease leads the stage to enter the so-called 'mild surge' regime when the operational point orbits around the surge margin 9 periodically entering the rotating stall at a part of the surge cycle 10 ; .…”

Section: Introductionmentioning

confidence: 99%

“…2 The instabilities usually develop in a following order: As the compressor operational mass flow m· becomes lower than the value of m·crit (also known as ‘stability margin’) the first set of local flow instabilities appear. 3 These are typically referred to as rotating stall 4,5 or/and inlet recirculation 6–8 and appear respectively in radial diffuser and in impeller inducer; Further mass flow decrease leads the stage to enter the so-called ‘ mild surge ’ regime when the operational point orbits around the surge margin 9 periodically entering the rotating stall at a part of the surge cycle 10 ; Subsequent mass flow reduction to the values lower than those of the mild surge makes the stage enter the ‘ deep surge ’ regime when the surge cycle no longer contains a rotating stall phase, the minimal mass flow during the cycle is almost zero and the dynamic loads on the machine elements are the greatest. …”

Section: Introductionmentioning

confidence: 99%

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Experimental investigation of the influence of the inlet duct configuration on the unstable operation of a single-stage centrifugal blower

Kabalyk

Kryłłowicz

Liśkiewicz

et al. 2016

Proceedings of the Institution of Mechanical Engineers, Part A:

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The article is devoted to the experimental investigation of the interactions between the amplitudes and frequencies of surge in a single-stage centrifugal blower and the configuration of its inlet duct. In this work, the term 'configuration' implies the combination of the following: the volume of the duct, the presence of the filter inside the duct and the inlet guide vane position. The high-response pressure measurements were performed at three points along the impeller shroud (inlet, middle, outlet) and at a single point downstream the volute outlet and then processed with the use of fast Fourier transform (FFT). The results of the measurements show that the response of the surging system to a change introduced into the duct's configuration is complex. The closure of the inlet guide vane typically causes a drop in the amplitude and frequency of fluctuating pressure. The introduction of a filter body into the duct most often damps the amplitudes of fluctuations, but leaves the frequencies unaltered. The change of the duct's volume controls the rate of this damping.

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“…The dispersion and the average value of the signal were calculated by the equations (1) (2) where N is the number of signal counts on which the calculation is based, (N -1)∆t is the time aperture, ∆t is the time between signal counts, and x i the value of the signal at the moment of the last count t 0 -(N -1)∆t. Use of the normalizing factor in Eqs.…”

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confidence: 99%

Methods of rotating stall and surge detection in centrifugal compressors

Guzel’baev¹,

Khavkin²,

Khisameev³

2006

Chem Petrol Eng

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Systems for prevention of surging of centrifugal compressors and methods of rotating stall detection and early surge diagnosis using statistical processing of sensor signals of various parameters, i.e., the method of calculation of the correlation function of the signal and the method of calculation of signal dispersion, are discussed. The results of routine tests of air and high-speed air centrifugal compressors and their detachable flow parts are adduced.The presently available systems for prevention of surging of centrifugal compressors (CC) can be divided roughly into two groups.1. Systems preventing surge, which are often called antisurge control systems. In this case, the surge boundary is plotted on the gas-dynamic curve of the compressor and to its right (10-15% toward the flow rate increase) is drawn the antisurge control line. If the working point of the compressor curve lies to the left of the control line, the bypass (or dump) valve slightly opens up, which prevents surging of the compressor. The surge boundary is determined experimentally in the course of surge tests or by calculation. As an example, in Fig. 1 are shown the surge boundary line for the supercharger N133-21-01 (curve 1) determined in the course of the surge tests and the antisurge control line (curve 2).2. Systems responding to incipient surge (surge signal indicators). In these systems, use is made of the distinguishing features of the behavior of the signals from the sensor, which characterize the compressor operation conditions (flow rate, supercharging pressure, current strength of the main electric drive, etc.), and a discrete signal is generated for forced opening of the bypass valve and/or for stopping of the compressor.A surge signal indicator can be installed in addition to the antisurge control system, and if this system fails either due to variation in the parameters of the gas being compressed or due to inadmissible increase in the thickness of the deposit layer in the flow part, the surge signal indicator prevents operation of the compressor in inadmissible surge conditions. Let us examine the second group of surge prevention systems. Research carried out by developers of surge prevention systems for centrifugal compressors was focused on detection of distinguishing features of incipient surge, which is characterized by fluctuations of the (discharge) pressure and the rate of gas flow through the compressor, the delivery temperature, the current strength of the electric drive, etc. Many patents have been granted on this subject in Russia and abroad. For example, an antisurge device based on fixing of the moment of concurrent drop in the delivery pressure and the rate of gas flow through the compressor has been patented [1].In a series of experiments performed in the 1960s [2, 3], it was found that rotating stall appears in the centrifugal compressor in the region of the working points of the compressor characteristics (curve) near the surge boundary. Theoretical and experimental studies of rotating stall that precedes surg...

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Unsteady processes in centrifugal compressors

Cited by 4 publications

References 3 publications

Improving the reliability of the compressor unit using the wavelet transform method

Improving the reliability of the compressor unit using the wavelet transform method

Experimental investigation of the influence of the inlet duct configuration on the unstable operation of a single-stage centrifugal blower

Methods of rotating stall and surge detection in centrifugal compressors

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