Experimental Study of Rotating Stalls in a Four-Stage Axial Compressor

2002 ◽  
Author(s):  
Y. Levy ◽  
J. Pismenny ◽  
A. Reissner ◽  
W. Riess
Keyword(s):  
Cross Section ◽  
Axial Compressor ◽  
Pressure Oscillation ◽  
Transverse Cross Section ◽  
Rotating Stall ◽  
Pressure Variation ◽  
Time Diagram ◽  
Rotor Speed ◽  
Axial Compressors

The relationships between the frequencies of pressure oscillation ωOSC and the rotor speed (frequencies of rotor rotation) ωRR, as well as between the phases of pressure oscillation and geometrical angles of the sensor locations on the compressor casing (in the transverse cross-section) were determined experimentally. In addition, the phase–location relation permitted determination of the number of stall cells under established rotating stall. Literature on rotating stall in axial compressors typically refers to rotating stall with frequencies less than the rotor speed. This paper is concerned with two types of rotating stall, observed during experiments in a four-stage axial compressor, operating at the same rotor speed, n/nd = 0.95, where n is the rotor speed and nd the rotor data-sheet speed. The rotating stall frequencies were both, smaller and larger than the rotor speed. The relationships between ωOSC and ωRR were determined by four methods: directly from the time diagram of the pressure oscillation, from the diagrams of pressure variation in space and time, from the autocorrelation characteristics, and from the frequency characteristics of the pressure signals. All methods indicated values of ωOSC/ωRR in the form of integer ratios, 3:7 and 11:2. The phases of pressure oscillation in the transverse cross-section are equal to the sensor angles in compressor stator (in the case ωOSC/ωRR = 3:7) or are three times larger (in the case ωOSC/ωRR = 11:2), in accordance with the classical theory of single-cell and three-cell configurations of rotating stall, respectively.

The Number and Speed of Stall Cells During Rotating Stall

2003 ◽  
Author(s):  
Y. Levy ◽  
J. Pismenny
Keyword(s):  
Cross Section ◽  
Cross Sections ◽  
Pressure Oscillation ◽  
Transverse Cross Section ◽  
Rotating Stall ◽  
Joint Analysis ◽  
Distinctive Features ◽  
Multistage Compressor ◽  
Stall Cells ◽  
Original Interpretation

The number of stall cells and their rotational speed are distinctive features of the rotating stall phenomenon and play an important role in the prediction and analysis of the pressure fields during rotating stall. Various aspects of numbers and speed of stall cells are analyzed using an original interpretation method based on the pressure distribution in the circumference of a specific transverse cross-section at a specific time. This characteristic is similar to that of the pressure variation with time at a certain location on the compressor circumference. In some cases, the number of stall cells in any transverse cross-section may be defined after graphing the phase of pressure oscillation versus sensor positions and their joint analysis with the pressure signal variations in time and space. It is shown that whereas the numbers of stall cells in different transverse cross-sections of a multistage compressor may vary, the pressure field rotational speeds and accordingly the rotation speeds of all stall cells seem to be the same.

scholarly journals Comparison and Sensibility Analysis of Warning Parameters for Rotating Stall Detection in an Axial Compressor

2020 ◽  
Vol 5 (3) ◽  
pp. 16 ◽  
Author(s):  
Gabriel Margalida ◽  
Pierric Joseph ◽  
Olivier Roussette ◽  
Antoine Dazin
Keyword(s):  
Research Work ◽  
Axial Compressor ◽  
Rotating Stall ◽  
Stall Inception ◽  
Axial Compressors ◽  
Sensibility Analysis ◽  
Stall Warning ◽  
Two Parameters ◽  
Unsteady Pressure Measurements

The present paper aims at evaluating the surveillance parameters used for early stall warning in axial compressors, and is based on unsteady pressure measurements at the casing of a single stage axial compressor. Two parameters—Correlation and Root Mean Square (RMS)—are first compared and their relative performances discussed. The influence of sensor locations (in both radial and axial directions) is then considered, and the role of the compressor’s geometrical irregularities in the behavior of the indicators is clearly highlighted. The influence of the throttling process is also carefully analyzed. This aspect of the experiment’s process appears to have a non-negligible impact on the stall warning parameters, despite being poorly documented in the literature. This last part of this research work allow us to get a different vision of the alert parameters compared to what is classically done in the literature, as the level of irregularity that is reflected by the magnitude of the parameters appears to be an image of a given flow rate value, and not a clear indicator of the stall inception.

Tailored Structural Design and Aeromechanical Control of Axial Compressor Stall: Part II — Evaluation of Approaches

2003 ◽  
Author(s):  
L. G. Fre´chette ◽  
O. G. McGee ◽  
M. B. Graf
Keyword(s):  
Structural Parameters ◽  
Axial Compressor ◽  
Coupled System ◽  
Rotating Stall ◽  
Rotor Blades ◽  
Tip Clearance ◽  
Theoretical Evaluation ◽  
Axial Compressors ◽  
Spatial Modes ◽  
Control Authority

A theoretical evaluation was conducted delineating how aeromechanical feedback control can be utilized to stabilize the inception of rotating stall in axial compressors. Ten aeromechanical control methodologies were quantitatively examined based on the analytical formulations presented in the first part of this paper (McGee et al, 2003a). The maximum operating range for each scheme is determined for optimized structural parameters, and the various schemes are compared. The present study shows that the most promising aeromechanical designs and controls for a class of low-speed axial compressors were the use of dynamic fluid injection. Aeromechanically incorporating variable duct geometries and dynamically re-staggered IGV and rotor blades were predicted to yield less controllability. The aeromechanical interaction of a flexible casing wall was predicted to be destabilizing, and thus should be avoided by designing sufficiently rigid structures to prevent casing ovalization or other structurally-induced variations in tip clearance. Control authority, a metric developed in the first part of this paper, provided a useful interpretation of the aeromechanical damping of the coupled system. The model predictions also show that higher spatial modes can become limiting with aeromechanical feedback, both in control of rotating stall as well as in considering the effects of lighter, less rigid structural aeroengine designs on compressor stability.

Qualitative Analysis of an Axial Compressor Model With Non-Constant Speed

2011 ◽  
Author(s):  
Gh. Sari ◽  
O. Akhrif ◽  
L. Saydy
Keyword(s):  
Bifurcation Analysis ◽  
Axial Compressor ◽  
Rotating Stall ◽  
Constant Speed ◽  
Effective Control ◽  
Qualitative Behavior ◽  
Initial Speed ◽  
Variable Speed ◽  
Qualitative Properties ◽  
Axial Compressors

In this research we have addressed the study of the qualitative behavior of nonlinear variable speed axial compressors model exhibiting surge and stall instabilities. Such a study can shed some light on the development of an effective control approach being capable of simultaneously controlling the speed and instabilities. The controller can stabilize the system around an effective operating point and improve performance and reliability of variable speed axial compressors widely used in aeronautic industries. Although previous studies [1, 2] have focused on developing a model for non-constant speed axial compressors, qualitative characteristic of such a model is still unclear and its active control including both rotating stall and compressor speed is still a challenging problem. In this study we are particularly interested in investigating effects of the acceleration of the compressor rotor on qualitative properties of the model. To this end, bifurcation analysis of an axial compressor model with spool dynamics was performed and the simulation of the model was developed along the way. Preliminary surprising results revealed that the type of instability, surge or rotating stall, not only depends on the final speed as thought before but is also deeply affected by the rate of the rotor acceleration. Impacts of the initial speed on the qualitative properties of the model were demonstrated as well. Furthermore previous work [1, 2] showed that amplitudes of stall harmonics grow during the speed transition and cause a temporary pressure drop at the compressor output. Our simulation results supporting the bifurcation analysis of the model revealed that during speed transitions both amplitudes of high order stall harmonics and the number of dominant harmonics also depend on the rate of the acceleration and the initial speed.

scholarly journals Relative Flow Structure at Exit From an Axial Compressor Rotor in Rotating Stall

1984 ◽  
Author(s):  
R. Cheng ◽  
H. Ekerol ◽  
J. W. Railly
Keyword(s):  
Reverse Flow ◽  
Cell Structure ◽  
Axial Compressor ◽  
Orientation Angle ◽  
Rotating Stall ◽  
Compressor Rotor ◽  
Flow Vector ◽  
Trailing Edges ◽  
Probe Orientation

The phase-lock-averaging (PLA) technique is used in association with a traverse gear mounted on an axial compressor rotor to explore the flow field at exit from the rotor during rotating stall. The technique requires the use of a trigger hot-wire anemometer also mounted on the rotor to ensure the proper location of the stall cell in relation to the measurement probe. The probe consists of a three-wire non-orthogonal array which may be traversed radially and peripherally over a complete blade passage. By a systematic adjustment of the probe orientation angle, the presence of reverse flow is detected. A mathematical procedure for the determination of the magnitude and direction of the flow vector is presented. On the basis of a large collection of phase-locked data it is demonstrated that the leading and trailing edges of the cell travel at a non-uniform rate and in such a way as to vary cyclically in peripheral extent with a period related to the blade passing fequency. The peripheral distribution of the flow vector at successive instants of relative time is also produced from the data collection and the evolution of the stall cell structure is presented.

1997 Best Paper Award—Controls and Diagnostics Committee: Active Stabilization of Rotating Stall and Surge in a Transonic Single-Stage Axial Compressor

1998 ◽  
Vol 120 (4) ◽  
pp. 625-636 ◽  
Author(s):  
H. J. Weigl ◽  
J. D. Paduano ◽  
L. G. Fre´chette ◽  
A. H. Epstein ◽  
E. M. Greitzer ◽  
...  
Keyword(s):  
Mass Flow ◽  
Control Strategies ◽  
Axial Compressor ◽  
Gain Control ◽  
Rotating Stall ◽  
Forced Response ◽  
Single Stage ◽  
Rotor Speed ◽  
Stall Inception ◽  
Spatial Harmonics

Rotating stall and surge have been stabilized in a transonic single-stage axial compressor using active feedback control. The control strategy is to sense upstream wall static pressure patterns and feed back the signal to an annular array of twelve separately modulated air injectors. At tip relative Mach numbers of 1.0 and 1.5 the control achieved 11 and 3.5 percent reductions in stalling mass flow, respectively, with injection adding 3.6 percent of the design compressor mass flow. The aerodynamic effects of the injection have also been examined. At a tip Mach number, Mtip, of 1.0, the stall inception dynamics and effective active control strategies are similar to results for low-speed axial compressors. The range extension was achieved by individually damping the first and second spatial harmonics of the prestall perturbations using constant gain feedback. At a Mtip of 1.5 (design rotor speed), the prestall dynamics are different than at the lower speed. Both one-dimensional (surge) and two-dimensional (rotating stall) perturbations needed to be stabilized to increase the compressor operating range. At design speed, the instability was initiated by approximately ten rotor revolutions of rotating stall followed by classic surge cycles. In accord with the results from a compressible stall inception analysis, the zeroth, first, and second spatial harmonics each include more than one lightly damped mode, which can grow into the large amplitude instability. Forced response testing identified several modes traveling up to 150 percent of rotor speed for the first three spatial harmonics; simple constant gain control cannot damp all of these modes and thus cannot stabilize the compressor at this speed. A dynamic, model-based robust controller was therefore used to stabilize the multiple modes that comprise the first three harmonic perturbations in this transonic region of operation.

A Method of Stall and Surge Prediction in Axial Compressors Based On Three-Dimensional Body-Force Model

2021 ◽  
Author(s):  
Hanxuan Zeng ◽  
Xinqian Zheng ◽  
Mehdi Vahdati
Keyword(s):  
Body Force ◽  
Reverse Flow ◽  
Three Dimensional ◽  
Axial Compressor ◽  
Rotating Stall ◽  
The Body ◽  
Force Model ◽  
Computational Domain ◽  
Forward Flow ◽  
Axial Compressors

Abstract The occurrence of stall and surge in axial compressors has a great impact on the performance and reliability of aero-engines. Accurate and efficient prediction of the key features during these events has long been the focus of engine design processes. In this paper, a new body-force model that can capture the three-dimensional and unsteady features of stall and surge in compressors at a fraction of time required for URANS computations is proposed. To predict the rotating stall characteristics, the deviation of local airflow angle from the blade surface is calculated locally during the simulation. According to this local deviation, the computational domain is divided into stalled and forward flow regions, and the body-force field is updated accordingly; to predict the surge characteristics, the local airflow direction is used to divide the computational domain into reverse flow regions and forward flow regions. A single-stage axial compressor and a three-stage axial compressor are used to verify the proposed model. The results show that the method is capable of capturing stall and surge characteristics correctly. Compared to the traditional fully three-dimensional URANS method (fRANS), the simulation time for multi-stage axial compressors is reduced by 1 to 2 orders of magnitude.

Tailored Structural Design and Aeromechanical Control of Axial Compressor Stall—Part II: Evaluation of Approaches

2004 ◽  
Vol 126 (1) ◽  
pp. 63-72 ◽  
Author(s):  
L. G. Fre´chette ◽  
O. G. McGee ◽  
M. B. Graf
Keyword(s):  
Structural Parameters ◽  
Axial Compressor ◽  
Coupled System ◽  
Rotating Stall ◽  
Rotor Blades ◽  
Tip Clearance ◽  
Theoretical Evaluation ◽  
Axial Compressors ◽  
Spatial Modes ◽  
Control Authority

A theoretical evaluation was conducted delineating how aeromechanical feedback control can be utilized to stabilize the inception of rotating stall in axial compressors. Ten aeromechanical control methodologies were quantitatively examined based on the analytical formulations presented in the first part of this paper. The maximum operating range for each scheme is determined for optimized structural parameters, and the various schemes are compared. The present study shows that the most promising aeromechanical designs and controls for a class of low-speed axial compressors were the use of dynamic fluid injection. Aeromechanically incorporating variable duct geometries and dynamically re-staggered IGV and rotor blades were predicted to yield less controllability. The aeromechanical interaction of a flexible casing wall was predicted to be destabilizing, and thus should be avoided by designing sufficiently rigid structures to prevent casing ovalization or other structurally induced variations in tip clearance. Control authority, a metric developed in the first part of this paper, provided a useful interpretation of the aeromechanical damping of the coupled system. The model predictions also show that higher spatial modes can become limiting with aeromechanical feedback, both in control of rotating stall as well as in considering the effects of lighter, less rigid structural aeroengine designs on compressor stability.    

Incoming Stall Identification in Axial Compressors by Vibration Analysis

2013 ◽  
Author(s):  
Gianluca D’Elia ◽  
Giorgio Dalpiaz
Keyword(s):  
Vibration Analysis ◽  
Axial Compressor ◽  
Acoustic Signals ◽  
Rotating Stall ◽  
Test Results ◽  
Vibration Signals ◽  
Axial Compressors ◽  
Centrifugal Stage ◽  
Acoustic Characterization

This work addresses on a complete vibro-acoustic characterization of an axial compressor with the aim to foresee the rotor instability. The tests were performed on a turboshaft Allison 250-C18. The compressor is composed of six axial stages and one centrifugal stage. Four vibration signals were simultaneously measured by means of accelerometers, while the acoustic signals were measured by means of two microphones. Two different kinds of tests have been carried out on the compressor that operates at constant speed: in the course of the first test the six signals were acquired at different positions of the throttle opening, whereas during the second test, the signals were acquired while the throttle was gradually opened. The test results show a sensitive increase of the sub-synchronous activity in the accelerometers spectrum map, moreover, closing the throttle, the amplitude of the spectrum components increases. These phenomena can be related to the rotating stall behavior.

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