Rotating Waves as a Stall inception Indication in Axial Compressors

1991 ◽  
Vol 113 (2) ◽  
pp. 290-301 ◽  
Author(s):  
V. H. Garnier ◽  
A. H. Epstein ◽  
E. M. Greitzer
Keyword(s):  
Growth Rate ◽  
Small Amplitude ◽  
High Speed ◽  
Rotating Stall ◽  
Analytical Models ◽  
Stall Inception ◽  
Axial Compressors ◽  
Spatially Resolved ◽  
Two Stages ◽  
The Waves

Stall inception has been studied in two low-speed compressors (a single-stage and a three-stage) and in a high-speed three-stage compressor, using temporally and spatially resolved measurements. In all three machines, rotating stall was preceded by a period in which small-amplitude waves were observed traveling around the circumference of the machine at a speed slightly less than the fully developed rotating stall cell speed. The waves evolved smoothly into rotating stall without sharp changes in phase or amplitude, implying that, in the machines tested, the prestall waves and the fully developed rotating stall are two stages of the same phenomenon. The growth rate of these disturbances was in accord with that predicted by current analytical models. The prestall waves were observed both with uniform and with distorted inflow, but were most readily discerned with uniform inflow. Engineering uses and limitations of these waves are discussed.

scholarly journals Rotating Waves as a Stall Inception Indication in Axial Compressors

1990 ◽  
Author(s):  
V. H. Garnier ◽  
A. H. Epstein ◽  
E. M. Greitzer
Keyword(s):  
Growth Rate ◽  
Small Amplitude ◽  
High Speed ◽  
Rotating Stall ◽  
Analytical Models ◽  
Stall Inception ◽  
Axial Compressors ◽  
Spatially Resolved ◽  
Two Stages ◽  
The Waves

Stall inception has been studied in two low speed compressors (a single-stage and a three-stage) and in a high speed three-stage compressor, using temporally and spatially resolved measurements. In all three machines, rotating stall was preceded by a period in which small amplitude waves were observed travelling around the circumference of the machine at a speed slightly less than the fully developed rotating stall cell speed. The waves evolved smoothly into rotating stall without sharp changes in phase or amplitude, implying that, in the machines tested, the prestall waves and the fully developed rotating stall are two stages of the same phenomenon. The growth rate of these disturbances was in accord with that predicted by current analytical models. The prestall waves were observed both with uniform and with distorted inflow, but were most readily discerned with uniform inflow. Engineering uses and limitations of these waves are discussed.

Aeromechanical Control of High-Speed Axial Compressor Stall and Engine Performance— Part I: Control-Theoretic Models

2013 ◽  
Vol 135 (3) ◽  
Author(s):  
O. G. McGee ◽  
K. L. Coleman
Keyword(s):  
High Speed ◽  
Axial Compressor ◽  
Engine Performance ◽  
Maximum Flow ◽  
Rotating Stall ◽  
Design Flow ◽  
Systematic Evaluation ◽  
Stable Operation ◽  
Stall Inception ◽  
Axial Compressors

General methodologies are proposed in this two-part paper that further phenomenological understanding of compressible stall inception and aeromechanical control of high-speed axial compressors and engine performance. Developed in Part I are strategies for passive stabilization of compressible rotating stall, using tailored structural design and aeromechanical feedback control, implemented in certain classes of high-speed axial compressors used in research laboratories and by industry. Fundamentals of the stability of various dynamically-compensated, high-speed compressors was set down from linearized, compressible structural-hydrodynamic equations of modal stall inception extended further in this study from previous work. A dimensionless framework for performance-based design of aeromechanically-controlled compression system stall mitigation and engine performance is established, linking specified design flow and work-transfer (pressure) operability to model stages or local blade components, velocity triangle environment, optimum efficiency, extended stall margin and operability loci, and aeromechanical detailed design. A systematic evaluation was made in Part II (Coleman and McGee, 2013, “Aeromechanical Control of High-Speed Axial Compressor Stall and Engine Performance—Part II: Assessments of Methodology,” ASME J. Fluids Eng. (to be published)) on the performance of ten aeromechanical feedback controller schemes to increase the predicted range of stable operation of two laboratory compressor characteristics assumed, using static pressure sensing and local structural actuation to rudimentary postpone high-speed modal stall inception. The maximum flow operating range for each of the ten dynamically-compensated, high-speed compression systems was determined using optimized or “tailored” structural controllers, and the results described in Part II of the companion paper are compared to maximum operating ranges achieved in corresponding low-speed compression systems.

Numerical Simulation of Flow Instabilities in High Speed Multistage Compressors

2010 ◽  
Author(s):  
Huan Zhang ◽  
Jun Hu ◽  
Baofeng Tu ◽  
Zhiqiang Wang
Keyword(s):  
High Speed ◽  
Rotating Stall ◽  
Flow Instabilities ◽  
Two Dimensional ◽  
Duct Flow ◽  
Disk Model ◽  
Stall Inception ◽  
Axial Compressors ◽  
Multistage Compressors ◽  
The Stability

In the present paper, a nonlinear multi “actuator disk” model is proposed to analyze the dynamic behavior of flow instabilities, including rotating stall and surge, in high speed multistage axial compressors. The model describes the duct flow fields using two dimensional, compressible and unsteady Euler equations, and accounts for the influences of downstream plenum and throttle in the system as well. It replaces each blade row of multistage compressors with a disk. For numerical calculations, the time marching procedure, using MacCormack two steps scheme, is used. The main purpose of this paper is to predict the mechanism of two dimensional short wavelength rotating stall inception, the interaction between blade rows in high speed multistage compressors and the influence of rotating inlet distortion on the stability. It has been demonstrated that the model has the ability to predict those phenomena, and the results show that some system parameters have a strong effect on the stall features as well. Results for a five stage high speed compressor are analyzed in detail, and comparison with the experimental data demonstrates that the model and calculating results are reliable.

Prestall Behavior of Several High-Speed Compressors

1995 ◽  
Vol 117 (1) ◽  
pp. 62-80 ◽  
Author(s):  
M. Tryfonidis ◽  
O. Etchevers ◽  
J. D. Paduano ◽  
A. H. Epstein ◽  
G. J. Hendricks
Keyword(s):  
Wave Energy ◽  
Traveling Wave ◽  
Small Amplitude ◽  
High Speed ◽  
Rotating Stall ◽  
Shaft Speed ◽  
New Techniques ◽  
Rotating Waves ◽  
Strong Function ◽  
Stall Inception

High-speed compressor data immediately prior to rotating stall inception are analyzed and compared to stability theory. New techniques for the detection of small-amplitude rotating waves in the presence of noise are detailed, and experimental and signal processing pitfalls discussed. In all nine compressors examined, rotating stall precedes surge. Prior to rotating stall inception, all the machines support small-amplitude (< 1 percent of fully developed stall) waves traveling about the circumference. Traveling wave strength and structure are shown to be a strong function of corrected speed. At low speeds, a ∼0.5 times shaft speed wave is present for hundreds of rotor revolutions prior to stall initiation. At 100 percent speed, a shaft speed rotating wave dominates, growing as stall initiation is approached (fully developed rotating stall occurs at about 1/2 of shaft speed). A new, two-dimensional, compressible hydrodynamic stability analysis is applied to the geometry of two of the compressors and gives results in agreement with data. The calculations show that, at low corrected speeds, these compressors behave predominantly as incompressible machines. The wave that first goes unstable is the 1/2 shaft frequency mode predicted by the incompressible Moore–Greitzer analysis and previously observed in low-speed compressors. Compressibility becomes important at high corrected speeds and adds axial structure to the rotating waves. At 100 percent corrected speed, one of these hitherto unrecognized compressible modes goes unstable first. The rotating frequency of this mode is constant and predicted to be approximately coincident with shaft speed at design. Thus, it is susceptible to excitation by geometric nonuniformities in the compressor. This new understanding of compressor dynamics is used to introduce the concept of traveling wave energy as a real time measure of compressor stability. Such a wave energy-based scheme is shown consistently to give an indication of low stability for significant periods (100–200 rotor revolutions) before stall initiation, even at 100 percent corrected speed.

scholarly journals Pre-Stall Behavior of Several High-Speed Compressors

1994 ◽  
Author(s):  
M. Tryfonidis ◽  
O. Etchevers ◽  
J. D. Paduano ◽  
A. H. Epstein ◽  
G. J. Hendricks
Keyword(s):  
Wave Energy ◽  
Small Amplitude ◽  
High Speed ◽  
Travelling Wave ◽  
Rotating Stall ◽  
Shaft Speed ◽  
New Techniques ◽  
Rotating Waves ◽  
Strong Function ◽  
Stall Inception

High speed compressor data immediately prior to rotating stall inception are analyzed and compared to stability theory. New techniques for the detection of small amplitude rotating waves in the presence of noise are detailed and experimental and signal processing pitfalls discussed. In all nine compressors examined, rotating stall precedes surge. Prior to rotating stall inception, all the machines support small-amplitude (<1% of fully developed stall) waves travelling about the circumference. Travelling wave strength and structure are shown to be a strong function of corrected speed. At low speeds, a −0.5 times shaft speed wave is present for hundreds of rotor revolutions prior to stall initiation. At 100% speed, a shaft speed rotating wave dominates, growing as stall initiation is approached (fully developed rotating stall occurs at about 1/2 of shaft speed). A new, 2-D, compressible hydrodynamic stability analysis is applied to the geometry of two of the compressors and gives results in agreement with data. The calculations show that, at low corrected speeds, these compressors behave predominantly as incompressible machines. The wave which first goes unstable is the 1/2 shaft frequency mode predicted by the incompressible Moore-Greitzer analysis and previously observed in low speed compressors. Compressibility becomes important at high corrected speeds and adds axial structure to the rotating waves. At 100% corrected speed, it is one of these hitherto unrecognized compressible modes which goes unstable first. The rotating frequency of this mode is constant and predicted to be approximately coincident with shaft speed at design. Thus, it is susceptible to excitation by geometric nonuniformities in the compressor. This new understanding of compressor dynamics is used to introduce the concept of travelling wave energy as a measure of compressor stability. Such a wave energy-based scheme is shown to consistently give an indication of low stability for significant periods (100–200 rotor revolutions) before stall initiation, even at 100% corrected speed.

Stall Inception in a High Speed Centrifugal Compressor During Speed Transients

2017 ◽  
Author(s):  
Fangyuan Lou ◽  
John C. Fabian ◽  
Nicole L. Key
Keyword(s):  
Heat Transfer ◽  
Centrifugal Compressor ◽  
High Speed ◽  
Flow Instability ◽  
Leading Edge ◽  
Fast Response ◽  
Rotating Stall ◽  
Transient Performance ◽  
Stall Inception ◽  
Pressure Transducers

The inception and evolution of rotating stall in a high-speed centrifugal compressor are characterized during speed transients. Experiments were performed in the Single Stage Centrifugal Compressor (SSCC) facility at Purdue University and include speed transients from sub-idle to full speed at different throttle settings while collecting transient performance data. Results show a substantial difference in the compressor transient performance for accelerations versus decelerations. This difference is associated with the heat transfer between the flow and the hardware. The heat transfer from the hardware to the flow during the decelerations locates the compressor operating condition closer to the surge line and results in a significant reduction in surge margin during decelerations. Additionally, data were acquired from fast-response pressure transducers along the impeller shroud, in the vaneless space, and along the diffuser passages. Two different patterns of flow instabilities, including mild surge and short-length-scale rotating stall, are observed during the decelerations. The instability starts with a small pressure perturbation at the impeller leading edge and quickly develops into a single-lobe rotating stall burst. The stall cell propagates in the direction opposite of impeller rotation at approximately one third of the rotor speed. The rotating stall bursts are observed in both the impeller and diffuser, with the largest magnitudes near the diffuser throat. Furthermore, the flow instability develops into a continuous high frequency stall and remains in the fully developed stall condition.

Fan Stability With Leading Edge Damage: Blind Prediction and Validation

2021 ◽  
Author(s):  
E. J. Gunn ◽  
T. Brandvik ◽  
M. J. Wilson ◽  
R. Maxwell
Keyword(s):  
Supersonic Flow ◽  
High Speed ◽  
Leading Edge ◽  
Rotating Stall ◽  
Stall Inception ◽  
Blind Prediction ◽  
Edge Damage ◽  
The Impact ◽  
Operating Points ◽  
Relative Flow

Abstract This paper considers the impact of a damaged leading edge on the stall margin and stall inception mechanisms of a transonic, low pressure ratio fan. The damage takes the form of a squared-off leading edge over the upper half of the blade. Full-annulus, unsteady CFD simulations are used to explain the stall inception mechanisms for the fan at low- and high-speed operating points. A combination of steady and unsteady simulations show that the fan is predicted to be sensitive to leading edge damage at low speed, but insensitive at high speed. This blind prediction aligns well with rig test data. The difference in response is shown to be caused by the change between subsonic and supersonic flow regimes at the leading edge. Where the inlet relative flow is subsonic, rotating stall is initiated by growth and propagation of a subsonic leading edge flow separation. This separation is shown to be triggered at higher mass flow rates when the leading edge is damaged, reducing the stable flow range. Where the inlet relative flow is supersonic, the flow undergoes a supersonic expansion around the leading edge, creating a supersonic flow patch terminated by a shock on the suction surface. Rotating stall is triggered by growth of this separation, which is insensitive to leading edge shape. This creates a marked difference in sensitivity to damage at low- and high-speed operating points.

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.

About the Numerical Simulation of Rotating Stall Mechanisms in Axial Compressors

2006 ◽  
Author(s):  
N. Gourdain ◽  
S. Burguburu ◽  
G. J. Michon ◽  
N. Ouayahya ◽  
F. Leboeuf ◽  
...  
Keyword(s):  
Numerical Simulation ◽  
Pressure Rise ◽  
Rotating Stall ◽  
Tip Clearance ◽  
Stall Inception ◽  
Axial Compressors ◽  
Time Frequency ◽  
Flow Phenomena ◽  
Temporal Modes ◽  
Inception Point

This paper deals with the first instability which occurs in compressors, close to the maximum of pressure rise, called rotating stall. A numerical simulation of these flow phenomena is performed and a comparison with experimental data is made. The configuration used for the simulation is an axial single-stage and low speed compressor (compressor CME2, LEMFI). The whole stage is modeled with a full 3D approach and tip clearance is taken into account. The numerical simulation shows that at least two different mechanisms are involved in the stall inception. The first one leads to a rotating stall with 10 cells and the second one leads to a configuration with only 3 cells. Unsteady signals from the computation are analyzed thanks to a time-frequency spectral analysis. An original model is proposed, in order to predict the spatial and the temporal modes which are the results of the interaction between stall cells and the compressor stage. A comparison with measurements shows that the computed stall inception point corresponds to the experimental limit of stability. The performance of the compressor during rotating stall is also well predicted by the simulation.

On the Interpretation of Casing Measurements in Axial Compressors

2008 ◽  
Author(s):  
Joshua D. Cameron ◽  
Scott C. Morris ◽  
Sean T. Barrows ◽  
Jen-Ping Chen
Keyword(s):  
Experimental Studies ◽  
Rotating Stall ◽  
Basic Flow ◽  
Tip Clearance ◽  
Stall Inception ◽  
Tip Clearance Flow ◽  
Axial Compressors ◽  
Clearance Flow ◽  
Flow Variables ◽  
Insight Into

Experimental studies of stall inception in axial compressors typically involve the measurement of basic flow variables (often pressure or velocity) with low spatial resolution. These measurements are used to make inferences about the fluid dynamics of stall. This experimental paradigm has been used by many investigators to great effect over the last several decades. However, several limitations remain which restrict the utility of these types of measurements for developing further insight into stall inception physics. Primary among these limitations is the impracticality of making measurements within the rotating blade passages. This is especially troublesome in light of recent computational studies which indicate that the generation of short length-scale rotating disturbances is related to the rotor tip clearance flow. This study utilized the results of a recent full annulus rotating stall simulation to investigate the relationships between the casing pressure field and less observable flow quantities which are believed to be causally related to the generation of rotating disturbances. The CFD results are assumed to represent the true flow physics within the compressor. To the extent that this approximation is true, these results can be used to interpret the meaning of experimental measurements of basic flow variables. These observations not only provide new insight into the interpretation of the large catalog of experimental stall measurements found in the literature, they also give directives for future measurements and numerical simulations.

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