A Theory of Rotating Stall of Multistage Axial Compressors: Part I—Small Disturbances

1984 ◽  
Vol 106 (2) ◽  
pp. 313-320 ◽  
Author(s):  
F. K. Moore
Keyword(s):  
Pressure Rise ◽  
Propagation Speed ◽  
Rotating Stall ◽  
Flow Coefficient ◽  
Fluid Inertia ◽  
Flow Distortion ◽  
Axial Compressors ◽  
Experimental Values ◽  
Stagger Angle ◽  
Small Disturbances

An analysis is made of rotating stall in compressors of many stages, finding conditions under which a flow distortion can occur which is steady in a traveling reference frame, even though upstream total and downstream static pressure are constant. In the compressor, a pressure-rise hysteresis is assumed. Flow in entrance and exit ducts yield additional lags. These lags balance to give a formula for stall propagation speed. For small disturbances, it is required that the compressor characteristics be flat in the neighborhood of average flow coefficient. Results are compared with the experiments of Day and Cumpsty. If a compressor lag of about twice that due only to fluid inertia is used, predicted propagation speeds agree almost exactly with experimental values, taking into account changes of number of stages, stagger angle, row spacing, and number of stall zones. The agreement obtained gives encouragement for the extension of the theory to account for large amplitudes.

scholarly journals Stalled Flow Performance for Axial Compressors: I — Axisymmetric Characteristic

1984 ◽  
Author(s):  
S. G. Koff ◽  
E. M. Greitzer
Keyword(s):  
Flow Model ◽  
Flow Characteristic ◽  
Pressure Rise ◽  
Rotating Stall ◽  
Reversed Flow ◽  
Axial Compressors ◽  
Point Pressure ◽  
Multistage Compressors ◽  
Entire Flow ◽  
Stagger Angle

A study of stalled flow performance of multistage compressors is presented. A new compressor characteristic is developed, describing the axisymmetric pumping performance over the entire compressor flow range, including reversed flow. This axisymmetric characteristic is required in any current rotating stall model. It is possible for the axisymmetric performance to rise above the measured stall point pressure rise, thus indicating greater unstalled pressure rise potential. In this context, the axisymmetric characteristic in forward flow is viewed as paralleling diffuser performance. A simple two-dimensional reversed flow model is presented, and is shown to be in reasonable agreement with available high backflow compressor data. The model predicts that the blade stagger angle greatly influences the reversed flow characteristic. Calculations are carried out using the rotating stall model of Moore and the axisymmetric characteristic developed herein, and a technique is suggested for estimating the axisymmetric curve over the entire flow range.

A Theory of Rotating Stall of Multistage Axial Compressors: Part III—Limit Cycles

1984 ◽  
Vol 106 (2) ◽  
pp. 327-334 ◽  
Author(s):  
F. K. Moore
Keyword(s):  
Limit Cycles ◽  
Propagation Speed ◽  
Nonlinear Damping ◽  
External Flow ◽  
Rotating Stall ◽  
Flow Coefficient ◽  
Width Ratio ◽  
Average Performance ◽  
Axial Compressors

A theory of rotating stall, based on single parameters for blades-passage lag and external-flow lag and a given compressor characteristic yields limit cycles in velocity space. These limit cycles are governed by Lienard’s equation with the characteristic playing the role of nonlinear damping function. Cyclic integrals of the solution determine stall propagation speed and the effect of rotating stall on average performance. Solution with various line-segment characteristics and various throttle settings are found and discussed. There is generally a limiting flow coefficient beyond which no solution is possible; this probably represents stall recovery. This recovery point is independent of internal compressor lag, but does depend on external lags and on the height-to-width ratio of the diagram. Tall diagrams and small external lags (inlet and diffusor) favor recovery. Suggestions for future theoretical and experimental research are discussed.

Axisymmetrically Stalled Flow Performance for Multistage Axial Compressors

1986 ◽  
Vol 108 (2) ◽  
pp. 216-223 ◽  
Author(s):  
S. G. Koff ◽  
E. M. Greitzer
Keyword(s):  
Reasonable Agreement ◽  
Flow Model ◽  
Flow Characteristic ◽  
Pressure Rise ◽  
Rotating Stall ◽  
Two Dimensional ◽  
Reversed Flow ◽  
Axial Compressors ◽  
Point Pressure ◽  
Stagger Angle

A study of the stalled flow performance of multistage axial compressors is presented. A proposal is made regarding the form of axisymmetric pumping performance in stall (which is a requisite of current rotating stall models) over the entire compressor flow range, including reversed flow. It is also shown that the axisymmetric performance can rise above the measured stall point pressure rise, thus indicating greater unstalled pressure rise potential. A simple two-dimensional reversed flow model is presented, and is shown to be in reasonable agreement with available high backflow compressor data. The model predicts that the blade stagger angle greatly influences the reversed flow characteristic. Calculations are also carried out applying this axisymmetric characteristic to the rotating stall model of Moore.

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.

Calculations of Effects of Rotating Inlet Distortion on Flow Instabilities in Compression Systems

1995 ◽  
Author(s):  
Jun Hu ◽  
Leonhard Fottner
Keyword(s):  
Propagation Speed ◽  
Transient Behavior ◽  
Rotating Stall ◽  
Flow Coefficient ◽  
Flow Instabilities ◽  
Resonant Response ◽  
Response Frequency ◽  
System Parameters ◽  
Inlet Distortion ◽  
The Stability

In the present paper calculations are presented to predict the post stall transient behavior and the onset of flow instabilities in axial compression systems with rotating inlet circumferential total pressure distortion. The effects of system parameters and the compressor characteristic are taken into account, and the effects on the boundaries of rotating stall and surge are investigated. It has been found that both the inlet distortion amplitude and rotating frequency have a strong effect on the stability and post stall transient behavior, and the rotating frequency has the same strong influence on the onset of surge as the influence on the onset of rotating stall. But the resonant response frequency (i.e., the rotating frequency of inlet distortion at which the greatest loss of stability occurs) strongly depends on the frequency at which the stall cell rotates. The study of the effects of system parameters shows that the loading and the flow coefficient of the compressor at the design point have a significant effect on the onset of instability, but they have little effect on the propagation speed of rotating stall and the resonant response frequency. The Greitzer B-parameter affects the onset of rotating stall, but it has little effect on the onset of surge. Some qualitative comparisons with available experimental results are made in this paper and show that the results are reliable.

Correlation and Prediction of Rotating Stall Inception by Divergence Method

1985 ◽  
Vol 107 (2) ◽  
pp. 191-196
Author(s):  
V. J. Zika
Keyword(s):  
Pressure Rise ◽  
Area Ratio ◽  
Rotating Stall ◽  
Compressor Blade ◽  
Flow Coefficient ◽  
Geometric Form ◽  
Form Parameter ◽  
Stall Inception ◽  
Multi Stage ◽  
Stall Angle

An empirical correlation of rotating stall inception points of elementary compressors (isolated rotors, stages without prerotation, complete single stages, and multi-stage machines with repeating stages), modeled as equivalent diffusers, is presented. From it, two inception criteria for self-induced rotating stall are derived. Compressor blade rows are classified according to a geometric form parameter, (L/A∞)cor, into two groups, subcritical and supercritical. The subcritical geometries stall at a constant kinematic area ratio AE/A∞, in what appears to be a pure rotating stall mode, which occurs before the airfoil stalls. In supercritical geometries, the rotating stall is delayed until it is triggered by the airfoil stall. Thus, for the latter geometries, the airfoil stall and rotating stall are coincident. In contrast to other diffuser-analog methods, the divergence method determines the stall angle and the stalled flow coefficient rather than the stalled pressure rise.

A Transonic Mixed Flow Compressor for an Extreme Duty

2014 ◽  
Author(s):  
Hamid Hazby ◽  
Michael Casey ◽  
Ryusuke Numakura ◽  
Hideaki Tamaki
Keyword(s):  
Test Data ◽  
Pressure Rise ◽  
High Flow ◽  
Flow Coefficient ◽  
Compressor Stage ◽  
Aerodynamic Optimization ◽  
Mixed Flow ◽  
Axial Compressors ◽  
Blade Shape ◽  
Flow Compressor

This paper describes the design of a transonic mixed flow compressor stage for an extreme duty, with an extremely high flow coefficient (Φ) of 0.25 and a high isentropic pressure rise coefficient (ψ) of 0.56. The impeller design makes use of modern aerodynamic practice from radial and transonic axial compressors, whereby the aerodynamic blade shape involved arbitrary surfaces on several spanwise sections. Some aspects of the aerodynamic optimization of the design were limited by mechanical considerations, but nevertheless the test data obtained on a prototype stage demonstrates that acceptable performance levels can be achieved at these extreme design conditions, although map width enhancement devices were needed to obtain an acceptable operating range. The test data is compared with CFD predictions to demonstrate the validity of the design methods used.

Clearance Effects on Centrifugal Compressor Characteristic and Stability

2007 ◽  
Author(s):  
Yong Sang Yoon ◽  
Shin Hyung Kang ◽  
Seung Jin Song
Keyword(s):  
Centrifugal Compressor ◽  
Rotational Speed ◽  
Pressure Rise ◽  
Rotating Stall ◽  
Tip Clearance ◽  
Flow Coefficient ◽  
Component Level ◽  
Stall Inception ◽  
Stability Model ◽  
Number Of Cells

The effects of impeller inlet tip clearance and diffuser width on centrifugal compressor characteristic and stability have been experimentally investigated in a centrifugal compressor with a vaneless diffuser. An increase in the impeller inlet tip clearance decreases the overall pressure rise across the compressor, mainly due to the tip clearance loss in the impeller. However, the effect of inlet tip clearance on diffuser pressure rise or compressor stability is weak. A decrease in the diffuser width significantly lowers the compressor pressure rise, especially at hight flow rates. At the component level, the impeller is insensitive to the diffuser width variation, and the pressure rise across the diffuser actually increases as diffuser width is decreased. Upon further investigation, it has been found that the overall compressor characteristic is strongly influenced by the region between the impeller exit and the diffuser inlet. Also, a decrease in the diffuser width delays stall inception by increasing the radial velocity of the flow in the diffuser. Thus, the stalling flow coefficient is more sensitive to the variation in the diffuser than the inlet tip clearance. In all cases, rotating stall consists of two or three cells rotating at about approximately one tenth of the compressor rotational speed. When the number of cells changes from three to two, the rotational speed drops. However, when the number of cells remains constant, the cells’ rotational speed increases as flow coefficient is lowered. All of these trends agree well with predictions from a new stability model developed by the first author.

A Transonic Mixed Flow Compressor for an Extreme Duty

2015 ◽  
Vol 137 (5) ◽  
Author(s):  
Hamid Hazby ◽  
Michael Casey ◽  
Ryusuke Numakura ◽  
Hideaki Tamaki
Keyword(s):  
Test Data ◽  
Pressure Rise ◽  
High Flow ◽  
Flow Coefficient ◽  
Aerodynamic Optimization ◽  
Mixed Flow ◽  
Axial Compressors ◽  
Blade Shape ◽  
Computational Fluid Dynamics Cfd ◽  
Flow Compressor

This paper describes the design of a transonic mixed flow compressor stage for an extreme duty, with an extremely high flow coefficient (φ) of 0.25 and a high isentropic pressure rise coefficient (ψ) of 0.56. The impeller design makes use of modern aerodynamic practice from radial and transonic axial compressors, whereby the aerodynamic blade shape involved arbitrary surfaces on several spanwise sections. Some aspects of the aerodynamic optimization of the design were limited by mechanical considerations, but nevertheless the test data obtained on a prototype stage demonstrates that acceptable performance levels can be achieved at these extreme design conditions, although map width enhancement (MWE) devices were needed to obtain an acceptable operating range. The test data are compared with computational fluid dynamics (CFD) predictions to demonstrate the validity of the design methods used.

A Theory of Post-Stall Transients in Axial Compression Systems: Part I—Development of Equations

1986 ◽  
Vol 108 (1) ◽  
pp. 68-76 ◽  
Author(s):  
F. K. Moore ◽  
E. M. Greitzer
Keyword(s):  
Partial Differential Equations ◽  
Differential Equations ◽  
Angular Dependence ◽  
Axial Compression ◽  
Pressure Rise ◽  
Rotating Stall ◽  
Flow Coefficient ◽  
Approximate Theory ◽  
Third Order ◽  
First Order

An approximate theory is presented for post-stall transients in multistage axial compression systems. The theory leads to a set of three simultaneous nonlinear third-order partial differential equations for pressure rise, and average and disturbed values of flow coefficient, as functions of time and angle around the compressor. By a Galerkin procedure, angular dependence is averaged, and the equations become first order in time. These final equations are capable of describing the growth and possible decay of a rotating-stall cell during a compressor mass-flow transient. It is shown how rotating-stall-like and surgelike motions are coupled through these equations, and also how the instantaneous compressor pumping characteristic changes during the transient stall process.

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