A Review of Nonsteady Flow Models for Compressor Stability

Longley, John P.

doi:10.1115/1.2928354

Cited by 73 publications

(25 citation statements)

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“…As seen in, e.g., [2, 24, 251, the models found in literature can be classified in several ways. The classification in this study is based on the fact that the modeling of surge and rotating stall requires two different approaches [48]; surge is associated with primary axisymmetric disturbances and involves mass flow and pressure variations in the entire compression system. Therefore, the plenum and throttle have to be incorporated in the model t o study this unstable phenomenon.…”

Section: Discussionmentioning

confidence: 99%

Modeling and control of compressor flow instabilities

1999

IEEE Control Syst.

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Stable operation of both axial and radial compressors is constrained by the occurence of aerodynamic flow instabilities: rotating stall and surge. Developments in the understanding of the physics behind these instabilities and ideas of how t o stabilize the compressor system, have opened the door t o a new era in the field of compressor control.This study gives an overview of the current state in modeling and control of surge and rotating stall in axial and radial compressors. It summarizes different types of aerodynamic flow instabilities that can occur in these machines. Compressor performance is discussed on the basis of compressor maps and important features of these instabilities are treated. But, this work focuses on active control systems applied in experimental systems. Compressor models that are used frequently in controller designs are described and the effect of assumptions on the prediction capability of these models is discussed. Furthermore, this report deals with control concepts t o guarantee stable operation and an outline is given of sensors, actuators and controllers applied in laboratory set-ups.The main contribution of this study is the comparison of aerodynamical flow instabilities found in axial and radial compressors, of several models, and of controllers implemented on experimental set-ups. It appeared that the behavior of a compressor system subsequent to instability onset is reasonably grasped but the considered models can not describe all types of instabilities encountered. Nevertheless, the Moore-Greitzer model seems an useful starting point for further research since it describes the compressor behavior subsequent t o the onset of rotating stall and surge. A better understanding of the mechanism(s) behind the onset of these instabilities may allow refinements to existing models and may give insights into new control methods. Currently, apart from a few exceptions, only complex-valued proportional feedback controllers are used. More advanced, nonlinear controllers are expected to improve the performance of the compressor system.

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Section: Discussionmentioning

confidence: 99%

Modeling and control of compressor flow instabilities

1999

IEEE Control Syst.

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“…By separating the large and small scale flow and then averaging over the small scale in the large scale equations one gets the effective large scale flow. This then allows one to explain why the quasi-steady approximation, see [30] and [23], did give good results for the spatially largest Fourier components. It was because the approximation was good for the flow in these very largest scales.…”

Section: Introductionmentioning

confidence: 99%

“…The flow in the compressor is first assumed to be axisymmetric and in a steady state and then terms are added to represent the time dependent and nonaxisymmetric flow effects. The flow instabilities surge and stall as well as non-uniformities in the inlet flow are relatively large length scale and long time scale flow phenomena compared to the length scale of the blade pitch and time scale of a blade passage (rotorstator pair) convection, see [23]. Thus the conventional Moore-Greitzer model represent the effective performance of the blades when averaged over the short length and time scales.…”

Section: Introductionmentioning

confidence: 99%

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Derivation of the viscous Moore-Greitzer equation for aeroengine flow

Birnir

Hou

Wellander

2007

Journal of Mathematical Physics

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The viscous Moore-Greitzer equation modeling the airflow through the compression system in turbomachines, such as a jet engine, is derived using a scaled Navier-Stokes equation. The method utilizes a separation of scales argument, based on the different spatial scales in the engine and the different time scales in the flow. The pitch and size of the rotor-stator pair of blades provides a small parameter, which is the size of the local cell. The motion of the stator and rotor blades in the compressor produces a very turbulent flow on a fast time scale. The leading order equation, for the fast-time and local scale, describes this turbulent flow. The next order equations, produce an axi-symmetric swirl and a flow-pattern analogous to Rayleigh-Bénard convection rolls in Rayleigh-Bénard convection. On a much larger spatial scale and a slower time scale, there exist modulations of the flow including instabilities called surge and stall. A higher order equation, in the small parameter, describes these global flow modulations, when averaged over the small (local) spatial scales, the fast time scale and the time scale of the vortex rotations. Thus a more general system of spatially global, slow-time equations is obtained. This system can be solved numerically without any approximations. The viscous Moore-Greitzer equation is obtained when small inertial terms are dropped from these slow-time, spatially global equations, averaged once more in the axial direction. The new equations are simulated with two different simplifying assumptions and the results compared with simulations of the viscous Moore-Greitzer equations.

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“…Its important characteristic is that the phase of fluctuations of pressure on a compressor circle changes in any cross-section depending on the angle of sensor positions (see, e.g., [1], , [2], Longley, 1994 and2007, [3,4], Day and Freeman, 1994 [5], Camp and Day, 1998, [6], Day et al, 1999, [7], Bright et al, 1999, [8], Inoue et al, 2002, [9], Bergner et al, 2006, [10], etc. ).…”

Section: Introductionmentioning

confidence: 99%

Links between Main Frequencies of Established Rotating Stall and Rotational Frequencies and/or Blade Passing Frequencies

Levy

Modelevsky

Pismenny

et al. 2013

International Journal of Rotating Machinery

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The ratios between the main frequency of rotating stall and rotational frequency may be considered in the form of exact ratios of small natural numbers if the pressure signals in compressors during rotating stall include the rotor rotation frequency component. During rotating stall in compressors with good rotor balancing (with absence of the rotational frequency component in the frequency characteristics of pressure signals), these ratios between the main frequency of rotating stall and rotational frequency are or are not in the form of ratios of small natural numbers. The experimentally received characteristics of power spectral density of pressure signals also show the presence of components with combinations of blade passing frequency and different harmonics of main rotating stall frequency.

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A Review of Nonsteady Flow Models for Compressor Stability

Cited by 73 publications

References 0 publications

Modeling and control of compressor flow instabilities

Modeling and control of compressor flow instabilities

Derivation of the viscous Moore-Greitzer equation for aeroengine flow

Links between Main Frequencies of Established Rotating Stall and Rotational Frequencies and/or Blade Passing Frequencies

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