Multistage Centrifugal Compressor Surge Analysis: Part II—Numerical Simulation and Dynamic Control Parameters Evaluation

1999 ◽  
Vol 121 (2) ◽  
pp. 312-320 ◽  
Author(s):  
G. L. Arnulfi ◽  
P. Giannattasio ◽  
C. Giusto ◽  
A. F. Massardo ◽  
D. Micheli ◽  
...  
Keyword(s):  
Active Control ◽  
Centrifugal Compressor ◽  
Dynamic Control ◽  
Point Of View ◽  
Lumped Parameter Model ◽  
Theoretical Point ◽  
Control Parameters ◽  
Compression System ◽  
Compressor Surge ◽  
Multistage Centrifugal Compressor

This paper describes, from a theoretical point of view, the behavior of compression systems during surge and the effect of passive and active control devices on the instability limit of the system. A lumped parameter model is used to simulate the compression system described in Part I of this work (Arnulfi et al., 1999), based on an industrial multistage centrifugal compressor. A comparison with experimental results shows that the model is accurate enough to describe quantitatively all the features of the phenomenon. A movable wall control system is studied in order to suppress surge in the compressor. Passive and active control schemes are analyzed; they both address directly the dynamic behavior of the compression system to displace the surge line to lower flow rates. The influence of system, geometry and compressor speed is investigated: the optimum values of the control parameters and the corresponding increase in the extent of the stable operating range are presented in the paper.

scholarly journals Multistage Centrifugal Compressor Surge Analysis: Part II — Numerical Simulation and Dynamic Control Parameters Evaluation

1998 ◽  
Author(s):  
Gianmario L. Arnulfi ◽  
Pietro Giannattasio ◽  
Cristiana Giusto ◽  
Aristide F. Massardo ◽  
Diego Micheli ◽  
...  
Keyword(s):  
Active Control ◽  
Centrifugal Compressor ◽  
Dynamic Control ◽  
Point Of View ◽  
Lumped Parameter Model ◽  
Theoretical Point ◽  
Control Parameters ◽  
Compression System ◽  
Compressor Surge ◽  
Multistage Centrifugal Compressor

This paper describes, from a theoretical point of view, the behaviour of compression systems during surge and the effect of passive and active control devices on the instability limit of the system. A lumped parameter model is used to simulate the compression system described in Part I of this work (Arnulfi et al., 1998), based on an industrial multistage centrifugal compressor. A comparison with experimental results shows that the model is accurate enough to describe quantitatively all the features of the phenomenon. A moveable wall control system is studied in order to suppress surge in the compressor. Passive and active control schemes are analysed; they both address directly the dynamic behaviour of the compression system to displace the surge line to lower flow rates. The influence of system geometry and compressor speed is investigated; the optimum values of the control parameters and the corresponding increase in the extent of the stable operating range are presented in the paper.

Multistage Centrifugal Compressor Surge Analysis: Part I — Experimental Investigation

1998 ◽  
Author(s):  
G. L. Arnulfi ◽  
P. Giannattasio ◽  
C. Giusto ◽  
A. F. Massardo ◽  
D. Micheli ◽  
...  
Keyword(s):  
Experimental Investigation ◽  
Centrifugal Compressor ◽  
Reference Data ◽  
Dynamic Control ◽  
Rotating Stall ◽  
Operating Conditions ◽  
Multi Stage ◽  
Compressor Surge ◽  
Multistage Centrifugal Compressor ◽  
Insight Into

This paper reports an experimental investigation on centrifugal compressor surge. The compression system consists of a four-stage blower with vaned diffusers and a large plenum discharging into the atmosphere through a throttle valve. Measurements of unsteady pressure and flow rate in the plant, and of instantaneous velocity in the diffusers of the first and fourth compressor stage are performed during deep surge, at several valve settings and three different rotation speeds. Additional tests have been carried out on a different system configuration, i.e., without plenum, in order to obtain the steady-state compressor characteristics and to collect reference data on stall in surge-free conditions. In this configuration, a fully developed rotating stall was detected in the compressor diffusers, while during surge it affects only a limited part of the surge cycle. The goal of the present experimental work was to get a deeper insight into unstable operating conditions of multi-stage centrifugal compressors and to validate a theoretical model of the system instability to be used for the design of dynamic control systems.

scholarly journals Dynamic Control of Centrifugal Compressor Surge Using Tailored Structures

1990 ◽  
Author(s):  
D. L. Gysling ◽  
J. Dugundji ◽  
E. M. Greitzer ◽  
A. H. Epstein
Keyword(s):  
Centrifugal Compressor ◽  
Structural Control ◽  
Dynamic Control ◽  
Operating Conditions ◽  
Parameter Analysis ◽  
Compression System ◽  
Lumped Parameter ◽  
Stable Operating ◽  
Compressor Surge ◽  
Structural Motion

A new method for dynamic control of centrifugal compressor surge is presented. The approach taken is to suppress surge by modifying the compression system dynamic behavior using structural feedback. More specifically, one wall of a downstream volume, or plenum, is constructed so to move in response to small perturbations in pressure. This structural motion provides a means for absorbing the unsteady energy perturbations produced by the compressor, thus extending the stable operating range of the compression system. In the paper, a lumped parameter analysis is carried out to define the coupled aerodynamic and structural system behavior and the potential for stabilization. First-of-a-kind experiments are then carried out to examine the conclusions of the analysis. As predicted by the model and demonstrated with experiment, a moveable plenum wall lowered the mass flow at which surge occurred in a centrifugal compression system by roughly 25% for a large range of operating conditions. In addition, because the tailored dynamics of the structure acts to suppress instabilities in their initial stages, this control was achieved with relatively little power being dissipated by the moveable wall system, and with no noticeable decrease in steady state performance. Although designed on the basis of linear system considerations, the structural control is shown to be capable of suppressing existing large amplitude limit cycle surge oscillations.

scholarly journals Dynamic Control of Centrifugal Compressor Surge Using Tailored Structures

1991 ◽  
Vol 113 (4) ◽  
pp. 710-722 ◽  
Author(s):  
D. L. Gysling ◽  
J. Dugundji ◽  
E. M. Greitzer ◽  
A. H. Epstein
Keyword(s):  
Centrifugal Compressor ◽  
Structural Control ◽  
Dynamic Control ◽  
Operating Conditions ◽  
Parameter Analysis ◽  
Compression System ◽  
Lumped Parameter ◽  
Stable Operating ◽  
Compressor Surge ◽  
Structural Motion

A new method for dynamic control of centrifugal compressor surge is presented. The approach taken is to suppress surge by modifying the compression system dynamic behavior using structural feedback. More specifically, one wall of a downstream volume, or plenum, is constructed so as to move in response to small perturbations in pressure. This structural motion provides a means for absorbing the unsteady energy perturbations produced by the compressor, thus extending the stable operating range of the compression system. In the paper, a lumped parameter analysis is carried out to define the coupled aerodynamic and structural system behavior and the potential for stabilization. First-of-a-kind experiments are then conducted to examine the conclusions of the analysis. As predicted by the model and demonstrated by experiment, a movable plenum wall lowered the mass flow at which surge occurred in a centrifugal compression system by roughly 25 percent for a range of operating conditions. In addition, because the tailored dynamics of the structure acts to suppress instabilities in their initial stages, this control was achievable with relatively little power being dissipated by the movable wall system, and with no noticeable decrease in steady-state performance. Although designed on the basis of linear system considerations, the structural control is shown to be capable of suppressing existing large-amplitude limit cycle surge oscillations.

Multistage Centrifugal Compressor Surge Analysis: Part I—Experimental Investigation

1999 ◽  
Vol 121 (2) ◽  
pp. 305-311 ◽  
Author(s):  
G. L. Arnulfi ◽  
P. Giannattasio ◽  
C. Giusto ◽  
A. F. Massardo ◽  
D. Micheli ◽  
...  
Keyword(s):  
Experimental Investigation ◽  
Control Systems ◽  
Centrifugal Compressor ◽  
Reference Data ◽  
Dynamic Control ◽  
Rotating Stall ◽  
Operating Conditions ◽  
Compressor Surge ◽  
Multistage Centrifugal Compressor ◽  
Insight Into

This paper reports an experimental investigation on centrifugal compressor surge. The compression system consists of a four-stage blower with vaned diffusers and a large plenum discharging into the atmosphere through a throttle valve. Measurements of unsteady pressure and flow rate in the plant, and of instantaneous velocity in the diffusers of the first and fourth compressor stage, are performed during deep surge, at several valve settings and three different rotation speeds. Additional tests have been carried out on a different system configuration, i.e., without plenum, in order to obtain the steady-state compressor characteristics and to collect reference data on stall in surge-free conditions. In this configuration, a fully developed rotating stall was detected in the compressor diffusers, while during surge it affects only a limited part of the surge cycle. The goal of the present experimental work was to get a deeper insight into unstable operating conditions of multistage centrifugal compressors and to validate a theoretical model of the system instability to be used for the design of dynamic control systems.

scholarly journals Active Stabilization of Centrifugal Compressor Surge

1990 ◽  
Author(s):  
J. E. Pinsley ◽  
G. R. Guenette ◽  
A. H. Epstein ◽  
E. M. Greitzer
Keyword(s):  
Centrifugal Compressor ◽  
Control Strategies ◽  
Pressure Rise ◽  
Control Valve ◽  
Lumped Parameter Model ◽  
Stable Operation ◽  
Time Resolved ◽  
Compression System ◽  
Compressor Surge ◽  
Surge Line

Active suppression of centrifugal compressor surge has been demonstrated on a centrifugal compressor equipped with a servo-actuated plenum exit throttle controller. The control scheme is fundamentally different from conventional surge control techniques in that it addresses directly the dynamic behavior of the compression system to displace the surge line to lower mass flows. The method used is to feed back perturbations in plenum pressure rise, in real time, to a fast acting control valve. The increased aerodynamic damping of incipient oscillations due to the resulting valve motion allows stable operation past the normal surge line. For the compressor used, a 25% reduction in the surge point mass flow was achieved, over a range of speeds and pressure ratios. Time-resolved measurements during controlled operation revealed that the throttle required relatively little power to suppress the surge oscillations, because the disturbances are attacked in their initial stages. Although designed for operation with small disturbances, the controller was also able to eliminate existing, large amplitude, surge oscillations. Comparison of experimental results with theoretical predictions showed that a lumped parameter model appeared adequate to represent the behavior of the compression system with the throttle controller and, perhaps more importantly, to be used in the design of more sophisticated control strategies.

Active Stabilization of Centrifugal Compressor Surge

1991 ◽  
Vol 113 (4) ◽  
pp. 723-732 ◽  
Author(s):  
J. E. Pinsley ◽  
G. R. Guenette ◽  
A. H. Epstein ◽  
E. M. Greitzer
Keyword(s):  
Centrifugal Compressor ◽  
Control Strategies ◽  
Pressure Rise ◽  
Control Valve ◽  
Lumped Parameter Model ◽  
Stable Operation ◽  
Time Resolved ◽  
Compression System ◽  
Compressor Surge ◽  
Surge Line

Active suppression of centrifugal compressor surge has been demonstrated on a centrifugal compressor equipped with a servo-actuated plenum exit throttle controller. The control scheme is fundamentally different from conventional surge control techniques in that it addresses directly the dynamic behavior of the compression system to displace the surge line to lower mass flows. The method used is to feed back perturbations in plenum pressure rise, in real time, to a fast-acting control valve. The increased aerodynamic damping of incipient oscillations due to the resulting valve motion allows stable operation past the normal surge line. For the compressor used, a 25 percent reduction in the surge point mass flow was achieved over a range of speeds and pressure ratios. Time-resolved measurements during controlled operation revealed that the throttle required relatively little power to suppress the surge oscillations, because the disturbances are attacked in their initial stages. Although designed for operation with small disturbances, the controller was also able to eliminate existing, large-amplitude, surge oscillations. Comparison of experimental results with theoretical predictions showed that a lumped parameter model appeared adequate to represent the behavior of the compression system with the throttle controller and, perhaps more importantly, to be used in the design of more sophisticated control strategies.

Pressure Oscillations Occurring in a Centrifugal Compressor System With and Without Passive and Active Surge Control

1994 ◽  
Author(s):  
Wiktor M. Jungowski ◽  
Marvin H. Weiss ◽  
Glenn R. Price
Keyword(s):  
Active Control ◽  
Centrifugal Compressor ◽  
Passive Control ◽  
Side Branch ◽  
Lumped Parameter Model ◽  
Stability Criteria ◽  
Pressure Oscillations ◽  
Short Side ◽  
Lumped Parameter ◽  
Surge Control

A study of pressure oscillations occurring in small centrifugal compressor systems without a plenum is presented. Active and passive surge control were investigated theoretically and experimentally for systems with various inlet and discharge piping configurations. The determination of static and dynamic stability criteria was based on Greitzer’s (1981) lumped parameter model modified to accommodate capacitance of the piping. Experimentally, passive control using globe valves closely coupled to the compressor prevented the occurrence of surge even with the flow reduced to zero. Active control with a sleeve valve located at the compressor was effective but involved a significant component of passive throttling which reduced the compressor efficiency. With an oscillator connected to a short side-branch at the compressor, effective active control was achieved without throttling. Both methods of active control reduced the flow rate at surge onset by about 30%. In general, the experiments qualitatively confirmed the derived stability criteria.

Pressure Oscillations Occurring in a Centrifugal Compressor System With and Without Passive and Active Surge Control

1996 ◽  
Vol 118 (1) ◽  
pp. 29-40 ◽  
Author(s):  
W. M. Jungowski ◽  
M. H. Weiss ◽  
G. R. Price
Keyword(s):  
Active Control ◽  
Centrifugal Compressor ◽  
Passive Control ◽  
Side Branch ◽  
Lumped Parameter Model ◽  
Stability Criteria ◽  
Pressure Oscillations ◽  
Short Side ◽  
Lumped Parameter ◽  
Surge Control

A study of pressure oscillations occurring in small centrifugal compressor systems without a plenum is presented. Active and passive surge control were investigated theoretically and experimentally for systems with various inlet and discharge piping configurations. The determination of static and dynamic stability criteria was based on Greitzer’s (1981) lumped parameter model modified to accommodate capacitance of the piping. Experimentally, passive control using globe valves closely coupled to the compressor prevented the occurrence of surge even with the flow reduced to zero. Active control with a sleeve valve located at the compressor was effective but involved a significant component of passive throttling which reduced the compressor efficiency. With an oscillator connected to a short side branch at the compressor, effective active control was achieved without throttling. Both methods of active control reduced the flow rate at surge onset by about 30 percent. In general, the experiments qualitatively confirmed the derived stability criteria.

Timber Auctions in the Context of the Modern Auction Theory

2007 ◽  
pp. 86-94
Author(s):  
A. Manakov
Keyword(s):  
Theoretical Analysis ◽  
Auction Theory ◽  
Point Of View ◽  
Theoretical Point ◽  
English Auction ◽  
Analysis And Evaluation

The article provides theoretical analysis and evaluation of the timber auctions reforms in Russia. The author shows that the mechanism of the "combined auctions", which functioned until recently, is more appropriate from the theoretical point of view (and from the point of view of the Russian practice) as compared to the officially approved format of the English auction.

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