Centrifugal Compressor Surge Research Articles

New Aerodynamic Design Aspect For Active Stabilization of Centrifugal Compressor Surge

Recent Work has shown that centrifugal compression systems can be actively stabilized against the instability known as surge , thereby realizing a significant gain in system mass flow range . In this context , the paper presents the influence of a new impeller design aspects on increasing the range of stabilized compressor performance; the impeller is made of two coaxial parts working as full bladed impeller at stable regime . It could be transferred into tandem bladed impeller with zero overlap when the flow decreases below the minimum value, so the surge will be delayed or suppressed, and the stabilization range will be increased. Herein the effect of tandem shift angle on the stabilization range is studied . It has been found that the stabilization range is increased in the form of decreasing the surge mass flow rate limit by about 56%, when the two parts o !ha impeller are shifted by half the pitch angle at high speeds.

Multistage Centrifugal Compressor Surge Analysis: Part I—Experimental Investigation

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.

Centrifugal compressor surge and speed control

Previous work on stabilization of compressor surge is extended to include control of the angular velocity of the compressor. A low-order centrifugal compressor model is presented, where the states are mass flow, pressure rise, and rotational speed of the spool. Energy transfer considerations are used to develop a compressor characteristic. In order to stabilize equilibria to the left of the surge line, a close coupled valve is used in series with the compressor. Controllers for the valve pressure drop and spool speed are derived. Semiglobal exponential stability is proved using a Lyapunov argument.

Developments in Centrifugal Compressor Surge Control—A Technology Assessment

There are a number of surge control schemes in current use for centrifugal compressors employed in natural gas transmission systems. Basically, these schemes consist of a set of detection devices that either anticipate surge or detect it at its inception, and a set of control devices that act to prevent surge from occurring. A patent search was conducted in an attempt to assess the level and direction of technology development over the last 20 years and to define the focus for future R&D activities. In addition, the paper presents the current state of technology in three areas: surge control, surge detection, and surge suppression. Patent data obtained from on-line databases showed that most of the emphasis has been on surge control rather than on detection and control and that the current trend in surge control will likely continue toward incremental improvement of a basic or conventional surge control strategy. Various surge suppression techniques can be grouped in two categories: (i) those that are focused on better compressor interior design, and (ii) others that attempt to suppress surge by external and operational means.

Experimental and Numerical Analysis of Active Suppression of Centrifugal Compressor Surge by Suction-Side Valve Control.

We conducted a series of experiments in order to investigate the feasibility of active surge suppression in life-size industrial machines. The diameter of the impeller used in these experiments was 250 mm. These experiments were performed with closed-loop and open-loop compressor systems with a control valve on the suction pipe, both of which differed from Epstein's model. Active surge suppression was possible in both compressor systems. The action of the control valve was observed to suppress flow fluctuations from the dynamically unstable equilibrium point at every instant. We also numerically analysed the open-loop case. The action of the control valve was modeled by on-off throttle control and the compressor system was analyzed numerically using a lumped parameter model

Dynamic Control of Centrifugal Compressor Surge Using Tailored Structures

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.

Active Stabilization of Centrifugal Compressor Surge

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.

A Discussion of the Factors Affecting Surge in Centrifugal Compressors

The process of surge in a centrifugal compressor has been studied and found to be dependent on a number of complex and often interrelated factors. A major factor defining surge in high-speed, vaned diffuser designs appears to be the flow in the semivaneless space. By developing work initiated by others it has been possible to propose some explanation of previously presented apparently conflicting data. In addition, a more complex mathematical model capable of assessing additional factors is proposed. Using this model good agreement with experimental surge has been obtained. This model takes into consideration pressure losses in the impeller, diffuser, and collector, and by using this model it was possible to identify the stalling elements that are responsible for overall compressor instability.

On the Transient Interaction of Centrifugal Compressors and Their Piping Systems

The problems of surge and other low-frequency pulsation phenomena in centrifugal compressors are described in terms of both machine (head curve) characteristics and the flow impedance characteristics of its attached piping. Flow stability criteria are presented in terms of net modal damping, as the combination of piping acoustic damping and equivalent negative damping of the compressor in the surge region of its performance curve. Surge and instability frequencies are related to acoustic reactance of the piping system. Finally, theoretical concepts are verified both by electrical analog models and by field and laboratory data on real compressors. This paper provides some new and significant findings on the dynamic interaction of centrifugal compressors with piping systems and describes the basic phenomena underlying these interactions. Good agreement is shown between predicted and measured surge frequencies, and for those termed “piping resonance surge” produced by high flow offsets or flat spots in the head curve.

Experimental and Theoretical Study of Surge in a Small Centrifugal Compressor

Experimental results for deep surge in a small single-stage centrifugal compressor are compared to predictions based on the lumped parameter Greitzer model developed for axial compressors. Both negative and positive flow branches of the steady characteristic, being essential for the model, were measured. Predictions are in fair agreement with data when using a relaxation time smaller than the one proposed for axial compressors. The stability limit of the model equations have been studied for finite amplitude disturbances.

Closure to “Discussion of ‘Experimental and Theoretical Study of Surge in a Small Centrifugal Compressor’” (1981, ASME J. Fluids Eng., 103, p. 395)

Closure to “Discussion of ‘Experimental and Theoretical Study of Surge in a Small Centrifugal Compressor’” (1981, ASME J. Fluids Eng., 103, p. 395)

Reasons for Centrifugal Compressor Surging and Surge Control

The paper discusses conventional modes of presenting axial and radial compressor operating envelopes and the conditions under which changes of factors such as the polytropic index n and the Reynolds number Re are negligible. It is shown on the basis of operating envelopes under what conditions compressors will surge (erratic flow conditions or stalling). In axial or radial compressor installations, surging can only be controlled by shifting the operating point in the operating envelope to the right away from the surge limit line. One method of doing this is to open the bypass valve to recycle part of the gas from the discharge piping to the suction piping. The paper describes in detail the control system required and discusses universal and simplified control systems. Modifications of control systems to fit, for example, wide suction pressure ranges are studied. The paper concludes with an investigation of methods of providing for high surge control reliability.

Discussion: “The Time Domain of Centrifugal Compressor and Pump Stability and Surge” (Dean, Jr., R. C., and Young, L. R., 1977, ASME J. Fluids Eng., 99, pp. 53–59)

Discussion: “The Time Domain of Centrifugal Compressor and Pump Stability and Surge” (Dean, Jr., R. C., and Young, L. R., 1977, ASME J. Fluids Eng., 99, pp. 53–59)

Discussion: “The Time Domain of Centrifugal Compressor and Pump Stability and Surge” (Dean, Jr., R. C., and Young, L. R., 1977, ASME J. Fluids Eng., 99, pp. 53–59)

Discussion: “The Time Domain of Centrifugal Compressor and Pump Stability and Surge” (Dean, Jr., R. C., and Young, L. R., 1977, ASME J. Fluids Eng., 99, pp. 53–59)

Discussion: “The Time Domain of Centrifugal Compressor and Pump Stability and Surge” (Dean, Jr., R. C., and Young, L. R., 1977, ASME J. Fluids Eng., 99, pp. 53–59)

Discussion: “The Time Domain of Centrifugal Compressor and Pump Stability and Surge” (Dean, Jr., R. C., and Young, L. R., 1977, ASME J. Fluids Eng., 99, pp. 53–59)

Closure to “Discussions of ‘The Time Domain of Centrifugal Compressor and Pump Stability and Surge’” (1977, ASME J. Fluids Eng., 99, pp. 59–62)

Closure to “Discussions of ‘The Time Domain of Centrifugal Compressor and Pump Stability and Surge’” (1977, ASME J. Fluids Eng., 99, pp. 59–62)

Discussion: “The Time Domain of Centrifugal Compressor and Pump Stability and Surge” (Dean, Jr., R. C., and Young, L. R., 1977, ASME J. Fluids Eng., 99, pp. 53–59)

Discussion: “The Time Domain of Centrifugal Compressor and Pump Stability and Surge” (Dean, Jr., R. C., and Young, L. R., 1977, ASME J. Fluids Eng., 99, pp. 53–59)

The Time Domain of Centrifugal Compressor and Pump Stability and Surge

New evidence about the time domain operation of centrifugal compressors and pumps in compliant systems is presented. Data from Toyama [1,2] plus unpublished data from another compressor indicate that the flow rate oscillates continuously, at large amplitudes, when a compressor is operating in its supposedly stable regime. A tentative flow model predicts similar oscillations. The model assumes that the compressor operation at all times is described by its quasi-steady characteristic; no hysteresis or complex aerodynamic phenomena have been invoked.

Discussion: “The Time Domain of Centrifugal Compressor and Pump Stability and Surge” (Dean, Jr., R. C., and Young, L. R., 1977, ASME J. Fluids Eng., 99, pp. 53–59)

Discussion: “The Time Domain of Centrifugal Compressor and Pump Stability and Surge” (Dean, Jr., R. C., and Young, L. R., 1977, ASME J. Fluids Eng., 99, pp. 53–59)

On the Dynamics of Compressor Surge

The one-dimensional equations of surge in centrifugal compressors are solved graphically for the pressure head and mass flow rate as functions of time for a variety of situations, and the results are discussed in terms of the acoustical properties of the external piping. Two important parameters affecting the nature of the surge limit cycle are found to be simply related to the acoustic capacitance and acoustic inductance of the system.