Rotating Stall Control in a High-Speed Stage With Inlet Distortion: Part II—Circumferential Distortion

1999 ◽  
Vol 121 (3) ◽  
pp. 517-524 ◽  
Author(s):  
Z. S. Spakovszky ◽  
C. M. van Schalkwyk ◽  
H. J. Weigl ◽  
J. D. Paduano ◽  
K. L. Suder ◽  
...  
Keyword(s):  
Mass Flow ◽  
High Speed ◽  
Axial Flow ◽  
Rotating Stall ◽  
Forced Response ◽  
Feedback Stabilization ◽  
Single Stage ◽  
Nasa Lewis Research ◽  
Control Laws ◽  
Inlet Distortion

This paper presents the first attempt to stabilize rotating stall in a single-stage transonic axial flow compressor with inlet distortion using active feedback control. The experiments were conducted at the NASA Lewis Research Center on a single-stage transonic core compressor inlet stage. An array of 12 jet injectors located upstream of the compressor was used for forced response testing and feedback stabilization. Results for a circumferential total pressure distortion of about one dynamic head and a 120 deg extent (DC(60) = 0.61) are reported in this paper. Part I (Spakovszky et al., 1999) reports results for radial distortion. Control laws were designed using empirical transfer function estimates determined from forced response results. Distortion introduces coupling between the harmonics of circumferential pressure perturbations, requiring multivariable identification and control design techniques. The compressor response displayed a strong first spatial harmonic, dominated by the well-known incompressible Moore–Greitzer mode. Steady axisymmetric injection of 4 percent of the compressor mass flow resulted in a 6.2 percent reduction of stalling mass flow. Constant gain feedback, using unsteady asymmetric injection, yielded a further range extension of 9 percent. A more sophisticated robust H∞ controller allowed a reduction in stalling mass flow of 10.2 percent relative to steady injection, yielding a total reduction in stalling mass flow of 16.4 percent.

scholarly journals Rotating Stall Control in a High-Speed Stage With Inlet Distortion: Part II — Circumferential Distortion

1998 ◽  
Author(s):  
Z. S. Spakovszky ◽  
C. M. van Schalkwyk ◽  
H. J. Weigl ◽  
J. D. Paduano ◽  
K. L. Suder ◽  
...  
Keyword(s):  
Mass Flow ◽  
High Speed ◽  
Axial Flow ◽  
Rotating Stall ◽  
Forced Response ◽  
Feedback Stabilization ◽  
Single Stage ◽  
Nasa Lewis Research ◽  
Control Laws ◽  
Inlet Distortion

This paper presents the first attempt to stabilize rotating stall in a single-stage transonic axial flow compressor with inlet distortion using active feedback control. The experiments were conducted at the NASA Lewis Research Center on a single-stage transonic core compressor inlet stage. An array of 12 jet injectors located upstream of the compressor was used for forced response testing and feedback stabilization. Results for a circumferential total pressure distortion of about one dynamic head and a 120° extent (DC(60) = 0.61) are reported in this paper. Part I (Spakovszky et al. (1998)) reports results for radial distortion. Control laws were designed using empirical transfer function estimates determined from forced response results. Distortion introduces coupling between the harmonics of circumferential pressure perturbations, requiring multi-variable identification and control design techniques. The compressor response displayed a strong first spatial harmonic, dominated by the well known incompressible Moore-Greitzer mode. Steady axisymmetric injection of 4% of the compressor mass flow resulted in a 6.2% reduction of stalling mass flow. Constant gain feedback, using unsteady asymmetric injection, yielded a further range extension of 9%. A more sophisticated robust controller allowed a reduction in stalling mass flow of 10.2% relative to steady injection, yielding a total reduction in stalling mass flow of 16.4%.

scholarly journals Rotating Stall Control in a High-Speed Stage With Inlet Distortion: Part I — Radial Distortion

1998 ◽  
Author(s):  
Z. S. Spakovszky ◽  
H. J. Weigl ◽  
J. D. Paduano ◽  
C. M. van Schalkwyk ◽  
K. L. Suder ◽  
...  
Keyword(s):  
Mass Flow ◽  
High Speed ◽  
Transfer Functions ◽  
Axial Flow ◽  
Rotating Stall ◽  
Forced Response ◽  
Single Stage ◽  
Nasa Lewis Research ◽  
Radial Distortion ◽  
Inlet Distortion

This paper presents the first attempt to stabilize rotating stall in a single-stage transonic axial flow compressor with inlet distortion using active feedback control. The experiments were conducted at the NASA Lewis Research Center on a single-stage transonic core compressor inlet stage. An annular array of 12 jet-injectors located upstream of the rotor tip was used for forced response testing and to extend the compressor stable operating range. Results for radial distortion are reported in this paper. First, the effects of radial distortion on the compressor performance and the dynamic behavior were investigated. Control laws were designed using empirical transfer function estimates determined from forced response results. The transfer functions indicated that the compressor dynamics are decoupled with radial inlet distortion, as they are for the case of undistorted inlet flow. Single-input-single-output (SISO) control strategies were therefore used for the radial distortion controller designs. Steady axisymmetric injection of 4% of the compressor mass flow resulted in a reduction in stalling mass flow of 9.7% relative to the case with inlet distortion and no injection. Use of a robust H∞ controller with unsteady non-axisymmetric injection achieved a further reduction in stalling mass flow of 7.5%, resulting in a total reduction of 17.2%.

Rotating Stall Control in a High-Speed Stage With Inlet Distortion: Part I—Radial Distortion

1999 ◽  
Vol 121 (3) ◽  
pp. 510-516 ◽  
Author(s):  
Z. S. Spakovszky ◽  
H. J. Weigl ◽  
J. D. Paduano ◽  
C. M. van Schalkwyk ◽  
K. L. Suder ◽  
...  
Keyword(s):  
Mass Flow ◽  
High Speed ◽  
Transfer Functions ◽  
Axial Flow ◽  
Rotating Stall ◽  
Forced Response ◽  
Single Stage ◽  
Nasa Lewis Research ◽  
Radial Distortion ◽  
Inlet Distortion

This paper presents the first attempt to stabilize rotating stall in a single-stage transonic axial flow compressor with inlet distortion using active feedback control. The experiments were conducted at the NASA Lewis Research Center on a single-stage transonic core compressor inlet stage. An annular array of 12 jet-injectors located upstream of the rotor tip was used for forced response testing and to extend the compressor stable operating range. Results for radial distortion are reported in this paper. First, the effects of radial distortion on the compressor performance and the dynamic behavior were investigated. Control laws were designed using empirical transfer function estimates determined from forced response results. The transfer functions indicated that the compressor dynamics are decoupled with radial inlet distortion, as they are for the case of undistorted inlet flow. Single-input-single-output (SISO) control strategies were therefore used for the radial distortion controller designs. Steady axisymmetric injection of 4 percent of the compressor mass flow resulted in a reduction in stalling mass flow of 9.7 percent relative to the case with inlet distortion and no injection. Use of a robust H∞ controller with unsteady nonaxisymmetric injection achieved a further reduction in stalling mass flow of 7.5 percent, resulting in a total reduction of 17.2 percent.

1997 Best Paper Award—Controls and Diagnostics Committee: Active Stabilization of Rotating Stall and Surge in a Transonic Single-Stage Axial Compressor

1998 ◽  
Vol 120 (4) ◽  
pp. 625-636 ◽  
Author(s):  
H. J. Weigl ◽  
J. D. Paduano ◽  
L. G. Fre´chette ◽  
A. H. Epstein ◽  
E. M. Greitzer ◽  
...  
Keyword(s):  
Mass Flow ◽  
Control Strategies ◽  
Axial Compressor ◽  
Gain Control ◽  
Rotating Stall ◽  
Forced Response ◽  
Single Stage ◽  
Rotor Speed ◽  
Stall Inception ◽  
Spatial Harmonics

Rotating stall and surge have been stabilized in a transonic single-stage axial compressor using active feedback control. The control strategy is to sense upstream wall static pressure patterns and feed back the signal to an annular array of twelve separately modulated air injectors. At tip relative Mach numbers of 1.0 and 1.5 the control achieved 11 and 3.5 percent reductions in stalling mass flow, respectively, with injection adding 3.6 percent of the design compressor mass flow. The aerodynamic effects of the injection have also been examined. At a tip Mach number, Mtip, of 1.0, the stall inception dynamics and effective active control strategies are similar to results for low-speed axial compressors. The range extension was achieved by individually damping the first and second spatial harmonics of the prestall perturbations using constant gain feedback. At a Mtip of 1.5 (design rotor speed), the prestall dynamics are different than at the lower speed. Both one-dimensional (surge) and two-dimensional (rotating stall) perturbations needed to be stabilized to increase the compressor operating range. At design speed, the instability was initiated by approximately ten rotor revolutions of rotating stall followed by classic surge cycles. In accord with the results from a compressible stall inception analysis, the zeroth, first, and second spatial harmonics each include more than one lightly damped mode, which can grow into the large amplitude instability. Forced response testing identified several modes traveling up to 150 percent of rotor speed for the first three spatial harmonics; simple constant gain control cannot damp all of these modes and thus cannot stabilize the compressor at this speed. A dynamic, model-based robust controller was therefore used to stabilize the multiple modes that comprise the first three harmonic perturbations in this transonic region of operation.

Active Stabilization of Axial Compressors With Circumferential Inlet Distortion

1998 ◽  
Vol 120 (3) ◽  
pp. 431-439 ◽  
Author(s):  
C. M. van Schalkwyk ◽  
J. D. Paduano ◽  
E. M. Greitzer ◽  
A. H. Epstein
Keyword(s):  
Transfer Function ◽  
Active Control ◽  
A Priori ◽  
Rotating Stall ◽  
Forced Response ◽  
Control Laws ◽  
Axial Compressors ◽  
Inlet Distortion ◽  
Dynamic Head ◽  
Active Stabilization

This paper describes the first experimental validation of transfer function modeling and active stabilization for axial compressors with circumferential inlet distortion. The inlet distortion experiments were carried out in a three-stage low-speed compressor. Theory–experiment comparisons of steady performance, unsteady stall precursor, and forced response (transfer function) data were all used to assess a control-theoretic version of the Hynes–Greitzer distorted flow model. The tests showed good agreement between theory and data and demonstrated that a priori predictions, based on geometry and steady-state performance data, can be used to design control laws that stabilize rotating stall with inlet distortion. Based on these results, active feedback control has been used to stabilize the inlet distortion induced instability associated with rotating stall onset. The stabilization allowed stall-free operation to be extended below the natural (distorted flow) stall point by up to 3.7 percent for a 0.8 dynamic head distortion. For a 1.9 dynamic head distortion, 40 percent of the mass flow range lost due to inlet distortion was regained through active control. The paper elucidates the difficulties associated with active control with distortion, and introduces a new control law that addresses many of these challenges.

scholarly journals Active Stabilization of Axial Compressors With Circumferential Inlet Distortion

1997 ◽  
Author(s):  
C. M. van Schalkwyk ◽  
J. D. Paduano ◽  
E. M. Greitzer ◽  
A. H. Epstein
Keyword(s):  
Transfer Function ◽  
Active Control ◽  
A Priori ◽  
Rotating Stall ◽  
Forced Response ◽  
Control Laws ◽  
Axial Compressors ◽  
Inlet Distortion ◽  
Dynamic Head ◽  
Active Stabilization

This paper describes the first experimental validation of transfer function modeling and active stabilization for axial compressors with circumferential inlet distortion. The inlet distortion experiments were carried out in a three stage low-speed compressor. Theory-experiment comparisons of steady performance, unsteady stall precursor, and forced response (transfer function) data were all used to assess a control-theoretic version of the Hynes-Greitzer distorted flow model. The tests showed good agreement between theory and data and demonstrated that a priori predictions, based on geometry and steady-state performance data, can be used to design control laws which stabilize rotating stall with inlet distortion. Based on these results, active feedback control has been used to stabilize the inlet distortion induced instability associated with rotating stall onset. The stabilization allowed stall free operation to be extended below the natural (distorted flow) stall point by up to 3.7% for a 0.8 dynamic head distortion. For a 1.9 dynamic head distortion, 40% of the mass flow range lost due to inlet distortion was regained through active control. The paper elucidates the difficulties associated with active control with distortion, and introduces a new control law that addresses many of these challenges.

A Method for Evaluating the Effect of Circumferential Inlet Distortion on the Aerodynamic Stability of Multi-Stage Axial-Flow Compressors

2010 ◽  
Author(s):  
Tsuguji Nakano ◽  
Andy Breeze-Stringfellow
Keyword(s):  
Steady State ◽  
High Speed ◽  
Axial Flow ◽  
Pressure Rise ◽  
Stability Limit ◽  
Rotating Stall ◽  
Classical Dynamic ◽  
Inlet Flow ◽  
Inlet Distortion ◽  
Multi Stage

A simple engineering parameter to evaluate the stability of high-speed multi-stage compressors with distorted inlet flow has been derived based on a simplified semi-compressible linear stability model. The parameter consists of steady-state flow quantities and geometric parameters of the compressor and it indicates that the circumferential integral of the slope of the steady-state individual blade row static pressure rise characteristics is important in the determination of the compressor stability limit in the presence of distortion. The parameter reduces to the author’s rotating stall inception parameter in the limit of non-distorted inlet flow. Since the model includes a downstream plenum and throttle, a condition for pure surge inception with undistorted inlet flow has been deduced. The pure surge conditions can be reduced to the classical dynamic and static instability conditions in the limit of a constant annulus area incompressible compressor. The results indicate that rotating stall always precedes surge instability, as many engineers and researchers would expect from experience. The parameter for instability with inlet distortion was calculated using test data measured in a high-speed 5-stage compressor with two different types of circumferential inlet distortion, and the results show that the parameter has a strong correlation with the data and is an improvement over the classical incompressible stability parameter. The results demonstrate that the parameter captures much of the physics important during the instability inception in a high-speed multi-stage compressor subjected to circumferential inlet distortion. The parameter clearly shows how each compressor component’s characteristics contribute to the overall stability in a high speed axial multi-stage compressor, therefore, it will aid engineers and designers in their understanding and prediction of the aerodynamic instability inception phenomena.

scholarly journals Active Stabilization of Rotating Stall and Surge in a Transonic Single Stage Axial Compressor

1997 ◽  
Author(s):  
H. J. Weigl ◽  
J. D. Paduano ◽  
L. G. Fréchette ◽  
A. H. Epstein ◽  
E. M. Greitzer ◽  
...  
Keyword(s):  
Mass Flow ◽  
Control Strategies ◽  
Axial Compressor ◽  
Gain Control ◽  
Rotating Stall ◽  
Forced Response ◽  
Single Stage ◽  
Rotor Speed ◽  
Stall Inception ◽  
Spatial Harmonics

Rotating stall and surge have been stabilized in a transonic single-stage axial compressor using active feedback control. The control strategy is to sense upstream wall static pressure patterns and feed back the signal to an annular array of twelve separately modulated air injectors. At tip relative Mach numbers of 1.0 and 1.5 the control achieved a 11% and 3.5% reduction in stalling mass flow respectively, with injection adding 3.6% of the design compressor mass flow. The aerodynamic effects of the injection have also been examined. At a tip Mach number, Mtip, of 1.0, the stall inception dynamics and effective active control strategies are similar to results for low-speed axial compressors. The range extension was achieved by individually damping the first and second spatial harmonics of the pre-stall perturbations using constant gain feedback. At a Mtip of 1.5 (design rotor speed), the pre-stall dynamics are different than at the lower speed. Both one-dimensional (surge) and two-dimensional (rotating stall) perturbations needed to be stabilized to increase the compressor operating range. At design speed, the instability was initiated by approximately 10 rotor revolutions of rotating stall followed by classic surge cycles. In accord with the results from a compressible stall inception analysis, the zeroth, first, and second spatial harmonics each include more than one lightly damped mode which can grow into the large amplitude instability. Forced response testing identified several modes traveling up to 150% of rotor speed for the first three spatial harmonics; simple constant gain control cannot damp all of these modes and thus cannot stabilize the compressor at this speed. A dynamic, model-based robust controller was therefore used to stabilize the multiple modes which comprise the first three harmonic perturbations in this transonic region of operation.

Stall Warning Using the Rotor Tip Pressure in a Transonic Axial Compressor With Circumferential Grooves

2018 ◽  
Author(s):  
Byeung Jun Lim ◽  
Tae Choon Park ◽  
Young Seok Kang
Keyword(s):  
Mass Flow Rate ◽  
Mass Flow ◽  
Flow Rate ◽  
Axial Compressor ◽  
Rotating Stall ◽  
Single Stage ◽  
Stall Inception ◽  
Casing Treatment ◽  
Stall Warning ◽  
Transonic Axial Compressor

In this study, characteristics of stall inception in a single-stage transonic axial compressor with circumferential grooves casing treatment were investigated experimentally. Additionally, the characteristic of increasing irregularity in the pressure inside circumferential grooves as the compressor approaches the stall limit was applied to the stall warning method. Spike-type rotating stall was observed in the single-stage transonic axial compressor with smooth casing. When circumferential grooves were applied, the stall inception was suppressed and the operating point of the compressor moved to lower flow rate than the stall limit. A spike-like disturbance was developed into a rotating stall cell and then the Helmholtz perturbation was overlapped on it at N = 80%. At N = 70 %, the Helmholtz perturbation was observed first and the amplitude of the wave gradually increased as mass flow rate decreased. At N = 60%, spike type stall inceptions were observed intermittently and then developed into continuous rotating stall at lower mass flow rate. Pressure measured at the bottom of circumferential grooves showed that the level of irregularity of pressure increased as flow rate decreased. Based on the characteristic of increasing irregularity of the pressure signals inside the circumferential grooves as stall approaches, an autocorrelation technique was applied to the stall warning. This technique could be used to provide warning against stall and estimate real-time stall margins in compressors with casing treatments.

Active Stabilization of Rotating Stall in a Three-Stage Axial Compressor

1993 ◽  
Author(s):  
Joel M. Haynes ◽  
Gavin J. Hendricks ◽  
Alan H. Epstein
Keyword(s):  
High Speed ◽  
Travelling Waves ◽  
Axial Compressor ◽  
Open Loop ◽  
Rotating Stall ◽  
Forced Response ◽  
Flow Coefficient ◽  
Design Parameters ◽  
Time Lags ◽  
Active Stabilization

A three-stage, low speed axial research compressor has been actively stabilized by damping low amplitude circumferentially travelling waves which can grow into rotating stall. Using a circumferential array of hot wire sensors, and an array of high speed individually positioned control vanes as the actuator, the first and second spatial harmonics of the compressor were stabilized down to a characteristic slope of 0.9, yielding an 8% increase in operating flow range. Stabilization of the third spatial harmonic did not alter the stalling flow coefficient. The actuators were also used open loop to determine the forced response behavior of the compressor. A system identification procedure applied to the forced response data then yielded the compressor transfer function. The Moore-Greitzer, 2-D, stability model was modified as suggested by the measurements to include the effect of blade row time lags on the compressor dynamics. This modified Moore-Greitzer model was then used to predict both the open and closed loop dynamic response of the compressor. The model predictions agreed closely with the experimental results. In particular, the model predicted both the mass flow at stall without control and the design parameters needed by, and the range extension realized from, active control.

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