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.

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.

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.

Effects of Rotating Inlet Distortion on Multisage Compressor Stability

1994 ◽  
Author(s):  
J. P. Longley ◽  
H.-W. Shin ◽  
R. E. Plumley ◽  
P. D. Silkowski ◽  
I. J. Day ◽  
...  
Keyword(s):  
Theoretical Model ◽  
Stability Margin ◽  
Rotating Stall ◽  
Forced Response ◽  
Single Peak ◽  
Rotor Speed ◽  
Stall Inception ◽  
Stall Margin ◽  
Inlet Distortion ◽  
Two Peaks

In multi-spool engines, rotating stall in an upstream compressor will impose a rotating distortion on the downstream compressor, thereby affecting its stability margin. In this paper experiments are described in which this effect was simulated by a rotating screen upstream of several multistage low-speed compressors. The measurements are complemented by, and compared with, a theoretical model of multistage compressor response to speed and direction of rotation of an inlet distortion. For co-rotating distortions (i.e., distortions rotating in the same direction as rotor rotation), experiments show that the compressors exhibited significant loss in stability margin and that they could be divided into two groups according to their response. The first group exhibited a single peak in stall margin degradation when the distortion speed corresponded to roughly 50% of rotor speed. The second group showed two peaks in stall margin degradation corresponding to distortion speeds of approximately 25–35% and 70–75% of rotor speed. These new results demonstrate that multistage compressors can have more than a single resonant response. Detailed measurements suggest that the two types of behavior are linked to differences between the stall inception processes observed for the two groups of compressors and that a direct connection thus exists between the observed forced response and the unsteady flow phenomena at stall onset. For counter-rotational distortions, all the compressors tested showed minimal loss of stability margin. The results imply that counter-rotation of the fan and core compressor, or LP and HP compressors, could be a worthwhile design choice. Calculations based on the two-dimensional theoretical model show excellent agreement for the compressors which had a single peak for stall margin degradation. We take this first-of-a-kind comparison as showing that the model, though simplified, captures the essential fluid dynamic features of the phenomena. Agreement is not good for compressors which had two peaks in the curve of stall margin shift versus distortion rotation speed. The discrepancy is attributed to the three-dimensional and short length scale nature of the stall inception process in these machines; this includes phenomena that have not yet been addressed in any model.

Experimental Study of Modal Disturbance and Rotating Stall Distribution

2013 ◽  
Vol 718-720 ◽  
pp. 1804-1810
Author(s):  
An Qing Lai ◽  
Jun Hu ◽  
Liang Li ◽  
Ju Luo
Keyword(s):  
Axial Compressor ◽  
Leading Edge ◽  
Propagation Speed ◽  
Axial Direction ◽  
Rotating Stall ◽  
Tip Clearance ◽  
Rotor Speed ◽  
Stall Inception ◽  
Tip Clearance Flow ◽  
Modal Type

To execute stall active control technology effectively and make clear of stall inception induced by modal disturbance, this paper carries out the correlative research on modal disturbance and rotating stall on the two-stage low-speed axial compressor. The results indicate that the stall inception of the compressor is modal style and the modal oscillation propagates at 38% rotor speed while the stall cell propagation speed is 42% rotor speed. The phase angles of modal oscillation and rotating stall along the axial direction are different, but their trajectories are both similar to the blade passage shape. The stall mechanisms of modal-type and spike-type inceptions are different. It doesnt appear that leading-edge tip clearance flow spillage blow the blade tip while the modal-type stall formation.

An Experimental Study of the Inception of Rotating Stall in a Single-Stage Low-Speed Axial Compressor

2007 ◽  
Author(s):  
Alexander K. Simpson ◽  
John P. Longley
Keyword(s):  
Axial Compressor ◽  
Axial Flow ◽  
Rotating Stall ◽  
Single Stage ◽  
Predictive Tool ◽  
Stall Inception ◽  
Low Speed ◽  
Blade Row ◽  
Flow Compressor ◽  
Critical Incidence

There are two established mechanisms, spike and modal inception, by which rotating stall is initiated in an axial flow compressor. Whilst the “Critical incidence hypothesis” and the “Zero slope criterion” are useful ideas in explaining the different stability boundaries for spikes and modes they do not provide the designer with a predictive tool. A detailed experimental investigation utilising a single-stage low-speed compressor is presented in which the aerodynamic environment of a rotor blade row is changed (rotor geometry is held fixed) so that it exhibited both spike and modal inception upon throttling into stall. The dominant mechanism of stall inception was found to be dependent on both the inlet flowfield and the downstream stator. The measurements are analysed and show that the meridional acceleration across the tip region of the rotor influences the mechanism by which rotating stall is incepted. This research is presented as a contribution towards the prediction of the stall inception mechanism.

Performance and Short Length-Scale Disturbance Generation in an Axial Compressor With Non-Uniform Tip Clearance

2008 ◽  
Author(s):  
Scott C. Morris ◽  
Joshua D. Cameron ◽  
Matthew A. Bennington ◽  
G. Scott McNulty ◽  
Aspi Wadia
Keyword(s):  
Flow Field ◽  
Mass Flow ◽  
Axial Compressor ◽  
Rotating Stall ◽  
Short Length ◽  
Tip Clearance ◽  
Length Scale ◽  
Stagnation Temperature ◽  
Local Flow ◽  
Stall Inception

The performance, efficiency, and stall inception of an axial compressor was investigated experimentally with small levels of rotor centerline offset. The measurements were acquired using a high-speed, single-stage compressor. The rotor was levitated magnetically during operation which allowed precise positioning of the rotor centerline within the circular casing. The offset magnitude used in this study was 0.23% of the rotor tip chord, equivalent to approximately 24% of the nominal gap value. The resulting asymmetry in the tip gap resulted in circumferential and radial variations in the measured stagnation pressure and stagnation temperature downstream of the stage. However, the spatially averaged performance of the compressor was not measurably different from that obtained with a concentric rotor. An array of unsteady (Kulite) pressure transducers was used to investigate the flow field during stall inception. These measurements were recorded during transient throttle movements which quickly decreased the mass flow in the compressor until the onset of rotating stall. A second set of measurements was acquired during quasi-transient throttling starting from a mass flow about 1% larger than the stalling mass flow. In both the symmetric and offset cases the flow breakdown was consistent with spike type inception. The measurements with offset indicated that the asymmetries in the local compressor flow field produced significant changes in the number of short-length scale rotating disturbances observed during throttling to stall. These disturbances appeared in the region of the annulus where the local flow coefficient was lowest and usually decayed upon rotating to the higher flow region. In this way, the addition of very small amounts of rotor offset tended to fix the disturbance generation location in the stationary reference frame. This was in contrast to the symmetric tip clearance case where the location of spike generation appeared stochastic.

scholarly journals Unsteady Transition Characteristics of Rotating Stall in a Single-Stage Transonic Axial Compressor

1999 ◽  
Author(s):  
Chaoqun Nie ◽  
Jingyi Chen ◽  
Xingmin Gui ◽  
Qing Yu ◽  
Tongqing Wang
Keyword(s):  
Flow Field ◽  
Dynamic Behavior ◽  
Frequency Spectrum ◽  
Axial Compressor ◽  
Rotating Stall ◽  
Single Stage ◽  
Frequency Spectra ◽  
Stall Inception ◽  
Blade Passage ◽  
Transonic Axial Compressor

The unsteady transition characteristics of rotating stall have been studied experimentally in a single-stage transonic axial compressor. Three tested conditions in the near design and below design speed range, at tip relative Mach numbers from 1.26 to 1.0, were performed. The characteristics of rotating stall were studied by its dynamic behavior on the scale of compressor circumference and also by the flow field details in the blade passage. The dynamic behavior was analyzed by the technique of successive frequency spectrum and the flow field details were studied through internal transient pressure patterns in the blade passage plotted by the dynamic pressure data measured on the compressor shroud. It has been shown that intermittent pre-stall perturbations are evident for all the tested speeds and distinct by the different time and length scale of their existence. These are also interpreted by the difference of pressure loading and shock structure visualized in the pressure plots in the blade passage during stall inception. The pre-stall perturbations, with rather scattered frequency spectra, grow into fully developed stall abruptly. Nevertheless, the frequency spectrum of rotating stall falls into constant fraction of the frequency of compressor rotation for all the tested conditions. The increasing trend of the amplitude of pressure oscillation of rotating stall while gathering at its frequency spectrum could be detected in the stage of stall inception. Based on these two observations, there is a possibility of warning the stall precursors even for the high speed transonic compressor like the one tested in this paper.

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.

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.

Sign in / Sign up

Export Citation Format

Share Document