Experiments in Active Stall Control of a Twin-Spool Turbofan Engine

2002 ◽  
Author(s):  
Dirk C. Leinhos ◽  
Stephen G. Scheidler ◽  
Leonhard Fottner ◽  
Frank Grauer ◽  
Jakob Hermann ◽  
...  
Keyword(s):  
Active Control ◽  
High Speed ◽  
Control Strategies ◽  
External Source ◽  
Rotating Stall ◽  
Operating Conditions ◽  
Air Injection ◽  
Rotor Speed ◽  
Direct Drive ◽  
Specific Operating Condition

The aerodynamic stability of aero engine compressors must be assured by active control systems in all operating conditions when the design surge margin is reduced in order to improve efficiency. While this has been investigated only on compressor rigs and single-spool engines in the past, this study focuses on the active control of the LARZAC 04 twin-spool turbofan. The objective is to demonstrate potential benefits, problems and solutions and also to provide a data base for numerical modeling and simulation of the capabilities of active control. Three different control strategies have been employed each of which refers to a specific operating condition and instability inception of the engine: The attenuation of disturbances travelling at rotor speed by modulated air injection into the LPC in the high speed range, the recovery of fully developed LPC stall at low speeds with a minimized amount of air and finally a constant air recirculation (HPC exit to LPC inlet) for stabilizing the compression system at different speeds based on the monitoring of a stability parameter. The injector is mounted upstream of the LPC and has ten circumferentially distributed nozzles for air injection into the tip region of the first rotor. The injected air which is either taken from an external source or from bleed air ports at the HPC exit is controlled by high-bandwidth direct-drive-valves. Disturbances travelling at rotor speed can be detected and attenuated with modulated air injection leading to a delay of stall onset. Fully developed rotating stall in the LPC was eliminated by asymmetric injection based on modal control strategies with less air than needed with constant air injection. By using online-stability-monitoring it is possible to initiate constant air recirculation when approaching the surge line, though the current design of the injector does not allow for large extension of the operating range for all spool speeds.

Integrated Control of Rotating Stall and Surge in High-Speed Multi-Stage Compression Systems

1997 ◽  
Author(s):  
K. M. Eveker ◽  
D. L. Gysling ◽  
C. N. Nett ◽  
O. P. Sharma
Keyword(s):  
Active Control ◽  
Control Strategy ◽  
High Speed ◽  
Control Strategies ◽  
Integrated Control ◽  
Axial Flow ◽  
Rotating Stall ◽  
Low Flow ◽  
Multi Stage ◽  
Simultaneous Control

Aeroengines operate in regimes for which both rotating stall and surge impose low flow operability limits. Thus, active control strategies designed to enhance operability of aeroengines must address both rotating stall and surge as well as their interaction. In this paper, a previously developed nonlinear control strategy that achieves simultaneous active control of rotating stall and surge is applied to a high-speed 3-stage axial flow compression system with operating parameters representative of modern aeroengines. The controller is experimentally validated for 2 compressor builds and its robustness to radial distortion assessed. For actuation, the control strategy utilizes an annulus-averaged bleed valve with bandwidth on the order of the rotor frequency. For sensing, measurements of the circumferential asymmetry and annulus-averaged unsteadiness of the flow through the compressor are used. Experimental validation of simultaneous control of rotating stall and surge in a high-speed environment with minimal sensing and actuation requirements is viewed as another important step towards applying active control to enhance operability of compression systems in modem aeroengines.

Integrated Control of Rotating Stall and Surge in High-Speed Multistage Compression Systems

1998 ◽  
Vol 120 (3) ◽  
pp. 440-445 ◽  
Author(s):  
K. M. Eveker ◽  
D. L. Gysling ◽  
C. N. Nett ◽  
O. P. Sharma
Keyword(s):  
Active Control ◽  
Control Strategy ◽  
High Speed ◽  
Control Strategies ◽  
Integrated Control ◽  
Axial Flow ◽  
Rotating Stall ◽  
Low Flow ◽  
Simultaneous Control ◽  
Flow Compression

Aeroengines operate in regimes for which both rotating stall and surge impose low-flow operability limits. Thus, active control strategies designed to enhance operability of aeroengines must address both rotating stall and surge as well as their interaction. In this paper, a previously developed nonlinear control strategy that achieves simultaneous active control of rotating stall and surge is applied to a high-speed three-stage axial flow compression system with operating parameters representative of modern aeroengines. The controller is experimentally validated for two compressor builds and its robustness to radial distortion assessed. For actuation, the control strategy utilizes an annulus-averaged bleed valve with bandwidth on the order of the rotor frequency. For sensing, measurements of the circumferential asymmetry and annulus-averaged unsteadiness of the flow through the compressor are used. Experimental validation of simultaneous control of rotating stall and surge in a high-speed environment with minimal sensing and actuation requirements is viewed as another important step toward applying active control to enhance operability of compression systems in modern aeroengines.

Rotating Instability in an Annular Cascade: Detailed Analysis of the Instationary Flow Phenomena

2013 ◽  
Vol 136 (6) ◽  
Author(s):  
Benjamin Pardowitz ◽  
Ulf Tapken ◽  
Robert Sorge ◽  
Paul Uwe Thamsen ◽  
Lars Enghardt
Keyword(s):  
Unsteady Flow ◽  
High Speed ◽  
Pressure Sensors ◽  
Rotating Stall ◽  
Operating Conditions ◽  
Tip Vortex ◽  
Pressure Waves ◽  
Flow Profile ◽  
Rotating Instability ◽  
Annular Cascade

Rotating instability (RI) occurs at off-design conditions in compressors, predominantly in configurations with large tip or hub clearance ratios of s* ≥3%. RI is the source of the blade tip vortex noise and a potential indicator for critical operating conditions like rotating stall and surge. The objective of this paper is to give more physical insight into the RI phenomenon using the analysis results of combined near-field measurements with high-speed particle image velocimetry (PIV) and unsteady pressure sensors. The investigation was pursued on an annular cascade with hub clearance. Both the unsteady flow field next to the leading edge as well as the associated rotating pressure waves were captured. A special analysis method illustrates the characteristic pressure wave amplitude distribution, denoted as “modal events” of the RI. Moreover, the slightly adapted method reveals the unsteady flow structures corresponding to the RI. Correlations between the flow profile, the dominant vortex structures, and the rotating pressure waves were found. Results provide evidence to a new hypothesis, implying that shear layer instabilities constitute the basic mechanism of the RI.

Experimental investigations on instability evolution in a transonic compressor at different rotor speeds

2015 ◽  
Vol 229 (18) ◽  
pp. 3378-3391 ◽  
Author(s):  
Qiushi Li ◽  
Tianyu Pan ◽  
Tailu Sun ◽  
Zhiping Li ◽  
Yifang Gong
Keyword(s):  
Low Frequency ◽  
Axial Flow ◽  
Rotating Stall ◽  
Operating Conditions ◽  
Experimental Investigations ◽  
Rotor Speed ◽  
Axial Flow Compressor ◽  
Transonic Compressor ◽  
New Type ◽  
Flow Compressor

Experimental investigations are conducted to study the instability evolution in a transonic axial flow compressor at four specific rotor speeds covering both subsonic and transonic operating conditions. Two routes of evolution to final instability are observed in the test compressor: at low rotor speeds, a disturbance in the rotor tip region occurs and then leads to rotating stall, while at high rotor speeds, a low-frequency disturbance in the hub region leads the compressor into instability. Different from stall and surge, this new type of compressor instability at high rotor speed is initiated through the development of a low-frequency axisymmetric disturbance at the hub, and we name it “partial surge”. The frequency of this low-frequency disturbance is approximately the Helmholtz frequency of the system and remains constant during instability inception. Finally, a possible mechanism for the occurrence of different instability evolutions and the formation of partial surge are also discussed.

scholarly journals Stall Inception in a High-Speed Low Aspect Ratio Fan Including the Effects of Casing Treatments

1994 ◽  
Author(s):  
S. E. Gorrell ◽  
P. M. Russler
Keyword(s):  
Aspect Ratio ◽  
High Speed ◽  
Static Pressure ◽  
Pressure Ratio ◽  
Rotating Stall ◽  
Operating Conditions ◽  
Stall Inception ◽  
Casing Treatment ◽  
Low Aspect Ratio ◽  
Casing Treatments

The stall inception process in high-speed compressor components is important to understand in order to increase stage loading while maintaining stall margin. This paper presents the results of an in depth experimental investigation on the stall inception of a two stage, high-speed, low aspect ratio fan that is representative of current operational commercial and military fan technology. High-response static pressure measurements are presented which detail the stall inception process of the fan under various operating conditions. These conditions include: varied corrected speeds, a smooth case, a circumferential groove casing treatment, and a recirculating cavity casing treatment. Stage pressure characteristics and radial pressure ratio profiles are presented for the different operating conditions. The stage performance data, together with the static pressure data, are analyzed to provide a clear and thorough understanding of the stall inception process and how the process may vary under different conditions. Experimental results show that a stage may stall on the positive, neutral, or negative sloped part of the pressure characteristic. The three casing treatments had a significant effect on the rotor tip flow and these variations changed the stall inception path of the fan. Stall inception was characterized by the formation of a stall inception cell which grew to fully developed rotating stall. Properties affected by the changing tip flow include the stall inception duration, stall inception cell frequency, existence of modal waves, duration of modal waves, and modal wave frequency. In some instances modal waves appear to play a role in stall inception, in others they do not.

High Speed Compressor Surge With Application to Active Control

1990 ◽  
Author(s):  
A. M. Cargill ◽  
C. Freeman
Keyword(s):  
Active Control ◽  
Blast Wave ◽  
High Speed ◽  
High Amplitude ◽  
Rotating Stall ◽  
Effective Control ◽  
Small Scale ◽  
Compressor Surge ◽  
Aero Engines ◽  
Global Type

This paper discusses the mechanics of surge as observed on the high speed axial compressors of modern aero-engines. It argues that the initial stage of the instability consists of a high amplitude blast wave that develops non-linearly from a small scale disturbance and is thus not correctly described by traditional small perturbation stability theories. It follows from this that active control schemes of the global type may be inappropriate, since to be effective, control would have to be applied in a short time and in a very detailed manner, requiring a large number of transducers and actuators. Active control may, though, be effective in controlling the disturbances that grow into the above blast wave and in the control of other phenomena such as rotating stall, given an adequate number of transducers.

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.

Examination of Rotating Stall Inception in a Small High Speed Axial Compressor

2009 ◽  
Author(s):  
L. G. N. Bennett ◽  
W. D. E. Allan
Keyword(s):  
High Speed ◽  
Gasoline Engine ◽  
Axial Compressor ◽  
Rotating Stall ◽  
Operating Conditions ◽  
Pressure Measurements ◽  
Operating Life ◽  
Fourier Decomposition ◽  
Stall Inception ◽  
Prediction And Prevention

Rotating stall is an internal aerodynamic disturbance that limits the performance and operating life of a compressor. It has been studied with the aim of developing techniques for its prediction and prevention. To further the understanding of rotating stall inception, a test rig was constructed with the axial stages of a Rolls Royce Model 250-C20B small, high speed axial compressor as the test article. A gasoline engine was used to power the compressor and airflow was throttled through a pneumatically controlled valve. Simultaneous static pressure measurements were taken with seven high speed transducers arranged in two configurations: distributed both axially and circumferentially around the compressor casing. The compressor characteristic was mapped and detailed pressure measurements were taken between normal and surge operating conditions. Previous studies of high speed multi-stage compressors have shown both modal and spike type stall inception at different compressor stages. Other examinations of the Model 250 compressor have shown stall inception occurring at the first stage of the compressor. Similar results were observed in this study and an analysis was conducted using a variety of signal processing techniques including pressure trace inspection and discrete spatial Fourier decomposition.

scholarly journals Modeling for Control of Rotating Stall in High Speed Multi-Stage Axial Compressors

1994 ◽  
Author(s):  
Matthew R. Feulner ◽  
Gavin J. Hendricks ◽  
James D. Paduano
Keyword(s):  
Transfer Function ◽  
Compressible Flow ◽  
Active Control ◽  
High Speed ◽  
Standard Form ◽  
Pressure Sensors ◽  
Rotating Stall ◽  
Input Output ◽  
Axial Compressors ◽  
Blade Row

Using a two dimensional compressible flow representation of axial compressor dynamics, a control-theoretic input-output model is derived which is of general utility in rotating stall/surge active control studies. The derivation presented here begins with a review of the fluid dynamic model, which is a 2D stage stacking technique that accounts for blade row pressure rise, loss and deviation as well as blade row and inter-blade row compressible flow. This model is extended to include the effects of the upstream and downstream geometry and boundary conditions, and then manipulated into a transfer function form that dynamically relates actuator motion to sensor measurements. Key relationships in this input-output form are then approximated using rational polynomials. Further manipulation yields an approximate model which is in standard form for studying active control of rotating stall and surge. As an example of high current relevance, the transfer function from an array of jet actuators to an array of static pressure sensors is derived. Numerical examples are also presented, including a demonstration of the importance of proper choice of sensor and actuator locations, as well as a comparison between sensor types. Under a variety of conditions, it was found that sensor locations near the front of the compressor or in the downstream gap are consistently the best choices, based on a quadratic optimization criterion and a specific 3-stage compressor model. The modeling and evaluation procedures presented here are a first step toward a rigorous approach to the design of active control systems for high speed axial compressors.

Real time implementation of a new fuzzy-sliding-mode-observer for sensorless IM drive

2017 ◽  
Vol 36 (4) ◽  
pp. 938-958 ◽  
Author(s):  
Zineb Kandoussi ◽  
Zakaria Boulghasoul ◽  
Abdelhadi Elbacha ◽  
Abdelouahed Tajer
Keyword(s):  
Induction Motor ◽  
High Speed ◽  
Sliding Mode ◽  
Industrial Applications ◽  
Operating Conditions ◽  
Sliding Mode Observer ◽  
Experimental Results ◽  
Rotor Speed ◽  
Content Type ◽  
Fuzzy Sliding Mode

Purpose The purpose of this paper is to improve the performance of sensorless vector control of induction motor drives by developing a new sliding mode observer for rotor speed and fluxes estimation from measured stator currents and voltages and estimated stator currents. Design/methodology/approach In the present paper, the discontinuity in the sliding mode observer is smoothed inside a thin boundary layer using fuzzy logic techniques instead of sign function to reduce efficiently the chattering phenomenon that affects the rotor speed. Findings The feasibility of the proposed fuzzy sliding mode observer has been verified by experimentation. The experimental results are obtained with a 1 kW induction motor using a dSPACE system with DS1104 controller board showing clearly the effectiveness of the proposed approach in terms of dynamic performance compared to the classical sliding mode observer. Practical implications The experimental results of the whole control structure highlights that this kind of sensorless induction motor drive can be used for variable speed drive in industrial applications such as oil drilling, electric vehicles, high speed trains (HSTs) and conveyers. Such drives may work properly at zero and low speed in both directions of rotation. Originality/value Both the proposed speed observer and the classical sliding mode observer have been developed and implemented experimentally with other adaptive observers for detailed comparison under different operating conditions, such as parameter variation, no-load/load disturbances and speed variations in different speed operation regions.

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