Experimental Operating Range Extension of a Twin-Spool Turbofan Engine by Active Stability Control Measures

2004 ◽  
Vol 128 (1) ◽  
pp. 20-28 ◽  
Author(s):  
Stephan G. Scheidler ◽  
Leonhard Fottner
Keyword(s):  
Control System ◽  
Stability Control ◽  
Rotating Stall ◽  
Control Measures ◽  
Air Injection ◽  
Range Extension ◽  
Engine Operation ◽  
Turbofan Engine ◽  
Operating Range ◽  
The Stability

Modern engine operation is guided by the aim to broaden the operating range and to increase the stage loading allowing the stage count to be reduced. This is possible by active stability control measures to extend the available stable operating range. Different strategies of an active control system, such as air injection and air recirculation have been applied. While in the past results have been published mainly regarding the stability enhancement of compressor rigs or single-spool engines, this experimental study focuses on both the stability as well as the operating range extension of a twin-spool turbofan engine as an example of a real engine application on an aircraft. The objective of this investigation is the analysis of the engine behavior with active stabilization compared to unsupported operation. For this purpose, high-frequency pressure signals are used and analyzed to investigate the effects of air injection with respect to the instability onset progress and the development of any instabilities, such as rotating stall and surge in the low-pressure compression (LPC) system. These Kulite signals are fed to a control system. Its amplified output signals control fast acting direct-drive valves circumferentially distributed ahead of the LPC. For the application of air injection described in the paper, the air is delivered by an external source. The control system responsible for air injection is a real-time system which directly reacts on marked instabilities and their precursors. It allows the LPC System to recover from fully developed rotating stall by asymmetric air injection based on the pressure signals. Additionally, a delayed appearance of instabilities can be provoked by the system. Air injection guided by this control system resulted in a reduction of the required amount of air compared to constant air injection. Also, disturbances travelling at rotor speed can be detected, damped, and eliminated by this control system with a modulation of the injected air in such a way that the injection maximum travels around the ten injection positions.

Experimental Operating Range Extension of a Twin-Spool Turbofan Engine by Active Stability Control Measures

2004 ◽  
Author(s):  
Stephan G. Scheidler ◽  
Leonhard Fottner
Keyword(s):  
Control System ◽  
Stability Control ◽  
Rotating Stall ◽  
Control Measures ◽  
Air Injection ◽  
Range Extension ◽  
Turbofan Engine ◽  
Compression System ◽  
Operating Range ◽  
The Stability

Modern engine operation is guided by the aim to broaden the operating range and to increase the stage loading allowing the stage count to be reduced. This is possible by active stability control measures to extend the available stable operating range. Different strategies of an active control system like air injection and air recirculation have been applied. While in the past mainly results have been published regarding the stability enhancement of compressor rigs or single-spool engines, this experimental study focuses as well on the stability as also on the operating range extension of a twin-spool turbofan engine as an example for a real engine application on an aircraft. The objective of this investigation is the analysis of the engine behavior with active stabilization compared to not supported operation. For this purpose high frequency pressure signals are used and analyzed to investigate the effects of air injection with respect to the instability onset progress and the development of any instabilities like rotating stall and surge in the LP Compression system. These Kulite signals are fed to a control system. Its amplified output signals control fast acting Direct Drive Valves circumferentially distributed ahead of the LPC. For the application of air injection described in the paper, the air is delivered by an external source. The control system responsible for air injection is a real-time system which directly reacts on marked instabilities and their pre-cursors. It allows the LP Compression System to recover from fully developed rotating stall by asymmetric air injection based on the pressure signals. Additionally, a delayed appearance of instabilities can be provoked by the system. Air injection guided by this control system resulted in a reduction of the required amount of air compared to constant air injection. Also, disturbances travelling at rotor speed can be detected, damped and eliminated by this control system with a modulation of the injected air in such a way that the injection maximum travels around the 10 injection positions.

Design and Implementation of Large-Scale Temperature Stability Control System

2014 ◽  
Vol 644-650 ◽  
pp. 313-316
Author(s):  
Wen Lai Liu
Keyword(s):  
Control System ◽  
System Design ◽  
Large Scale ◽  
Control Method ◽  
Temperature Stability ◽  
Stability Control ◽  
Control System Design ◽  
Scale Temperature ◽  
Stability Control System ◽  
The Stability

large-scale temperature stability control method is studied in this paper. In the process of large-scale temperature control, the stability of control is a very important indicator. To this end, this paper proposes a large-scale temperature stability control algorithm based on hierarchical control method. Balance equation of large-scale temperature stability control is created for the effective transmission of control data. According to the constant control theory, large-scale temperature stability control system design is achieved. Experimental results show that the proposed algorithm for large-scale temperature stability control system design, can greatly improve the stability of control, and get the satisfactory results.

The Vehicles ESP Test System Based on Active Braking Control

2012 ◽  
Vol 588-589 ◽  
pp. 1552-1559
Author(s):  
Lu Zhang ◽  
Guo Ye Wang ◽  
Guo Yan Chen ◽  
Zhong Fu Zhang
Keyword(s):  
Control System ◽  
Test System ◽  
Stability Control ◽  
Control Test ◽  
Control Performance ◽  
Vehicle System ◽  
Braking Control ◽  
Set Up ◽  
The Stability ◽  
Driving Stability

This paper proposes an active braking control dynamical system in order to establish a safe and efficient vehicle driving stability control test system. Aiming at Chery A3 sedan, set up the active braking control dynamic simulation system base on MATLAB/Simulink. Adopting the brake driving integration ESP control strategy, analyze and verify the stability control performance of independent vehicle system and vehicle ESP test system based on active braking control respectively in under steering and excessive steering two test conditions. The analyzing results indicate that the test system based on active braking control can effectively assist vehicle travelling in the absence of ESP control or ESP control system failure; when vehicle has ESP control system, the driving stability control performance of this system and independent vehicle system has remarkable consistency. The active braking control system provides a basis for research of vehicle driving stability control test.

scholarly journals Vehicle Stability Control Strategy Based on Recognition of Driver Turning Intention for Dual-Motor Drive Electric Vehicle

2020 ◽  
Vol 2020 ◽  
pp. 1-18
Author(s):  
Shu Wang ◽  
Xuan Zhao ◽  
Qiang Yu
Keyword(s):  
Control System ◽  
Electric Vehicle ◽  
Control Strategy ◽  
Stability Control ◽  
Motor Drive ◽  
Vehicle Stability ◽  
Lane Change ◽  
Vehicle Stability Control ◽  
Stability Control System ◽  
The Stability

Vehicle stability control should accurately interpret the driving intention and ensure that the actual state of the vehicle is as consistent as possible with the desired state. This paper proposes a vehicle stability control strategy, which is based on recognition of the driver’s turning intention, for a dual-motor drive electric vehicle. A hybrid model consisting of Gaussian mixture hidden Markov (GHMM) and Generalized Growing and Pruning RBF (GGAP-RBF) neural network is constructed to recognize the driver turning intention in real time. The turning urgency coefficient, which is computed on the basis of the recognition results, is used to establish a modified reference model for vehicle stability control. Then, the upper controller of the vehicle stability control system is constructed using the linear model predictive control theory. The minimum of the quadratic sum of the working load rate of the vehicle tire is taken as the optimization objective. The tire-road adhesion condition, performance of the motor and braking system, and state of the motor are taken as constraints. In addition, a lower controller is established for the vehicle stability control system, with the task of optimizing the allocation of additional yaw moment. Finally, vehicle tests were carried out by conducting double-lane change and single-lane change experiments on a platform for dual-motor drive electric vehicles by using the virtual controller of the A&D5435 hardware. The results show that the stability control system functions appropriately using this control strategy and effectively improves the stability of the vehicle.

Research on Root Locus Correction Algorithm in Automatic Control System

2020 ◽  
Vol 12 (3) ◽  
pp. 30-45
Author(s):  
Weifang Zhai ◽  
Juan Feng
Keyword(s):  
Control System ◽  
Automatic Control ◽  
Automatic Control System ◽  
Control Object ◽  
Correction Method ◽  
Stability Control ◽  
Root Locus ◽  
Expected Performance ◽  
The Stability ◽  
Classical Control

Aiming at the stability control of the automatic control system, this paper proposes a root locus correction scheme. By establishing the mathematical model of the control object and using the root locus correction method in the classical control theory, the design of the control system is completed. The simulation experiment of the control system is carried out in the MATLAB environment, and the key points of the scheme are summarized. The simulation results show that the scheme not only successfully achieves the stability control of the system, but also meets the expected performance index, which fully proves its correctness and effectiveness.

Rotating Stall Inception Inside the Low Pressure Compressor of a Twin-Spool Turbofan Engine

2013 ◽  
Author(s):  
Marcel Stößel ◽  
Stefan Bindl ◽  
Reinhard Niehuis
Keyword(s):  
Low Pressure ◽  
Rotating Stall ◽  
Engine Test ◽  
Test Vehicle ◽  
Engine Operation ◽  
Turbofan Engine ◽  
Stall Inception ◽  
Jet Propulsion ◽  
Flow Phenomena ◽  
Pressure Compressor

In order to preserve fossil resources aviation industry faces major challenges to reduce engine fuel consumption. Therefore efforts are concentrated to increase efficiency of any engine component. Investigations at the Institute of Jet Propulsion at the University of Federal Armed Forces in Munich focus on the compressor module. Especially the compression system of a gas turbine is designed to operate at very high aerodynamic loads. This makes it one of the most critical components during transient engine operation or inlet flow distortion. Rotating stall and surge have to be avoided in any situation during engine operation. For this reason a detailed knowledge of the flow phenomena of the compressor in normal conditions as well as near the stability limit is essential. Often those research activities are carried out at compressor rigs but not in by utilizing real turbo engines. As a research test vehicle at the Institute of Jet Propulsion the Larzac 04 C5 twin-spool turbofan engine is operated at the engine test facility. The gas turbine is equipped with additional instrumentation and control systems exceeding those of conventional engine monitoring systems by far. Especially a set of high frequency pressure transducers has been installed above the tip of the first stage of the low pressure compressor in order to investigate tip flow phenomena. Besides the information on the flow phenomena in the tip region of the compressor blades these signals can also be used to detect the upcoming of rotating stall precursors. A special algorithm which was developed at the institute is able to estimate the stall and to trigger an active countermeasure. This was demonstrated successfully for a wide range of operating points. Stall inception in different speed ranges is crucial to be detected reliably. More than all high spool speeds challenge an active stabilization system. With the stall typically rising in time periods of less than three rotor revolutions, the requirements regarding high speed data processing are enormous. Since computer technology now provides systems, which are capable to handle such a task and still are compact and robust enough to be used in the rough environment of engine test beds, the challenge remains to set up fitting actuator systems. The test vehicle at the Institute of Jet Propulsion is therefore equipped with fast acting valves, which feed an injector casing mounted closely upstream of the low-pressure compressor. Test series have been performed, which proof the stabilizing capabilities of the entire system. Even at high spool speeds the stall was sufficiently suppressed and a stable operation of the engine was guaranteed.

Investigation of Passage Flow Features in a Transonic Compressor Rotor With Casing Treatments

2011 ◽  
Author(s):  
M. W. Mu¨ller ◽  
H.-P. Schiffer ◽  
Melanie Voges ◽  
Chunill Hah
Keyword(s):  
Measurement Techniques ◽  
Stability Limit ◽  
Rotating Stall ◽  
Tip Leakage Flow ◽  
Stall Margin ◽  
Tip Leakage ◽  
Operating Range ◽  
Transonic Compressor ◽  
The Stability ◽  
Casing Treatments

An experimental investigation on casing treatments in a one-stage transonic compressor is presented. The reference case consists of a radially staggered blisk and six circumferential grooves. Speedlines show that this axisymmetric treatment already provided a substantial increase in operating range with relatively small losses in efficiency. Since the onset of rotating stall in tip-critical high-speed compressors is always linked to the tip-leakage flow and the build-up of blockage within the blade passage. High-resolution measurement techniques have been employed to investigate the corresponding effects. Results with Particle Image Velocimetry show that the interaction between the tip leakage vortex and the shock front cause a blockage area. When throttled further, the blockage increases. The shock structure changes similar to the phenomena of vortex breakdown described by different researchers in the past, but a stagnation point is not present. Before reaching the stability limit, the interface line between the incoming flow and the blocked area moves towards the inlet plane of the rotor indicating spike-type stall inception. Wall pressure measurements confirmed this theory for the smooth wall, but with circumferential grooves applied, a part span stall cell develops prior to the stability limit. In order to assess the performance of circumferential grooves, two additional configurations are presented. The corresponding measurements addressed the questions whether circumferential grooves also provide an operating range extension when applied to an optimized rotor design with higher initial stall margin. Therefore, an identical casing treatment is applied to a forward swept rotor. The second question is, how circumferential grooves perform in direct comparison to a non-axisymmetric endwall structure. Axial slots have been applied to the radially staggered rotor. While the stall margin exceeds all other configurations, detrimential effects in efficiency are observed. A detailed anaylsis of probe data shows the changes of the radial profile at the rotor outlet which allows recommendations for more efficient CT designs. Parameters allowing to evaluate the CT influence are presented.

Modeling for the Development and Evaluation of Strategies for Controlling Flow Instabilities in Transonic Compressors

2007 ◽  
Author(s):  
John N. Chi
Keyword(s):  
Gas Turbine ◽  
Mass Flow ◽  
High Speed ◽  
Rotating Stall ◽  
Air Injection ◽  
Stall Inception ◽  
Operating Range ◽  
Transonic Compressor ◽  
Hot Air ◽  
Injection Model

A gas turbine engine consists of three primary components: a compressor, a combustion chamber, and a turbine. The operating range, performance, and reliability of gas turbine engines are limited by aerodynamic instabilities that occur in the compressor at low mass flow rates. Two of such compressor instabilities are rotating stall and surge. The stabilization of compression systems by means of active control has been demonstrated on several research compressors using different actuators such as inlet guide vanes, bleed valves, and air injection to manipulate the compressor flow field. This paper presents validated models of the steady and unsteady behaviors of air injection in high speed axial flow compressors that can be used for feasibility studies and control algorithm development. The steady air injection model consists of a control volume analysis coupled with wind tunnel measurements to characterize the changes in flow profiles entering the compressor and a streamline curvature analysis to model the response of the compressor blade rows to the different inlet span-wise profiles generated by the jet actuator. The steady air injection model was validated with experimentally measured span-wise profiles and compressor speed-lines, and then used to study the effect of hot air injection on the performance of a transonic compressor. The results show that injecting hot air into a transonic compressor has a potential increase in the operating range (i.e., decrease in the stalling mass flow rate) and a decrease in the total pressure rise across the transonic compressor. A modified theoretical stall inception model for high speed machines with air injection actuation is also presented. The compressible rotating stall inception model is a two-dimensional linearized stability model and pre-stall dynamics measurements from a single stage transonic compressor were used to validate the model. The compressible rotating stall inception model is an important tool that can be used for studying the effects of compressor design parameters on stability during compressor redesign, and for designing and evaluating feedback controllers.

Nonlinear Dynamics Mechanism for Stability Control of the Overlapped Tunnels System

2011 ◽  
Vol 90-93 ◽  
pp. 113-120
Author(s):  
Zhen Liu ◽  
Cui Ying Zhou
Keyword(s):  
Nonlinear Dynamics ◽  
Process Analysis ◽  
Control Process ◽  
Stability Control ◽  
Control Measures ◽  
Structure Theory ◽  
Underground Engineering ◽  
Whole Process ◽  
The Stability ◽  
Control Principle

The stability control of the overlapped tunnels system has been one of the hot issues and difficulties in tunnel and underground engineering field. According to the whole process analysis for instability evolution of the overlapped tunnels, its nonlinear dynamics characteristics are studied by the nonlinear dynamics method, including material and energy metabolism, fluctuation, thermodynamics irreversible process, correlation dimension and entropy. On this basis, combining with stability control measures such as grouting, bolt and gunite and so on, the dynamics mechanism and energy dissipation mechanism for stability control of the overlapped tunnels system are studied by synergetics and dissipative structure theory. The nonlinear dynamics evolution law of the control process is also revealed. This research is not only able to provide theoretical support for establishing optimal control model and risk control principle based the nonlinear dynamics, but also of great significance for the stability control technology of the overlapped tunnels.

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