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Special Issue “Technologies for Future Distributed Engine Control Systems”

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Abstract

Current trends in aviation greatly expand the use of highly integrated, increasingly autonomous air vehicles, with distributed engine control systems (DECS) [...]
aerospace
Editorial
Special Issue “Technologies for Future Distributed Engine
Control Systems”
Radoslaw Przysowa


Citation: Przysowa, R. Special Issue
“Technologies for Future Distributed
Engine Control Systems”. Aerospace
2021,8, 379. https://doi.org/
10.3390/aerospace8120379
Received: 30 November 2021
Accepted: 1 December 2021
Published: 6 December 2021
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Instytut Techniczny Wojsk Lotniczych, ul. Ksiecia Boleslawa 6, 01-494 Warsaw, Poland;
radoslaw.przysowa@itwl.edu.pl
Current trends in aviation greatly expand the use of highly integrated, increasingly
autonomous air vehicles, with distributed engine control systems (DECS). Such systems
allow for optimizing engine performance by enhancing propulsion control architecture.
The weight of wiring and need for cooling are significantly reduced in the engine controlled
by a DECS when compared to the traditional centralized FADEC. Each element of DECS,
such as a sensor, actuator or controller, individually connects to the network and has
multiple functions.
This Special Issue includes seven selected papers presented during AVT-357 Research
Workshop on Technologies for future distributed engine control systems (DECS), held
online, 11–13 May 2021 [
1
]. The event was sponsored by NATO Science and Technology
Organization. The programme covered advanced hardware and software technologies
grouped into the following sessions: Distributed Architectures, Control Systems, Chips
and software, Smart Sensors and Diagnostic and Prognostic Systems. Compelling keynotes
and papers were presented by speakers from universities, government research centres
and industry from nine nations.
The key problems discussed during the meeting included:
Reliability of engine control systems in the face of multi-core processing and the
perceived perfection of consumer electronics;
Balance between innovation and unforgiving demands for safe and rugged operational
availability for military applications;
Opportunities and limitations of AI-based control and prognostics;
Standardization and certification of new DECS technologies.
This issue of Aerospace presents recent advances in gas-turbine engine control systems.
The articles introduce novel engine control approaches, robust sensing solutions, high-
temperature electronics and open architectures that can be applied in on-board systems.
Their implementation will contribute to ensuring the required engine performance and
reducing the overall cost of ownership.
Lytviak et al. [
2
] studied the self oscillations of the free turbine governor. The control
system was modelled in two configurations: with the main rotor and with water brakes.
The simulation results are invaluable for effective adjusting the hydromechanical governor.
De Giorgi et al. [
3
] used two Nonlinear Autoregressive Neural Networks to predict the
specific fuel consumption of a degraded turboshaft for several transient flight maneuvers.
Rokicki et al. [
4
] proposed inductive sensor for measuring blade vibration in high pressure
compressors and turbines and used a rotor rig and turbojet to validate it at elevated
temperatures (200–1000
C). Flaszynski et al. [
5
] discussed turbine stator’s potential effect
on flow in a combustor and the clocking effect on temperature distribution in a nozzle
guide vane (NGV). It was shown that the NGV potential effect on flow distribution at the
combustor–turbine interface located at 42.5% of the axial chord is weak. The clocking effect
due to the azimuthal position of guide vanes downstream of the swirlers strongly affects
the temperature and flow conditions in a stator cascade. Villarreal-Valderrama et al. [
6
]
studied the possible advantages of an exhaust gas control through a variable exhaust nozzle
Aerospace 2021,8, 379. https://doi.org/10.3390/aerospace8120379 https://www.mdpi.com/journal/aerospace
Aerospace 2021,8, 379 2 of 2
in a micro turbojet. It was found that the proposed controller improves the expansion
of the exhaust gas to the ambient pressure for the whole operating range of the turbojet,
increasing the thrust by 14%. Popov et al. [
7
] demonstrated two designs of a more-electric
turbofan in distributed architecture for small and medium-sized unmanned aerial vehicles.
The pumps and guide vane actuators were electrically driven. Control and monitoring
signals were transmitted via a digital bus. The functional and reliability analyses of each
subsystem were presented. Templalexis et al. [
8
] compared the life consumption rate of the
AE 3007 turbofan powering the surveillance and passenger variant of the Embraer aircraft
(EMB-145 and EMB-135 LR). The rainflow method was used to determine LCF cycles,
whereas the Larson - Miller parameter method was used to determine the consumed life
due to creep of HPT blades. It was found that the engine in the EMB-145 military variant is
much more loaded and has to be closely monitored.
I wish to thank Ms. Monika Vavrikova from AVT Executive Office and Dr. William
D.E. Allan, the AVT-357 technical evaluator for their involvement and hard work with
the workshop papers. With great pleasure, I would like to thank and congratulate the
authors of accepted manuscripts who successfully expanded and revised their workshop
papers to be published in this peer-reviewed Special Issue. Furthermore, the invited
reviewers deserve praise and appreciation for their insightful critique and suggestions,
which contributed directly to improving the technical content of the journal articles.
Finally, I would like to express my gratitude to Mr. Peter Liu and the editorial team of
Aerospace for offering a possibility to publish a number of workshop papers and for their
continuous support in preparing this Special Issue. I would also like to thank Prof Hany
Moustapha, the AVT-357 co-chair, for his valuable support and advice.
Conflicts of Interest: The author declares no conflict of interest.
References
1.
Przysowa, R.; Moustapha, H. (Eds.) Technologies for Future Distributed Engine Control Systems (DECS). STO-MP-AVT-357; NATO
STO CSO: Neuilly-sur-Seine, France, 2021.
2.
Lytviak, O.; Loginov, V.; Komar, S.; Martseniuk, Y. Self-Oscillations of the Free Turbine Speed in Testing Turboshaft Engine with
Hydraulic Dynamometer. Aerospace 2021,8, 114. [CrossRef]
3.
De Giorgi, M.G.; Strafella, L.; Ficarella, A. Neural Nonlinear Autoregressive Model with Exogenous Input (Narx) for Turboshaft
Aeroengine Fuel Control Unit Model. Aerospace 2021,8, 206. [CrossRef]
4.
Rokicki, E.; Przysowa, R.; Kotkowski, J.; Majewski, P. High Temperature Magnetic Sensors for the Hot Section of Aeroengines.
Aerospace 2021,8, 261. [CrossRef]
5.
Flaszynski, P.; Piotrowicz, M.; Bacci, T. Clocking and Potential Effects in Combustor–Turbine Stator Interactions. Aerospace
2021
,
8, 285. [CrossRef]
6.
Villarreal-Valderrama, F.; Zambrano-Robledo, P.; Hernandez-Alcantara, D.; Amezquita-Brooks, L. Turbojet Thrust Augmentation
through a Variable Exhaust Nozzle with Active Disturbance Rejection Control. Aerospace 2021,8, 293. [CrossRef]
7.
Popov, V.; Yepifanov, S.; Kononykhyn, Y.; Tsaglov, A. Architecture of Distributed Control System for Gearbox-Free More Electric
Turbofan Engine. Aerospace 2021,8, 316. [CrossRef]
8.
Templalexis, I.; Lionis, I.; Christou, N. Comparative Study of a Powerplant Life Consumption Rate When Installed in Two
Different Aircraft Variants. Aerospace 2021,8, 327. [CrossRef]
ResearchGate has not been able to resolve any citations for this publication.
Article
Full-text available
The Hellenic Air Force (HAF) operates both EMB-145 and EMB-135 LR versions of Embraer aircraft, used in surveillance and civil missions respectively. These aircraft are equipped with the same version of Rolls Royce, AE 3007 turbofan engine. This study aims to quantify and compare the life consumption rate of this engine when installed in each of the two aircraft variants. Two typical missions, one for each variant, were constructed based on mission profile data dictated by the aircraft commanders. For each mission profile segment, corresponding engine data were matched out of the engine recordings archives held by the Hellenic Air Force. The life consumption rate was based on the Low Cycle Fatigue (LCF) and creep cumulative detrimental effect on the rotor blades of the 1st High-Pressure Turbine stage. For the LCF, the rainflow method was used to determine the respective loading cycles, whereas the Larson - Miller parameter method was used to determine the consumed life fractions due to creep. The main conclusion of the study was that the engine when installed in the EMB-145 military variant, is much more loaded. Despite the fact absolute life consumption values could hide a great level of uncertainty, the comparative outcomes wherein errors are, to a certain extent, cancelled out, could be used as a rule of thumb when monitoring engine life consumption rates.
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Turbojets require variable exhaust nozzles to fit high-demanding applications; however, few reports on nozzle control are available. The purpose of this paper is to investigate the possible advantages of an exhaust gas control through a variable exhaust nozzle. The control design method combines successful linear active disturbance rejection control (LADRC) capabilities with a loop shaping controller (LSC) to: (i) allow designing the closed-loop characteristics in terms of gain margin, phase margin and bandwidth, and (ii) increase the LSC disturbance rejection capabilities with an extended state observer. A representation of the nozzle dynamics is obtained from first principles and adapted to achieve a stream-velocity-based control loop. The results show that the resulting controller allows improving the expansion of the exhaust gas to the ambient pressure for the whole operating range of the turbojet, increasing the estimated thrust by 14.23% during the tests with experimental data.
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Investigations of combustors and turbines separately have been carried out for years by research institutes and aircraft engine companies, but there are still many questions about the interaction effect. In this paper, a prediction of a turbine stator’s potential effect on flow in a combustor and the clocking effect on temperature distribution in a nozzle guide vane are discussed. Numerical simulation results for the combustor simulator and the nozzle guide vane (NGV) of the first turbine stage are presented. The geometry and flow conditions were defined according to measurements carried out on a test section within the framework of the EU FACTOR (full aerothermal combustor–turbine interactions research) project. The numerical model was validated by a comparison of results against experimental data in the plane at a combustor outlet. Two turbulence models were employed: the Spalart–Allmaras and Explicit Algebraic Reynolds Stress models. It was shown that the NGV potential effect on flow distribution at the combustor–turbine interface located at 42.5% of the axial chord is weak. The clocking effect due to the azimuthal position of guide vanes downstream of the swirlers strongly affects the temperature and flow conditions in a stator cascade.
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Magnetic sensors are widely used in aeroengines and their health management systems, but they are rarely installed in the engine hot section due to the loss of magnetic properties by permanent magnets with increasing temperature. The paper presents and verifies models and design solutions aimed at improving the performance of an inductive sensor for measuring the motion of blades operated at elevated temperatures (200–1000 °C) in high pressure compressors and turbines. The interaction of blades with the sensor was studied. A prototype of the sensor was made, and its tests were carried out on the RK-4 rotor rig for the speed of 7000 rpm, in which the temperature of the sensor head was gradually increased to 1100 °C. The sensor signal level was compared to that of an identical sensor operating at room temperature. The heated sensor works continuously producing the output signal whose level does not change significantly. Moreover, a set of six probes passed an initial engine test in an SO-3 turbojet. It was confirmed that the proposed design of the inductive sensor is suitable for blade health monitoring (BHM) of the last stages of compressors and gas turbines operating below 1000 °C, even without a dedicated cooling system. In real-engine applications, sensor performance will depend on how the sensor is installed and the available heat dissipation capability. The presented technology extends the operating temperature of permanent magnets and is not specific for blade vibration but can be adapted to other magnetic measurements in the hot section of the aircraft engine.
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Self-oscillations are one of the common problems in the complex automatic system, that can occur due to the features of the workflow and the design of the governor. The development of digital control systems has made it possible to damp self-oscillations by applying complex control laws. However, for hydromechanical systems, such way is unacceptable due to the design complexity and the governor cost. The objective of this work is to determine the parameters of the hydromechanical free turbine speed controller, ensuring the absence of self-oscillations during ground tests of the turboshaft engine with a hydraulic dynamometer. The TV3-117VM engine (Ukraine) with the NR-3VM regulator pump (Ukraine) was selected as the object of the study. However, self-oscillations can also occur in any modifications of the TV3-117 engine with any NR-3 regulator pump. The results of the research may be of interest to engineers and scientists who investigate the dynamics of automatic control systems for similar engines. The paper analyses the nonlinear features of the empirical characteristics of the FTSC leading to self-oscillations of the engine speed. The authors propose the mathematical model of the automatic control system dynamics, which takes into account all the features of the engine and regulator pump. It is shown that the load characteristics of the water brake and the helicopter main rotor can differ significantly. Research of the dynamic characteristics of the TV3-117VM engine was carried out. The analysis showed a good agreement between the calculation results and the field test results, and made it possible to determine the parameters of the controller, which lead to self-oscillations during test. Two cases are considered. The first case includes ground tests of the engine with a water brake; the second case—flight tests of the engine as part of the helicopter’s power plant. The data obtained make it possible to develop recommendations for adjusting the hydromechanical governor without testing it on the engine.
Research Proposal
Full-text available
Preliminary Meeting Announcement and Call for Papers AVT-357 Research Workshop (RSW) on Technologies for future distributed engine control systems (DECS) organized by the Members of the Applied Vehicle Technology Panel AVT-357 Programme Committee to be held in Berlin, Germany 17-19 May 2021