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1
Sarti Leme, Alexandre Domingos, Geraldo Creci, Edilson Rosa Barbosa de Jesus, Túlio César Rodrigues et João Carlos Menezes. « Finite Element Analysis to Verify the Structural Integrity of an Aeronautical Gas Turbine Disc Made from Inconel 713LC Superalloy ». Advanced Engineering Forum 32 (avril 2019) : 15–26. http://dx.doi.org/10.4028/www.scientific.net/aef.32.15.
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Gas turbines are very important because they can be used in several areas, such as aeronautics and electric power generation systems. The operation of a gas turbine can be done by less pollutant fuels when compared to traditional kerosene, for example, resulting in less degradation to environment. Gas turbines may fail from a variety of sources, with the possibility of serious damage results. In this work, the structural integrity of the hot disc of an aeronautical gas turbine is addressed. Several numerical analyses have been performed by the finite element method: Temperature Distributions, Thermal Stresses and Dilatations, Structural Stresses and Deformations, Modal Behaviors and Fatigue Analysis. Creep of blades has also been considered. These are the most important failure modes that can happen to the studied hot disc under operating service. All these analysis have been performed considering the boundary conditions at the design point with maximum rotational speed. The mesh of the problem has been strictly evaluated by adaptive refinement of nodes and elements combined with a convergence analysis of results. Then, the material and basic properties of the hot disc have been defined to assure a normal operation free from failures. Therefore, the mechanical drawings of the studied hot turbine disc have been released for manufacturing and the construction of the first prototype of the aeronautical gas turbine is in testing phase showing that the results presented in this work are consistent.
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Dediu, Gabriel, et Daniel Eugeniu Crunteanu. « Automatic Control System for Gas Turbines Test Rig ». Applied Mechanics and Materials 436 (octobre 2013) : 398–405. http://dx.doi.org/10.4028/www.scientific.net/amm.436.398.
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The technical evolution of the industrial and aeronautical groups involving gas turbines, determined by the request of increased efficiency and reliability, imposes the control through modern command and control automation systems. The paper describes a system destined to safely monitor, command and control the working conditions through complete automation of all command functions of a gas turbine. The system is suitable for all series of applications involving gas turbines, also providing a decrease in exploitation and maintenance costs.
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Dunham, J. « 50 years of turbomachinery research at Pyestock — part 2 : turbines ». Aeronautical Journal 104, no 1034 (avril 2000) : 199–207. http://dx.doi.org/10.1017/s0001924000028104.
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Abstract The two parts of this paper summarise the turbomachinery research undertaken at Pyestock during the 50 years since the National Gas Turbine Establishment was formed in 1946. The theoretical and experimental activities are described, and their influence on UK military and civil aero engines is assessed. The way in which NGTE supported non-aeronautical gas turbines is also explained. Part 2 covers turbines.
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Dunham, J. « 50 years of turbomachinery research at Pyestock — part one : compressors ». Aeronautical Journal 104, no 1033 (mars 2000) : 141–51. http://dx.doi.org/10.1017/s0001924000025331.
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Abstract The two parts of this paper summarise the turbomachinery research undertaken at Pyestock during the 50 years since the National Gas Turbine Establishment was formed in 1946. The theoretical and experimental activities are described, and their influence on UK military and civil aero engines is assessed. The way in which NGTE supported non-aeronautical gas turbines is also explained. Part one provides a general introduction and then covers compressors.
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Fatsis, Antonios. « Performance Enhancement of One and Two-Shaft Industrial Turboshaft Engines Topped With Wave Rotors ». International Journal of Turbo & ; Jet-Engines 35, no 2 (25 mai 2018) : 137–47. http://dx.doi.org/10.1515/tjj-2016-0040.
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Abstract Wave rotors are rotating equipment designed to exchange energy between high and low enthalpy fluids by means of unsteady pressure waves. In turbomachinery, they can be used as topping devices to gas turbines aiming to improve performance. The integration of a wave rotor into a ground power unit is far more attractive than into an aeronautical application, since it is not accompanied by any inconvenience concerning the over-weight and extra dimensioning. Two are the most common types of ground industrial gas turbines: The one-shaft and the two-shaft engines. Cycle analysis for both types of gas turbine engines topped with a four-port wave rotor is calculated and their performance is compared to the performance of the baseline engine accordingly. It is concluded that important benefits are obtained in terms of specific work and specific fuel consumption, especially compared to baseline engines with low compressor pressure ratio and low turbine inlet temperature.
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Lino, Vinicius da Silva, Damásio Sacrini, Adilson Vitor Rodrigues, Geraldo Creci et João Carlos Menezes. « Dynamic Characteristics of a Squeeze Film Damper used as Rear Bearing in a Single Spool Aeronautic Gas Turbine ». International Journal of Advanced Engineering Research and Science 10, no 1 (2023) : 019–24. http://dx.doi.org/10.22161/ijaers.101.4.
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Squeeze film dampers are widely used in aeronautic gas turbines because they effectively absorb vibrations and lessen the stresses on the structural components. In this study, we calculated the stiffness and damping dynamic coefficients of a squeeze film damper with open ends and a circumferential oil-feeding groove. This squeeze film damper was used as a rear bearing in an aeronautic gas turbine designed to generate 5-kN of thrust under ISA conditions. Three different radial clearances were investigated to determine the optimal bearing design configuration for the application because the radial clearance of a squeeze film damper is a crucial element in determining its dynamic stiffness and damping coefficients. To provide superior performance and avoid issues, a rotordynamic analysis using the calculated stiffness and damping dynamic coefficients can be conducted to predict the vibratory behavior of the entire rotating assembly.
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Derbal-Habak,, Hassina. « Alternative Materials for Performant TBCs : Short Review ». Journal of Mineral and Material Science (JMMS) 4, no 1 (30 janvier 2023) : 1–2. http://dx.doi.org/10.54026/jmms/1051.
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Thermal Barrier Coating (TBC) is a thermal insulation, which enables the coated substrate material to work above its melting temperature. The TBCs have been used to enhance the performance of the gas turbine for aeronautic and energy applications. Yttria stabilized zirconia YSZ (ZrO2 +7-8 wt.% Y2 O3 ) is a topcoat ceramic which is applied for more than 40 years to gas turbine components. YSZ has a high toughness and a good temperature capability up to about 1200 °C, higher operating temperatures is required for enhanced efficiency of gas turbine. Alternative materials for TBC application were developed during the last years allowing a higher temperature capability and lower thermal conductivity combined to higher toughness and thermochemical stability a of the TBCs.
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Amato, Giorgio, Matteo Giovannini, Michele Marconcini et Andrea Arnone. « Unsteady Methods Applied to a Transonic Aeronautical Gas Turbine Stage ». Energy Procedia 148 (août 2018) : 74–81. http://dx.doi.org/10.1016/j.egypro.2018.08.032.
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Brookes, Stephen Peter, Hans Joachim Kühn, Birgit Skrotzki, Hellmuth Klingelhöffer, Rainer Sievert, Janine Pfetzing, Dennis Peter et Gunther F. Eggeler. « Multi-Axial Thermo-Mechanical Fatigue of a Near-Gamma TiAl-Alloy ». Advanced Materials Research 59 (décembre 2008) : 283–87. http://dx.doi.org/10.4028/www.scientific.net/amr.59.283.
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A material family to replace the current superalloys in aeronautical gas turbine engines is considered to be that of gamma Titanium Aluminide (-TiAl) alloys. Structural components in aeronautical gas turbine engines typically experience large variations in temperatures and multiaxial states of stress under non-isothermal conditions. The uniaxial, torsional and bi-axial thermo-mechanical fatigue (TMF) behaviour of this -TiAl alloy have been examined at 400 – 800oC with strain amplitudes from 0.15% to 0.7%. The tests were conducted at both in-phase (IP) and out-of-phase (OP). The effects of TMF on the microstructure were also investigated. For the same equivalent mechanical strain amplitude uniaxial IP tests showed significantly longer lifetimes than pure torsional TMF tests. The non-proportional multiaxial OP test showed the lowest lifetimes at the same equivalent mechanical strain amplitude compared to the other types of tests.
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Sarnecki, Jarosław, Tomasz Białecki, Bartosz Gawron, Jadwiga Głąb, Jarosław Kamiński, Andrzej Kulczycki et Katarzyna Romanyk. « Thermal Degradation Process of Semi-Synthetic Fuels for Gas Turbine Engines in Non-Aeronautical Applications ». Polish Maritime Research 26, no 1 (1 mars 2019) : 65–71. http://dx.doi.org/10.2478/pomr-2019-0008.
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Abstract This article concerns the issue of thermal degradation process of fuels, important from the perspective of the operation of turbine engines, especially in the context of new fuels/bio-fuels and their implementation. The studies of the kerosene-based jet fuel (Jet A-1) and its blends with synthetic components manufactured according to HEFA and ATJ technology, were presented. Both technologies are currently approved by ASTM D7566 to produce components to be added to turbine fuels. Test rig investigations were carried out according to specific methodology which reflects the phenomena taking place in fuel systems of turbine engines. The mechanism of thermal degradation process was assessed on the basis of test results for selected properties, IR spectroscopy and calculation of activation energy. The results show that with the increase of the applied temperature there is an increment of the content of solid contaminants, water and acid for all tested fuels. Thermal degradation process is different for conventional jet fuel when compared to blends, but also semi-synthetic fuels distinguished by different thermal stability depending on a given manufacturing technology.
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Adami, P., et F. Martelli. « Three-dimensional unsteady investigation of HP turbine stages ». Proceedings of the Institution of Mechanical Engineers, Part A : Journal of Power and Energy 220, no 2 (1 mars 2006) : 155–67. http://dx.doi.org/10.1243/095765005x69189.
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This article deals with a three-dimensional unsteady numerical simulation of the unsteady rotor—stator interaction in a HP turbine stage. The numerical approach consists of a computational fluid dynamics (CFD) parallel code, based on an upwind total variation diminishing finite volume approach. The computation has been carried out using a sliding plane approach with hybrid unstructured meshes and a two-equation turbulent closure. The turbine rig under investigation is representative of the first stage of aeronautic gas turbine engines. A brief description of the cascade, the experimental setup, and the measuring technique is provided. Time accurate CFD computations of pressure fluctuations and Nusselt number are discussed against the experimental data.
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Lewitowicz, Jerzy, Mirosław Kowalski et Andrzej Żyluk. « Modern Diagnostics of Aircraft Gas Turbine Engines – Some Selected Issues / Nowoczesna Diagnostyka Lotniczych Silników Turbinowych - Wybrane Zagadnienia ». Journal of KONBiN 29, no 1 (1 décembre 2014) : 33–40. http://dx.doi.org/10.2478/jok-2014-0004.
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Abstract In aeronautics, the question of maintaining the highest possible level of flight safety is the most crucial issue. This is the reason why the scientists, engineers, and aerospace/aviation engineering staff keep searching for ever newer and more reliable methods of increasing the safety level. Therefore, new methods - primarily nondestructive ones - to diagnose aircraft turbine engines are looked for. These methods are expected to prove useful for the real-time monitoring of actual health of the engine and its assemblies. The paper has been intended to outline the most recent methods of diagnosing aircraft turbine engines, including the computed tomography methods as applied to assess health/maintenance status of turbine blades, for the phase mapping of increments in the engine’s rotational speed, to diagnose health/maintenance status of the compressor’s 1st stage rotor blades in pure jets. Other methods discussed are, e.g. vibroacoustic and tribological ones
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Boudier, G., L. Y. M. Gicquel, T. Poinsot, D. Bissières et C. Bérat. « Comparison of LES, RANS and experiments in an aeronautical gas turbine combustion chamber ». Proceedings of the Combustion Institute 31, no 2 (janvier 2007) : 3075–82. http://dx.doi.org/10.1016/j.proci.2006.07.067.
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Alajmi, Amer, Fnyees Alajmi, Ahmed Alrashidi, Naser Alrashidi et Nor Mariah Adam. « Application of Ultrasonic Atomization on a Micro Jet Engine Using Biofuel for Improving Performance ». Processes 9, no 11 (3 novembre 2021) : 1963. http://dx.doi.org/10.3390/pr9111963.
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Jet engines are commonly used in aeronautical applications, and are one of the types of gas turbine engines. The circulation of air releases heat energy to expand the volume of hot fluids and impact the turbine wheel to generate power of hot gases. The present study investigates the potential of using ultrasonic atomization technology to assist in the combustion process. An experimental rig was set up to determine the performance of jet engines using ultrasonic droplets. A gas analyzer was used to measure various greenhouse emissions of exhaust gas. The performance of the engine was tested under three load levels (high, medium, low), starting from 10 psi at a steady state, to the minimum value. A significant result was tested for a low value of nitrogen monoxide at the three levels of load, and a specific result was tested for an efficiency value of 2% at the three levels of load. Carbon dioxide was found to decrease at the low load level. The use of an ultrasonic atomization device to assist in the combustion process was useful in achieving engine efficiency of 1% and a reduction of 25% in carbon dioxide exhaust gas.
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Mohammadi Doulabi Fard, Seyed Jalal, et Soheil Jafari. « Fuzzy Controller Structures Investigation for Future Gas Turbine Aero-Engines ». International Journal of Turbomachinery, Propulsion and Power 6, no 1 (22 février 2021) : 2. http://dx.doi.org/10.3390/ijtpp6010002.
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The Advisory Council for Aeronautics Research in Europe (ACARE) Flight Path 2050 focuses on ambitious and severe targets for the next generation of air travel systems (e.g., 75% reduction in CO2 emissions per passenger kilometer, a 90% reduction in NOx emissions, and 65% reduction in noise emission of flying aircraft relative to the capabilities of typical new aircraft in 2000). In order to meet these requirements, aircraft engines should work very close to their operating limits. Therefore, the importance of advanced control strategies to satisfy all engine control modes simultaneously while protecting them from malfunctions and physical damages is being more crucial these days. In the last three decades, fuzzy controllers (FCs) have been proposed as a high potential solution for performance improvement of the next generation of aircraft engines. Based on an analytic review, this paper divides the trend of FCs design into two main lines including pure FCs (PFC) and min–max FCs (MMFC). These two main architectures are then designed, implemented on hardware, and applied in a case study to analyze the advantages and disadvantages of each structure. The analysis of hardware-in-the-loop (HIL) simulation results shows that the pure FC structure would be a high potential candidate for maneuverability and response time indices improvement (e.g., military applications); while min–max FC architecture has a great potential for future civil aero-engines where the fuel consumption and steady-state responses are more important. The simulation results are also compared with those of industrial min–max controllers to confirm the feasibility and reliability of the fuzzy controllers for real-world application. The results of this paper propose a general roadmap for fuzzy controllers’ structure selection for new and next generation of aircraft engines.
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Apostolidis, Asteris, Nicolas Bouriquet et Konstantinos P. Stamoulis. « AI-Based Exhaust Gas Temperature Prediction for Trustworthy Safety-Critical Applications ». Aerospace 9, no 11 (17 novembre 2022) : 722. http://dx.doi.org/10.3390/aerospace9110722.
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Data-driven condition-based maintenance (CBM) and predictive maintenance (PdM) strategies have emerged over recent years and aim at minimizing the aviation maintenance costs and environmental impact by the diagnosis and prognosis of aircraft systems. As the use of data and relevant algorithms is essential to AI-based gas turbine diagnostics, there are different technical, operational, and regulatory challenges that need to be tackled in order for the aeronautical industry to be able to exploit their full potential. In this work, the machine learning (ML) method of the generalised additive model (GAM) is used in order to predict the evolution of an aero engine’s exhaust gas temperature (EGT). Three different continuous synthetic data sets developed by NASA are employed, known as New Commercial Modular Aero-Propulsion System Simulation (N-CMAPSS), with increasing complexity in engine deterioration. The results show that the GAM can be predict the evolution of the EGT with high accuracy when using several input features that resemble the types of physical sensors installed in aero gas turbines currently in operation. As the GAM offers good interpretability, this case study is used to discuss the different data attributes a data set needs to have in order to build trust and move towards certifiable models in the future.
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Beranoagirre, A., et Luis Norberto López de Lacalle. « Topography Prediction on Grinding of Emerging Aeronautical TiAl Intermetallic Alloys ». Materials Science Forum 797 (juin 2014) : 84–89. http://dx.doi.org/10.4028/www.scientific.net/msf.797.84.
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Gamma-TiAl intermetallic materials are the focus of all leading aerospace / gas turbine manufacturers, as a replacement for some nickel-based superalloy components in parts of the engine subject to temperatures < 900°C. Although applicable for only a relatively narrow range of applications, titanium intermetallic materials are likely to play a significant role in the production of future aeroengines. This work presents the results from grinding tests on two types of Gamma TiAl alloys.
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Lemco, Ian. « Wittgenstein's aeronautical investigation ». Notes and Records of the Royal Society 61, no 1 (22 décembre 2006) : 39–51. http://dx.doi.org/10.1098/rsnr.2006.0163.
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After a rigorous German education in the physical sciences, young Ludwig Wittgenstein entered Manchester University as an aeronautical engineering research student. There he devised and patented a novel aero-engine employing an airscrew propeller driven by blade tip-jets. Within the context of the growth of English aviation during the first half of the twentieth century (including the contributions of many Fellows of the Royal Society) and taking into account related aspects of his life, this paper examines an unfulfilled engineering aspiration. In enlarging upon what Wittgenstein might have accomplished during his stay at Manchester, it contrasts his invention with later comparable proven designs, albeit applied to hybrid rotorcraft. His engine employed centrifugal flow compression and arguably was a precursor of Sir Frank Whittle's gas turbine. In conclusion, reasons are given for Wittgenstein's departure from Manchester.
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Sun, Xiaohuan, Soheil Jafari, Seyed Alireza Miran Fashandi et Theoklis Nikolaidis. « Compressor Degradation Management Strategies for Gas Turbine Aero-Engine Controller Design ». Energies 14, no 18 (10 septembre 2021) : 5711. http://dx.doi.org/10.3390/en14185711.
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The Advisory Council for Aeronautics Research in Europe (ACARE) Flight Path 2050 focuses on ambitious and severe targets for the next generation of air travel systems (e.g., 75% reduction in CO2 emissions per passenger kilometre, a 90% reduction in NOx emissions, and a 65% reduction in the noise emissions of flying aircraft relative to the capabilities of typical new aircraft in 2000). Degradation is an inevitable phenomenon as aero-engines age with significant impacts on the engine performance, emissions level, and fuel consumption. The engine control system is a key element capable of coping with degradation consequences subject to the implementation of an advanced management strategy. This paper demonstrates a methodological approach for aero-engine controller adjustment to deal with degradation implications, such as emission levels and increased fuel consumption. For this purpose, a component level model for an aero-engine was first built and transformed to a block-structured Wiener model using a system identification approach. An industrial Min-Max control strategy was then developed to satisfy the steady state and transient limit protection requirements simultaneously while satisfying the physical limitation control modes, such as over-speed, surge, and over-temperature. Next, the effects of degradation on the engine performance and associated changes to the controller were analysed thoroughly to propose practical degradation management strategies based on a comprehensive scientometric analysis of the topic. The simulation results show that the proposed strategy was effective in restoring the degraded engine performance to the level of the clean engine while protecting the engine from physical limitations. The proposed adjustments in the control strategy reduced the fuel consumption and, as a result, the emission level and carbon footprint of the engine.
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Santin, M., A. Traverso et A. Massardo. « Technological aspects of gas turbine and fuel cell hybrid systems for aircraft : a review ». Aeronautical Journal 112, no 1134 (août 2008) : 459–67. http://dx.doi.org/10.1017/s0001924000002426.
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The objective of this work is to make an overview of opportunities and issues related to the aeronautical application of solid oxide fuel cell hybrid systems. The great interest on fuel cells comes from their capacity of producing electric energy with high efficiency at low pollutant production. The application of these systems as full-time auxiliary power units is an interesting alternative in a future scenario, which is supposed to include a More Electric Aircraft and more restrictive environmental standards. A review of the technological aspects of this application is presented. The physical models found in literature were investigated and the results were compared and discussed.
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dos Santos, Bertolino Junio, Damásio Sacrini, Adilson Vitor Rodrigues, Geraldo Creci et João Carlos Menezes. « Dynamic Characteristics of a 5-kN Thrust Gas Turbine Front Bearing Composed of a Vibration Absorber Element and Deep Groove Ball Bearing ». Advanced Engineering Forum 47 (31 août 2022) : 43–53. http://dx.doi.org/10.4028/p-7916wb.
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Rolling bearings enable the development of high rotational speeds with a good load-bearing capacity and low frictional resistance. Therefore, rolling bearings can be used on a wide variety of rotating machines. This study investigated the dynamic stiffness and damping coefficients of the front bearing of a 5-kN thrust gas turbine. A Barden® 206(T) deep-groove ball bearing was the main part of the front bearing. Computational models were developed using MATLAB® for both the structural dynamics problem governed by Hertzian contact theory and the lubricated problem governed by elastohydrodynamic theory. In addition, the front bearing was composed of a vibration absorber element, which was also considered. Finite element analysis was performed on both the ball bearing and the vibration-absorbing element to assist in its final characterization. As the main results, the stiffness and damping dynamic coefficients of the front bearing were estimated and can be used to predict the rotordynamic behavior of the aeronautical gas turbine rotating set to avoid possible vibration problems during operation.
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Talero, Gabriel, Camilo Bayona-Roa, Giovanny Muñoz, Miguel Galindo, Vladimir Silva, Juan Pava et Mauricio Lopez. « Experimental Methodology and Facility for the J69-Engine Performance and Emissions Evaluation Using Jet A1 and Biodiesel Blends ». Energies 12, no 23 (28 novembre 2019) : 4530. http://dx.doi.org/10.3390/en12234530.
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Aeronautic transport is a leading energy consumer that strongly contributes to greenhouse gas emissions due to a significant dependency on fossil fuels. Biodiesel, a substitution of conventional fuels, is considered as an alternative fuel for aircrafts and power generation turbine engines. Unfortunately, experimentation has been mostly limited to small scale turbines, and technical challenges remain open regarding operational safety. The current study presents the facility, the instrumentation, and the measured results of experimental tests in a 640 kW full-scale J69-T-25A turbojet engine, operating with blends of Jet A1 and oil palm biodiesel with volume contents from 0% to 10% at different load regimes. Findings are related to the fuel injection system, the engine thrust, and the emissions. The thrust force and the exhaust gas temperature do not expose a significant variation in all the operation regimes with the utilization of up to 10% volume content of biodiesel. A maximum increase of 36% in fuel consumption and 11% in injection pressure are observed at idle operation between B0 and B10. A reduction of the CO and HC emissions is also registered with a maximum variation at the cruise regime (80% Revolutions Per Minute—RPM).
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Abrams, Michael. « The Little Engine ». Mechanical Engineering 129, no 03 (1 mars 2007) : 30–33. http://dx.doi.org/10.1115/1.2007-mar-2.
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This article focuses on research and development works in the field of silicon-gas turbine engines to enable them produce power for portable devices. Alan Epstein, a professor of aeronautics and astronautics at the Massachusetts Institute of Technology, and his team are working on tiny silicon gas-turbine engines that could soon power laptops or cell phones. The group chose pressurized gas bearings, which can hold more weight relative to their size as they get smaller. Thrust bearings with spiral grooves and holes in their centers are self-pumping and keep the rotor in the right position. Epstein’s group considered magnetic bearings early on, but found that in addition to the manufacturing difficulties, the magnetic materials had too Iowa Curie point and would not stay magnetic at the temperatures at which the engine would operate: Instead, they chose pressurized gas bearings, which conveniently can hold more weight relative to their size as they get smaller. Thrust bearings with spiral grooves and holes in their centers are self-pumping and keep the rotor free and in the right position. While there is clearly plenty of room for improving efficiency, the microengine may very well end up as the only significant way to power, say, a laptop, an iPod, or a soldier's thermal weapon sight, to say nothing of a palm-size plane.
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Hu, Ke-Qi, Yi-Fan Xia, Yao Zheng et Gao-Feng Wang. « Effects of inlet turbulence intensity on wall heat transfer in a turbine guide vane ». International Journal of Modern Physics B 34, no 14n16 (30 mai 2020) : 2040082. http://dx.doi.org/10.1142/s0217979220400822.
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Heat transfer is an important phenomenon that exists in many industrial applications, especially for gas turbines, aeronautical engines. In this work, two different turbulence models ([Formula: see text] and SAS model) are used to investigate the effects of inlet turbulence on wall heat transfer and the characteristics of flow field in a well-known turbine guide vane (LS89). In order to handle the transition, Menter’s [Formula: see text] transition model is used. The simulations show that the inlet turbulence has an apparent effect on the wall heat transfer of the vane. Not only the maximum wall heat transfer coefficient is increased, the distribution of wall heat flux at the suction side is also modified. The isentropic Mach number along the vane surface is insensitive to the variance of inlet turbulence intensity. Besides, a shock appears in the throat and a laminar-to-turbulence transition position moves forward after the main flow turbulence is enhanced. Moreover, the results indicate that SAS model is capable of capturing more flow structures such as reflecting pressure waves and shedding vortexes while the [Formula: see text] model misses them due to the dissipation.
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Odgers, J., D. Kretschmer et G. F. Pearce. « The Combustion of Droplets Within Gas Turbine Combustors : Some Recent Observations on Combustion Efficiency ». Journal of Engineering for Gas Turbines and Power 115, no 3 (1 juillet 1993) : 522–32. http://dx.doi.org/10.1115/1.2906739.
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For many years investigators studying the combustion behavior within gas turbines have presumed droplet size to play a very important role in defining combustion efficiency. Recently a very large number of experiments have been conducted jointly by Laval University and the Aeronautical Research Laboratory in Melbourne. In the course of these investigations, over a wide range of operating conditions, a single combustor has been investigated using three different Simplex atomizers at each of the conditions for three fuels. In addition, the same combustor has been used to investigate a very wide range of fuels (87) at ambient inlet conditions. The measured combustion efficiencies show no measurable effects due to droplet size, although volatility effects have been noted (measured as TAV). It is thought that these effects are reflected in terms of a transfer number and related to diffusional phenomena, rather than evaporative phenomena. A great number of experimental data are reviewed, and in addition to showing the absence of effects of droplets, a small section deals with the precision of experimental values of combustion efficiency and how it might influence models predicting combustion efficiency, especially with respect to possible future pollution requirements.
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Schafrik, Robert, et Robert Sprague. « Superalloy Technology - A Perspective on Critical Innovations for Turbine Engines ». Key Engineering Materials 380 (mars 2008) : 113–34. http://dx.doi.org/10.4028/www.scientific.net/kem.380.113.
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High temperature structural materials, such as nickel-based superalloys, have contributed immensely to societal benefit. These materials provide the backbone for many applications within key industries that include chemical and metallurgical processing, oil and gas extraction and refining, energy generation, and aerospace propulsion. Within this broad application space, the best known challenges tackled by these materials have arisen from the demand for large, efficient land-based power turbines and light-weight, highly durable aeronautical jet engines. So impressive has the success of these materials been that some have described the last half of the 20th century as the Superalloy Age. Many challenges, technical and otherwise, were overcome to achieve successful applications. This paper highlights some of the key developments in nickel superalloy technology, principally from the perspective of aeronautical applications. In the past, it was not unusual for development programs to stretch out 10 to 20 years as the materials technology was developed, followed by the development of engineering practice, and lengthy production scaleup. And many developments fell by the wayside. Today, there continue to be many demands for improved high temperature materials. New classes of materials, such as intermetallics and ceramic materials, are challenging superalloys for key applications, given the conventional wisdom that superalloys are reaching their natural entitlement level. Therefore, multiple driving forces are converging that motivate improvements in the superalloy development process. This paper concludes with a description of a new development paradigm that emphasizes creativity, development speed, and customer value that can provide superalloys that meet new needs.
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Liu, Han Wu, Nan Li, Qiao Nan Tian et De Chao Dong. « Microstructure Changes and Computer Simulation of K4169 Superalloy Using Chemical Grain Refinement Casting ». Advanced Materials Research 189-193 (février 2011) : 3954–59. http://dx.doi.org/10.4028/www.scientific.net/amr.189-193.3954.
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As an important aeronautical assembly materials, such as aeronautical gas turbine and turbine plate et al, K4169 alloy has enough high ability of resistance to high temperature deformation and a long low-period fatigue life when working, and its grain structure should be equiaxed dendrite as fine as possible in casting. Chemical grain refinement method was used to refine K4169 alloy to satisfy the demands mentioned above. By using new intermetallic compound grain refiners, chemical grain refinement casting technology was carried out to refine K4169 superalloy. The results show that the grain morphology has been transformed from dendrite to granulation, the average principal axis length of the primary dendrites has been shorted and the segregation ratios of main alloy elements mitigate with the decrease of grain size in fine-grained castings, which indicates the remarkable effects of grain refinement. In addition, basing on the model of equiaxed dendrite growth solute diffusion, continuous nucleation model, dendrite tip growth kinetics model and cellular automata (CA) technique to coupled simulate the grain structure formation process of K4169 alloy in chemical grain refinement casting, which agreed very well with experiments results, this will do much contribution to the theoretic base for studying high temperature mechanics performance and performance of resistance to corrosion of K4169 superalloy.
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Huber, F. W., P. D. Johnson, O. P. Sharma, J. B. Staubach et S. W. Gaddis. « Performance Improvement Through Indexing of Turbine Airfoils : Part 1—Experimental Investigation ». Journal of Turbomachinery 118, no 4 (1 octobre 1996) : 630–35. http://dx.doi.org/10.1115/1.2840918.
Texte intégralRésumé :
This paper describes the results of a study to determine the performance improvements achievable by circumferentially indexing successive rows of turbine stator airfoils. An experimental/analytical investigation has been completed that indicates significant stage efficiency increases can be attained through application of this airfoil clocking concept. A series of tests was conducted at the National Aeronautics and Space Administration’s (NASA) Marshall Space Flight Center (MSFC) to experimentally investigate stator wake clocking effects on the performance of the Space Shuttle Main Engine Alternate Fuel Turbopump Turbine Test Article. Extensive time-accurate Computational Fluid Dynamics (CFD) simulations have been completed for the test configurations. The CFD results provide insight into the performance improvement mechanism. Part one of this paper describes details of the test facility, rig geometry, instrumentation, and aerodynamic operating parameters. Results of turbine testing at the aerodynamic design point are presented for six circumferential positions of the first stage stator, along with a description of the initial CFD analyses performed for the test article. It should be noted that first vane positions 1 and 6 produced identical first to second vane indexing. Results obtained from off-design testing of the “best” and “worst” stator clocking positions, and testing over a range of Reynolds numbers are also presented. Part two of this paper describes the numerical simulations performed in support of the experimental test program described in part one. Time-accurate Navier–Stokes flow analyses have been completed for the five different turbine stator positions tested. Details of the computational procedure and results are presented. Analysis results include predictions of instantaneous and time-average midspan airfoil and turbine performance, as well as gas conditions throughout the flow field. An initial understanding of the turbine performance improvement mechanism is described.
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Woike, Mark, Ali Abdul-Aziz, Nikunj Oza et Bryan Matthews. « New Sensors and Techniques for the Structural Health Monitoring of Propulsion Systems ». Scientific World Journal 2013 (2013) : 1–10. http://dx.doi.org/10.1155/2013/596506.
Texte intégralRésumé :
The ability to monitor the structural health of the rotating components, especially in the hot sections of turbine engines, is of major interest to aero community in improving engine safety and reliability. The use of instrumentation for these applications remains very challenging. It requires sensors and techniques that are highly accurate, are able to operate in a high temperature environment, and can detect minute changes and hidden flaws before catastrophic events occur. The National Aeronautics and Space Administration (NASA), through the Aviation Safety Program (AVSP), has taken a lead role in the development of new sensor technologies and techniques for the in situ structural health monitoring of gas turbine engines. This paper presents a summary of key results and findings obtained from three different structural health monitoring approaches that have been investigated. This includes evaluating the performance of a novel microwave blade tip clearance sensor; a vibration based crack detection technique using an externally mounted capacitive blade tip clearance sensor; and lastly the results of using data driven anomaly detection algorithms for detecting cracks in a rotating disk.
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Galinsky, Andrey A., Anton V. Ryabkov, Vladimir I. Berg et Aslan F. Zakuraev. « To the question of thermal joining of composite Al-B materials ». Journal of Composite Materials 53, no 19 (27 mars 2019) : 2715–25. http://dx.doi.org/10.1177/0021998319839130.
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This work deals with the application of new approaches to welding production of modern light, strong, and heat-resistant metal composite materials in aeronautical and space technology. The objective of this article is to substantiate introduction of modern technology for welding composites in production, namely the development of argon-arc welding technology and the choice of equipment when using composites of the Al-B system for manufacturing the flame tube of the combustion chamber of an aircraft engine. Based on the study of technical literature and scientific publications, a short analysis of the existing technological processes for welding heat-resistant glass-ceramic composites was carried out. The problems arising in the process of welding aluminum composites reinforced with boron and steel fibers are considered. A modern gas tungsten arc welding based on new technological processes is offered with an example of welding in manufacturing a combustion chamber of a modern gas turbine modified engine.
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Halford, G. R., T. G. Meyer, R. S. Nelson, D. M. Nissley et G. A. Swanson. « Fatigue Life Prediction Modeling for Turbine Hot Section Materials ». Journal of Engineering for Gas Turbines and Power 111, no 2 (1 avril 1989) : 279–85. http://dx.doi.org/10.1115/1.3240249.
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This paper presents a summary of the life prediction methods developed under the NASA Lewis Research Center’s Hot Section Technology (HOST) program. A major objective of the fatigue and fracture efforts under the HOST program was to significantly improve the analytic life prediction tools used by the aeronautical gas turbine engine industry. This has been achieved in the areas of high-temperature thermal and mechanical fatigue of bare and coated high-temperature superalloys. Such technical improvements will eventually reduce life cycle costs. The cyclic crack initiation and propagation resistance of nominally isotropic polycrystalline alloys and highly anisotropic single crystal alloys have been addressed. A sizeable data base has been generated for three alloys [cast PWA 1455 (B–1900 + Hf), wrought Inconel 718, and cast single-crystal PWA 1480] in bare and coated conditions. Two coating systems, diffusion aluminide (PWA 273) and plasma-sprayed MCrAlY overlay (PWA 286), were employed. Life prediction modeling efforts were devoted to creep-fatigue interaction, oxidation, coatings interactions, multiaxially of stress-strain states, mean stress effects, cumulative damage, and thermomechanical fatigue. The fatigue crack initiation life models developed to date include the Cyclic Damage Accumulation (CDA) Model of Pratt & Whitney and the Total Strain Version of Strainrange Partitioning (TS-SRP) of NASA Lewis for nominally isotropic materials, and the Tensile Hysteretic Energy Model of Pratt & Whitney for anisotropic superalloys. The fatigue model being developed by the General Electric Company is based upon the concepts of Path-Independent Integrals (PII) for describing cyclic crack growth under complex non-linear response at the crack tip due to thermomechanical loading conditions. A micromechanistic oxidation crack extension model has been derived by researchers at Syracuse University. The models are described and discussed in the paper. Only limited verification has been achieved to date as several of the technical programs are still in progress and the verification tasks are scheduled, quite naturally, near the conclusion of the program. To date, efforts have concentrated on developement of independent models for cyclic constitutive behavior, cyclic crack initiation, and cyclic crack propagation. The transition between crack initiation and crack propagation has not been thoroughly researched as yet, and the integration of these models into a unified life prediction method has not been addressed.
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Bray, K. N. C., et N. Riley. « John Frederick Clarke. 1 May 1927 — 11 June 2013 ». Biographical Memoirs of Fellows of the Royal Society 60 (janvier 2014) : 87–106. http://dx.doi.org/10.1098/rsbm.2014.0012.
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Flying, and an enthusiasm for aviation, motivated John Clarke’s early career choices: he flew Fairey Fireflys in the Fleet Air Arm, worked in the Gas Turbine Division of Armstrong Siddeley Motors, and studied aeronautical engineering at Queen Mary College, where he graduated with first-class honours. He stayed on there to do a PhD, and then worked at English Electric, before moving to Cranfield in 1958. John Clarke’s many important publications, mainly in the general area of chemically reacting flows, cover a wide range of topics including flames, ignition processes, shock waves and detonations, the dynamics and physics of burning gases and internal ballistics, to name but a few. In all of his contributions to his subject it is perhaps too easy to overlook the individual. He had a delightful sense of humour, wore his distinctions lightly and was a most generous and friendly man.
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Qi, Hong Yu, Hai Quan Ma, Xu Li, Xiao Guang Yang et Duo Qi Shi. « Thermal Fatigue of Thermal Barrier Coatings by Atmospheric Plasma Spraying ». Key Engineering Materials 385-387 (juillet 2008) : 405–8. http://dx.doi.org/10.4028/www.scientific.net/kem.385-387.405.
Texte intégralRésumé :
Turbine vanes and blades are the most intensively loaded elements in that they are subjected to a large variety of mechanical and high temperature loads. The thermal barrier coatings (TBCs) are widely used on different hot components of gas turbines, as blades and vanes, for both, power engineering as well as aeronautical applications. Currently, two methods are used for depositing TBCs on substrate, which are plasma spray (PS) and electron beam-physical vapor deposition (EB-PVD). A typical TBCs system consists of two thin coatings, including a ceramic coating and a metallic bond coat. Despite considerable efforts, the highly desirable prediction of their life time is still a demanding task. The PS coating was focused on in this work. Firstly, the TBCs systems are multiplayer material systems. The material properties are not easily determined, such as Young’s modulus of the top-coating of TBCs. Using the resonant frequency and the composite beam theory, the Young’s modulus of APS TBCs was gotten under from room temperature to 1150°C. Then using a commercial finite-element program, the model geometry is that of a cylinder specimen. The interface region between bond coat and top coating is modeled and meshed with a sinusoidal geometry. The temperature was designed and cycled over a range from room temperature to 1050°C. The force-air-cooling was designed to form temperature gradient across the thickness of TBCs. Finally, the fatigue life of TBCs was predicated. The maximum relative error is 20.1%.
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Cavalier, Jean Claude, Isabelle Berdoyes et Eric Bouillon. « Composites in Aerospace Industry ». Advances in Science and Technology 50 (octobre 2006) : 153–62. http://dx.doi.org/10.4028/www.scientific.net/ast.50.153.
Texte intégralRésumé :
Since more than twenty five years, composite materials have been with continuously increasing spatial and aeronautical applications requirements. The thermostructural composites materials are of utmost importance for satisfying the needs of mechanical and thermal characteristics at very high temperature and in severe environments. This paper deals with a large variety of applications concerning the aerospace and nuclear applications like nozzles and hot gas valves for Solid Rocket Motor (SRM), brake disks for planes, aerospace turbine engine exhaust nozzles, thermal protection system for reentry vehicles, but also Divert and Attitude Control System (DACS) for interceptors, heat exchangers for hypersonic propulsion systems, plasma facing components for nuclear fusion applications and special components for nuclear fission applications. We will see that Carbon/Carbon and Ceramic Matrix Composites are leading candidate materials for these hightemperature structural applications. This lecture will identify the current state-of-the-art and new technological developments. A description of the main steps of the manufacturing processes will be made.
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Teo, C. J., et Z. S. Spakovszky. « Modeling and Experimental Investigation of Micro-hydrostatic Gas Thrust Bearings for Micro-turbomachines ». Journal of Turbomachinery 128, no 4 (1 février 2005) : 597–605. http://dx.doi.org/10.1115/1.2219760.
Texte intégralRésumé :
One major challenge for the successful operation of high-power-density micro-devices lies in the stable operation of the bearings supporting the high-speed rotating turbomachinery. Previous modeling efforts by Piekos (2000, “Numerical Simulation of Gas-Lubricated Journal Bearings for Microfabricated Machines,” Ph.D. thesis, Department of Aeronautics and Astronautics, MIT), Liu et al. (2005, “Hydrostatic Gas Journal Bearings for Micro-Turbo Machinery,” ASME J. Vib. Acoust., 127, pp. 157–164), and Spakovszky and Liu (2005, “Scaling Laws for Ultra-Short Hydrostatic Gas Journal Bearings,” ASME J. Vib. Acoust. 127, pp. 254–261) have focused on the operation and stability of journal bearings. Thrust bearings play a vital role in providing axial support and stiffness, and there is a need to improve the understanding of their dynamic behavior. In this work, a rigorous theory is presented to analyze the effects of compressibility in micro-flows (characterized by low Reynolds numbers and high Mach numbers) through hydrostatic thrust bearings for application to micro-turbomachines. The analytical model, which combines a one-dimensional compressible flow model with finite-element analysis, serves as a useful tool for establishing operating protocols and assessing the stability characteristics of hydrostatic thrust bearings. The model is capable of predicting key steady-state performance indicators, such as bearing mass flow, axial stiffness, and natural frequency as a function of the hydrostatic supply pressure and thrust-bearing geometry. The model has been applied to investigate the static stability of hydrostatic thrust bearings in micro-turbine generators, where the electrostatic attraction between the stator and rotor gives rise to a negative axial stiffness contribution and may lead to device failure. Thrust-bearing operating protocols have been established for a micro-turbopump, where the bearings also serve as an annular seal preventing the leakage of pressurized liquid from the pump to the gaseous flow in the turbine. The dual role of the annular pad poses challenges in the operation of both the device and the thrust bearing. The operating protocols provide essential information on the required thrust-bearing supply pressures and axial gaps required to prevent the leakage of water into the thrust bearings. Good agreement is observed between the model predictions and experimental results. A dynamic stability analysis has been conducted, which indicates the occurrence of instabilities due to flow choking effects in both forward and aft thrust bearings. A simple criterion for the onset of axial rotor oscillations has been established and subsequently verified in a micro-turbocharger experiment. The predicted frequencies of the unstable axial oscillations compare well with the experimental measurements.
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Higashimori, Hirotaka, Kiyoshi Hasagawa, Kunio Sumida et Tooru Suita. « Detailed Flow Study of Mach Number 1.6 High Transonic Flow With a Shock Wave in a Pressure Ratio 11 Centrifugal Compressor Impeller ». Journal of Turbomachinery 126, no 4 (1 octobre 2004) : 473–81. http://dx.doi.org/10.1115/1.1791645.
Texte intégralRésumé :
Requirements for aeronautical gas turbine engines for helicopters include small size, low weight, high output, and low fuel consumption. In order to achieve these requirements, development work has been carried out on high efficiency and high pressure ratio compressors. As a result, we have developed a single stage centrifugal compressor with a pressure ratio of 11 for a 1000 shp class gas turbine. The centrifugal compressor is a high transonic compressor with an inlet Mach number of about 1.6. In high inlet Mach number compressors, the flow distortion due to the shock wave and the shock boundary layer interaction must have a large effect on the flow in the inducer. In order to ensure the reliability of aerodynamic design technology, the actual supersonic flow phenomena with a shock wave must be ascertained using measurement and Computational Fluid Dynamics (CFD). This report presents the measured results of the high transonic flow at the impeller inlet using Laser Doppler Velocimeter (LDV) and verification of CFD, with respect to the high transonic flow velocity distribution, pressure distribution, and shock boundary layer interaction at the inducer. The impeller inlet tangential velocity is about 460 m/s and the relative Mach number reaches about 1.6. Using a LDV, about 500 m/s relative velocity was measured preceding a steep deceleration of velocity. The following steep deceleration of velocity at the middle of blade pitch clarified the cause as being the pressure rise of a shock wave, through comparison with CFD as well as comparison with the pressure distribution measured using a high frequency pressure transducer. Furthermore, a reverse flow is measured in the vicinity of casing surface. It was clarified by comparison with CFD that the reverse flow is caused by the shock-boundary layer interaction. Generally CFD shows good agreement with the measured velocity distribution at the inducer and splitter inlet, except in the vicinity of the casing surface.
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De Giorgi, Maria Grazia, Luciano Strafella, Nicola Menga et Antonio Ficarella. « Intelligent Combined Neural Network and Kernel Principal Component Analysis Tool for Engine Health Monitoring Purposes ». Aerospace 9, no 3 (24 février 2022) : 118. http://dx.doi.org/10.3390/aerospace9030118.
Texte intégralRésumé :
An efficient maintenance plan is an important aspect for aeronautical companies to increase flight safety and decrease costs. Modern technologies are widely used in the Engine Health Monitoring (EHM) discipline to develop intelligent tools capable of monitoring the health status of engines. In this work, Artificial Neural Networks (ANNs) and in-detail Feed-Forward Neural Networks (FFNNs) were exploited in addition to a Kernel Principal Component Analysis (KPCA) to design an intelligent diagnostic tool capable of predicting the Performance Parameters (PPs) of the main components used as their health index. For this purpose, appropriate datasets containing information about degraded engines were generated using the Gas Turbine Simulation Program (GSP). Finally, the original datasets and the reduced datasets obtained after the application of KPCA to the original datasets were both used in the training and testing process of neural networks, and results were compared. The goal was to obtain a reliable intelligent tool useful for diagnostic purposes. The study showed that the degraded component detection and estimation of its performance achieved by using the hybrid KPCA–FFNNs were predicted with accurate and reliable performance, as demonstrated through detailed quantitative confusion matrix analysis.
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Evdokimenkov, V. N., R. V. Kim, M. N. Krasilshchikov et N. I. Selvesyuk. « INTEGRATED LOGISTICAL SUPPORT OF AERONAUTICAL EQUIPMENT BASED ON PROBABILITY-GUARANTEEING ESTIMATION OF THE RISKS, ASSOCIATED WITH THE AIRCRAFT TECHNICAL CONDITION ». Vestnik komp'iuternykh i informatsionnykh tekhnologii, no 206 (août 2021) : 29–37. http://dx.doi.org/10.14489/vkit.2021.08.pp.029-037.
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In this article, we analyze the modern concepts in the field of the aeronautical equipment integrated logistical support (ILS). The key element of the traditional logistical support system under consideration is the data on detected failures and malfunctions, recorded in the air flight and maintenance log (AFML), chart-orders, non-routine write-ups and accumulated within the structure of the logistic support analysis database. We propose a method for expanding the ILS capabilities by means of including of an additional element, called the flight information database, in the logistics center structure, along with the traditional database for analyzing the logistical support. This database is constantly growing during the aircraft operation. It also contains the values of the parameters recorded by the standard onboard flight data recorder, which reflect the state of the onboard systems. The inclusion of a flight information database into the structure of the logistical support center makes it possible to implement the probability-guaranteeing estimation method in respect of the risks, associated with the aircraft technical condition, for benefit of the integrated logistical support. The proposed method uses an inverse probabilistic criterion (quantile) as an integral characteristic of the aircraft systems technical condition. This is fully consistent with modern approaches to organizing condition-based maintenance. Among these approaches, the data-driven methodology (DDM) has the greatest potential and practical efficiency. The applicative value of the described method is in the fact that its implementation needs neither a priori information about the principles of the maintained equipment operation, nor information about the functioning principles of the on-board controller network, which is used to control the equipment physical parameters. In this article, we also present the accuracy estimates of forecasting the residual life of an aircraft gas turbine engine, using the proposed method. These estimates are based on the actual flight data presented in the National Aeronautics and Space Administration (NASA) repository.
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Camilleri, R., S. Ogaji et P. Pilidis. « Applying heat pipes to a novel concept aero engine : Part 2 – Design of a heat-pipe heat exchanger for an intercooled-recuperated aero engine ». Aeronautical Journal 115, no 1169 (juillet 2011) : 403–10. http://dx.doi.org/10.1017/s0001924000006023.
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Abstract With the ever-increasing pressure for cleaner and more fuel efficient aero engines, gas turbine manufacturers are faced with a big challenge which they are bound to accept and act upon. The path from current high bypass ratio (BPR) engines to ultra high BPR engines via geared turbo fans will enable a significant reduction in SFC and CO2 emissions. However, in order to reach the emission levels set by the advisory council for aeronautics research in Europe (ACARE), the introduction of more complex cycles that can operate at higher thermal efficiencies is required. Studies have shown that one possibility of achieving higher core efficiencies and hence lower SFC is through the use of an intercooled recuperated (ICR) core. The concept engine, expected to enter into service around 2020, will make use of a conventional fin plate heat exchangers (HEX) for the intercooler and a tube type HEX as the recuperator. Although the introduction of these two components promises a significant reduction in SFC levels, they will give also rise to higher engine complexity, pressure losses and additional weight. Thus, the performance of the engine relies not only on the behaviour of the usual gas turbine components, but will be heavily dependent on the two heat exchangers. This paper seeks to introduce a heat pipe heat exchanger (HPHEX) as alternative designs for the intercooler and the recuperator. The proposed HPHEX designs for application in an ICR aero engine take advantage of the convenience of the geometry of miniature heat pipes to provide a reduction in pressure losses and weight when compared to conventional HEX. The proposed HPHEX intercooler design eliminates any ducting to and from the intercooler, offering up to 32% reduction in hot pressure losses, 34% reduction in cold pressure losses and over 41% reduction in intercooler weight. On the other hand the proposed HPHEX recuperator design can offer 6% improvement in performance, while offering 36% reduction in cold pressure losses, up to 80% reduction in hot pressure losses and over 31% reduction in weight. An ICR using HPHEX for the intercooler and recueprator may offer up to 2·5% increase in net thrust, while still offering 3% reduction in SFC and up to 7·7% reduction in NOX severity parameter, when compared to the ICR using conventional HEX.
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Monceau, Daniel, Djar Oquab, Claude Estournès, Mathieu Boidot, Serge Selezneff et Nicolas Ratel-Ramond. « Thermal Barrier Systems and Multi-Layered Coatings Fabricated by Spark Plasma Sintering for the Protection of Ni-Base Superalloys ». Materials Science Forum 654-656 (juin 2010) : 1826–31. http://dx.doi.org/10.4028/www.scientific.net/msf.654-656.1826.
Texte intégralRésumé :
Aeronautic gas turbine blades, vanes and combustion chambers are protected against high temperature oxidation and corrosion by single or multilayered coatings. These include environmental coatings, generally based on Pt-modified Ni aluminides or MCrAlY overlays (where M = Ni and/or Co), thermal barrier coating (TBC) systems including a ceramic thermally insulating layer, and abradable seals. The present work shows the ability of the Spark Plasma Sintering technique to rapidly develop new coatings compositions and microstructures. This technique allows combining powders and metallic foils on a superalloy substrate in order to obtain multilayered coatings in a single short production step. Fabrication of MCrAlY overlays with local Pt and/or Al enrichments is shown, as well as fabrication of coatings made of -PtAl2, -PtAl, α-AlNiPt2, martensitic and (Ni,Pt)Al or Pt-rich ’ phases, including their doping with reactive elements. The fabrication of a complete TBC system with a porous and adherent Yttria Stabilized Zirconia (YSZ) layer on a bond-coating is also demonstrated, as well as the fabrication of a CoNiCrAlY-based cermet coating for abradable seal application. Difficulties of fabrication are reviewed, such as Y segregation, risks of carburization, local over-heating, or difficulty to coat complex shaped parts. Solutions are given to overcome these difficulties.
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Samulenkov, Yu I., Ya A. Filatova et A. D. Gruzd. « Aircraft maintenance system simulation mathematical model construction ». Civil Aviation High Technologies 24, no 4 (27 août 2021) : 38–49. http://dx.doi.org/10.26467/2079-0619-2021-24-4-38-49.
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The development of the aviation transport system is characterized by sophistication of interacting objects, the multi-criteria nature of the tasks to be solved and difficulties in making management decisions. For example, modern medium haul aircraft are fitted with up to 25,000 sensors to monitor the performance capabilities of functional systems components. Numerous ground-based instrumental methods and means of diagnosing the technical condition are used. This requires the development of methods and algorithms for determining and monitoring the criteria of limiting state of the monitored components and functional systems of aeronautical equipment. In this regard, analytical models of predictive estimate for the technical condition of aeronautical equipment, determination of aircraft maintenance modes and provision of spare parts and materials become essential. The paper proposes a scheme of the aircraft fleet maintenance system modeling algorithm and deducing the mathematical model of the optimal number of aircraft states in order to exclude secondary and subjective factors. The method of statistical modeling based on Markov processes with discrete states and continuous time is the basis of the proposed analytical model. The proposed method is reduced to the synthesis of some modeling algorithm of the investigated process that simulates the complex system components behavior and interaction as well as random perturbing factors. A distinctive feature of the presented algorithm is determination of the predominant estimated dependences of transition probabilities and intensities taking into account the requirements of the modern regulatory framework in terms of reliability of equipment and diagnosing the technical condition. The analysis of the predominant estimated dependencies study results in the conditions of operation of the aircraft maintenance system confirmed a high degree of correlation of the time duration effect on the particular states in order to diagnose the technical condition depending on the diagnostic concept. The proposed simulation model can be used for the aircraft technical condition predictive estimate, aircraft gas turbine engines and functional systems.
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Ebus, Tobias, Markus Dietz et Andreas Hupfer. « Experimental and numerical studies on small contra-rotating electrical ducted fan engines ». CEAS Aeronautical Journal 12, no 3 (29 mai 2021) : 559–71. http://dx.doi.org/10.1007/s13272-021-00517-7.
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AbstractElectrical propulsion has been identified as one of the key fields of future research within the aerospace sector. The Institute of Aeronautical Engineering at the Universität der Bundeswehr München aims to contribute to the ongoing development of small-sized electrical ducted fan engines with a thrust in the range of 100 N. A special emphasis is placed on electrically powered contra-rotating fan stages. When compared to a conventional rotor–stator stage, contra-rotating fan stages allow for a more compact design, considering a given pressure ratio, or an increased pressure ratio at a constant fan diameter. Since numerous new aircraft concepts are presently being developed, a high demand for compact and powerful electrically driven engines arises. Electrically driven contra-rotating fan engines provide a high potential in terms of compactness, emissions and efficiency. Using electric motors offers the ability to overcome common issues, such as design and integration of a contra-rotating stage into a gas turbine. An innovative new engine design featuring such a contra-rotating stage is developed and tested at one of the Institute’s test benches for electrical propulsion. Key components are two brushless motors powering the fan stage, one for each rotor. Various operation points are investigated experimentally during an extensive test campaign. Experimental results are compared to results of numerical simulations computed by ANSYS CFX. Results indicate a good agreement between experiment and simulation. The engine is running very smooth throughout all tested operation points. Yet, intensive heating up of the electric motors and high-temperature zone are found to be an issue at higher rotation speeds.
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Newton, A. G. « Aerothermodynamics of Gas Turbine and Rocket Propulsion — Revised and enlarged edition. G.C. Oates. American Institute of Aeronautics and Astronautics, Washington, DC, 1988. 452 pp. Illustrated. $39.95. (AIM Members), $49.95 (Non-Members). » Aeronautical Journal 92, no 918 (octobre 1988) : 336. http://dx.doi.org/10.1017/s0001924000016377.
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Zanini, Nicola, Alessio Suman, Riccardo Friso et Michele Pinelli. « Analysis of satellite-derived data for the study of fouling in aircraft engines ». Journal of Physics : Conference Series 2385, no 1 (1 décembre 2022) : 012134. http://dx.doi.org/10.1088/1742-6596/2385/1/012134.
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Abstract Atmospheric particulate is one of the main causes of performance degradation in gas turbine engines, especially in the aeronautical field where filter barriers are absent. The ingested particles can stick to the blade surfaces of the engine, varying their shape and roughness. As a consequence, engine performance degradation takes place. The type and the amount of the particles ingested depend on the flight zones and altitude. During their missions, aircrafts follow a prescribed path defined in terms of altitude, longitude, and latitude. During its route, the aircraft engine encounters different environments characterized by different temperature, pressure, and air composition. Regarding the latter issue, the knowledge of this characteristic can be key information when these statistics are needed for obtaining data useful for engine degradation assessment or prediction. Many satellites, such as the environmental satellite CALIPSO, are employed to study the terrestrial aerosol and clouds profile by using a LIDAR (Laser Detection and Ranging). This technology is commonly used to determine the distance between a light emitter and an object and it is based on the light refraction phenomenon. Backscatter coefficients profiles data, which characterize the distribution of particles and aerosols in the atmosphere, are available in the open literature from the findings of CALIPSO. In this work, a new methodology to estimate the aerosol type and concentration encountered by an aircraft during a mission is proposed. To test the feasibility of this method, two aircraft missions for different length scales (medium and long haul) are analyzed and an estimate of the particulate encountered by the engines is provided. The mission analysis has been conducted by discretizing the altitude profile, longitude, and latitude coordinates of each flight and then cross-referencing them with the particulate concentration obtained from CALIPSO data.
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SAWYER, JOHN W. « MARINE GAS TURBINE, FREE PISTON GAS TURBINE BIBLIOGRAPHY ». Journal of the American Society for Naval Engineers 70, no 1 (18 mars 2009) : 159–69. http://dx.doi.org/10.1111/j.1559-3584.1958.tb03285.x.
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Singh, Riti. « Elements of Gas Turbine Propulsion J.D. Mattingly American Institute of Aeronautics and Astronautics, 1801 Alexander Bell Drive, Reston, VA 20191, USA. 2005. 960pp. Illustrated. $79.95 (AIAA members), $109.95 (non-members). ISBN 1-56347-778-5. » Aeronautical Journal 110, no 1104 (février 2006) : 126. http://dx.doi.org/10.1017/s0001924000086607.
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Ford, Terry. « Gas Turbine Combustion ». Aircraft Engineering and Aerospace Technology 62, no 5 (mai 1990) : 21–22. http://dx.doi.org/10.1108/eb036941.
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Olsson, Erik. « Gas turbine combustion ». International Journal of Heat and Mass Transfer 28, no 1 (janvier 1985) : 316. http://dx.doi.org/10.1016/0017-9310(85)90037-7.
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Spittle, Peter. « Gas turbine technology ». Physics Education 38, no 6 (1 novembre 2003) : 504–11. http://dx.doi.org/10.1088/0031-9120/38/6/002.
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Clark, Jim A. « Gas turbine combustion ». Combustion and Flame 63, no 1-2 (janvier 1986) : 307. http://dx.doi.org/10.1016/0010-2180(86)90131-8.
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