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1
GĘCA, Michał, Zbigniew CZYŻ et Mariusz SUŁEK. « Diesel engine for aircraft propulsion system ». Combustion Engines 169, no 2 (1 mai 2017) : 7–13. http://dx.doi.org/10.19206/ce-2017-202.
Texte intégralRésumé :
Stricter requirements for power in engines and difficulties in fueling gasoline engines at the airport make aircraft engine manufac-turers design new engines capable of combusting fuel derived from JET-A1. New materials used in compression-ignition engines enable weight reduction, whereas the technologies of a Common Rail system, supercharging and 2-stroke working cycle enable us to increasethe power generated by an engine of a given displacement. The paper discusses the parameters of about 40 types of aircraft compression ignition engines. The parameters of these engines are compared to the spark-ignition Rotax 912 and the turboprop. The paper also shows trends in developing aircraft compression-ignition engines.
2
OPARA, Tadeusz. « History and future of turbine aircraft engines ». Combustion Engines 127, no 4 (1 novembre 2006) : 3–18. http://dx.doi.org/10.19206/ce-117335.
Texte intégralRésumé :
This paper discusses stages of development of air propulsion from piston engines up to three-rotor turbine ones. Limitations in speed and altitude of flight, caused by traditional system of a piston engine and an airscrew, became an impulse to conduct research on jet propulsion. Accomplishments of the designers of the first jet-propelled engines: F. Whitle and H. von Ohain are a reflection of rivalry in this field. In the second half of the 20th centur y turbine propulsion (turbojet, turboprop and helicopter engines) dominated air force and civil aviation. In 1960 the age of turbofans began, owing to better operating properties and electronic and digital systems of automatic regulation. Further development of turbine engines is connected with application of qualitatively new materials (particularly composites), optimization of the shape of compressor and turbine blades and technologies of their production. The paper discusses design changes decreasing the destructive effects of foreign matter suction and indicates the possibility of increasing the maneuverability of airplanes by thrust vectoring. Finally, development prospects of turbine propulsion are analyzed.
3
BERBENTE, Sorin, Irina-Carmen ANDREI, Gabriela STROE et Mihaela-Luminita COSTEA. « Topical Issues in Aircraft Health Management with Applications to Jet Engines ». INCAS BULLETIN 12, no 1 (1 mars 2020) : 13–26. http://dx.doi.org/10.13111/2066-8201.2020.12.1.2.
Texte intégralRésumé :
Aircraft Health Management Technology for jet engines represents a very important problem, since it develops a large impact on reducing the engine life cycle costs, improving the fuel efficiency, increasing the engines durability and life cycle. This technology is high-end and, in order to enable an improved level of performance that far exceeds the current one, propulsion systems must comply with terms of reducing harmful emissions, maximizing fuel efficiency and minimizing noise, while improving system’s affordability and safety. Aircraft Health Management Technology includes multiple goals of aircraft propulsion control, diagnostics problems, prognostics realized, and their proper integration in control systems. Modern control for Aircraft Health Management Technology is based on improved control techniques and therefore provides improved aircraft propulsion system performances. The study presented in this paper approaches a new concept, of attractive interest currently, that is the intelligent control; in this context, the Health Management of jet engines is crucial, being focused on engine controllers which are designed to match certain operability and performance constraints. Automated Engine Health Management has the capacity to significantly reduce the maintenance effort and propulsion systems’ logistical footprint. In order to prioritize and resolve problems in the field of support engineering there are required more detailed data on equipment reliability and failures detection and management; the equipment design, operations and maintenance procedures and tooling are also very important.
4
Żokowski, Mariusz, Paweł Majewski et Jarosław Spychała. « Detection Damage in Bearing System of Jet Engine Using the Vibroacoustic Method ». Acta Mechanica et Automatica 11, no 3 (1 septembre 2017) : 237–42. http://dx.doi.org/10.1515/ama-2017-0037.
Texte intégralRésumé :
Abstract The article discusses typical, operational systems for monitoring vibrations of jet engines, which constitute the propulsion of combat aircraft of the Armed Forces of the Republic of Poland. After that, the paper presents the stage of installing vibration measuring sensors in the direct area of one of the jet engine bearings, which is a support system for its rotor. The article discusses results of carried out analyses of data gathered during tests of the engine in the conditions a jet engine test bed. Results of detecting damages to the bear-ing, using sensors built in the direct area will be presented.
5
Lee, Incheol, Yingzhe Zhang et Dakai Lin. « Empirical estimation of engine-integration noise for high bypass ra-tio turbofan engines ». INTER-NOISE and NOISE-CON Congress and Conference Proceedings 263, no 2 (1 août 2021) : 4511–19. http://dx.doi.org/10.3397/in-2021-2723.
Texte intégralRésumé :
To investigate the impact of installation on jet noise from modern high-bypass-ratio turbofan engines, a model-scale noise experiment with a jet propulsion system and a fuselage model in scale was conducted in the anechoic wind tunnel of ONERA, CEPRA 19. Two area ratios (an area of the secondary nozzle over an area of the primary nozzle), 5 and 7, and various airframe configurations such as wing positions relative to the tip of the engine nacelle and flap angles, were considered. Based on the analysis of experimental data, an empirical model for the prediction of engine installation noise was proposed. The model comprises two components: one is the interaction be-tween the jet and the pressure side of the wing, and the other is the interaction between the jet and the flap tip. The interaction between the jet and the pressure side of the wing contributes to the noise at the low frequencies (≤ 1.5 kHz), and the interaction between the jet and the flap tip con-tributes to the noise at the high frequencies. The proposed model showed a good agreement with the experimental data.
6
Denning, R. M., et N. A. Mitchell. « Trends in Military Aircraft Propulsion ». Proceedings of the Institution of Mechanical Engineers, Part G : Journal of Aerospace Engineering 203, no 1 (janvier 1989) : 11–23. http://dx.doi.org/10.1243/pime_proc_1989_203_049_01.
Texte intégralRésumé :
The major factors determining the choice of engine cycle for a combat aircraft are the requirements of the design mission and those of aircraft speed and agility. The requirement for jet-borne flight in short take-off vertical landing (STOVL) aircraft imposes further demands on cycle and configuration. The changing nature of combat aircraft requirements is the reason for changes in engine design. Specific thrust is shown to be the major parameter defining engine suitability for a particular role. An examination of mixed turbofan characteristics shows that specific thrust is also the key to understanding the relationships between engine characteristics. The future development of combat engines is discussed, in particular the implications of stoichiometric limits on cycle temperatures and the benefits of variable cycle engines are examined. Recent work on advanced STOVL (ASTOVL) aircraft is reviewed and aircraft/engine concepts designed to meet the requirements of the role are assessed. Experience shows that the technology for these advanced engines must be fully demonstrated before production to minimize the risks and costs of the development programme.
7
Osei-Agyemang, Eric, Jean-Francois Paul, Romain Lucas, Sylvie Foucaud et Sylvain Cristol. « Stability, equilibrium morphology and hydration of ZrC(111) and (110) surfaces with H2O : a combined periodic DFT and atomistic thermodynamic study ». Physical Chemistry Chemical Physics 17, no 33 (2015) : 21401–13. http://dx.doi.org/10.1039/c5cp03031e.
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CHIESA, Sergio, Marco FIORITI et Roberta FUSARO. « POSSIBLE HYBRID PROPULSION CONFIGURATION FOR TRANSPORT JET AIRCRAFT ». Aviation 20, no 3 (29 septembre 2016) : 145–54. http://dx.doi.org/10.3846/16487788.2016.1200849.
Texte intégralRésumé :
This research is aimed at studying the possible advantages of installing, for a hybrid propulsion aircraft, electric motors and related propellers into the dedicated supplementary nacelles. This innovative solution is different from the configuration, already studied for a regional turboprop (Chiesa et al.2013), in which the electric motors are in the same nacelles of the internal combustion engines. As it has been expected, it offers the advantages of avoiding mechanical links between the two units and, more importantly, can also be applied to jet aircraft. In fact, the main contribution of electric motors is expected during ground operations, take-off and descent phases (i.e. at low speed), in which it can be useful to integrate the propellers or even substitute the jet engines with them. At high speed, the propellers, of course, are configured in order to reduce drag. When considering the design of a new airliner concept, a preliminary design study is necessary to optimize the location of the supplementary nacelles. The nacelles, which only hold the electrical motor, can also be considered retractable, as is usual for a RAT (Ram Air Turbine). Please note that in the hybrid propulsion context, the RAT function can be clearly allocated to the electric motor, with the advantages of optimizing drag at high speed, taking into account installation problems.
9
Woods, Robert O. « Power to the Glider ». Mechanical Engineering 130, no 08 (1 août 2008) : 46–48. http://dx.doi.org/10.1115/1.2008-aug-6.
Texte intégralRésumé :
This article discusses developments in powered sailplane. Jet propulsion clearly demonstrates the future direction of powered sailplanes. Powered glider applies to a new class of aircraft that takes off under their own power, and then, with the power plant stopped and streamlined, behave as true sailplanes. The advent of radio control has allowed model aviation to progress to an almost unbelievable degree. There are now small turbojet engines commercially available that weigh a little over 5 pounds and deliver 40 pounds force of thrust. Jet propulsion clearly demonstrates the future direction of powered sailplanes.
10
Danko, Gene A. « By Leaps and Bounds : The Realization of Jet Propulsion through Innovative Materials and Design ». Key Engineering Materials 380 (mars 2008) : 135–46. http://dx.doi.org/10.4028/www.scientific.net/kem.380.135.
Texte intégralRésumé :
Innovations in gas turbine engine design and materials are tracked from the earliest days of functional engines to the present. Materials and design are shown to be mutually interdependent, driving engine capability to unprecedented levels of performance with each succeeding product generation.
11
Norton, Lord Kings. « The beginnings of jet propulsion ». Aeronautical Journal 103, no 1022 (avril 1999) : 200–209. http://dx.doi.org/10.1017/s0001924000096494.
Texte intégralRésumé :
The chairman: I know that everyone here shares with me our pleasure in welcoming as our lecturer one of the most distinguished and one of the most erudite and delightful people of all those who over the years have made their mark on British aeronautics. Lord Kings Norton has been Chancellor of Cranfield Institute of Technology since 1969. He began his career in aviation sixty-one years ago at Cardington, as a young engineer working on the design and construction of that much maligned major project, the airship R101, and then subsequently as Dr. Harold Roxbee Cox (as many of us still remember him) he was the head of the Air Defence Department of the Royal Aircraft Establishment at Farnborough. Next he was Chief Technical Officer of the newly formed Air Registration Board before he returned to the RAE in 1939 as Superintendent of Scientific Research.
12
Huete, J., D. Nalianda et P. Pilidis. « Propulsion system integration for a first-generation hydrogen civil airliner ? » Aeronautical Journal 125, no 1291 (28 mai 2021) : 1654–65. http://dx.doi.org/10.1017/aer.2021.36.
Texte intégralRésumé :
ABSTRACTAn unusual philosophical approach is proposed here to decarbonise larger civil aircraft that fly long ranges and consume a large fraction of civil aviation fuel. These inject an important amount of carbon emissions into the atmosphere, and holistic decarbonising solutions must consider this sector. A philosophical–analytical investigation is reported here on the feasibility of an airliner family to fly over long ranges and assist in the elimination of carbon dioxide emissions from civil aviation.Backed by state-of-the-art correlations and engine performance integration analytical tools, a family of large airliners is proposed based on the development and integration of the body of a very large two-deck four-engine airliner with the engines, wings and flight control surfaces of a very long-range twin widebody jet. The proposal is for a derivative design and not a retrofit. This derivative design may enable a swifter entry to service.The main contribution of this study is a philosophical one: a carefully evaluated aircraft family that appears to have very good potential for first-generation hydrogen-fuelled airliners using gas turbine engines for propulsion. This family offers three variants: a 380-passenger aircraft with a range of 3,300nm, a 330-passenger aircraft with a range of 4,800nm and a 230-passenger aircraft with a range of 5,500nm. The latter range is crucially important because it permits travel from anywhere in the globe to anywhere else with only one stop. The jet engine of choice is a 450kN high-bypass turbofan.
13
Золотько, Олександр Євгенович, Олена Василівна Золотько, Олександра Валеріївна Сосновська, Олександр Сергійович Аксьонов et Ірина Сергіївна Савченко. « ОСОБЛИВОСТІ КОНСТРУКТИВНИХ СХЕМ ДВИГУНІВ З ІМПУЛЬСНИМИ ДЕТОНАЦІЙНИМИ КАМЕРАМИ ». Aerospace technic and technology, no 2 (27 avril 2020) : 4–10. http://dx.doi.org/10.32620/aktt.2020.2.01.
Texte intégralRésumé :
The pressure of the products of chemical reactions in the chamber of a rocket engine increases significantly if the rocket fuel components burn in the detonation mode. In this case, it can get to a simpler and more reliable expulsion propellant feed system instead of a turbopump feed system. The value of heat release power (MW / liter) of detonation engines is several orders of magnitude larger than that of aircraft and rocket engines operating in the Brighton cycle. The high rate of energy released in the detonation mode can significantly reduce the mass, the inertia, and overall dimensions of the propulsion system. Due to these features, detonation chambers are advisable to be used as part of ejector pulsed detonation engines, together with a turbine – in electric power generators of spacecraft, in a hybrid design – together with turbofan or turboprop engines, etc. In the article are considered various design schemes of pulse detonation engines (PDE): single-chamber and multi-chamber pulsed detonation engines; an ejector PDE system; a hybrid PDE and an integrated detonation-turbine unit with a detonation chamber in the form of a spiral and with a multi-chamber detonation device. The possibility of pulsation frequency increase is realized in the multi-chamber pulsed detonation engine, and the possibility of thrust size increase is realized in PDE with ejector. Replacing traditional chambers with detonation chambers in the construction of gas turbine jet engine will allow providing a decrease in propellant flow rate value from 8 % to 10 % on some estimations. In the hybrid detonation propulsion plant advantages inherent to the detonation cycle combine with positive features of a turbo-compressor jet engine. A combination of PDE and turbine allows creating the cogeneration propulsion system in that a turbine is used for the production of electric power, and detonation chamber – for the creation of thrust impulse. Practical realization of hybrid pulse detonation turbo-engine and the integrated detonation-turbine device is possible if two key complex problems will be solved. These problems are the detonation waves weakening on input in a turbine and the bearing and shaft necessary work resource increasing into a detonation pulsating stream
14
Goods, Daniel E. « Revelations at the Jet Propulsion Laboratory ». Leonardo 38, no 5 (octobre 2005) : 376–81. http://dx.doi.org/10.1162/leon.2005.38.5.376.
Texte intégralRésumé :
The author's 2 years of developing installations for the Jet Propulsion Laboratory have led him to an appreciation of how similar his thinking and work process are to those of the laboratory's engineers and scientists. For both, certain ideas and processes at first appear crazy and impracticable, but vision and persistence bring them to realization. The three installations described in this article pertain to a future mission that, if successful, will locate a planet similar to Earth and once again change humanity's understanding of its position in the universe.
15
Norton, Lord Kings. « Extract from A Wrack Behind : Frank Whittle ». Aeronautical Journal 103, no 1022 (avril 1999) : 210–11. http://dx.doi.org/10.1017/s0001924000096500.
Texte intégralRésumé :
Whittle is one of the great engineers of the century, perhaps the greatest if judged by the scale of the consequences of his invention. Only the discoverer of the properties of the silicon chip could claim comparable importance. Jet propulsion was first demonstrated by Hero of Alexandria in AD 60. The gas turbine was patented by Barber of Nuneaton in 1791. Whittle patented a design for an aircraft engine in 1930 in which propulsion was to be achieved by a jet produced by a gas turbine. By combining the thoughts of two men separated in time by over 1,700 years he made an engine which revolutionised world air transport.
16
Cwojdziński, Leszek, et Mirosław Adamski. « POWER UNITS AND POWER SUPPLY SYSTEMS IN UAV ». Aviation 18, no 1 (3 avril 2014) : 1–8. http://dx.doi.org/10.3846/16487788.2014.865938.
Texte intégralRésumé :
One of the major tasks in the process of designing future unmanned aerial vehicles is the appropriate choice of a propulsion system and a power source. Depending on the role and size of a given UAV, the following engines are used: electric, jet, turbine and piston (combustion). The following paper also analyses the faultiness of UAVs. Moreover, the most appropriate propulsion systems and power sources depending on the type and description of the mission performed by a UAV are recommended.
17
Korakianitis, T., et D. G. Wilson. « Models for Predicting the Performance of Brayton-Cycle Engines ». Journal of Engineering for Gas Turbines and Power 116, no 2 (1 avril 1994) : 381–88. http://dx.doi.org/10.1115/1.2906831.
Texte intégralRésumé :
Gas turbine performance is the result of choices of type of cycle, cycle temperature ratio, pressure ratio, cooling flows, and component losses. The output is usually given as efficiency (thermal, propulsive, specific thrust, overall efficiency) versus specific power. This paper presents a set of computer programs for the performance prediction of shaft-power and jet-propulsion cycles: simple, regenerative, intercooled-regenerative, turbojet, and turbofan. Each cycle is constructed using individual component modules. Realistic assumptions are specified for component efficiencies as functions of pressure ratio, cooling mass-flow rate as a function of cooling technology levels, and various other cycle losses. The programs can be used to predict design point and off-design point operation using appropriate component efficiencies. The effects of various cycle choices on overall performance are discussed.
18
Trazzi, P. E. « DESIGN AND DEVELOPMENT OF A 70 N THRUST CLASS TURBOJET ENGINE ». Revista de Engenharia Térmica 3, no 1 (30 juin 2004) : 09. http://dx.doi.org/10.5380/reterm.v3i1.3484.
Texte intégralRésumé :
Small turbojet engines are being used for propulsion of radio-controlled
model airplanes. The design and development of the model 505 small jet
engine are reviewed. Small size gas turbines present special design and
construction difficulties, some of which are addressed; design choices
leading to the final configuration are discussed. Aero-thermodynamic
aspects are covered along with experimental data when available. The unit
is comprised of a radial compressor, an annular combustion chamber, and
an axial turbine plus accessories; details on these components and on
production aspects are presented.
19
Kroon, R. P. « JET PROPULSION ENGINES AND PROPELLER DRIVE GAS TURBINES-THEIR APPLICATION IN FUTURE AVIATION.* ». Journal of the American Society for Naval Engineers 58, no 4 (18 mars 2009) : 664–72. http://dx.doi.org/10.1111/j.1559-3584.1946.tb02719.x.
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SZWAJCA, Filip, et Krzysztof WISŁOCKI. « Thermodynamic cycles variability of TJI gas engine with different mixture preparation systems ». Combustion Engines 181, no 2 (30 juin 2020) : 46–52. http://dx.doi.org/10.19206/ce-2020-207.
Texte intégralRésumé :
Gas engines are a viable source of propulsion due to the ecological indicators of gas fuels and the large amount of the needed natural resources. Combustion of lean homogeneous gas mixtures allows achieving higher thermal efficiency values, which is a key factor in current engine development trends. Using the spark-jet ignition system (also called as Turbulent Jet Ignition or Two-stage combustion) significantly improves the efficiency and stability of the combustion process, especially in the part-load operation on lean or very lean mixtures. This paper presents the impact of using two different fuel injection methods: Port Fuel Injection or Mixer on the operation stability of a gas engine designed for LDVs. Comparative studies of two different mixture preparation systems were carried out on a single-cylinder AVL 5804 test engine. By re-cording the cylinder pressure for a significant number of engine cycles, it became possible to determine the repeatability of engine operation and to correlate the results with the mixture formation system and the air-fuel ratio. In the performed research the beneficial effect of the mixer system application on the engine operation stability in the part-load conditions was found.
21
Férand, Mélissa, Thomas Livebardon, Stéphane Moreau et Marlène Sanjosé. « Numerical Prediction of Far-Field Combustion Noise from Aeronautical Engines ». Acoustics 1, no 1 (19 février 2019) : 174–98. http://dx.doi.org/10.3390/acoustics1010012.
Texte intégralRésumé :
A hybrid methodology combining a detailed Large Eddy Simulation of a combustion chamber sector, an analytical propagation model of the extracted acoustic and entropy waves at the combustor exit through the turbine stages, and a far-field acoustic propagation through a variable exhaust temperature field was shown to predict far-field combustion noise from helicopter and aircraft propulsion systems accurately for the first time. For the single-stream turboshaft engine, the validation was achieved from engine core to the turbine exit. Propagation to the far field was then performed through a modeled axisymmetric jet. Its temperature modified the acoustic propagation of combustion noise significantly and a simple analytical model based on the Snell–Descarte law was shown to predict the directivity for axisymmetric single jet exhaust accurately. Good agreement with measured far-field spectra for all turboshaft-engine regimes below 2 kHz stresses that combustion noise is most likely the dominant noise source at low frequencies in such engines. For the more complex dual-stream turbofan engine, two regime computations showed that direct noise is mostly generated by the unsteady flame dynamics and the indirect combustion noise by the temperature stratification induced by the dilution holes in the combustion chamber, as found previously in the turboshaft case. However, in the turboengine, direct noise was found dominant at the combustor exit for the low power case and equivalent contributions of both combustion noise sources for the high power case. The propagation to the far-field was achieved through the temperature field provided by a Reynolds-Averaged Navier–Stokes simulation. Good agreement with measured spectra was also found at low frequencies for the low power turboengine case. At high power, however, turboengine jet noise overcomes combustion noise at low frequencies.
22
Chen, Min, Zihao Jia, Hailong Tang, Yi Xiao, Yonghang Yang et Feijia Yin. « Research on Simulation and Performance Optimization of Mach 4 Civil Aircraft Propulsion Concept ». International Journal of Aerospace Engineering 2019 (14 janvier 2019) : 1–19. http://dx.doi.org/10.1155/2019/2918646.
Texte intégralRésumé :
Supersonic civil aircraft is of a promising area in the development of future civil transport, and aircraft propulsion system is one of the key issues which determine the success of the aircraft. To get a good conceptual design and performance investigation of the supersonic civil aircraft engine, in this article, a fast, versatile as well as trust-worthy numerical simulation platform was established to analyze the Mach 4 turbine-based combined cycle (TBCC) engine concept so as to be applied to the supersonic civil aircraft. First, a quick and accurate task requirement analysis module was newly established to analyze the mission requirement of the Mach 4 supersonic civil aircraft. Second, the TBCC engine performance simulation model was briefly presented and the number of engines on the supersonic civil aircraft was analyzed, considering single engine inoperative. Third, the Stone model and the DLR method were investigated to estimate the engine jet noise and the NOx emission of the Mach 4 supersonic civil aircraft. Finally, a multiobjective optimization tool made up of a response surface method and a genetic algorithm was developed to optimize the design parameters and the control law of the TBCC engine, in order to make the Mach 4 supersonic civil aircraft engine with better performance, lower noise, and lower emissions. The uniqueness of the developed analysis tool lies in that it affords a numerical simulation platform capable of investigating the task requirement analysis module of the supersonic civil aircraft, engine jet noise prediction model, and the NOx emission prediction model, as well as a multiobjective performance optimization tool, which is beneficial for the conceptual design and performance research of Mach 4 supersonic civil aircraft’s propulsion system.
23
Lee, Hsing-Juin, et Hsing-Wei Lee. « Deriving the Generalized Total Kinetic Power Equation for Jet Engine ». Journal of Mechanics 14, no 3 (septembre 1998) : 145–52. http://dx.doi.org/10.1017/s1727719100000174.
Texte intégralRésumé :
ABSTRACTIn light of incessant quest of better propulsion performance, it would be opportune to probe some propulsion insights for jet engine (JE) from a power point of view. In this study, we endeavor to prescribe logic reasoning process for obtaining the JE total kinetic power and prove its degenerated counterpart. With the Lagrangian Reynolds transport approach, we also rigorously derive the highly generalized equation for this power. Moreover, the validity, significance, and importance of this novel generalized power equation are delicately demonstrated by an interesting spring/mass model with known total kinetic power. Notably, the JE total kinetic power equations are quite reasonable physically speaking, since all the velocity quantities involved are of relative nature; otherwise, the JE total kinetic power may violate the energy conservation law under certain conditions. This total kinetic power produced by jet engine involves a few more physical effects including vehicle acceleration, relative flow velocity/steadiness, inlet/exit pressures, and gravity, thus open an original route for more efficient propulsion design.
24
Lilley, G. M. « The generation of sound in turbulent motion ». Aeronautical Journal 112, no 1133 (juillet 2008) : 381–94. http://dx.doi.org/10.1017/s0001924000002347.
Texte intégralRésumé :
Abstract The present paper reviews and discusses the physical mechanisms of noise generation and reduction in turbulent flows with their applications towards aircraft noise reduction at takeoff and on the approach. This work began in 1948 when Lilley undertook an experimental investigation into the source of jet noise as a necessary precursor to finding methods for the reduction of high speed jet engine noise on civil jet airliners. Westley and Lilley completed this experimental programme in 1951, which included the design of a range of devices for high speed jet noise reduction. It was about this time that similar studies on jet noise were being started elsewhere and in particular by Lassiter and Hubbard in USA. The major contribution to the subject of turbulence as a source of noise came from Sir James Lighthill’s remarkable theory in 1952. In spite of the difficulties attached to theoretical and experimental studies on noise from turbulence, it is shown that with the accumulated knowledge on aerodynamic noise over the past 50 years, together with an optimisation of aircraft operations including flight trajectories, we are today on the threshold of approaching the design of commercial aircraft with turbofan propulsion engines that will not be heard above the background noise of the airport at takeoff and landing beyond 1-2km, from the airport boundary fence. It is evident that in the application of this work, which centres on the physical mechanisms relating to the generation of noise from turbulence and turbulent shear flows, to jet noise, there is not one unique mechanism of jet noise generation for all jet Mach numbers. This author in this publication has concentrated on what appears to be the dominant mechanism of noise generation from turbulence, where the mean convection speeds of the turbulence are subsonic. The noise generated at transonic and supersonic jet speeds invariably involves extra mechanisms, which are only briefly referred to here.
25
Lukasik, Borys, et Witold Wisniowski. « All-electric propulsion for future business jet aircraft : A feasibility study ». Proceedings of the Institution of Mechanical Engineers, Part G : Journal of Aerospace Engineering 231, no 12 (1 septembre 2017) : 2203–13. http://dx.doi.org/10.1177/0954410017727027.
Texte intégralRésumé :
The main goal of this paper is to investigate feasibility of using all-electric propulsion system for a mid-light business jet aircraft in the near future (20–30 years from now). The secondary goal is to assess the impact of using such system on operating costs and emission reduction. This paper presents calculations of business jet aircraft mission energy demands and compares them with batteries capabilities. Three different types of lithium batteries are investigated in terms of their energy densities projected for three different time frames. Mass of batteries that is required to provide demanded amount of energy to perform the mission is compared with the maximum mass of fuel that the baseline aircraft is able to take. On this basis, the feasibility of all-electric propulsion system is assessed. Additionally, in order to show the limitations of such system, maximum range is calculated for the mass of batteries that would potentially enable to perform the flight. Furthermore, CO2 and NOx emission of the baseline aircraft engines are compared with the amount of gaseous pollutants which are emitted by the power plant, when energy needed to recharge batteries is being produced. Finally, the potential fuel cost reduction is calculated based on the cost of electricity that would be used to recharge batteries.
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Li, Kun, et Wen Hui Li. « Study on the Acceleration Process of Water-Jet Propulsion Ship ». Applied Mechanics and Materials 263-266 (décembre 2012) : 756–61. http://dx.doi.org/10.4028/www.scientific.net/amm.263-266.756.
Texte intégralRésumé :
The acceleration process was studied in the form of co-simulation. The diesel engine model and water-jet pump model were derived and presented respectively in AMESim & Simulink. The engine acceleration parameters are calculated through the simulation which ran taking operation restricted zone of the pump as a constraint.
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Goulos, I., J. Otter, T. Stankowski, D. Macmanus, N. Grech et C. Sheaf. « Design optimisation of separate-jet exhausts for the next generation of civil aero-engines ». Aeronautical Journal 122, no 1256 (19 septembre 2018) : 1586–605. http://dx.doi.org/10.1017/aer.2018.95.
Texte intégralRésumé :
ABSTRACTThe next generation of civil large aero-engines will employ greater bypass ratios compared with contemporary architectures. This results in higher exchange rates between exhaust performance and specific fuel consumption (SFC). Concurrently, the aerodynamic design of the exhaust is expected to play a key role in the success of future turbofans. This paper presents the development of a computational framework for the aerodynamic design of separate-jet exhaust systems for civil aero-engines. A mathematical approach is synthesised based on class-shape transformation (CST) functions for the parametric geometry definition of gas-turbine exhaust components such as annular ducts and nozzles. This geometry formulation is coupled with an automated viscous and compressible flow solution method and a cost-effective design space exploration (DSE) approach. The framework is deployed to optimise the performance of a separate-jet exhaust for very-high-bypass ratio (VHBR) turbofan engine. The optimisations carried out suggest the potential to increase the engine’s net propulsive force compared with a baseline architecture, through optimum exhaust re-design. The proposed method is able to identify and alleviate adverse flow-features that may deteriorate the aerodynamic behaviour of the exhaust system.
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Saeed, B., G. Gratton et C. Mares. « A feasibility assessment of annular winged VTOL flight vehicles ». Aeronautical Journal 115, no 1173 (novembre 2011) : 683–92. http://dx.doi.org/10.1017/s0001924000006400.
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AbstractThis paper presents a feasibility study to integrate a developed lift system (an annular wing wrapped around a centrifugal flow generator) into a Vertical/Short Take-Off and Landing V/STOL aircraft. Different physical scales, from micro aerial vehicle to a Harrier Jump Jet scale, for a variety of propulsion systems are explored. The system has shown to be viable for several classes of aircraft but with better performance offered by a micro-aerial-vehicle (~40g) and a large vehicle (~10,000kg) with a turbofan engine, albeit in both cases with apparently worse performance than is offered by current technologies. The wingform does not appear to be feasible in the light aircraft scale whilst using internal combustion engines.
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Dimri, Ankit, et Racheet Matai. « Improved Air Turbo Rocket for Space Applications Application to Orbital Vehicles and Reentry ». Applied Mechanics and Materials 110-116 (octobre 2011) : 2554–61. http://dx.doi.org/10.4028/www.scientific.net/amm.110-116.2554.
Texte intégralRésumé :
An Air Turbo Rocket (ATR) is a propulsion system which combines a turbo jet with a rocket engine. Currently it is being touted as a propulsion system for future missile systems, as these engines have a higher thrust density when compared to other air breathing engines. This paper explores the possibility of modifying the ATR for use in space application as well as during spacecraft re-entry. Such modified ATR’s could be used to power space vehicles up to the Low Earth Orbit (LEO) to dock with the International Space Station (ISS). In addition, thrust reversal techniques on the ATR systems could be used to improve the accuracy of Ballistic Missiles and hypersonic space planes upon Re-entry. Challenges faced would be in this type of air breathing engine would be operating at different atmospheric conditions. This paper will explore an ATR design, which will operate at different modes namely conventional mode, which will be used during below absolute ceiling, and the mission mode, which will be employed during flight in vacuum. Lastly, the reentry mode, which can be used for lessening the entry velocity of a vehicle to reduce the risks associated with reentry. The paper will try to emphasize the advantages of ATR as an affordable launch system for space shuttles and satellites with high maneuverability.
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Ciulin, Dan. « Contributions to a Future Inertial Motor and More ». International Journal of Strategic Information Technology and Applications 4, no 1 (janvier 2013) : 63–97. http://dx.doi.org/10.4018/jsita.2013010105.
Texte intégralRésumé :
For a future interplanetary trip, a space ship must be able to take off and/or land on a planet and travel at a convenient speed, insure convenient life conditions for the embarked crew, and keep contact with Earth. Chemical jet-engines used for the space ships must throw masses with enough speed to insure a convenient lifting force. Ion jet-engines, which have a much bigger jet-speed than chemical, may work for a longer time but the resulting force is small and cannot insure the take off and/or landing on a planet. A future inertial motor does not need to throw masses but needs only energy to produce the necessary lifting force. The paper presents contributions to build such a motor. As on a given vehicle, mainly rotations may be done to insure its propulsion, we start by presenting generally the rotations, at first for the electronic devices and then for mechanical one Methods that may convert the rotation into translation are after presented. Observing that the mathematical models used for rotations are extended from trigonometric functions to elliptical and ultra-elliptical ones, the author presents the differential equations that define such functions. Finally, using the modified Euler equations, a mathematical model for the gravitational waves is deduced. By using this type of waves, a permanent contact between an interplanetary ship and the earth can be kept. The presented tools may be used for modeling the fields and insure also a more comprehensive understanding.
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Tindell, R. H. « Computational Fluid Dynamic Applications for Jet Propulsion System Integration ». Journal of Engineering for Gas Turbines and Power 113, no 1 (1 janvier 1991) : 40–50. http://dx.doi.org/10.1115/1.2906529.
Texte intégralRésumé :
The impact of computational fluid dynamics (CFD) methods on the development of advanced aerospace vehicles is growing stronger year by year. Design engineers are now becoming familiar with CFD tools and are developing productive methods and techniques for their applications. This paper presents and discusses applications of CFD methods used at Grumman to design and predict the performance of propulsion system elements such as inlets and nozzles. The paper demonstrates techniques for applying various CFD codes and shows several interesting and unique results. A novel application of a supersonic Euler analysis of an inlet approach flow field, to clarify a wind tunnel-to-flight data conflict, is presented. In another example, calculations and measurements of low-speed inlet performance at angle of attack are compared. This is highlighted by employing a simplistic and low-cost computational model. More complex inlet flow phenomena at high angles of attack, calculated using an approach that combines a panel method with a Navier-Stokes (N-S) code, is also reviewed. The inlet fluid mechanics picture is rounded out by describing an N-S calculation and a comparison with test data of an offset diffuser having massively separated flow on one wall. Finally, the propulsion integration picture is completed by a discussion of the results of nozzle-afterbody calculations, using both a complete aircraft simulation in a N-S code, and a more economical calculation using an equivalent body of revolution technique.
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Bartlett, C. S. « Turbine Engine Icing Spray Bar Design Issues ». Journal of Engineering for Gas Turbines and Power 117, no 3 (1 juillet 1995) : 406–12. http://dx.doi.org/10.1115/1.2814110.
Texte intégralRésumé :
Techniques have been developed at the Engine Test Facility (ETF) of the Arnold Engineering Development Center (AEDC) to simulate flight through atmospheric icing conditions of supercooled liquid water droplets. Ice formed on aircraft and propulsion system surfaces during flight through icing conditions can, even in small amounts, be extremely hazardous. The effects of ice are dependent on many variables and are still unpredictable. Often, experiments are conducted to determine the characteristics of the aircraft and its propulsion system in an icing environment. Facilities at the ETF provide the capability to conduct icing testing in either the direct-connect (connected pipe) or the free-jet mode. The requirements of a spray system for turbine engine icing testing are described, as are the techniques used at the AEDC ETF to simulate flight in icing conditions. Some of the key issues facing the designer of a spray system for use in an altitude facility are identified and discussed, and validation testing of the design of a new spray system for the AEDC ETF is detailed. This spray system enables testing of the newest generation of high-thrust turbofan engines in simulated icing conditions.
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Volotsuev, V. V., et V. V. Salmin. « An Analysis of the Efficiency of Electric Propulsion Engines for Maintaining a Low Orbit of Small Spacecraft ». Proceedings of Higher Educational Institutions. Маchine Building, no 10 (727) (novembre 2020) : 65–74. http://dx.doi.org/10.18698/0536-1044-2020-10-65-74.
Texte intégralRésumé :
This paper examines the problem of maintaining the plane parameters of the working orbit of a small spacecraft using an electric propulsion engine. In low working orbits, due to the Earth’s atmosphere, a spacecraft is subjected to aerodynamic drag forces, which results in a decrease in the radius of the orbit and a potential termination of the useful target functioning. The time parameters of the cyclogram for maintaining the working orbit of a small spacecraft with an electric low thrust engine are analyzed taking into account the variability of the atmospheric density. The cyclogram consists of sections of the passive and active movement under the action of the low thrust engine. For the satellite under study, suitable thrust parameters of the electric engine are selected, which allow the correction of the plane parameters of the low orbit. Using the characteristics of the thrust and specific impulse of the electric jet engine, fuel reserves for correction over a long period of time are calculated. The results of the analysis confirm the effectiveness of the electric propulsion engine in terms of fuel consumption for correction.
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Kovtun, V. S. « The methodology of variable management of propellant fuel consumption by jet-propulsion engines of a spacecraft ». Thermal Engineering 59, no 13 (décembre 2012) : 960–69. http://dx.doi.org/10.1134/s0040601512130046.
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Karczewski, Mirosław, Leszek Szczęch et Filip Polak. « Energy Balance of a Vehicle Equipped with Hybrid Propulsion System Fuelled with Alternative Fuels ». Journal of KONES 26, no 4 (1 décembre 2019) : 91–96. http://dx.doi.org/10.2478/kones-2019-0094.
Texte intégralRésumé :
AbstractArticle presents the energetic balance of small-unmanned vehicle hybrid power transmission. The vehicle equipped with serial hybrid transmission consisted of electric engines connected to the battery pack and small Diesel power generator. In mentioned construction, battery is used as energy buffer and combustion engine is used more as emergency power supply, and is turned on when battery is depleted. In other condition, power generator can be turned off, without reducing power of transmission parameters, except its range. Vehicles with hybrid drive are very common chosen vehicles by users. More and more often, we also talk about searching for replacement fuels for internal combustion engines, so also for those with hybrid drive. The research was carried out on an unmanned land platform equipped with a hybrid propulsion system supplied as standard with Diesel oil. The article presents the problems of comparing the efficiency of a hybrid vehicle fuelled with Diesel oil, but also with alternative fuels based on kerosene and other components. For test, three types of fuels were used, standard Diesel oil, F-34 and with experimental mixture of Jet A-1 fuel with 10% of 2-ethylhexanol. Energy used for charging of the battery, from tank-to-wheel, was calculated. This also enables to calculate total efficiency of such hybrid power transmission, powered with different fuels.
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Langston, Lee S. « Old and New ». Mechanical Engineering 141, no 06 (1 juin 2019) : 38–43. http://dx.doi.org/10.1115/1.2019-jun2.
Texte intégralRésumé :
As prime movers go, gas turbines are virtually brand new, compared to, say, wind and water turbines which have been around for millennia. But they have also reached a considerable level of maturity. Gas turbines now dominate both the world’s aircraft propulsion and a good portion of electric power generation. The fortunes of the industry are not uniform, however. The commercial jet engine market is robust and growing; the military jet engine, electric power, and other markets have been relatively flat or declining. But those are the sectors where the possibilities lie. They aren’t new, but they have the potential for renewal. This study delves deeper into the current status and trends in theworldwide gas turbine market.
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Alves, Pedro, Miguel Silvestre et Pedro Gamboa. « Aircraft Propellers—Is There a Future ? » Energies 13, no 16 (11 août 2020) : 4157. http://dx.doi.org/10.3390/en13164157.
Texte intégralRésumé :
The race for speed ruled the early Jet Age on aviation. Aircraft manufacturers chased faster and faster planes in a fight for pride and capability. In the early 1970s, dreams were that the future would be supersonic, but fuel economy and unacceptable noise levels made that era never happen. After the 1973 oil crisis, the paradigm changed. The average cruise speed on newly developed aircraft started to decrease in exchange for improvements in many other performance parameters. At the same pace, the airliner’s power-plants are evolving to look more like a ducted turboprop, and less like a pure jet engine as the pursuit for the higher bypass ratios continues. However, since the birth of jet aircraft, the propeller-driven plane has lost its dominant place, associated with the idea that going back to propeller-driven airplanes, and what it represents in terms of modernity and security, has started a propeller avoidance phenomenon with travelers and thus with airlines. Today, even with the modest research effort since the 1980s, advanced propellers are getting efficiencies closer to jet-powered engines at their contemporary typical cruise speeds. This paper gives a brief overview of the performance trends in aviation since the last century. Comparison examples between aircraft designed on different paradigms are presented. The use of propellers as a reborn propulsive device is discussed.
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Gany, Alon, et Aviad Gofer. « Study of a Novel Air-augmented Waterjet Boost Concept ». Journal of Ship Production and Design 30, no 01 (1 février 2014) : 1–6. http://dx.doi.org/10.5957/jspd.2014.30.1.1.
Texte intégralRésumé :
This research presents analysis, experiment, and prediction of the performance of a unique marine propulsion concept, the air-augmented waterjet, having a revolutionary potential for significant thrust augmentation and boost capability of waterjet systems. So far, this concept has not been realized in any operational vessel. The air-augmented waterjet propulsion concept is similar to an after-burner in the aeronautical turbojet engine. The thrust augmentation results from the injection of air bubbles into the water flow, converting their expansion work òpdV into additional kinetic energy of the exhaust jet without affecting the pump operation. It can enable substantially augmenting boost capability, overcoming hump resistance, and increasing maximum attainable vessel speed while avoiding cavitation problems. Static tests at the Technion's water tank, using a jetski waterjet engine of a nominal power of 50 kW, have been conducted with and without air injection over a range of motor revolutions per minute (rpm). The addition of air increased the thrust by 20% to 50% depending on the airflow rate and engine rpm. Air expansion work increased the exhaust jet kinetic energy at an efficiency of 70% approximately. Based on the static experiments, prediction of the system behavior for different vessel speeds and engine power levels has been made, revealing a higher relative thrust augmentation for the same pump power and airflow rate at higher vessel speeds. The air-augmented waterjet concept may add a new dimension to marine propulsion as well as upgrade existing vessels.
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Hönen, Herwart, et Matthias Panten. « Recontouring of Jet Engine Compressor Blades by Flow Simulation ». International Journal of Rotating Machinery 7, no 5 (2001) : 365–74. http://dx.doi.org/10.1155/s1023621x01000306.
Texte intégralRésumé :
In modern jet propulsion systems the core engine has an essential influence on the total engine performance. Especially the high pressure compressor plays an important role in this scheme. Substantial factors here are losses due to tip clearance effects and aerodynamic airfoil quality. During flight operation the airfoils are subject to wear and tear on the leading edge. These effects cause a shortening of the chord length and the leading edge profiles become deformed. This results in a deterioration of the engine efficiency performance level and a reduced stall margin.The paper deals with the re-contouring of the leading edges of compressor airfoils by application of a new developed method for the profile definition. The common procedure of smoothing out the leading edges manually on a wheel grinding machine can not provide a defined contour nor a reproducible result of the overhaul process. In order to achieve optimized flow conditions in the compressor blade rows, suitable leading edge contours have to be defined for the worn airfoils. In an iterative process the flow behavior of these redesigned profiles is checked by numerical flow simulations and the shape of the profiles is improved. The following machining of the new defined leading edge contours is achieved on a grinding station handled by an appropriately programmed robot.
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Zhang, Sheng Min, Chun Bo Hu, Sheng Yong Xia, Lin Li et Xiang Geng Wei. « Ignition and Combustion of Magnesium Particles in Carbon Dioxide ». Applied Mechanics and Materials 152-154 (janvier 2012) : 220–25. http://dx.doi.org/10.4028/www.scientific.net/amm.152-154.220.
Texte intégralRésumé :
Metal-CO2 propulsion is less known than in-situ resource utilization (ISRU) technologies. This concept, based on using Martian carbon dioxide as an oxidizer in jet or rocket engines, offers the advantage of no chemical processing for CO2 and thus requires less power consumption than ISRU alternatives. In this paper, we study the burning behavior of the Mg in a CO2 atmosphere to assess the feasibility of using Mg/CO2 reactions as an in situ resource utilization technology for rocket propulsion and energy generation on other planets. From the experimental results, we can see that the critical ignition temperature increases with increasing the particle size and decreases with increasing the ambient pressure. In the CO2 atmosphere, we found the complicated sequence of interaction modes including pulsating combustion in a wide range of ambient temperatures. The pulsation frequency is determined by the sample temperature at the phases of slow heterogeneous combustion between the flashes. The combustion mechanisms are discussed with consideration of processes in both a surface film and gas phase.
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Petrov, Nikolay, et Tamara Antonova. « Increasing the specific impulse of the ion engine by zone engineering of the solid-state field cathode ». Proceedings of the Russian higher school Academy of sciences, no 4 (20 janvier 2021) : 41–50. http://dx.doi.org/10.17212/1727-2769-2020-4-41-50.
Texte intégralRésumé :
With the rapid development of space technology, the scale of human space exploration is expanding significantly. However, the growing demand for deep space travel cannot be met with conventional chemical engines. Thus, the need for new mechanisms for providing jet thrust, including electric motors, becomes clear. Electric propulsion technology has significant advantages over traditional chemical engines in deep space flight due to its characteristics such as high specific impulse, small size, long service life. A negative feature of electric motors can be called low thrust, however, firstly, in open space this is insignificant and, secondly, the thrust of electric motors can be significantly increased, and for this, there are reserves available at the current level of technology development. Ways to increase the thrust of electric ion thrusters will be detailed and discussed in this work. The increase in the power of ion engines is limited to a large extent by the erosion of the control grids; the ion flow hits the surface of the solid material of the control grid electrode with energetic ions and gradually leads to the failure of this electrode. In this work, the authors will show that the use of field emission as a source of electron beams ionizing the working medium can solve the problem of erosion of control electrodes, due to which it will be possible to significantly increase the strength of the working fields for ion engines, which in turn will increase the specific impulse, efficiency, flow rate and power of the ion engine as a whole.
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Cooper, Maxim, Ashish Alex Sam et Apostolos Pesyridis. « Modelling of a Dual-Fuel-Mode Free-Jet Combustion System ». Aerospace 6, no 12 (17 décembre 2019) : 135. http://dx.doi.org/10.3390/aerospace6120135.
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The focus of this study is to design a combustion system able to sustain hypersonic flight at Mach 8. A Dual-Mode Free-Jet combustion chamber design, first tested in 2010 by NASA, is being adapted to run on hydrogen fuel instead of ethylene while addressing the excessive thermal heat load. This study is part of the FAME (Flight at Mach Eight) project, with the primary objective to design and analyse the engine configuration for a hypersonic commercial aircraft. This CFD analysis and validation study, the first to replicate this combustion chamber design, provides detailed instructions on the combustion system design. The analysis from this study can be used for future research to successfully reach a sustainable design and operation of a Dual-Mode Free-Jet combustion chamber. The 53% size reduction in the combustion system represents significant progress which encourages future research regarding in the design of combustion systems for hypersonic propulsion systems.
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Lin, Binbin, Hongliang Pan, Lei Shi et Jinying Ye. « Effect of Primary Rocket Jet on Thermodynamic Cycle of RBCC in Ejector Mode ». International Journal of Turbo & ; Jet-Engines 37, no 1 (26 mars 2020) : 61–70. http://dx.doi.org/10.1515/tjj-2017-0013.
Texte intégralRésumé :
AbstractThrust augmentation in ejector mode is important to improve engine performance so as to enable more propulsion applications of RBCC. Usually, the internal flow-path is configured mainly for combustion organization in ramjet and scramjet modes, thus the RBCC performance in ejector mode will mainly depend on the primary rocket operating parameters and jet expansion state. Considering such restrictions and requirements on the primary rocket, this paper studies the effects of the primary rocket jet on the thermodynamic cycle performance of ejector mode, in which incoming air is dominated by ejector-suction by the primary rocket jet at low flight Mach numbers. It is found that the engine performance in ejector mode will be improved by increasing the primary rocket chamber pressure and nozzle expansion ratio. Furthermore, for better design of primary rocket, primary rocket chamber pressure should be maximized on the basis of ensuring a complete expansion of primary rocket to the ambient pressure at the design point of flight conditions after 3-D CFD simulations for a full flow-path of RBCC including fore-airframe and aft-airframe of a flight vehicle. The results of 3-D numerical simulations show that the bypass ratio and specific impulse increase by 35.5 % and 12.5 % respectively at sea-level static condition.
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Kozakiewicz, Adam, Stanisław Jóźwiak, Przemysław Jóźwiak et Stanisław Kachel. « Material Origins of the Accelerated Operational Wear of RD-33 Engine Blades ». Materials 14, no 2 (11 janvier 2021) : 336. http://dx.doi.org/10.3390/ma14020336.
Texte intégralRésumé :
The structural and strength analysis of the materials used to construct an important engine element such as the turbine is of great significance, at both the design stage and during tests and training relating to emergency situations. This paper presents the results of a study on the chemical composition, morphology, and phased structure of the metallic construction material used to produce the blades of the high- and low-pressure turbines of the RD-33 jet engine, which is the propulsion unit of the MiG-29 aircraft. On the basis of an analysis of the chemical composition and phased structure, the data obtained from tests of the blade material allowed the grade of the alloy used to construct the tested elements of the jet engine turbine to be determined. The structural stability of the material was found to be lower in comparison with the engine operating conditions, which was shown by a clear decrease in the resistance properties of the blade material. The results obtained may be used as a basis for analyzing the life span of an object or a selection of material replacements, which may enable the production of the analyzed engine element.
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Kozakiewicz, Adam, Stanisław Jóźwiak, Przemysław Jóźwiak et Stanisław Kachel. « Material Origins of the Accelerated Operational Wear of RD-33 Engine Blades ». Materials 14, no 2 (11 janvier 2021) : 336. http://dx.doi.org/10.3390/ma14020336.
Texte intégralRésumé :
The structural and strength analysis of the materials used to construct an important engine element such as the turbine is of great significance, at both the design stage and during tests and training relating to emergency situations. This paper presents the results of a study on the chemical composition, morphology, and phased structure of the metallic construction material used to produce the blades of the high- and low-pressure turbines of the RD-33 jet engine, which is the propulsion unit of the MiG-29 aircraft. On the basis of an analysis of the chemical composition and phased structure, the data obtained from tests of the blade material allowed the grade of the alloy used to construct the tested elements of the jet engine turbine to be determined. The structural stability of the material was found to be lower in comparison with the engine operating conditions, which was shown by a clear decrease in the resistance properties of the blade material. The results obtained may be used as a basis for analyzing the life span of an object or a selection of material replacements, which may enable the production of the analyzed engine element.
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Ji, Zhixing, Jiang Qin, Kunlin Cheng, Fafu Guo, Silong Zhang et Peng Dong. « Comparative performance analysis of solid oxide fuel cell turbine-less jet engines for electric propulsion airplanes : Application of alternative fuel ». Aerospace Science and Technology 93 (octobre 2019) : 105286. http://dx.doi.org/10.1016/j.ast.2019.07.019.
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Jáquez-Muñoz, Jesús Manuel, Citlalli Gaona-Tiburcio, Jose Cabral-Miramontes, Demetrio Nieves-Mendoza, Erick Maldonado-Bandala, Javier Olguín-Coca, Francisco Estupinán-López, Luis Daimir López-León, José Chacón-Nava et Facundo Almeraya-Calderón. « Frequency Analysis of Transients in Electrochemical Noise of Superalloys Waspaloy and Ultimet ». Metals 11, no 5 (25 avril 2021) : 702. http://dx.doi.org/10.3390/met11050702.
Texte intégralRésumé :
Nickel or Cobalt-based superalloys represent an important class of engineering materials, finding widespread application in critical components within the gas turbine engines used for jet propulsion and electricity generation. This research aimed at the frequency analysis of transients in electrochemical noise of Waspaloy and Ultimet superalloys, immersed in 3.5 wt.% in H2SO4 and NaCl solutions at two different temperatures, 25 and 60 °C. Localized corrosion behavior of superalloys was assessed using the electrochemical noise technique (EN) according to ASTM-G199 standard. Three different statistical methods filtered the EN signal, and the polynomial method was employed to obtain the noise resistance (Rn), the localization index (LI), skew and kurtosis, and the power spectral density analysis (PSD). Results indicate that the current and potential noise transients have a better behavior with better clarity when a polynomial is used to show a localized corrosion kurtosis for both superalloys.
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ZAGOVORCHEV, Vladimir A., et Olga V. TUSHAVINA. « The use of jet penetrators for movement in the lunar soil ». INCAS BULLETIN 11, S (1 août 2019) : 221–30. http://dx.doi.org/10.13111/2066-8201.2019.11.s.22.
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The possibility of using penetrators for researching the subsurface layers of the moon is considered. Possible options for launching such penetrators are indicated, from the way the launch is carried out depends on the depth of penetration into the regolith. It was found that when the propulsion system has less traction than the static resistance of the lunar soil, movement does not occur if the launch of the penetrator is accomplished from the surface with zero entry speed. The dependences are given that permit calculating with sufficient accuracy the penetrator mass, penetration depth and the resulting overloads. The depth of penetration of the inertial penetrator depends on its mass-dimensional qualities and the speed of entry into the soil, which is limited by the level of permissible overloads. The use of a solid fuel engine on the penetrator facilitates increasing the allowable speed of the penetrator into the ground by reducing the overloads acting on it, and thereby increasing the penetration depth.
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Baldin, A. A. « Ecological aspect of launch vehicles development by criterion of minimal cost ». Ecology and Noospherology 25, no 3-4 (29 mai 2014) : 114–19. http://dx.doi.org/10.15421/031427.
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One of the topical problems in modern aerospace engineering is accordance between ecological requirements and performance of the vehicle. On the other hand, problem of economical efficiency leads to change of the main criterion of designing to the minimization of costs (instead of maximal performance). According to modern trends of “low-cost” vehicles, different concepts of the future cost-effective launch vehicles are considered. It is necessary to validate these concepts according to requirements of ecological safety for the purpose of detection of the dominant launch vehicle configuration. Typical configurations of the future 'low-cost' launch vehicle are presented by 6 conceptual groups (Koelle, 2001). Conceptual group 1 (CG1) is presented by the Ballistic “Single stage to orbit” (SSTO) reusable vehicle. All vehicles which use classical rocketry scheme of the propulsion trajectory are called “Ballistic” i.e. the ballistic vehicle is lifted to orbit under the impact of rocket engines thrust. CG1-vehicle is able to reach the low earth orbit (LEO) without stage separation reducing the number of required rocket engines. Technological feasibility of SSTO concepts is proven by numerous studies (Koelle, 2001). CG2 representatives are ballistic “Two stages to orbit” (TSTO) reusable vehicles. The difference between CG1 and CG2 consists in application of vacuum rocket engines in the second stage and, consequently, stage separation. CG2 are the most mass-effective vehicles. CG3 is presented by the winged SSTO vehicles with rocket propulsion by “Lifting body” aerodynamic scheme. Ascensional force is provided by the aerodynamic shape of the vehicle’s structure at high speeds. Winged TSTO vehicles with rocket propulsion and parallel or tandem staging form the CG4. The winged configuration provides wide landing capability for both stages. CG5 is presented by winged TSTO vehicles with airbreathing propulsion in the first stage and rocket-propelled second stage. Airbreathing jet engines provide high reusability ratio comparing with other concepts as well as the widest landing capability. Aerospace Plane with scramjet-rocket propulsion forms CG6. The vehicle is able to reach near-cosmic speed in rarefied layers of the atmosphere and then accelerate with rocket engines. The most ecologically important resemblance of represented concepts is reusability. This reduces space debris formation (due to lack of waste hardware). Reusable launch vehicles can also be used to return the spent satellites. Structural differences between the concepts form 3 criterions of comparison by ecological impact: 1) propellant toxicity; 2) safety of surface facilities (vehicle damage inside the atmosphere); 3) probability of space debris formation (vehicle damage outside the atmosphere). Comparison of the concepts by these criterions allows substantiating the most ecologically acceptable direction of research. Results of the comparison demonstrate that the most ecologically acceptable low-cost launch vehicle configuration is: Ballistic SSTO or TSTO reusable launch vehicle with “LOX+LH2” propellant. The results can be explained by following way: combustion products of the propellant “liquid oxygen + liquid hydrogen” are absolutely safe for environment. It also provides maximal performance of rocket engine (due to the highest specific impulse). Ballistic ascent scheme allows using relatively simple technologies and provides high reliability level. In combination with minimal time of atmospheric flight this provides high level of safety for surface facilities. These results may be used for substantiation of dominant research direction.
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Harjes, Lennart, Christoph Bode, Jonas Grubert, Philip Frantzheld, Patrick Koch et Jens Friedrichs. « INVESTIGATION OF JET ENGINE INTAKE DISTORTIONS CAUSED BY CROSSWIND CONDITIONS ». Journal of the Global Power and Propulsion Society 4 (14 mai 2020) : 48–62. http://dx.doi.org/10.33737/jgpps/118875.
Texte intégralRésumé :
The Propulsion Test Facility of the TU Braunschweig is capable of investigating future jet engine intakes and fan aerodynamics to a high level of detail. A goal of this facility is the examination of coupled fan-intake-interactions which is not possible in any existing test bench around the world. Before doing research on these interactions, it is important to undergo proper studies of isolated aspirated intakes and fans under varying operating conditions (design and off-design). Therefore comparable result of the well-known LARA nacelle to existing experimental and numerical data has been generated for a first validation purpose. Therefore, comparable studies have been conducted with the LARA nacelle, to that of experimental and numerical investigations performed in the early 1990s at the ONERA F1 wind tunnel (mention reference), in order to generate results for validation. The first results of the validation experiment show differences in peak Mach number between the ONERA F1 and PTF experimental data for identical boundary conditions based on Mach number and crosswind. To investigate this further, a comprehensive numerical study has been carried out. It was inferred that the discrepancy was mainly caused by the Reynolds number effect within the PTF environment and its sensitivity to the inlet flow angle distribution with regard to angle of attack for crosswind. Within the validation test campaign, the experimental investigations showed a separation and reattachment hysteresis, which was identified when crosswind as well as nacelle mass flow had been increased or decreased to set up the different operating points. This phenomenon has still no established theoretical basis for understanding the aerodynamic behaviour. Overall, the applicability of conventional RANS models is shown. Additionally, the sensitivity to the aforementioned boundary conditions and the numerical reproducibility of the hysteresis phenomenon are discussed and compared to new experimental data in detail.