Journal articles on the topic 'High power lasers engines'
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Cheng, Dennis, Dixon Fung, and Karl Guttag. "Digital High Resolution Small Pixel LCOS Technology." Solid State Phenomena 181-182 (November 2011): 233–36. http://dx.doi.org/10.4028/www.scientific.net/ssp.181-182.233.
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The progress in digital high resolution, small pixel liquid crystal on silicon (LCOS) microdisplays will be discussed and how it will lead to HD displays in very small form factors. The first generation of this technology is enabling very small yet high resolution projection engines devices that can be embedded in cell phones, cameras, head-mount displays, and set-top boxes and the next generation will bring HD resolution. As lasers become more affordable we see this LCOS display technology fundamentally changing the power consumption, cost, and size of pico-projectors and other display devices. One of the most interesting conclusions is that by using LCOS technology in combination with lasers, it should soon be possible to build an “ultra-green” television that would consume less than 1/8th the power of equivalent size LCD flat panel TV.
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HENTSCHEL, Werner. "New methods in optical diagnostics on production engines with only minor modifications." Combustion Engines 137, no. 2 (May 1, 2009): 50–61. http://dx.doi.org/10.19206/ce-117193.
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The aim of this paper is to demonstrate the performance of micro-invasive optical diagnostics as advanced tools in the development process of modern direct-injection (DI) gasoline engines. The use of endoscopes and optical probes minimise the mechanical modifications on the engine necessary to achieve the optical access to the combustion chamber. No expensive optical engines with large optical windows are required but only small holes of about 10 mm in the cylinder head or in a plate between cylinder head and cylinder liner are used to apply laser diagnostics. Basic in-cylinder phenomena, such as the formation of the flow field, the penetration of the spray at high fuel pressure, the interaction of spray and flow, the formation of an ignitable mixture and the start of combustion are analysed in detail. High-power solid-state pulsed lasers emitting ultraviolet or green light, state-of the-art high-speed colour video cameras, and newly designed optical probes were used for the investigations. Selected results from current research and development work demonstrate the capability of micro-invasive techniques and pinpoint how the design of the combustion process benefits from these experimental investigations.
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Афанасьєва, Ольга Валентинівна, Наталія Олексіївна Лалазарова, and Олена Георгіївна Попова. "Нові технології лазерної поверхневої обробки." Aerospace technic and technology, no. 2 (April 28, 2021): 59–65. http://dx.doi.org/10.32620/aktt.2021.2.07.
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Subject and purpose. Currently, gas, solid-state, and fiber lasers are used to process materials in the aviation industry. For the thermal treatment of steels, gas CO2 lasers with a capacity of more than 1 kW used, which are reliable in operation but have high cost and low efficiency. There are no results on the use of low-power (up to 20 W) pulsed-mode lasers for surface hardening of steel products. The purpose of this work is to determine the modes of surface hardening of products from carbon and alloy steels using low-power solid-state pulsed YAG lasers. Methodology. For laser hardening, a 5 W solid-state YAG laser was used (diode pumping, radiation wavelength λ = 1,064 μm, pulse mode). The use of a nonlinear crystal made it possible to obtain UV radiation with λ = 0,355 μm (third harmonic). The following modes were investigated: processing with single pulses (duration 0,1...0,4 ms) and multi-pulse processing with short (30...70 ms) pulses. The scanning speed was 8...2 mm/s. The energy in the pulse was determined by the photoelectric method. Thermal hardening was performed on the following steels: У12, P6M5. The possibility of UV radiation hardening was evaluated on steel 20, 45, У12, and ШХ15. Findings. The optimum values of pulse duration for maximum hardness in laser hardening of the investigated steels. With multi-pulse treatment of steels, the pulse duration is shorter than with single-pulse treatment, the hardening intensity is higher, and the quality of the processed surface is better. Single-pulse and multi-pulse processing are accompanied by partial melting of the surface of steel products, which does not allow it to be used in cases where a high quality of the surface is required. Laser hardening of steel by ultraviolet radiation is not accompanied by melting. Conclusion. For surface hardening of products, where partial melting of the surface is possible, low-power lasers in pulse mode can be used. Laser hardening by ultraviolet radiation is a promising direction for thermal hardening of steels, which allows maintaining the original quality of the surface layer. Thermal hardening with low-power lasers can be effective for small-sized areas of the processed parts of the fuel equipment of aircraft engines, friction elements, and, especially, the tool is small.
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Cattoni, Francesca, Lucrezia Ferrante, Sara Mandile, Giulia Tetè, Elisabetta Maria Polizzi, and Giorgio Gastaldi. "Comparison of Lasers and Desensitizing Agents in Dentinal Hypersensitivity Therapy." Dentistry Journal 11, no. 3 (February 27, 2023): 63. http://dx.doi.org/10.3390/dj11030063.
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The main objective of this review is to verify the validity of laser therapy in the treatment of dentin hypersensitivity, an extremely common problem in patients, with Nd: YAG lasers or high- and/or low-power diode lasers to obtain a definitive protocol for the treatment of hypersensitivity, given the multiplicity of laser treatments proposed by the numerous authors evaluated. The authors performed an electronic search on PubMed, favouring it as a search engine. Lasers represent a means of treating dentin hypersensitivity, used alone and/or in conjunction with specific products for the treatment of such a pathology. The selected articles that examined diode lasers were divided according to the wattage (w) used: low-level laser therapy protocols, i.e., those using a wattage of less than 1 W, and high-level laser therapy protocols, i.e., those using a wattage of 1 W or more. Regarding the Nd: YAG laser, it was not necessary to subdivide the studies in this way, as they used a wattage of 1 W or more. A total of 21 articles were included in the final selection. Laser therapy was found to be effective in the treatment of dentin hypersensitivity. However, the level of effectiveness depends on the laser used. The results obtained from this review show that both the Nd: YAG laser and the diode laser (high and low power) are effective in the treatment of dentin hypersensitivity. However, the high-power laser appears to be more effective in combination with fluoride varnish and the Nd: YAG laser achieved greater long-term benefits than the diode laser.
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George Done, Bogdan, and Ion Copae. "Performances of a Research CFR Octane Rating Unit Engine and Dacia Single Cylinder SI Engine Ignited by a LASER System." E3S Web of Conferences 112 (2019): 01009. http://dx.doi.org/10.1051/e3sconf/201911201009.
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At this time, the severe legislation regarding the level limits of the waste and exhaust gases released by thermal engines and also the necessity of engines efficiency improvement boost the engine research domain to bring in front the use of new technologies that can be used to control the in-cylinder combustion process. Now, the new technologies is represented by LASER spark plug systems which can be successfully used at petrol engines. LASER spark plug technology can have many advantages for engine operation control, an ignition system that could provide improved combustion is the one using plasma generation and a Q-switched LASER that results in pulses with high MW power. The LASER spark plug device used in the current research was a LASER medium Nd:YAG/Cr4+:YAG ceramic structure made up of a 8.0-mm long, 1.0-at.% Nd:YAG ceramic, optically-bonded to a Cr4+:YAG c. It was developed and constructed similar to classical spark plug and could be assembled on a CFR Octane Rating Unit Engine as well as on a Dacia Single Cylinder SI Engine which led to several results among which: influences on in-cylinder pressure, combustion and pollutant emissions.
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Barbato, Alessio, and Giuseppe Cantore. "3D CFD simulation of a gaseous fuel injection in a hydrogen-fueled internal combustion engine." E3S Web of Conferences 312 (2021): 07001. http://dx.doi.org/10.1051/e3sconf/202131207001.
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Nowadays, one of the hottest topic in the automotive engineering community is the reduction of fossil fuels. Hydrogen is an alternative energy source that is already providing clean, renewable, and efficient power being used in fuel cells. Despite being developed since a few decades, fuel cells are affected by several hurdles, the most impacting one being their cost per unit power. While waiting for their cost reduction and mass-market penetration, hydrogen-fueled internal combustion engines (H2ICEs) can be a rapidly applicable solution to reduce pollution caused by the combustion of fossil fuels. Such engines benefit from the advanced technology of modern internal combustion engines (ICEs) and the advantages related to hydrogen combustion, although some modifications are needed for conventional liquid-fueled engines to run on hydrogen. The gaseous injection of hydrogen directly into the combustion chamber is a challenge both for the designers and for the injection system suppliers. To reduce uncertainties, time, and development cost, computational fluid dynamics (CFD) tools appear extremely useful, since they can accurately predict mixture formation and combustion before the expensive production/testing phase. The high-pressure gaseous injection which takes place in Direct-Injected H2ICEs promotes a super-sonic flow with very high gradients in the zone between the bulk of the injected hydrogen and the flow already inside the combustion chamber. To develop a methodology for an accurate simulation of these phenomena, the SoPHy Engine of the Engine Combustion Network group (ECN) is used and presented. This engine is fed through a single nozzle H2-injector; planar laser-induced fluorescence (PLIF) data are available for comparison with the CFD outcomes.
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SHAPIRO, D. "ION LASER THEORY." International Journal of Modern Physics B 10, no. 18n19 (August 30, 1996): 2405–22. http://dx.doi.org/10.1142/s0217979296001070.
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Ion lasers, especially argon, are the most powerful sources of visible and near UV continuous coherent radiation. The active medium of lasers is low-temperature plasma. They are familiar to scientists and engineers from the 70’s. However, a series of physical effects remained unclear and there was a barrier to enhancing the power and improving the quality of the output radiation. The theory of ion lasers is developed at the interface between plasma physics and quantum optics. This paper covers the solution of some of these physical problems, particularly, the high-current regime of gas discharge and the quantum kinetics of ionic collisions. The high-current multi-component discharge is important for intense generation in the ultraviolet spectrum. The ionic scattering leads to the Lamb dip broadening in the single-frequency laser and increases its output.
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Pielecha, Ireneusz, Zbigniew Stępień, Filip Szwajca, and Grzegorz Kinal. "Effectiveness of Butanol and Deposit Control Additive in Fuel to Reduce Deposits of Gasoline Direct Injection Engine Injectors." Energies 16, no. 1 (December 21, 2022): 77. http://dx.doi.org/10.3390/en16010077.
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Modern internal combustion engines are designed to meet new emission standards and reduce fuel consumption. The wide application of direct fuel injection is associated with the problem of injector contamination. It leads to a deterioration of the engine’s environmental performance. The paper aims to evaluate the effect of applying gasoline–butanol blends and appropriate additives on the formation of injector deposits. The research involved testing the engine on a dynamometer, evaluating the injector tips visually at 1000× magnification, and registering the fuel spray using high-speed imaging techniques with a laser and halogen lighting source. The effect of engine operating with the reference fuel was to coke the injector tip with a linear pattern. It increased the linear injection time to keep the engine’s operating point constant over the 48 h test. The application of 20% (v/v) butanol reduced deposit formation. The best scavenging results were obtained by extending the engine operating time by the next 24 h and using a cleaning procedure. The procedure included a cleaning additive in addition to butanol. Among the cases analyzed, a combination of butanol and DCA (Deposit Control Additive) was the best method for injector patency restoration.
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Allocca, L., L. Andreassi, and S. Ubertini. "Enhanced Splash Models for High Pressure Diesel Spray." Journal of Engineering for Gas Turbines and Power 129, no. 2 (September 4, 2006): 609–21. http://dx.doi.org/10.1115/1.2432891.
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Mixture preparation is a crucial aspect for the correct operation of modern direct injection (DI) Diesel engines as it greatly influences and alters the combustion process and, therefore, the exhaust emissions. The complete comprehension of the spray impingement phenomenon is a quite complete task and a mixed numerical-experimental approach has to be considered. On the modeling side, several studies can be found in the scientific literature but only in the last years complete multidimensional modeling has been developed and applied to engine simulations. Among the models available in literature, in this paper, the models by Bai and Gosman (Bai, C., and Gosman, A. D., 1995, SAE Technical Paper No. 950283) and by Lee et al. (Lee, S., and Ryou, H., 2000, Proceedings of the Eighth International Conference on Liquid Atomization and Spray Systems, Pasadena, CA, pp. 586–593; Lee, S., Ko, G. H., Ryas, H., and Hong, K. B., 2001, KSME Int. J., 15(7), pp. 951–961) have been selected and implemented in the KIVA-3V code. On the experimental side, the behavior of a Diesel impinging spray emerging from a common rail injection system (injection pressures of 80 and 120MPa) has been analyzed. The impinging spray has been lightened by a pulsed laser sheet generated from the second harmonic of a Nd-yttrium-aluminum-garnet laser. The images have been acquired by a charge coupled device camera at different times from the start of injection. Digital image processing software has enabled to extract the characteristic parameters of the impinging spray with respect to different operating conditions. The comparison of numerical and experimental data shows that both models should be modified in order to allow a proper simulation of the splash phenomena in modern Diesel engines. Then the numerical data in terms of radial growth, height and shape of the splash cloud, as predicted by modified versions of the models are compared to the experimental ones. Differences among the models are highlighted and discussed.
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Kopecek, Herbert, Soren Charareh, Maximilian Lackner, Christian Forsich, Franz Winter, Johann Klausner, Gu¨nther Herdin, Martin Weinrotter, and Ernst Wintner. "Laser Ignition of Methane-Air Mixtures at High Pressures and Diagnostics." Journal of Engineering for Gas Turbines and Power 127, no. 1 (January 1, 2005): 213–19. http://dx.doi.org/10.1115/1.1805550.
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Methane-air mixtures at high fill pressures up to 30 bar and high temperatures up to 200°C were ignited in a high-pressure chamber with automated fill control by a 5 ns pulsed Nd:YAG laser at 1064 nm wavelength. Both, the minimum input laser pulse energy for ignition and the transmitted fraction of energy through the generated plasma were measured as a function of the air/fuel-equivalence ratio (λ). The lean-side ignition limit of methane-air mixtures was found to be λ=2.2. However, only λ<2.1 seems to be practically usable. As a comparison, the limit for conventional spark plug ignition of commercial natural gas engines is λ=1.8. Only with excessive efforts λ=2.0 can be spark ignited. The transmitted pulse shape through the laser-generated plasma was determined temporally as well as its dependence on input laser energy and properties of the specific gases interacting. For a first demonstration of the practical applicability of laser ignition, one cylinder of a 1 MW natural gas engine was ignited by a similar 5 ns pulsed Nd:YAG laser at 1064 nm. The engine worked successfully at λ=1.8 for a first test period of 100 hr without any interruption due to window fouling and other disturbances. Lowest values for NOx emission were achieved at λ=2.05 NOx=0.22 g/KWh. Three parameters obtained from accompanying spectroscopic measurements, namely, water absorbance, flame emission, and the gas inhomogeneity index have proven to be powerful tools to judge laser-induced ignition of methane-air mixtures. The following effects were determined by the absorption spectroscopic technique: formation of water in the vicinity of the laser spark (semi-quantitative); characterization of ignition (ignition delay, incomplete ignition, failed ignition); homogeneity of the gas phase in the vicinity of the ignition; and the progress of combustion.
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Мисюров, Александр, Aleksandr Misyurov, Александр Богданов, Aleksandr Bogdanov, Алексей Соловьев, Aleksey Soloviyev, Игорь Ильичев, et al. "Additive laser techniques of metal powder fritting to manufacture products of aerospace industry." Science intensive technologies in mechanical engineering 1, no. 9 (August 23, 2016): 24–29. http://dx.doi.org/10.12737/21236.
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A domestic plant for additive techniques of different materials fritting is presented. The plant in its basis has a high-powered (up to 2.5 kW) waveguide CO2 – laser possessing a unique in the uniformity of emission power density distribution on a target. The results of nickel-based heat-resistant alloy fritting of TCNA-1VR, VZhL12U and VZh159 types developed for manufacturing complex contoured parts of gas turbine engines (GTE) by a method of layered laser alloying and for complex contoured parts GTE repair by a method of gas powder laser surfacing are shown. During laser remelting of these powders it is possible to grow a billet with a homogeneous fine-grain structure which manufacturing is impossible at common techniques of casting.
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S, Shivakumar, Veena B. G, and Kumarswamy R. "Performance Requirements on Laser Ignition System." International Journal for Research in Applied Science and Engineering Technology 11, no. 1 (January 31, 2023): 1607–12. http://dx.doi.org/10.22214/ijraset.2023.48582.
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Abstract: Combustion is one of the most prominent energy conversion processes used in all areas of human life, even though it is being used on a large scale in various fields it has vital drawbacks like emission of greenhouse gases from IC engines majorly affecting the environment on a global level. One of the reasons of this issue being improper or inefficient ignition of the air-fuel mixture. However, this can be reduced to an extent by employing methods like lean combustion and re-circulating the exhaust gases. This is when the need of an alternative ignition system is required, one such concept being LASER IGNITION SYSTEM for internal combustion engines. On comparison laser ignition system provides number of potential benefits over conventional ignition by electric spark plug. Use of laser ignition system comes with advantages like- Reduction of NOx emission by 20% also improved efficiencies are obtained. The thermodynamic requirements of high compression ratios and high power density are fulfilled well by this system. Therefore, laser ignitors could replace conventional spark plugs in automobile industry. This not only provides better performance and fuel economy, but would also create less harmful emissions
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Habeeb, Mais A., Mohammed J. Kadhim, Fadhil A. Hashim, and Maryam A. Bash. "Effect of Laser Treatment on the Surface Roughness of Multilayer Plasma Sprayed Thermal Barrier Coating System." Engineering and Technology Journal 39, no. 2A (February 25, 2021): 180–88. http://dx.doi.org/10.30684/etj.v39i2a.1570.
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Thermal barrier coatings (TBCs) are used in advanced engines working at higher temperatures. Higher efficiency and performance of gas turbine engines will require careful selection of TBCs. In this study, Ni22Cr10Al1.0Y (Amdry 9625) bond coat and two types of top coat including ceria stabilized zirconia (CSZ) ZrO2-24CeO2-2.5Y2O3) and yttria stabilized zirconia (YSZ) ZrO2-8Y2O3 were deposited on IN 625 by air plasma spraying (APS). The thickness of the duplex ceramic coat based on zirconia was in the range between 350 to 400 µm. The effect of high power Yb:YAG solid state laser at different laser parameters on feature, microstructure and roughness of plasma sprayed and laser sealed coating of multilayer ceria stabilized zirconia/ yttria stabilized zirconia was investigated. Surface roughness has been reduced significantly after laser sealing. The effect of laser process parameters carried out using Taguchi’s L16 orthogonal array design. Minimum roughness can be obtained at moderate power density and longer interaction time with sufficient specific energy to produce complete melting of coating. Characterization and analysis of results was achieved by employing scanning electron microscopy (SEM) , (EDS) and image J analysis. It was found from the results, there were significant improvements in the performance of plasma sprayed coatings after laser sealing due to the reduction of surface coating defects.
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Phipps, C. R., and M. M. Michaelis. "LISP: Laser impulse space propulsion." Laser and Particle Beams 12, no. 1 (March 1994): 23–54. http://dx.doi.org/10.1017/s0263034600007217.
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It is not often that a new form of transportation suddenly appears and replaces what was hitherto regarded as mankind's only realistic option. In space and upper atmosphere transportation, chemical rockets have held center stage for over half a century. Tsiokolvsky's ideas led to Wernher von Braun's V2, which in turn led to the Soyuz, Apollo, and Ariane programs and the Space Shuttle. But recently theoretical and computational studies as well as a few initial experiments have pointed to a new option: laser impulse space propulsion (LISP). This may offer a more efficient and less ecologically damaging means of putting payloads into orbit. The world high-power laser community is well suited to following and aiding developments in LISP, though most practical research is still at an embryonic level. Obviously an effort of the size required to develop a laser-driven low-earth-orbit (LEO) launcher would require a multinational commitment. LISP could then be regarded as a parallel challenge to those of achieving ICF rriicrofusion yield and of improving X-ray lasers, especially in the “water window.” Any physicist or engineer involved with the latter projects would find many points in common with the former. It therefore seems appropriate to briefly review the progress made in LISP and also to communicate some recent results from high-power laser-matter experiments that have lead to conceptual designs.
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Klimpel, Andrzej, Aleksander Olejnik, Aleksander Lisiecki, Damian Janicki, and Andrzej St Klimpel. "Repair welding with high-power diode lasers of damaged resistance-welded joints in a jet engine's cooling jacket." Welding International 27, no. 9 (September 2013): 672–77. http://dx.doi.org/10.1080/09507116.2012.708474.
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Tishkunov, Alexander, Sergejs Gluhihs, Aleksandrs Korjakins, and Andris Popovs. "ANALYSIS OF REPAIRED GAS TURBINE AND COMPRESSOR BLADES." Aviation 12, no. 2 (June 30, 2008): 46–50. http://dx.doi.org/10.3846/1648-7788.2008.12.46-50.
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In order to reach desired levels of efficiency and power output of jet engines, advanced gas turbine and compressor blades made from Ti‐6AL‐4V alloy operate at very high temperatures (up to 600°C) and speeds (up to 10000 rpm) [3–4]. Pressure of springing streams and inertial forces are main reasons of stress appearance in the blades. Besides that, blade usually could be out of action after one's edges had become damaged under temperature or foreign object hit negative influence. High cycle fatigue (HCF) accounts for 56 % of major aircraft engine failures and ultimately limits the service life of most critical rotating components. Extensive inspection and maintenance programs have been developed to detect, renew and replace defected blades, to avoid catastrophic engine failure. Various modern technologies including laser cladding (filling layers of sprayed material) allow prolongation of blades’ life by damaged part's renovation with alternate material. The general aim of the present work concludes of blades’ mechanical bahavour comparison before and after renewal. Santrauka Šiame darbe aprašoma, kaip buvo atliekama suremontuotų turbinos ir kompresoriaus menčių atsparumo analizė. Svarbiausia buvo palyginti ekvivalentinių įtampų rezultatus iki ir po menčių renovavimo alternatyvia medžiaga. Modelių, kurie buvo suprojektuoti kompiuterine programa SolidWorks, medžiaga buvo keičiama tose darbinės mentės briaunos vietose, kur buvo galimi eksploataciniai defektai.
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Baratta, Mirko, Andrea E. Catania, Ezio Spessa, and Rui L. Liu. "Multidimensional Predictions of In-Cylinder Turbulent Flows: Contribution to the Assessment of k-ε Turbulence Model Variants for Bowl-in-Piston Engines." Journal of Engineering for Gas Turbines and Power 127, no. 4 (September 20, 2005): 883–96. http://dx.doi.org/10.1115/1.1852567.
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Multidimensional computational fluid dynamics (CFD) codes with reliable turbulence models are useful investigation and design tools for internal combustion engines, in-cylinder flow phenomena being critical to the combustion process and related emission sources. Although a variety of turbulence models has long been proposed, the assessment of even the most widely used k-ε model is still lacking, especially for bowl-in-piston engines. This paper provides a survey of k-ε turbulence model variants and their numerical implementation for in-cylinder flow analysis. Mean motion and turbulence quantities were simulated in the axisymmetric combustion chamber of a motored model engine featuring one centrally located valve and each of a flat-piston and cylindrical bowl-in-piston arrangements. A noncommercial CFD code developed by the authors was applied for calculation, using a finite-volume conservative implicit method and applying various order-of-accuracy numerical schemes. Simulation results are presented at the engine speed of 200 rpm throughout the whole engine cycle. These were obtained using three k-ε turbulence model versions, standard, renormalization group (RNG) and two scale, each of which focuses on one main engine flow feature, i.e., compressibility, anisotropy, and high unsteadiness, respectively. Modified boundary conditions with respect to conventional logarithmic wall functions were applied. Effects of equation-differencing scheme and computational-grid spacing effects on flow predictions were tested. The numerical results were compared to those of laser Doppler velocimetry measurements and the influence of the k-ε model variants on the flow-field features was examined during the induction stroke and around compression top dead center. For the flat-piston case, a comparison between the homemade and commercial STAR-CD® code results was also made.
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Basak, Amrita, and Suman Das. "A Study on the Microstructural Characterization of René 142 Deposited Atop René 125 Processed through Scanning Laser Epitaxy." Materials Science Forum 879 (November 2016): 187–92. http://dx.doi.org/10.4028/www.scientific.net/msf.879.187.
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Advancements in the design, optimization and manufacture of turbine engine hot-section components during the past few decades have contributed enormously to the improvement in power-ratings and efficiency levels of gas turbine engines. Nickel-base superalloys are extensively used to produce the hot-section components as this class of alloys offer improved creep strength and higher fatigue resistance compared to other alloys due to the presence of precipitate-strengthening γ' phases i.e. Ni3[Ti, Al, Ta etc.] in the normally face centered cubic (FCC) structure of the solidified nickel. Although this second phase is the main reason for the improvement in properties, it also results in increased processing difficulty as these alloys are prone to crack formation. In this work, we demonstrate powder-bed additive manufacturing of René 142 onto René 125 substrates through scanning laser epitaxy (SLE). René 142 is a high strength, nickel-base directionally solidified (DS) alloy that has high rupture strength, excellent resistance to grain boundary cracking, and superior high-velocity oxidation resistance. Successful deposition of René 142 on René 125 provides an avenue to repair legacy hot-section components by depositing superior quality alloys at the damage locations. The microstructure of the deposited René 142 is observed to follow the polycrystalline or EQ morphology of the underlying René 125 substrate. The SLE processed René 142 exhibits dense and crack-free deposits, and microstructure refinement compared to the underlying cast René 125 substrate. This work is sponsored by the Office of Naval Research through grants N00014-11-1-0670 and N00014-14-1-0658.
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Thomas, Marc. "Progress in the Understanding of the Microstructure Evolution of Direct Laser Fabricated TiAl." Materials Science Forum 879 (November 2016): 1939–44. http://dx.doi.org/10.4028/www.scientific.net/msf.879.1939.
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With the introduction of TiAl in aircraft jet engines, there is an increasing demand for the evaluation of novel processing routes for gamma titanium aluminides such as additive manufacturing (AM). A Ti-47Al-2Cr-2Nb powder material has been used as feedstock for laser fabrication of 3D samples by means of “Selective Laser Melting” (SLM) and “Direct Metal Deposition” (DMD). A number of processing parameters including laser power, laser scan rate, powder feed rate, have been varied to evaluate their effects on the material soundness. Optimised conditions can significantly reduce the crack sensitivity for this relatively low ductility material. In particular, crack-free experimental conditions have been identified by using additional heating strategies, thus limiting built-up residual stresses during fast cooling. The different samples have been examined using optical and scanning electron microscopy in the as-built condition. The non-equilibrium cooling conditions generate ultra-fine and metastable structures exhibiting high microhardness values. A range of post-heat treatments have been performed to relieve the residual stresses and to tailor more uniform microstructures. Conventional heat treatments in the α+γ two-phase domain or in the α single phase domain have been successfully used to fully restore homogeneous microstructures either duplex or fully lamellar. A comparison is made with microstructures of both laser treated materials and of conventionally processed materials.
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von Zahn, U., G. von Cossart, J. Fiedler, K. H. Fricke, G. Nelke, G. Baumgarten, D. Rees, A. Hauchecorne, and K. Adolfsen. "The ALOMAR Rayleigh/Mie/Raman lidar: objectives, configuration, and performance." Annales Geophysicae 18, no. 7 (July 31, 2000): 815–33. http://dx.doi.org/10.1007/s00585-000-0815-2.
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Abstract. We report on the development and current capabilities of the ALOMAR Rayleigh/Mie/Raman lidar. This instrument is one of the core instruments of the international ALOMAR facility, located near Andenes in Norway at 69°N and 16°E. The major task of the instrument is to perform advanced studies of the Arctic middle atmosphere over altitudes between about 15 to 90 km on a climatological basis. These studies address questions about the thermal structure of the Arctic middle atmosphere, the dynamical processes acting therein, and of aerosols in the form of stratospheric background aerosol, polar stratospheric clouds, noctilucent clouds, and injected aerosols of volcanic or anthropogenic origin. Furthermore, the lidar is meant to work together with other remote sensing instruments, both ground- and satellite-based, and with balloon- and rocket-borne instruments performing in situ observations. The instrument is basically a twin lidar, using two independent power lasers and two tiltable receiving telescopes. The power lasers are Nd:YAG lasers emitting at wavelengths 1064, 532, and 355 nm and producing 30 pulses per second each. The power lasers are highly stabilized in both their wavelengths and the directions of their laser beams. The laser beams are emitted into the atmosphere fully coaxial with the line-of-sight of the receiving telescopes. The latter use primary mirrors of 1.8 m diameter and are tiltable within 30° off zenith. Their fields-of-view have 180 µrad angular diameter. Spectral separation, filtering, and detection of the received photons are made on an optical bench which carries, among a multitude of other optical components, three double Fabry-Perot interferometers (two for 532 and one for 355 nm) and one single Fabry-Perot interferometer (for 1064 nm). A number of separate detector channels also allow registration of photons which are produced by rotational-vibrational and rotational Raman scatter on N2 and N2+O2 molecules, respectively. Currently, up to 36 detector channels simultaneously record the photons collected by the telescopes. The internal and external instrument operations are automated so that this very complex instrument can be operated by a single engineer. Currently the lidar is heavily used for measurements of temperature profiles, of cloud particle properties such as their altitude, particle densities and size distributions, and of stratospheric winds. Due to its very effective spectral and spatial filtering, the lidar has unique capabilities to work in full sunlight. Under these conditions it can measure temperatures up to 65 km altitude and determine particle size distributions of overhead noctilucent clouds. Due to its very high mechanical and optical stability, it can also employed efficiently under marginal weather conditions when data on the middle atmosphere can be collected only through small breaks in the tropospheric cloud layers.Key words: Atmospheric composition and structure (aerosols and particles; pressure · density · and temperature; instruments and techniques)
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Ding, Chenggang, Xu Cui, Jianqiang Jiao, and Ping Zhu. "Effects of Substrate Preheating Temperatures on the Microstructure, Properties, and Residual Stress of 12CrNi2 Prepared by Laser Cladding Deposition Technique." Materials 11, no. 12 (November 28, 2018): 2401. http://dx.doi.org/10.3390/ma11122401.
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The 12CrNi2 alloy steel powder studied in the present paper is mainly used to manufacture camshafts for nuclear power emergency diesel engines. Laser cladding deposition is of great significance for the manufacture of nuclear power emergency diesel camshafts, which has the advantages of reducing material cost and shortening the manufacturing cycle. However, due to the extremely uneven heating of the components during the deposition process, a complex residual stress field occurs, resulting in crack defects and residual deformation of the components. In the present paper, 12CrNi2 bulk specimens were prepared on the Q460E high-strength structural steel substrate at different preheating temperatures by laser cladding deposition technique, and a finite element residual stress analysis model was established to investigate the effects of different preheating temperatures on the microstructure, properties, and residual stress of the specimens. The results of the experiments and finite element simulations show that with the increase of preheating temperature, the content of martensite/bainite in the deposited layer decreases, and the ferrite content increases. The proper preheating temperature (150 °C) has good mechanical properties. The residual stress on the surface of each specimen decreases with the increase of the preheating temperature. The longitudinal stress is greater at the rear-end deposition part, and the lateral residual stress is greater on both sides along the scanning direction.
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Napadłek, Wojciech, Adam Woźniak, and Agnieszka Laber. "The Use of Laser Texturing the Surface Layer to Modify the Friction Pair Pin-Bushing." Solid State Phenomena 220-221 (January 2015): 708–13. http://dx.doi.org/10.4028/www.scientific.net/ssp.220-221.708.
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This paper presents the methodology and results of laser texturing of the surface layer steel 41Cr4, applied to the manufacture of crankshafts and selected aluminum alloy used for the production of slide bearings (bearings) for internal combustion engines. Laser treatment of the surface layer of this material was carried out using Nd: YAG laser with a wavelength of pulsed laser radiation λ-1064 nm. Application of laser ablation micromachining in sensitive zones of the crankshaft and slide bearing, mainly the surface layer of the friction pair, was aimed to formation of a suitable surface texture containing oil microchannels. Applying different parameters ablative laser micromachining (power density, repetition rate, number of pulses in the same area, the overlap area microchannels), a very interesting stereometry of the surface layer steel 41Cr4 and bearing alloy was obtained. The lubricant had characteristic microchannels, very important in the tribological process of the friction pair crankshaft – slide bearing. Laboratory metallographic tests showed the high dispersion microstructure of martensitic steel 41Cr4 in the superficial zone, melted and hardened. The transition zone was found to be of martensitic-bainitic microstructure and bainite. The microstructures are formed by ultrafast phase transformations over time crystallization of alloy Fe-Cr-C from the liquid phase (microhardness in the range of 550-680 HV0.05). The microstructures appear in the adjacent area to the lubricant microchannels produced during laser texturing. The studies of laser texturing the sliding layer of slide bearing made of aluminum alloy, destined to cooperate with tribological function pin engine crankshaft are preliminary results. The positive results: high repeatability of the process texturing regular geometric shape microchannels and ease process control. In the best version, technological preliminary tests showed the following oil microchannels dimensions: depth of about 3.2 microns, width 47 microns; it is a promising result.
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Liu, Siyu, Yu Huang, Yong He, Yanqun Zhu, and Zhihua Wang. "Review of Development and Comparison of Surface Thermometry Methods in Combustion Environments: Principles, Current State of the Art, and Applications." Processes 10, no. 12 (November 28, 2022): 2528. http://dx.doi.org/10.3390/pr10122528.
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Temperature is one of the most important parameters in the combustion processes. Accurate surface temperature can help to gain insight into the combustion characteristics of various solid or liquid fuels, as well as to evaluate the operating status of combustion power facilities such as internal combustion engines and gas turbines. This paper mainly summarizes and compares the main surface thermometry techniques, from the aspects of their principles, current state of development, and specific applications. These techniques are divided into two categories: contact-based thermometry and non-intrusive thermometry. In contact-based thermometry, conventional thermocouples as well as thin-film thermocouples are introduced. These methods have been developed for a long time and are simple and economical. However, such methods have disadvantages such as interference to flow and temperature field and poor dynamic performance. Furthermore, this paper reviews the latest non-intrusive thermometry methods, which have gained more interest in recent years, including radiation thermometry, laser-induced phosphorescence, liquid crystal thermography, the temperature-sensitive paint technique, and the temperature-indicating paint technique. Among them, we highlighted radiation thermometry, which has the widest measurement ranges and is easy to acquire results with spatial resolution, as well as laser-induced phosphorescence thermometry, which is not interfered with by the emissivity and surrounding environment, and has the advantages of fast response, high sensitivity, and small errors. Particularly, laser-induced phosphoresce has attracted a great deal of attention, as it gets rid of the influence of emissivity. In recent years, it has been widely used in the thermometry of various combustion devices and fuels. At the end of this paper, the research progress of the above-mentioned laser-induced phosphorescence and other techniques in recent years for the surface thermometry of various solid or liquid fuels is summarized, as well as applications of combustion facilities such as internal combustion engines, gas turbines, and aero engines, which reveal the great development potential of laser-induced phosphorescence technology in the field of surface thermometry.
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Vekilov, Samir Shamsievich, Volodymyr Ivanovich Lipovskyi, Roman Anatolevich Marchan, and Oleg Evgenevich Bondarenko. "DISTINCTIVE FEATURES OF SLM TECHNOLOGY APPLICATION FOR MANUFACTURING OF LPRE COMPONENTS." Journal of Rocket-Space Technology 29, no. 4 (November 17, 2021): 112–23. http://dx.doi.org/10.15421/452112.
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In view of the growing competition in the modern market for rocket and space technology products, the issue of maximizing the cost reduction of the process of its production is urgent. In particular, the rocket engine is traditionally one of the costliest and technologically demanding rocket units, which basically reduces the problem of reducing the cost of rocket production to the development of new, more technologically advanced and less costly, approaches to manufacturing LPRE components. Thus, it is of increased interest to use a relatively young method for producing parts by layer-by-layer melting of thin layers of metal powder by exposing it to high-power laser radiation. This method is a part of the methods of additive technologies and is called SLM (Selective Laser Melting). In order to assess the influence of the main features of the production of components, the study of hydraulic channels manufactured with the additive SLM technology was carried out, and a load-bearing element of the fastening structure was manufactured which geometry was obtained by applying topological optimization methods. The aim of the work is to determine the main hydraulic characteristics of inner channels of typical LPRE’s elements, as well as the limits of the technology applicability in terms of liquid-propellant rocket engines. The possibility of manufacturing elements, including hydraulic paths, was investigated: regeneratively cooled cylinders, throat inserts of a liquid-propellant engine, as well as experimental designs of film cooling rings were adapted to be produced by means of SLM. The possibility of producing thrust frame, the shape of which was obtained by the method of topological optimization, was investigated. Samples of designs of typical hydraulic channels, as well as the constituent elements of the design of the rocket engine chambers, were manufactured. The main hydraulic characteristics of the typical hydraulic channels, as well as the distinctive features of their production using the method of additive technologies SLM, were determined. The thrust frame, which geometry was obtained by means of topology optimization, was successfully manufactured.
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Vakil, S. S., and K. A. Thole. "Flow and Thermal Field Measurements in a Combustor Simulator Relevant to a Gas Turbine Aeroengine." Journal of Engineering for Gas Turbines and Power 127, no. 2 (April 1, 2005): 257–67. http://dx.doi.org/10.1115/1.1806455.
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The current demands for high performance gas turbine engines can be reached by raising combustion temperatures to increase power output. Predicting the performance of a combustor is quite challenging, particularly the turbulence levels that are generated as a result of injection from high momentum dilution jets. Prior to predicting reactions in a combustor, it is imperative that these turbulence levels can be accurately predicted. The measurements presented in this paper are of flow and thermal fields produced in a large-scale combustor simulator, which is representative of an aeroengine. Three-component laser Doppler velocimeter measurements were made to quantify the velocity field while a rake of thermocouples was used to quantify the thermal field. The results indicate large penetration depths for the high momentum dilution jets, which result in a highly turbulent flow field. As these dilution jets interact with the mainstream flow, kidney-shaped thermal fields result due to counter-rotating vortices that develop.
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Baiamonte, Lidia, Cecilia Bartuli, Francesco Marra, Annamaria Gisario, and Giovanni Pulci. "Hot Corrosion Resistance of Laser-Sealed Thermal-Sprayed Cermet Coatings." Coatings 9, no. 6 (May 28, 2019): 347. http://dx.doi.org/10.3390/coatings9060347.
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Hot corrosion affects the components of diesel engines and gas turbines working at high temperatures, in the presence of low-melting salts and oxides, such as sodium sulfate and vanadium oxide. Thermal-sprayed coatings of nickel–chromium-based alloys reinforced with ceramic phases, can improve the hot corrosion and erosion resistance of exposed metals, and a sealing thermal, post-treatment can prove effective in reducing the permeability of aggressive species. In this study, the effect of purposely-optimized high-power diode laser reprocessing on the microstructure and type II hot corrosion resistance of cermet coatings of various compositions was investigated. Three different coatings were produced by high velocity oxy-fuel and was tested in the presence of a mixture of Na2SO4 and V2O5 at 700 °C, for up to 200 h: (i) Cr3C2–25% NiCr, (ii) Cr3C2–25% CoNiCrAlY, and (iii) mullite nano–silica–60% NiCr. Results evidenced that laser sealing was not effective in modifying the mechanism, on the basis of the hot corrosion degradation but could provide a substantial increase of the surface hardness and a significant decrease of the overall coating material consumption rate (coating recession), induced by the high temperature corrosive attack.
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Schwarz, E., S. Gross, B. Fischer, I. Muri, J. Tauer, H. Kofler, and E. Wintner. "Laser-induced optical breakdown applied for laser spark ignition." Laser and Particle Beams 28, no. 1 (March 2010): 109–19. http://dx.doi.org/10.1017/s0263034609990668.
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AbstractIn the present article, the experimental investigation of optical breakdown induced by ns/mJ pulses at two wavelengths, 1064 nm and 532 nm, in air of atmospheric pressure is reported and discussed. The obtained breakdown thresholds were compared with theory and are in good agreement. The generated plasmas have been characterized by their amount of scattered laser light, energy transmission, and change of the transmitted temporal shape. Laser-induced plasma formation in a gas, in air, also generates an acoustic pressure wave. The acoustic energy is compared to the laser pulse energy and is found to be linearly dependent. Moreover, the frequency distribution of the characteristic acoustic pressure wave was analyzed. The experiments described were accomplished in order to optimize a laser ignition system with regard to efficiency and costs. The laser system employed for these investigations is a compact high peak power, passively Q-switched, longitudinally diode-pumped solid-state laser. Such a “laser spark plug” should replace conventional spark plugs in internal combustion engines because conventional ignition has reached its limits in terms of efficiency and durability. Thereby, a reduction of pollutant emission should also be feasible.
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Saprikin, A. A., Yurii P. Sharkeev, Natalya A. Saprykina, Margarita A. Khimich, and Egor A. Ibragimov. "Formation of Structural-Phase State in a Cobalt-Chromium-Molybdenum Alloy by Selective Laser Melting." Solid State Phenomena 313 (January 2021): 50–58. http://dx.doi.org/10.4028/www.scientific.net/ssp.313.50.
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Heat resistant cobalt-based alloys have found a specific niche in the present-day mechanical engineering due to their unique properties. To begin with, cobalt-based alloys are used as corrosion, heat and wear resistant materials intended for aggressive environments and operation at extreme temperatures, e.g. blades, nozzles, swirlers, rings and other elements of turbines and internal combustion engines. Traditional molding methods applied in the mechanical engineering fail to provide necessary operational and technological characteristics of aforementioned machine parts. Owing to selective laser melting it is possible to reduce a production time and manufacturing costs for machine elements with a complex physical configuration and generate an alloy with an extraordinary structure, which is not found in traditionally combined compounds. A structure of cobalt exists in two crystal modifications: a hexagonal close-packed epsilon phase, a low-temperature phase and a face-centered cubic lattice gamma phase, a high-temperature phase. The alloy hardness is directly related to an amount of a low-temperature phase. The laser melting shortens a laser beam impact time on a powder composition due to a higher power and laser travelling speed. A high value of heat conductivity seems to be the reason for rapid solidification and cooling, which, in their turn, increase a percent of an alpha-martensite phase in an alloy and improve the hardness and wear resistance of machine parts. The reported paper summarizes studies aimed at the development of a stable phase structure three-component alloy (Сo-66 mass % Cr-6 mass % Mo) based on the cobalt-chromium-molybdenum system and mixed up via selective laser melting.
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Saprikin, A. A., Yurii P. Sharkeev, Natalya A. Saprykina, Margarita A. Khimich, and Egor A. Ibragimov. "Formation of Structural-Phase State in a Cobalt-Chromium-Molybdenum Alloy by Selective Laser Melting." Solid State Phenomena 313 (January 2021): 50–58. http://dx.doi.org/10.4028/www.scientific.net/ssp.313.50.
Full textAbstract:
Heat resistant cobalt-based alloys have found a specific niche in the present-day mechanical engineering due to their unique properties. To begin with, cobalt-based alloys are used as corrosion, heat and wear resistant materials intended for aggressive environments and operation at extreme temperatures, e.g. blades, nozzles, swirlers, rings and other elements of turbines and internal combustion engines. Traditional molding methods applied in the mechanical engineering fail to provide necessary operational and technological characteristics of aforementioned machine parts. Owing to selective laser melting it is possible to reduce a production time and manufacturing costs for machine elements with a complex physical configuration and generate an alloy with an extraordinary structure, which is not found in traditionally combined compounds. A structure of cobalt exists in two crystal modifications: a hexagonal close-packed epsilon phase, a low-temperature phase and a face-centered cubic lattice gamma phase, a high-temperature phase. The alloy hardness is directly related to an amount of a low-temperature phase. The laser melting shortens a laser beam impact time on a powder composition due to a higher power and laser travelling speed. A high value of heat conductivity seems to be the reason for rapid solidification and cooling, which, in their turn, increase a percent of an alpha-martensite phase in an alloy and improve the hardness and wear resistance of machine parts. The reported paper summarizes studies aimed at the development of a stable phase structure three-component alloy (Сo-66 mass % Cr-6 mass % Mo) based on the cobalt-chromium-molybdenum system and mixed up via selective laser melting.
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Amer, Amer E., S. A. EL-Ghazaly, Y. S. Shash, and S. Weiss. "Influence of Microstructural Changes and Grain Boundary Precipitation on the Behavior of 25Ni-15Cr-2Ti Superalloy during High Temperature Creep." Materials Science Forum 475-479 (January 2005): 643–50. http://dx.doi.org/10.4028/www.scientific.net/msf.475-479.643.
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Iron-base superalloys are well known materials having excellent high temperature properties .They are used in turbo superchargers and turbine engines required for aerospace and power plants. In this investigation precipitation hardenable X5NiCrTi26-15 was used to study the influence of microstructural changes on the creep behavior at different conditions . Different creep cycles were applied for both base alloy and laser beam welded alloy (6kW CO2 ) namely at 600 , 625 and 650C at applied controlled creep stresses of 400 and 450 MPa . The base material sheet was used in as solution annealed state ( 30 min, 960 C, WQ ).The specimens were hardened in two steps (24h,760 C, FC and 16 h, 705 C,AC ) before being investigated . The microstructural changes due to grain boundary sliding, intergranual fracture perpendicular to the metal flow axis , and the type ,morphology of different secondary carbides were measured and discussed . To examine the changes in microstructure Philips EM 400 TEM with an acceleration voltage of 120KV, and SEM as well as light microscopy were used . It was found that , laser beam welded structure investigated after creep deformation at temperatures lower than 650C and at controlled stress of 400 and 450 MPa , showed a textured weld metal zone with dendrite having lower hardness combined with a higher creep resistance than that for base material .It was found also that creeping at 650C at the same stress values offsets any gain in creep resistance of welded joints as compared with that for the base material at the same conditions.
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Choi, Myeung Hwan, Jeongwoo An, and Jaye Koo. "Breakup Mechanism of a Jet in the L-Shape Crossflow of a Gas Turbine Combustor." Energies 15, no. 9 (May 5, 2022): 3360. http://dx.doi.org/10.3390/en15093360.
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Experimental investigations are conducted to determine the mechanism and characteristics of a jet in an L-shape crossflow simulating the radial swirl injector of a lean premixed-prevaporized (LPP) combustor. To simplify the radial flow of the actual injector while ignoring the centrifugal effect, the L-shaped 2D-channel is used for the crossflow, and water is used as a fuel simulant. The jet breakup is captured using a high-speed camera, and the density gradient magnitude is post-processed to clarify the spray. The Sauter mean diameter (SMD) of the spray is measured via a laser diffraction method with a helium–neon laser optical system (HELOS). The characteristics of the jet in the L-shape crossflow are compared with the characteristics of the jet in a typical crossflow through the flat channel. The results for different outlet heights of the L-shape channel (H/d0) and different injector positions (L/d0) are presented. A dimensionless number (τ) consisting of a time ratio is introduced to describe the jet characteristics. In a previous work, the spraying tendency was demonstrated for different injector positions. In addition, the effect of the recirculation area on H/d0 was empirically shown. H/d0 determines the size of the recirculation area, and the range of τ determines the jet breakup mechanism inside the L-shape channel. The results of this study present the breakup mechanism of the jet in the L-shape channel flow, which simulates a jet in a radial swirler injector for gas turbine engines. It is expected that these results can be used to assist in designing gas turbine engines with more combustion efficiency.
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Scully, John. "High power lasers." Corrosion Science 30, no. 11 (January 1990): 1153–54. http://dx.doi.org/10.1016/0010-938x(90)90063-b.
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Планковский, Сергей Игоревич, Евгений Сергеевич Палазюк, Вадим Олегович Гарин, and Юрий Вениаминович Дьяченко. "ЭКСПЕРИМЕНТАЛЬНОЕ ИССЛЕДОВАНИЕ ВЛИЯНИЯ ТЕРМОИМПУЛЬСНОЙ ОБРАБОТКИ ЛОПАТОК ТУРБИН ГТД НА СКЛОННОСТЬ К ВЫСОКОТЕМПЕРАТУРНОЙ ГАЗОВОЙ КОРРОЗИИ." Aerospace technic and technology, no. 2 (April 26, 2018): 4–13. http://dx.doi.org/10.32620/aktt.2018.2.01.
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One of the most important parts of gas turbine engines (GTE) are turbine blades, because from their operational characteristics depend the maximum gas temperature in a turbine, its reliability and service life, specific power and economy of an engine. Different mechanical damages, cracks, traces of general corrosion, changing their working section, are unacceptable on blades. Analysis of main causes of the parts destruction in GTE flow section shows that in most cases formation of shearing distortions and cracks occurs on blades edges in the surface layer of material. The main reason for appearance of these defects are sulphide-oxide and high-temperature gas corrosion. The basic development tendencies of blades reliability increasing show, that together with the development of new heat-resistant alloys another possible way to prevent the destruction of blade material is increasing of blade manufacturing quality. The final shape of turbine blades is often achieved by machining, which leads to formation of burrs on the edges. Thermal pulse deburring has a large number of technological advantages and is the most promising method for finishing treatment of the surfaces and edges of GTE blades. However, despite the numerous positive examples of the application of laser treatment of blade surfaces in order to increase the corrosion resistance, the mechanism of phase and structural transformations, occurring in the surface layers of heat-resistant steels and alloys of different compositions, is still not fully understood. To estimate the effect of thermal pulse deburring of gas turbine blades on their operational characteristics, accelerated tests of blade specimens on the tendency to high-temperature gas corrosion have been carried out. The tests consist of sequential chemical etching in electrolyte, electrochemical treatment and high-temperature treatment in aggressive gases. These tests allow to obtain the same corrosion layer on blades surfaces, like after real operation. Also influence of laser deburring on corrosion resistance was estimated in parallel. The experimental study was carried out on the example of treatment of GTE nozzle blades made from a heat-resistant alloy on a nickel basis ZhS26-VI. Specimens were obtained by cutting two new blades into small parts by hydroabrasive cutting method to ensure that there is no thermal impact on the material being processed and no burn-out of the alloying elements. Obtained specimens of GTE blades after the cutting have been undergone by additional machining to obtain burrs at the edges, which were removed by thermal pulse and laser deburring methods. Investigation of the surface layer state of specimens after accelerated tests for high-temperature gas corrosion has been carried out by means of microscopic analysis. For this purpose, microslices of specimens have been prepared. Using a comparative analysis of the corrosion layer thickness after the tests, it was shown that there is no influence of thermal pulse and laser deburring methods on the tendency to high-temperature gas corrosion.
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MATSUI, Sadayoshi, Takahiro SUYAMA, and Toshiki HIJIKATA. "High power semiconductor lasers." Review of Laser Engineering 18, no. 8 (1990): 560–63. http://dx.doi.org/10.2184/lsj.18.8_560.
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Nilsson, J., and D. N. Payne. "High-Power Fiber Lasers." Science 332, no. 6032 (May 19, 2011): 921–22. http://dx.doi.org/10.1126/science.1194863.
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Galvanauskas, Almantas. "High Power Fiber Lasers." Optics and Photonics News 15, no. 7 (July 1, 2004): 42. http://dx.doi.org/10.1364/opn.15.7.000042.
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Hecht, Jeff. "High-Power Fiber Lasers." Optics and Photonics News 29, no. 10 (October 1, 2018): 30. http://dx.doi.org/10.1364/opn.29.10.000030.
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Jauregui, Cesar, Jens Limpert, and Andreas Tünnermann. "High-power fibre lasers." Nature Photonics 7, no. 11 (October 20, 2013): 861–67. http://dx.doi.org/10.1038/nphoton.2013.273.
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Segal, D. M. "High-power Dye Lasers." Journal of Modern Optics 40, no. 5 (May 1993): 965–66. http://dx.doi.org/10.1080/09500349314550981.
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UEDA, Kenichi. "High power gas lasers." Review of Laser Engineering 15, no. 6 (1987): 342–46. http://dx.doi.org/10.2184/lsj.15.342.
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SUEMATSU, Yasuharu, and Shigehisa ARAI. "High power semiconductor lasers." Review of Laser Engineering 15, no. 6 (1987): 347–52. http://dx.doi.org/10.2184/lsj.15.347.
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Backus, Sterling, Charles G. Durfee, Margaret M. Murnane, and Henry C. Kapteyn. "High power ultrafast lasers." Review of Scientific Instruments 69, no. 3 (March 1998): 1207–23. http://dx.doi.org/10.1063/1.1148795.
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Takeya, M., T. Tojyo, T. Asano, S. Ikeda, T. Mizuno, O. Matsumoto, S. Goto, Y. Yabuki, S. Uchida, and M. Ikeda. "High-Power AlGaInN Lasers." physica status solidi (a) 192, no. 2 (August 2002): 269–76. http://dx.doi.org/10.1002/1521-396x(200208)192:2<269::aid-pssa269>3.0.co;2-z.
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Wittrock, Ulrich. "High-power Nd:YAG lasers." Advanced Materials 4, no. 4 (April 1992): 295–97. http://dx.doi.org/10.1002/adma.19920040413.
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Lou, Qi-hong, and Jun Zhou. "High power fiber lasers." Frontiers of Physics in China 2, no. 4 (October 2007): 410–23. http://dx.doi.org/10.1007/s11467-007-0054-z.
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Mans, Torsten, Jan Dolkemeyer, and Claus Schnitzler. "High Power Femtosecond Lasers." Laser Technik Journal 11, no. 3 (June 2014): 40–43. http://dx.doi.org/10.1002/latj.201400031.
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Tarasenko, V. F. "High-power high-density-gas lasers." Russian Physics Journal 42, no. 8 (August 1999): 691–95. http://dx.doi.org/10.1007/bf02509341.
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Tabakoff, W., and M. Metwally. "Coating Effect on Particle Trajectories and Turbine Blade Erosion." Journal of Engineering for Gas Turbines and Power 114, no. 2 (April 1, 1992): 250–57. http://dx.doi.org/10.1115/1.2906580.
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Gas turbine engines operating in dusty environments are exposed to erosion and performance deterioration. In order to improve the erosion resistance, nickel and cobalt superalloy blades and vanes are widely used in the hot section of gas turbines. Protective coatings have been used to enhance superalloy resistance to hot erosion. An investigation has been conducted to study coal ash particle dynamics and resulting blade erosion for both uncoated and coated blades of a two-stage axial flow gas turbine. A quasi-three-dimensional flow solution is obtained for each blade row for accurate computation of particle trajectories. The change in particle momentum due to collision with the turbine blades and casings is modeled using restitution parameters derived from three-component laser-Doppler velocimeter measurements. The erosion models for both blade superalloy and coatings are derived based on the erosion data obtained by testing the blade superalloy and coatings in a high-temperature erosion wind tunnel. The results show both the three-dimensional particle trajectories and the resulting blade impact locations for both uncoated and coated blade surfaces. In addition are shown the distribution of the erosion rate, impact frequency, impact velocity, and impact angle for the superalloy and the coating. The results indicate significant effects of the coating, especially on blade erosion and material deterioration.
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HONDA, Kazuo, Katsuhiro KIHARA, and Sirou UCHIDA. "Super high power semiconductor lasers." JOURNAL OF JAPAN SOCIETY FOR LASER SURGERY AND MEDICINE 16, no. 1 (1995): 23–28. http://dx.doi.org/10.2530/jslsm1980.16.1_23.
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WATANABE, Shuntaro. "Ultrashort pulse high power lasers." Review of Laser Engineering 19, no. 1 (1991): 82–84. http://dx.doi.org/10.2184/lsj.19.82.
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