Literatura académica sobre el tema "Surfaces ultra-planes"
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Artículos de revistas sobre el tema "Surfaces ultra-planes"
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Gajdardziska-Josifovska, M., B. G. Frost, E. Völkl y L. F. Allard. "On the Faceting of Polar Ceramic Surfaces: Microscopy and Holography Studies of MGO(111) Surfaces". Proceedings, annual meeting, Electron Microscopy Society of America 54 (11 de agosto de 1996): 366–67. http://dx.doi.org/10.1017/s0424820100164295.
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Polar surfaces are those crystallographic faces of ionically bonded solids which, when bulk terminated, have excess surface charge and a non-zero dipole moment perpendicular to the surface. In the case of crystals with a rock salt structure, {111} faces are the exemplary polar surfaces. It is commonly believed that such polar surfaces facet into neutral crystallographic planes to minimize their surface energy. This assumption is based on the seminal work of Henrich which has shown faceting of the MgO(111) surface into {100} planes giving rise to three sided pyramids that have been observed by scanning electron microscopy. These surfaces had been prepared by mechanical polishing and phosphoric acid etching, followed by Ar+ sputtering and 1400 K annealing in ultra-high vacuum (UHV). More recent reflection electron microscopy studies of MgO(111) surfaces, annealed in the presence of oxygen at higher temperatures, have revealed relatively flat surfaces stabilized by an oxygen rich reconstruction. In this work we employ a combination of optical microscopy, transmission electron microscopy, and electron holography to further study the issue of surface faceting.
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Waseda, Y., S. Suzuki y K. Urbanb. "Novel Morphology of Voids in Single-Quasicrystalline Icosahedral Al70.5Pd21.0Mn8.5". Zeitschrift für Naturforschung A 53, n.º 8 (1 de agosto de 1998): 679–83. http://dx.doi.org/10.1515/zna-1998-0806.
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Abstract This paper deals with the morphology and surface chemistry of faceted voids existing in singlequasicrystalline icosahedral Al70.5Pd21.0Mn8.5. By observation with a scanning electron microscope of surfaces obtained by cleavage of the quasicrystal, the habit planes of the dodecahedral voids were identified. The chemical surface composition of the void surface was determined by Auger electron spectroscopy after cleavage in ultra-high vacuum.
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Kong, Ling Bao, Chi Fai Cheung, Suet To y Wing Bun Lee. "Development of a Dynamic Model for Ultra-Precision Raster Milling". Key Engineering Materials 364-366 (diciembre de 2007): 58–63. http://dx.doi.org/10.4028/www.scientific.net/kem.364-366.58.
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Optical freeform surface requires submicrometer form accuracy and nanometer surface finish. Ultra-precision raster milling is an emerging technology in the fabrication of those surfaces in which the dynamics factors are vital to achieve the surface quality. This paper presents a theoretical dynamics model for ultra-precision raster milling. The cutting force is derived in the depth of cut (DOC) planes in the feed and raster directions. Hence, a 3D cutting force model is established. The cutting force induced deflection between tool and workpiece is determined which can be employed to analyze the influence of the deflection on the surface generation in raster milling. The dynamic model is useful for modeling of surface generation and further control of vibration between the tool and the workpiece.
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Guo, Zhong Ning, Z. G. Yang, Z. G. Hang, Z. Q. Yu, T. M. Yue y Wing Bun Lee. "Analysis of Dynamic Characteristics in Polishing Based on Two-Dimension Vibration of Fluid". Key Engineering Materials 304-305 (febrero de 2006): 295–99. http://dx.doi.org/10.4028/www.scientific.net/kem.304-305.295.
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A novel polishing technique based on the two-dimension vibration of fluid is put forward to obtain ultra-smooth surface without damage. In operation, the polishing pad is replaced by fluid where fine abrasive particles are mixed, and the impact and grinding effect can be produced by means of the vibration of fluid and the relative motion of workpiece. It can achieve the ultra-precise polishing for all kinds of planes and curved surfaces. A finite element method is employed to analyze the dynamic behaviors, including vibration mode and harmonic response under the action of the exciter, and the fluid field based on two-dimension vibration is simulated.
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Sander, Tim, Yi Liu, Tuan Anh Pham, Maximilian Ammon, Mirunalini Devarajulu y Sabine Maier. "Ultra-high vacuum cleaver for the preparation of ionic crystal surfaces". Review of Scientific Instruments 93, n.º 5 (1 de mayo de 2022): 053703. http://dx.doi.org/10.1063/5.0088802.
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Cleaving single crystals in situ under ultra-high vacuum conditions provides a reliable and straightforward approach to prepare clean and atomically well-defined surfaces. Here, we present a versatile sample cleaver to efficiently prepare ionic crystal surfaces under ultra-high vacuum conditions, which is suitable for preparation of softer materials, such as alkali halides, and harder materials, such as metal oxides. One of the advantages of the presented cleaver design is that the cleaving blade and anvil to support the crystal are incorporated into the device. Therefore, no particularly strong mechanical manipulator is needed, and it is compatible with existing vacuum chambers equipped with an xyz-manipulator. We demonstrate atomically flat terraces and the atomic structure of NaCl(001), KBr(001), NiO(001), and MgO(001) cleavage planes prepared in situ under ultra-high vacuum conditions and imaged by low-temperature non-contact atomic force microscopy.
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Touge, Mutsumi, Satoru Anan, Shogo Wada, Akihisa Kubota, Yoshitaka Nakanishi y Junji Watanabe. "Atomic-Scale Planarization of Single Crystal Diamond Substrates by Ultraviolet Rays Assisted Machining". Key Engineering Materials 447-448 (septiembre de 2010): 66–70. http://dx.doi.org/10.4028/www.scientific.net/kem.447-448.66.
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The ultra-precision polishing assisted by the ultraviolet rays irradiation was performed to achieve the atomic-scale planarization of the single crystal diamond substrates. This polishing method is a novel and simple polishing method characterizing by a quartz disk and an ultraviolet irradiation device. The principle three crystal planes of the diamond substrate were polished by this method. The polished surfaces were evaluated by an optical interferometric profilers (Wyko), an atom force microscope (AFM) and LEED (low-energy electron diffraction). The surface roughness of the polished diamond substrates was evaluated as 0.2 ~ 0.4 nmRa in (100), (110) and (111) crystal planes. The LEED (low-energy electron diffraction) patterns indicated the almost perfect crystallographic structure without the residual processed strain beneath the polished surface. In this paper, the optimum polishing condition to achieve the atomic-scale planarization of the diamond substrates has been investigated by the evaluation of LEED patterns, Wyko and AFM images. The mechanismof the ultraviolet rays assisted polishing is discussed in detail.
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Lai, Jin, Dong Li, Yong Ai, Hongkun Liu, Deyang Cai, Kangjun Chen, Yuqiang Xie y Guiwen Wang. "Structural diagenesis in ultra-deep tight sandstones in the Kuqa Depression, Tarim Basin, China". Solid Earth 13, n.º 6 (21 de junio de 2022): 975–1002. http://dx.doi.org/10.5194/se-13-975-2022.
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Abstract. The Lower Cretaceous Bashijiqike Formation of the Kuqa Depression is made up of ultra-deeply buried sandstones in fold-and-thrust belts. Few researches have linked diagenetic processes with structure. To fill this gap, a comprehensive analysis integrating diagenesis with structure pattern, fracture and in situ stress is performed following a structural diagenetic approach. The results show that the pore spaces include residual intergranular pores, intergranular and intragranular dissolution pores, and micro-fractures. The sandstones experienced a high degree of mechanical compaction, but compaction is limited in well-sorted rocks or abundant in rigid quartz grains. The most volumetrically important diagenetic minerals are calcites. The framework grains experienced a varied degree of dissolution, and intergranular and intragranular dissolution pores are formed. Special attention is paid on the dissolution associated with the fracture planes. Large numbers of natural fractures are cemented by carbonate cements, which limit fluid flow. In addition, the presence of fracture enhances dissolution and the fracture planes are enlarged by dissolution. Cementation and dissolution can occur simultaneously in fracture surfaces, and the enlarged fracture surfaces can be cemented by late-stage cements. The in situ stress magnitudes are calculated using well logs. The horizontal stress difference (Δσ) determines the degree of mechanical compaction, and rocks associated with low Δσ experienced a low degree of compaction, and these contain preserved intergranular pores. Natural fractures are mainly related to the low Δσ layers. The presence of intergranular and intragranular dissolution pores is mainly associated with the fractured zones. The high-quality reservoirs with intergranular pores or fractures are related to low Δσ layers. The structural diagenesis researches above help the prediction of reservoir quality in ultra-deep sandstones and reduce the uncertainty in deep natural gas exploration in the Kuqa Depression.
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Guo, Xiao Guang, Chang Heng Zhai, Zi Yuan Liu, Liang Zhang, Zhu Ji Jin y Ren Ke Kang. "Research on Elastic-Plastic Transition and Hardening Effect for Monocrystalline Silicon Surfaces". Advanced Materials Research 1027 (octubre de 2014): 101–6. http://dx.doi.org/10.4028/www.scientific.net/amr.1027.101.
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Based on molecular dynamics method, a nanoindentation simulation of the silicon crystal is built and the load-displacement curve is drawn. According to the load-displacement curve, the elastic-plastic transition of silicon crystal is analyzed. The results show that the critical point in the elastic-plastic transition is between 15 and 20 angstroms. In addition, different crystal planes of silicon crystal are loaded for five cycles respectively; the nanohardness is calculated and the nanohardness curve is obtained. The results show that after the first plastic deformation of the silicon crystal surface is occurred, the surface will have a higher hardness and a higher elasticity. Therefore, in the ultra precision machining, in order to reduce the occurrence of damage, the depth of the processing should be controlled in the range of elasticity. Moreover, the method of small quantities in high frequency can increase mechanical properties on the surface.
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Bertin, M., M. Doronin, X. Michaut, L. Philippe, A. Markovits, J. H. Fillion, F. Pauzat, Y. Ellinger y J. C. Guillemin. "Nitrile versus isonitrile adsorption at interstellar grain surfaces". Astronomy & Astrophysics 608 (diciembre de 2017): A50. http://dx.doi.org/10.1051/0004-6361/201731144.
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Context. Almost 20% of the ~200 different species detected in the interstellar and circumstellar media present a carbon atom linked to nitrogen by a triple bond. Of these 37 molecules, 30 are nitrile R-CN compounds, the remaining 7 belonging to the isonitrile R-NC family. How these species behave in their interactions with the grain surfaces is still an open question. Aims. In a previous work, we have investigated whether the difference between nitrile and isonitrile functional groups may induce differences in the adsorption energies of the related isomers at the surfaces of interstellar grains of various nature and morphologies. This study is a follow up of this work, where we focus on the adsorption on carbonaceous aromatic surfaces. Methods. The question is addressed by means of a concerted experimental and theoretical approach of the adsorption energies of CH3CN and CH3NC on the surface of graphite (with and without surface defects). The experimental determination of the molecule and surface interaction energies is carried out using temperature-programmed desorption in an ultra-high vacuum between 70 and 160 K. Theoretically, the question is addressed using first-principle periodic density functional theory to represent the organised solid support. Results. The adsorption energy of each compound is found to be very sensitive to the structural defects of the aromatic carbonaceous surface: these defects, expected to be present in a large numbers and great diversity on a realistic surface, significantly increase the average adsorption energies to more than 50% as compared to adsorption on perfect graphene planes. The most stable isomer (CH3CN) interacts more efficiently with the carbonaceous solid support than the higher energy isomer (CH3NC), however.
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Kokkalas, S., R. R. Jones, K. J. W. McCaffrey y P. Clegg. "Quantitative fault analysis at Arkitsa, Central Greece, using Terrestrial Laser- Scanning ("LIDAR")". Bulletin of the Geological Society of Greece 40, n.º 4 (1 de enero de 2007): 1959. http://dx.doi.org/10.12681/bgsg.17237.
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We applied terrestrial laser scanning (ground-based LiDAR) in the Arkitsa fault zone, an area of active extension along the North Evia Gulf in Central Greece. The study area includes well exposed fault surfaces with large accumulated slip and this allowed detailed measurements of the geometry of the fault planes to be acquired. Laser-scan data enable ultra high-resolution three-dimensional digital terrain models of the recently exposed active fault to be created, in order to apply quantitative fault and slip-vector analysis. This study demonstrates the way in which the Arkitsa Fault is segmented on a smaller scale. The variation in dip and strike across individual fault panels is quantified, and shows the extent to which the fault panel surfaces are non-planar. Although the dip of the different fault panels varies considerably, the average orientation of the slip-vectors on the panels are approximately coincident. The fault is steeply oblique sinistral-normal, with average displacement vector plunging 55° towards 340°.
Tesis sobre el tema "Surfaces ultra-planes"
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Squillace, Ophélie. "Membranes biomimétiques fluides ancrées sur électrodes ultra-planes". Thesis, Le Mans, 2016. http://www.theses.fr/2016LEMA1004/document.
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Les bicouches lipidiques constituent l’architecture socle des membranes biologiques et l’environnement bidimensionnel de leurs protéines. Ancrées sur une interface hydrophile hydratée, ces systèmes conservent leur fluidité et sont localisés durablement près d’un substrat. Dans ce domaine, nous avons développé une stratégie de fonctionnalisation rapide, peu coûteuse et versatile, permettant la formation d’une membrane biomimétique fluide, ancrée sur des substrats conducteurs spécifiquement conçus pour son étude structurale et dynamique. La chimie de surface proposée forme une liaison covalente forte entre le substrat et des molécules commerciales amphiphiles (Brij, etc), utilisées comme système ancre-harpon. L’extrémité hydrophile (coté ancre) possédant un alcool primaire peu réactif est engagée sur une première couche organique par substitution nucléophile. L’autre extrémité hydrophobe (l’harpon) peut s’insérer dans la membrane et la stabiliser. Un mélange adapté, de ces molécules ancre-harpon avec d’autres purement hydrophiles (PEG, etc), apporte l’hydratation et la densité d’ancres nécessaire à l’interface pour maintenir la membrane éloignée du substrat, permettant ainsi l’intégration de protéines et le transport ionique à travers la membrane. Grâce au support conducteur, la dynamique des ions face aux membranes peut être étudiée par spectroscopie d’impédance électrochimique. Sa faible rugosité et semi-transparence permettent aussi l’utilisation de nombreuses autres techniques dont les microscopies optiques, exaltées ou de fluorescence. Localisées sur une électrode, ces bicouches ancrées s’ouvrent également aux applications biotechnologiquesLipid bilayers are the structural backbone of biological membranes and provide a two-dimensional environment for proteins. Tethered on a hydrophilic substrate, these biomimetic models are fluid, long-term stable and localized. In this regard, we propose a direct, cheap and versatile strategy of surface functionalization to tether membranes on a substrate adapted to their structural and dynamics study. The process is based on the functionalization of any flat metal thin film by the covalent binding of commercial surfactant molecules (Brij, …) as “anchor-harpoons”-like systems. Most of these molecules possess unresponsive –OH terminated groups on their hydrophilic moiety (anchor) that can bind a first organic layer by nucleophilic substitution. The opposite hydrophobic tail (harpoon) of the molecule can insert into the membrane and make it stable. An ideal mixing ratio of anchor-harpoons molecules with purely hydrophilic ones (PEG, …), provides the required hydration and density of anchors to the interface for tethering fluid membranes away from the substrate. A few nanometers distance enable ionic flows through the membrane and protein inclusion. The substrate conductivity enables studying ion dynamics facing the membrane by means of electrochemical impedance spectroscopy. Flatness and semi-transparency of the conductor opens the route to many other techniques’ including exalted light microscopy or fluorescence. Localized on electrodes, tethered bilayers further provide a biomimetic model and a support for biotechnology applications
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Sanchez-Adaime, Esteban. "Caractérisation électrique de diodes moléculaires associées à des nano-antennes plasmoniques pour convertir la lumière en électricité". Electronic Thesis or Diss., Aix-Marseille, 2022. http://www.theses.fr/2022AIXM0171.
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La technologie des antennes rectifiantes (rectennas), association d’une antenne pour convertir la lumière en courant alternatif et d’un composant redresseur pour obtenir un courant continu, promet une conversion à haut rendement de la lumière telle que le laissait penser la démonstration de William Brown en 1964 dans le domaine des micro-ondes. Parmi toutes les structures de rectennas développées, nous avons retenu et étudié celle de l’assemblage d’antennes patch colloïdales à base de nanocubes métalliques avec des diodes moléculaires qui jouent aussi le rôle de maintien mécanique des nanocubes sur le substrat métallique. Les molécules sont situées dans les cavités situées entre les bases des nanocubes et le substrat métallique. Les molécules envisagées sont les ferrocène-alcanedithiols. L’état de surface des substrats d’argent et d’or est optimisé grâce à l’emploi de la méthode de template-stripping et d’une étude couplant microscopie à force atomique et diffraction à rayons X. Les paramètres peuvent alors être optimisés pour avoir des surfaces d’argent et d’or très peu rugueuses, 1.5(±0.6) Å et 2.1(±0.4) Å respectivement, et majoritairement orientées (111). Sur ces substrats optimisés, les ferrocène-alcanedithiols sont déposés par immersion et réaction de click, puis caractérisés avec un eutectique de gallium-indium pour mesurer les densités de courant. Ces mesures révèlent un taux de rectification de 34.7 prouvant le comportement de diode moléculaire de nos ferrocène-alcanedithiols. La méthode de Langmuir-Blodgett a permis de réussir le dépôt de nanocubes sur les diodes moléculaires. L’épaisseur de la cavité comprenant les molécules a été estimée entre 2.6 et 2.9 nmThe technology of rectifying antennas (rectennas), a combination of an antenna to convert light into alternating current and a rectifier component to obtain direct current, promises a high efficiency conversion of light as suggested by William Brown's demonstration in 1964 in the microwave field.Among all the rectenna structures developed, we have selected and studied the assembly of colloidal patch antennas based on metal nanocubes with molecular diodes which also play the role of mechanical holding of the nanocubes on the metal substrate. The molecules are located in cavities between the bases of the nanocubes and the metal substrate. The molecules considered are ferrocene-alkanedithiols. The surface state of the silver and gold substrates is optimized by using the template-stripping method and by a study combining atomic force microscopy and X-ray diffraction. The parameters can then be optimized to have very flat silver and gold surfaces, 1.5(±0.6) Å and 2.1(±0.4) Å respectively, and mostly oriented (111). On these optimized substrates, ferrocene-alkanedithiols are deposited by immersion and click reaction, and then characterized with a Gallium-Indium eutectic to measure current densities. These measurements reveal a rectification rate of 34.7 proving the molecular diode behavior of our ferrocene-alkanedithiols. The Langmuir-Blodgett method successfully deposited nanocubes on the self-assembled molecular diodes, deposited using the two step click chemistry process, on the surface of the metal substrate. The thickness of the cavity containing the molecules was estimated between 2.6 and 2.9 nm
Actas de conferencias sobre el tema "Surfaces ultra-planes"
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Alasty, A., S. H. Alemohamad, R. H. Khiabani y Y. Khalighi. "Modeling and Analysis of an Ultra Light Slow Flyer With Variable Shape Control Surfaces Using Shape Memory Alloy Actuators". En ASME 7th Biennial Conference on Engineering Systems Design and Analysis. ASMEDC, 2004. http://dx.doi.org/10.1115/esda2004-58427.
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Applying flexible variable shape control surfaces (wing and elevator) structures is a way to increase efficiency and maneuverability of the planes, which is recently under research. In this paper, modeling of the flight of an unmanned ultra light plane is discussed. The modeling is done based on a real ultra light plane presented recently. To increase maneuverability of the plane, flexible variable shape structures are designed for the wing and the elevator. In design procedure, having an ultra light plane is considered. The elevator and the wing are used as control surfaces for longitudinal and lateral maneuvers respectively. Shape memory alloys (SMA) are used for reshaping the flexible structures of the wing and the elevator. Because of its high power and low weight and nearly unlimited resolution, SMA is best suited as the actuator of the reshaping wing and elevator structures. In flight dynamic modeling of an ultra light plane with variable shape wing, aerodynamic coefficients are needed. Coefficients are computed using computational fluid dynamics (CFD). To determine the reshaped structures, finite element models of structures are constructed in ANSYS®. Using finite element analysis (FEA), reshaped structures are produced and transferred to FLUENT® for CFD analysis. Aerodynamic coefficients with respect to reshaped structures are computed and related to actuator forces as functions. Also, aerodynamic coefficients and their derivatives with respect to flight parameters, like the angle of attack and the angular velocities are computed. Finally, the results are combined for the complete simulation in MATLAB/Simulink®.
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Honda, F. y M. Goto. "A Mechanism of Sliding on the Nanometer-Thick Ag Layers". En World Tribology Congress III. ASMEDC, 2005. http://dx.doi.org/10.1115/wtc2005-63818.
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Tribological performance of sub-nano to nanometer-thick Ag layers deposited on Si(111) have been examined to understand the role of surface thin layers to the wear and friction characteristics. The slider was made of diamond sphere of 3 mm in radius. Sliding tests were carried out in an ultra-high vacuum environment (lower than 4 × 10−8 Pa) and analyzed in-situ by Auger electron spectroscopy (AES) for the quantitative thickness-measurements, by reflection high-energy electron diffraction (RHEED) to clarify the substrate cleanliness and crystallography of the Ag films, and by scanning probe microscopy (SPM) for the morphology of the deposited/slid film surfaces. As the results, a minimum of the friction coefficient 0.007 was observed from the film thickness range of 1.5–10 nm, and exactly no worn particles were found after 100 cycles of reciprocal sliding. Results have directly indicated that solid Ag(111) sliding planes allowed to reduce the friction coefficient very low without any detectable wear particles, and Ag nanocrystallites in Ag polycrystalline layers increase the size to 20–40 nm order, during sliding. The friction coefficient was slightly dependent to the normal load. Results were discussed on the role of the surface atoms to the friction, and a mechanism of sliding on Ag thin layers.
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Yamamoto, A. y E. Outa. "Low-Speed Annular Cascade Tests of an Ultra-Highly Loaded Turbine With Tip Clearance: Part 1 — Near Design Incidence". En ASME 1999 International Gas Turbine and Aeroengine Congress and Exhibition. American Society of Mechanical Engineers, 1999. http://dx.doi.org/10.1115/99-gt-212.
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Annular cascade tests were carried out to study the performance of an ultra-highly loaded turbine cascade (UHLTC) with a design turning angle of 160 deg. The UHLTC is for applications to future high-temperature gas turbine engines. This paper describes details of the secondary flows and the associated total pressure losses of the UHLTC obtained at a test incidence of −2.7 deg. The cascade flows were measured with a small five-hole Pitot probe located at 21 traverse measurement planes upstream, inside and downstream of the UHLTC. From the measurements, detailed flow structures and the loss evolution process were analyzed. Flow visualization tests were also carried out to see more details of the flows on the blade surfaces, on the endwalls and in the blade tip gap. Various flow separations and various small vortices associated with the passage and leakage vortices, such as corner vortices and edge vortices, separation bubbles, and the associated reverse flows, were seen. These were clarified from various flow lines showing separation, attachment/reattachment and division of each flow. The results obtained from the flow visualization were compared with those from the traverse measurements. Large total pressure losses occur inside the cascade passage as well as downstream of the cascade. Various strong passage vortices, strong leakage vortex, strong swirling flows upstream and downstream of the cascade and their associated various flow separations, are the main causes of the loss generation. The coefficient of total pressure loss generated inside the cascade was 0.28 at the test near-design incidence. The actual turning angle of the flow from the cascade inlet and the cascade outlet was 146 deg. Some schematic drawings of the flow structures in the present UHLTC were also given. The basic flow structures did not differ significantly from those seen in the conventional cascades with much smaller turning angles, except for stronger passage vortices, larger internal loss and larger downstream mixing loss due to the very high turning angle of the UHLTC.
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Treiber, M., R. S. Abhari y M. Sell. "Flow Physics and Vortex Evolution in Annular Turbine Cascades". En ASME Turbo Expo 2002: Power for Land, Sea, and Air. ASMEDC, 2002. http://dx.doi.org/10.1115/gt2002-30540.
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The evolution of flow vortices downstream of annular cascades with a specific focus upon the association between vorticity and the mechanisms of aerodynamic loss generation has been experimentally investigated. Spatially-resolved experimental results on an unstructured measurement pattern is used to identify small scale flow structures on the surface of the investigated blades and downstream of two different cascades. The test case comparison is based upon two moderately loaded turbine blade profiles, one stacked prismatically and the other on a bowed stacking line. The design operating conditions for both cascade is at a nominal exit Mach number of 0.5. The measurements were made using an ultra miniature (0.9 mm Dia) 5-hole probe. The measurement were made on 4 planes behind and one plane in front of the trailing and leading edge of the cascade respectively. The experimental results clearly show the influence of the flow structure on the evolution of the stream wise vorticities behind the blading. Detailed measurements are used to compare and evaluate the mixing processes downstream of these two cascades. It is shown that the interaction of the different vortices with the endwall boundary layer has a substantial impact on the overall total pressure loss generation.
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Zhou, Chao, Howard Hodson y Christoph Himmel. "The Effects of Trailing Edge Thickness on the Losses of Ultra-High Lift LP Turbine Blades". En ASME Turbo Expo 2013: Turbine Technical Conference and Exposition. American Society of Mechanical Engineers, 2013. http://dx.doi.org/10.1115/gt2013-94029.
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Experimental, numerical and analytical methods were used to investigate the effects of the blade trailing edge thickness on the profile loss of ultra-high lift low pressure turbine blades. Two cascades, the T106C and the T2, were studied. The loss obtained based on the data at the blade trailing edge plane and the plane 0.3 Chord downstream of the trailing edge agree with each other for T106C blade with and without upstream wakes at different Reynolds numbers. The blade profile losses were broken down as the suction surface boundary loss, the pressure side boundary loss and the mixing loss downstream of the trailing edge for six Reynolds numbers. Trailing edge thicknesses varying from 1.4% to 4.7% Pitch were investigated at a Reynolds number of 210000. It was found that the flow distributions across the passage at the trailing edge planes were highly non-uniform. In particular, and as a result, the trailing edge base pressure was higher than the mixed-out static pressure, so the contribution of the base pressure to the mixing loss downstream of the trailing edge plane was to reduce the loss. When the trailing edge thickness increases, there are three main effects: 1) The area with high base pressure region increase, which tends to reduce the downstream mixing loss; 2) The base pressure reduces, which tends to increase the loss; 3) The flow diffusion downstream of the trailing edge, which tends to increase the loss. The overall result is the combined effect. For the T106C cascade, increasing the trailing edge thickness from 1.9% Pitch to 2.8% Pitch has a small effect on the loss. Further increasing the trailing edge thickness increases the loss. The T2 blade has a higher lift than the T106C blade, so the effects of the base pressure in reducing the mixing loss downstream of the trailing edge is more evident. The experimental results show that the profile loss first decreases and then increases as the trailing edge thickness increases. CFD, using the transition k-ω SST model and the k-ω SST model, provides good predictions of the aerodynamic performance. It was used to study the cases with trailing edge thicknesses of 1.4% Pitch and 2.9% Pitch. The profile loss is almost the same for these two trailing edge thickness. The results show that it is possible to use thicker blade trailing edges in low pressure turbines without aerodynamic penalty. This can lead to benefits in terms of mechanical integrity and manufacturing cost reductions.