Artigos de revistas sobre o tema "UHBR fan"

Abstract In the frame of the CA3ViAR Clean Sky 2 (Composite fan Aerodynamic, Aeroelastic, and Aeroacoustic Validation Rig), the main objective is to design a low-speed (low-transonic) fan typical of a future large aircraft UHBR engine, in terms of aerodynamic shaping as well as structural design and analysis to make sure the test article experiences aerodynamic and aeroelastic instabilities in an expected way during wind tunnel (WT) operations. Eventually, open access to all the produced models will be provided, with the objective to establish an “open test-case” for the whole European scientific community, unique in the engine fans landscape. A preliminary fan stage design is presented in this paper, details about the aerodynamic design process and the results of the CFD analysis of the stage are shown. The present UHBR fan design fulfils the initial aerodynamic requirements and represents the starting point for the structural and aeroelastic analysis within the multidisciplinary design process employed to design the final CA3ViAR fan stage.

The application of composite fans enables disruptive design possibilities but increases sensitivity to multi-physical resonance between aerodynamic, structure dynamic and acoustic phenomena. As a result, aeroelastic problems increasingly set the stability limit. Test cases of representative geometries without industrial restrictions are a key element of an open scientific culture but are currently non-existent in the turbomachinery community. In order to provide a multi-physical validation benchmark representative of near-future UHBR fan concepts, the open-test-case fan stage ECL5 was developed at Ecole Centrale de Lyon. The design intention was to develop a geometry with high efficiency and a wide stability range that can be realized using carbon fibre composites. This publication aims to introduce the final test case, which is currently fabricated and will be experimentally tested. The fan blades are composed of a laminate made of unidirectional carbon fibres and epoxy composite plies. Their structural properties and the ply orientations are presented. To characterize the test case, details are given on the aerodynamic design of the whole stage, structure dynamics of the fan and aeroelastic stability of the fan. These are obtained with a state-of-art industrial design process: static and modal FEM, RANS and LRANS simulations. Aerodynamic analysis focuses on performance and shows critical flow structures such as tip leakage flow, radial flow migration and flow separations. Mechanical modes of the fan are described and discussed in the context of aeroelastic interactions. Their frequency distribution is validated in terms of resonance risk with respect to synchronous vibration. The aeroelastic stability of the fan is evaluated at representative operating points with a systematic approach. Potential instabilities are observed far from the operating line and do not compromise experimental campaigns.

Purpose The choke flutter is a fluid-structure interaction that can lead to the failure of fan or compressor blade in turbojet engines. In ultra high bypass ratio (UHBR) fans, the choke flutter appears at part-speed regimes and at low or negative incidence when a strong shock-wave chokes the blade to blade channel. The purpose of this study is to locate the main excitation sources and improving the understanding of the different work exchange mechanisms. This work contributes to avoiding deficient and dangerous fan design. Design/methodology/approach In this paper, an UHBR fan is analyzed using a time-linearized Reynolds-averaged Navier–Stokes equation solver to investigate the choke flutter. The steady-state and the imposed vibration (inter blade phase angle, reduced frequency and mode shape) are selected to be in choke flutter situation. Superposition principle induced by the linearization allow to decompose the blade in numerous small subsections to track the contribution of each local vibration to the global damping. All simulations have been performed on a two-dimensional blade to blade extraction. Findings Result analysis points to a restricted number of excitation sources at the trailing edge which induce a large part of the work exchange in a limited region of the airfoil. Main phenomena suspected are the shock-wave motion and the shock-wave/boundary layer interaction. Originality/value An original excitation source tracking methodology allowed by the linearized calculation is addressed and applied to a UHBR fan test case.

Abstract The ambition of the CA3ViAR project is to design an open test case fan that experiences instability mechanisms, which are representative for ultra-high bypass ratio (UHBR) fans of civil aircrafts, and to perform a comprehensive experimental investigation to measure aerodynamic, aeroelastic and aeroacoustic performance in a wide range of operational conditions. Experimental tests will be performed in the Propulsion-Test-Facility (PTF) of the Institute of Jet Propulsion and Turbomachinery (IFAS) of Technische Universität Braunschweig, Germany. The final objective of the project is to provide an open test case for the entire research community, with geometries, numerical and experimental results to establish a new reference for composite UHBR fan design. This will support the development of new methods and tools for the development of safer, lighter and more efficient composite fans for greener UHBR engines. In this work the preliminary design of the low transonic fan (LTF) to be used as test article, whose main requirement is to be operated in a safe and controlled way in conditions of aerodynamic and/or aeroelastic instability during wind tunnel operations, is presented. More in particular, consolidated aerodynamic design, strategy adopted to drive the structural design, flutter analysis taking into account acoustic reflection at the intake, dynamic and stress analyses, as well as aeroacoustic measurement optimization are presented and discussed. The preliminary mechanical design of composite blades and the rotor hub, together with the rotor instrumentation and related studies to embed sensors in the composite blades, are also part of this article, and complemented by manufacturing trials and demonstration tests give the full picture of all the project activities up to the preliminary design review.

Abstract Due to ecological requirements, the bypass-ratio of future civil turbofan engines will be increased. This leads to ultra-high bypass ratio (UHBR) engines, which bring in new challenges concerning the blade material, structural integration, and aeroelastic behaviour of the fan. The ambition of the project Composite fan Aerodynamic, Aeroelastic, and Aeroacoustic Validation Rig (CA3ViAR) is to design and test an open-test-case fan that experiences instability mechanisms, which are representative for UHBR fans of civil aircrafts. The optical measurement technique Digital Image Correlation (DIC) allows for the spatial measurement of deformations. The aim is to apply this technique to measure rotor blade deformation under loading and its vibration due to aeroelastic phenomena to get a better understanding of the structural and aeroelastic behaviour of the composite fan. However, the high rotational speeds, blade vibration frequencies, and expected amplitudes pose challenges for the measurement setup. In this work, a high-speed DIC system is prepared and tested to measure deformation and vibration of a fast rotating blade. Additionally, the requirements for the DIC setup are defined and presented. The expected blade tip speeds in the CA3ViAR project are up to 295 m/s and the blade frequencies of interest up to 650 Hz. Therefore, particular emphasis must be given to the setup in order to eliminate motion blur due to the rotation and to achieve the required frequency. This leads to a setup with synchronised high-speed cameras and a laser to measure frequency vibrations up to 1 kHz with an exposure time below 210 ns. Test measurements are conducted on a stationary beam and an axial blower with a max. blade tip speed of 50 m/s. A data analysis method is developed and described to eliminate the rigid body rotation, analyse the deformation of each blade compared to a reference condition, and analyse the spatial vibration in the frequency domain for a high number of data points per time step. The results of the structural beam are in agreement with the reference measurements and numerical simulations. By analysing the spatial vibration modes of the axial blower, the 1F-flap mode is identified at 38 Hz. In conclusion, this DIC setup shows promising results for future deformation and vibration measurements on a scaled UHBR fan.

Abstract In this paper, the effect of a 3D blade design on the aerodynamic, aeroelastic and structural behavior of a scaled UHBR fan is investigated numerically. First, an initial sensitivity analysis for the geometrical design features sweep and lean as well as an adaption of the thickness position in the fan hub region is conducted. Positive sweep is found to benefit the total pressure ratio, while positive lean improves the polytropic efficiency of the fan stage. Moving the maximum thickness position upwards leads to decreased flow turning and total pressure ratio. The mode shape and by that the twist-to-plunge ratio of the first mode is significantly influenced by the modifications. Thus, changing the aerodynamic damping of the blade and influencing the flutter behavior of the fan. Additionally, the fan displacements under aerodynamic and rotational loads are affected. For the fan presented a positive lean causes the blade to bend towards the pressure side when subjected to inertial forces, countering deformation from aerodynamic loads. Thickness adaption moves the shear center of the cross sections to the back. These results are used to optimize the fan blade behavior to achieve the project’s objectives. A final design, which satisfies the aerodynamic, aeroelastic and structrual needs of the CA3ViAR fan stage, is presented.

AbstractCivil aviation is aiming at fuel efficient aircraft concepts. Propulsion systems using boundary layer ingestion (BLI) are promising to reach this goal. The focus of this study is on the DLR UHBR fan stage of a tube and wing aircraft with rear-integrated engines. In this integration scenario the propulsion system and especially the fan stage receives distorted inflow in steady-state flight conditions. The distortion pattern and distortion intensity are dependent on the operating conditions. Consequently, the interaction of the fan and the distortion changes over the flight envelope. The first part of the paper aims at gaining knowledge of the BLI fan performance in the operating points end of field, approach, cruise (CR) and top of climb (TOC) using high-fidelity, unsteady RANS approaches. The analysis includes fan map performance metrics and a deeper insight into the flow field at CR and TOC. The preliminary design of a fan stage requires fast turn-around times, which are not fulfilled by high-fidelity approaches. Therefore, a fast, throughflow-based methodology is developed, which enables aerodynamicists to design distortion-tolerant fans. The main characteristics of the methodology is outlined in the second part. Consequently, the methodology is taken advantage of to investigate parameter sensitivities in terms of tip speed, blade thickness, solidity, the annulus geometry and a non-axisymmetric stator. This study suggests that distortion-tolerant fans should be designed at higher tip speeds than conventional design experience recommends to limit the local operating point excursion.

AbstractCivil aviation is aiming at fuel efficient aircraft concepts. Propulsion systems using boundary layer ingestion (BLI) are promising to reach this goal. The focus of this study is on the DLR UHBR fan stage of a tube and wing aircraft with rear-integrated engines. In this integration scenario the propulsion system and especially the fan stage receives distorted inflow in steady-state flight conditions. The distortion pattern and distortion intensity are dependent on the operating conditions. Consequently, the interaction of the fan and the distortion changes over the flight envelope. The first part of the paper aims at gaining knowledge of the BLI fan performance in the operating points end of field, approach, cruise (CR) and top of climb (TOC) using high-fidelity, unsteady RANS approaches. The analysis includes fan map performance metrics and a deeper insight into the flow field at CR and TOC. The preliminary design of a fan stage requires fast turn-around times, which are not fulfilled by high-fidelity approaches. Therefore, a fast, throughflow-based methodology is developed, which enables aerodynamicists to design distortion-tolerant fans. The main characteristics of the methodology is outlined in the second part. Consequently, the methodology is taken advantage of to investigate parameter sensitivities in terms of tip speed, blade thickness, solidity, the annulus geometry and a non-axisymmetric stator. This study suggests that distortion-tolerant fans should be designed at higher tip speeds than conventional design experience recommends to limit the local operating point excursion.

In the context of an increased focus on fuel efficiency and environmental impact, turbofan engine developments continue towards larger bypass ratio engine designs, with Ultra-High Bypass Ratio (UHBR) engines becoming a likely power plant option for future commercial transport aircraft. These engines promise low specific fuel consumption at the engine level, but the resulting size of the nacelle poses challenges in terms of the installation on the airframe. Thus, their integration on an aircraft requires careful consideration of complex engine–airframe interactions impacting performance, aeroelastics and aeroacoustics on both the airframe and the engine sides. As a partner in the EU funded Clean Sky 2 project ASPIRE, the DLR Institute of Aerodynamics and Flow Technology is contributing to an investigation of numerical analysis approaches, which draws on a generic representative UHBR engine configuration specifically designed in the frame of the project. In the present paper, project results are discussed, which aimed at demonstrating the suitability and accuracy of an unsteady RANS-based engine modeling approach in the context of external aerodynamics focused CFD simulations with the DLR TAU-Code. For this high-fidelity approach with a geometrically fully modeled fan stage, an in-depth study on spatial and temporal resolution requirements was performed, and the results were compared with simpler methods using classical engine boundary conditions. The primary aim is to identify the capabilities and shortcomings of these modeling approaches, and to develop a best-practice for the uRANS simulations as well as determine the best application scenarios.

Abstract Experimental monitoring of blade vibration in turbomachinery is typically based on blade-mounted strain gauges. Their signals are used to derive vibration amplitudes which are compared to previously determined modal scope limits, including a safety factor. According to industrial guidelines, this factor is chosen conservatively to ensure safe operation of the machine. For the experimental campaign with the open test case fan ECL5, which is representative for modern lightweight UHBR architectures, it is planned to conduct measurements close to the stability limit. These investigations require a close approach to the limit and hence demand for accurate quantification of vibration amplitudes to ensure secure operation without exhaustive safety margins. It is required that the surveillance is possible in real time and not only in post-processing. Historically, short-time Fourier transformations of vibration sensors are used, but the complex nature of coupled phenomena near the stability limit has an influence on the amplitude accuracy, depending on evaluation parameters. This was demonstrated in a previous study using fast response wall pressure transducers. The present study investigates the influence on blade vibration data of a modern composite material transonic fan. Different methods are compared, sensitivity to evaluation parameters is analyzed and guidelines are given for fast and robust surveillance of critical vibration modes.

In modern aircraft engines, the low-pressure compressor (LPC) is subjected to a flow characterized by strong wakes and secondary flows from the upstream fan. This concerns ultra-high bypass ratio (UHBR) turbofan engines, in particular. This paper presents the aerodynamic and aeroelastic sensitivities of parametric variations on the LPC, driven by the design considerations in the upstream fan. The goal of this investigation was to determine the influence of design-based geometry parameter variations on the LPC performance under realistic inlet flow distributions and the presence of an s-duct. Aerodynamic simulations are conducted at the design and off-design operating points with the fan outflow as the inlet boundary conditions. Based on the aerodynamic results, time-linearized unsteady simulations are conducted to evaluate the vibration amplitude at the resonance operating points. First, the bypass ratio is varied by reducing the channel height of the LPC. The LPC efficiency decreases by up to 1.7% due to the increase in blockage of the core flow. The forced response amplitude of the rotor decreases with increasing bypass ratio due to increased aerodynamic damping. Secondly, the fan cavity leakage flow is considered as it directly affects the near hub fan flow and thus the inflow of the LPC. This results in an increased total-pressure loss for the s-duct due to mixing losses. The additional mixing redistributes the flow at the s-duct exit leading to a total-pressure loss reduction of 4.3% in the first rotor at design point. This effect is altered at off-design conditions. The vibration amplitude at low speed resonance points is increased by 19% for the first torsion and 26% for second bending. Thirdly, sweep and lean are applied to the inlet guide vane (IGV) upstream of the LPC. Despite the s-duct and the variable inlet guide vane (VIGV) affecting the flow, the three-dimensional blade design achieves aerodynamic and aeroelastic improvements of rotor 1 at off-design. The total-pressure loss reduces by up to 18% and the resonance amplitude more than 10%. Only negligible improvements for rotor 1 are present at the design point. In a fourth step, the influence of axial gap size between the stator and the rotor rows in the LPC is examined in the range of small variations which shows no distinct aerodynamic and aeroelastic sensitivities. This finding not only supports previous studies, but it also suggests a correlation between mode shapes and locally increased excitaion with increasing axial gap size. As a result, potential design improvements in future fan-compressor design are suggested.

Experimental monitoring of blade vibration in turbomachinery is typically based on blade-mounted strain gauges. Their signals are used to derive vibration amplitudes which are compared to modal scope limits, including a safety factor. According to industrial guidelines, this factor is chosen conservatively to ensure safe operation of the machine. Within the experimental campaign with the open-test-case composite fan ECL5/CATANA, which is representative for modern lightweight Ultra High Bypass Ratio (UHBR) architectures, measurements close to the stability limit have been conducted. Investigation of phenomena like non-synchronous vibrations (NSV) and rotating stall require a close approach to the stability limit and hence demand for accurate (real-time) quantification of vibration amplitudes to ensure secure operation without exhaustive safety margins. Historically, short-time Fourier transforms of vibration sensors are used, but the complex nature of the mentioned coupled phenomena has an influence on amplitude accuracy, depending on evaluation parameters, as presented in a previous study using fast-response wall-pressure transducers. The present study investigates the sensitivity of blade vibration data to evaluation parameters for different spectral analysis methods and provides guidelines for fast and robust surveillance of critical vibration modes.

Future UHBR (Ultra-High Bypass-Ratio) engines might cause serious ‘turbine noise storms’ but, at present, turbine noise prediction capability is lacking. The large turning angle of the turbine blade is the first major factor deserving special attention. The RANS (Reynold Averaged Navier–Stokes equation)-informed (here called RI) method and LINSUB (the bound vorticity 2D model LINearized SUBsonic flow in cascade), developed to predict fan broadband noise, coupled with a two-flat-plates (here called TP) assumption for the turbine blade, is applied here, and one autonomous rapid RI-TP model for predicting turbine wake interaction broadband noise has been developed. Firstly, taking the single axial turbine test rig NPU-Turb as the object, both the experimental data and the DDES/AA (delayed Detached Eddy Simulation/Acoustic Analogy) hybrid model have been used to validate the RI-TP model. High consistency in the medium and high frequencies among the three designed and off-designed rotation speeds indicates that the RI-TP model has the ability to predict turbine broadband noise rapidly. And compared with the original RANS-informed method, with one thin-flat-plate assumption on the blade, the RI-TP model can enhance the PWL (sound power level) in almost the whole spectral range below 10 KHz, which, in turn, is closer to the experimental data and the DDES/AA prediction results. The PWL trend with a ‘dividing point’ position is also studied. The spectrum would move up or down if the location is away from true value. In addition, the extraction location for turbulence as an input for the RI-TP model is negligible. In the future, multi-stage characteristics and the blade thickness effect should be further considered when predicting turbine noise.

Das 1999 veröffentlichte Proust-Lexikon von Philippe Michel-Thiriet umfasst neben zahlreichen biographischen Daten ein »Lexikon der Personen in der Recherche« sowie ein »Lexikon der Orte der Recherche«. Es gibt jedoch kein Lexikon der Dinge der Recherche: kein Verzeichnis der Möbel im Salon von Madame Verdurin, keine Notiz zur »Feindseligkeit der violetten Vorhänge« im Hotel in Balbec, zum vergessenen Fächer der Königin von Neapel oder der Hängelampe im Esszimmer von Combray. Gehören diese Dinge demnach nicht dazu? Handelt es sich um Uneigentliches, um Beiwerk oder Requisiten? Oder sind diese Objekte im Ordnungssystem eines Lexikons einfach nicht adressierbar? Aber warum? Der Beitrag geht diesen Fragen nach und versucht, den Gegenständen in À la recherche du temps perdu die gleiche Aufmerksamkeit zu schenken, die in der Regel nur den handelnden Charakteren des Romans gewidmet wird. Zugleich geht es um die Hinterlassenschaften von Prousts Existenz, die gelegentlich mit Dingen im Roman identifiziert wurden. Aber wie kann ein reales Ding in einen Roman eingehen? Und findet es jemals wieder heraus? </br></br>Philippe Michel-Thiriet's , published in 1999, contains beside biographical data a »lexicon of characters« and a »lexicon of places in the Recherche.« There is, however, no »lexicon of objects:« No directory of the furniture in the parlor of Madame Verdurin, no comment on the »enmity of the violet curtains« in the Hotel of Balbec, the Queen of Naple's forgotten fan or the hanging lamp in the dining room in Combray. Are these objects thus not part of the novel? Are they mere accessories and requisites? Or are they simply not classifiable in the systematic categories of a lexicon? But why? The paper addresses these questions and tries to give the objects in the attention that usually only the novel's protagonists receive. At the same time, it deals with the legacies of Proust's existence that are occasionally identified with the objects in the novel. But how can a real object enter a novel? And does it ever find its way back out?

Har norsk økonomiutdanning fått et paradigmeskift med nye fag for etikk, samfunnsansvar og bærekraft? Faglig innovasjon for bærekraftsmål ved 15 institusjoner for økonomi og administrasjon i Norge kan tyde på det. Universitets- og høgskolerådets strategiske enhet for økonomi og administrasjon (UHR-ØA) i Norge gav i 2018 anbefaling om ny faglig satsing på etikk, samfunnsansvar og bærekraft. Det var første gang på lang tid at bachelorstudiets faglige søyler ble utvidet fra de fire disiplinene: Bedriftsøkonomi, samfunnsøkonomi, administrasjonsfag og metodefag. En ny faglig stolpe ble etablert: Etikk, samfunnsansvar og bærekraft (ESAB). Alle 15 institusjoner som utdanner kandidater i Norge innen økonomi og administrasjon i Norge ble anmodet om å innføre kurs på 7.5 – 15 studiepoeng dedikert til ESAB-fag. Artikkelen baserer seg på tekst og kvantitative data fra institusjonsundersøkelser fra 2012, 2017 og 2020 om hvordan norske institusjoner «bottom up» har endret sine fagporteføljer og kurs for å bidra til ansvarlig utdanning. Artikkelen viser også effekter av «top down» anbefalinger om gi alle studenter ESAB-undervisning fra UHR-ØA. Data og problemstilling er drøftet med Frank Geels’ multi-level perspective, Andrew Abbots begrep om profesjonell kunnskap og jurisdiksjon og elementer fra institusjonsteori.

The long-term future of large aircraft engines is seen to lie in ‘ultra high bypass ratio’ (UHB) powerplant. One possibility for such engines is to use reduction gearboxes to allow the relatively high-speed turbine and the low-speed fan to run at their optimum efficiencies. An important constraint upon the application of these gearboxes is the weight and drag of the cooling system. This paper presents an analysis of cooler requirements for a transmission with its own integral oil system. Results are presented for a 4.5 MW gearbox typical of the more powerful turbo prop engines currently in civil service. The importance of transmission efficiency and scavenge temperature in defining the necessary size (thus weight) of the cooler is demonstrated. It is shown that active control of the cooler duct results is further efficiency improvements.

Abstract Introduction: Glycogen is a readily deployed intracellular energy storage macromolecule composed of branched chains of glucose. Although glycogen primarily occurs in the liver and muscle, it can be found in most tissues throughout the body, and its metabolism has been shown to be important in cancers and immune cells. Robust analysis of glycogen turnover requires stable isotope tracing plus a reliable means of quantifying total and labeled glycogen derived from precursors such as 13C6-glucose. Current methods for analyzing glycogen are time- and sample-consuming, at best semi-quantitative, and unable to measure stable isotope enrichment. Methods: We have developed a microscale method for quantifying both intact and acid-hydrolyzed glycogen by ultra-high-resolution Fourier transform mass spectrometric (UHR-FTMS) and/or NMR analysis in stable isotope resolved metabolomics (SIRM) studies. Polar metabolites, including intact glycogen and their 13C positional isotopomer distributions were first measured in crude biological extracts by high resolution NMR, followed by rapid and efficient acid hydrolysis to glucose in 1 N HCl for 10 minutes at 110 °C under a N2 atmosphere in a microwave-assisted synthesis reactor. The resulting glucose and its 13C isotopologues were then analyzed by UHR-FTMS and/or NMR. Results: We optimized the microwave digestion time, temperature, and oxygen purging in terms of recovery versus degradation and found 10 minutes at 110-115 °C to give &gt; 90% recovery. The method was applied to track the fate of 13C6-glucose in primary human lung BEAS-2B cells, human macrophages, murine liver and patient-derived tumor xenograft (PDTX) in vivo, and the fate of 2H7-glucose in ex vivo lung organotypic tissue cultures of a lung cancer patient. We showed the incorporation of 13C6-glucose into glycogen and its metabolic intermediates, UDP-Glucose and glucose-1-phosphate, both in terms of the 13C levels and fractional enrichment, thereby demonstrating the utility of the method in tracing glycogen turnover in cells and tissues. Conclusions: The method offers a quantitative, sensitive, and convenient means to analyze glycogen turnover in mg amounts of complex biological materials. Keywords: glycogen turnover; 13C6-glucose, stable isotope resolved metabolomics (SIRM); microwave-assisted hydrolysis. Citation Format: Andrew N. Lane, Timothy L. Scott, Juan Zhu, Teresa A. Cassel, Sara Vicente-Munoz, Penghui Lin, Richard M. Higashi, Teresa W-M Fan. Small-scale microwave-assisted acid hydrolysis method for glycogen determination and turnover in tumors using Stable Isotope Resolved Metabolomics [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 2324.

Интерес к изучению систем, содержащих сульфиды формулой АIВIIIСVI2, обусловлен, прежде всего, открывающимися возможностями их практического использования в изготовлении нелинейных оптических приборов, детекторов, солнечных батарей, фотодиодов, люминофоров и др. Поэтому в связи с поиском новых перспективных материаловна основе тиогаллата серебра и железа целью этой работы является исследование квазибинарного разреза FeGa2S4–AgGaS2 четырехкомпонентной системы Fe–Ag–Ga–S.Синтез сплавов системы AgGaS2–FeGa2S4 проводили из лигатур с использованием высокой чистоты: железа – 99.995 %, галлия – 99.999 %, серебра – 99.99 % и серы – 99.99 %. Исследование сплавов проводили методами дифференциально-термического, рентгенофазового, микроструктурного анализов, а также измерением микротвердости и определениемплотности.Методами физико-химического анализа впервые изучена и построена Т-x фазовая диаграмма разреза AgGaS2–FeGa2S4, который является внутренним сечением квазитройной системы FeS–Ga2S3–Ag2S. Установлено, что система относится к простому эвтектическому типу. Состав эвтектической точки: 56 мол. % FeGa2S4 и Т = 1100 К. На основе исходных компонентов были определены области твердых растворов. Растворимость на основе FeGa2S4 и AgGaS2 при эвтектической температуре достигает до 10 и 16 мол. % соответственно. С уменьшением температуры твердые растворы сужаются и при комнатной температуре составляют на основе тиогаллата железа (FeGa2S4) 4 мол. % AgGaS2,а на основе тиогаллата серебра (AgGaS2) 11 мол. % FeGa2S4. ЛИТЕРАТУРА 1. Zhаo B., Zhu S., Li Z., Yu F., Zhu X., Gao D. Growth of AgGaS2 single crystal by descending cruciblewith rotation method and observation of properties. Chinese Sci. Bull. 2001; 46(23): 2009–2013. DOI:https://doi.org/10.1007/BF029019182. Горюнова Н. А. Сложные алмазоподобные полупроводники. М.: Сов. радио; 1968. 215 с.3. Абрикосов Н. Х., Шелимова Л. Е. Полупроводниковые материалы на основе соединений АIVBVI..М.:Наука; 1975. 195 с.4. Kushwaha A. 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AbstractA low-noise low-pressure ultra-high-bypass-ratio fan stage to be implemented in the next generation of aircraft engines is described and evaluated acoustically with semi-empirical and analytical methods suited for preliminary design. As expected, good reduction potentials are observed for the jet noise and fan tonal noise components when the UHBR design is compared to current fans in service. However, concerns are identified for fan broadband noise, which are attributed to the off-design operation of the UHBR fan too close from its stability limit. By unloading the fan and thus reducing the size of the rotor wakes, the variable-area nozzle provides a substantial fan broadband noise reduction with a nozzle opened by around 15% from its design value. Alternatively, with the variable-pitch fan, closing the rotor blades by roughly 5° turns out to be an even more effective method to reduce fan noise, as the unloading mechanism is combined with a stronger tilting of the rotor wakes and a lower intra-stage flow Mach number. Opening the nozzle or closing the blades beyond the setting that provides the best fan efficiency is not recommended as the acoustic benefit progressively vanishes, whereas technical feasibility becomes more challenging. Finally, the presence of one of these systems may allow for the design of a low-solidity rotor, with a smaller contribution from the rotor wakes and thus a weaker fan noise emission.

Abstract A composite fan stage representative of a modern Ultra High Bypass Ratio (UHBR) architecture has been investigated experimentally on a novel test facility at Ecole Centrale de Lyon. These measurements show indications for strong overloading of the tip region resulting in extensive blockage of the blade passage. The performance of the fan is analyzed with extensive instrumentation including radial profiles upstream and downstream of the rotor. Unsteady pressure measurements help to interpret the flow structure in the tip region. The results are presented across a range of operating points on the design speedline. At the stability limit, the machine suffers from non-synchronous vibrations, which result from small-scale aerodynamic disturbances propagating between the leading edges. Detailed analysis of the occurring waveforms is presented for two operating speeds. In order to further analyze the observed phenomena, a numerical study has been conducted using the Reynolds-averaged Navier–Stokes (RANS) solver elsA. The results of steady calculations are discussed in comparison with the detailed experiments. Unsteady simulations near the stability limit accurately predict the aerodynamic disturbances observed during non-synchronous vibrations (NSV). The obtained results are unusual for typical state-of-the-art transonic fans, as they show the same behavior as high-pressure compressor front stages, dominated by a blockage caused by tip-leakage flow. Even though flutter is not observed, the observed non-synchronous vibration mechanism is a critical aeroelastic phenomenon which is of great interest for future designs of low-speed fans.

Ultra-high bypass ratio (UHBR) engines are designed as compact as possible and are characterized by a short asymmetric air inlet and heterogeneous outlet guide vanes (OGVs). The flow close to the fan is therefore circumferentially nonuniform (or distorted) and the resulting noise might be impacted. This is studied here at take-off conditions by means of a simulation of the unsteady Reynolds-averaged Navier–Stokes (URANS) equations of a full-annulus fan stage. The model includes an asymmetric air inlet, a fan, heterogeneous OGVs, and homogeneous inlet guide vanes (IGVs). Direct acoustic predictions are given for both inlet and aft noises. A novel hydrodynamic/acoustic splitting method based on a modal decomposition is developed and is applied for the aft noise analysis. The noise mechanisms that are generally considered (i.e., interaction of fan-blade wakes with OGVs and fan self-noise) are shown to be impacted by the distortion. In addition, new sources caused by the interaction between the stationary distortion and the fan blades appear and contribute to the inlet noise.

Abstract With the advancement of modern fan architectures the lack of experimental benchmarks for the research community became apparent in recent years. Enormous effort in method development could not be validated on representative geometries and motivated the development of the open-test-case ECL5/CATANA. A carbon fibre fan stage has been designed by Ecole Centrale de Lyon and shared with the community in 2021. The fan is representative of modern UHBR architectures with sonic design speed. The reference configuration has been investigated experimentally with multi-physical instrumentation. In this publication the results of the first experimental campaign are presented with a detailed analysis of the aerodynamic performance and system symmetry. The presented results comprise full stage mappings across the whole operating range for three main speedlines (55%, 80% and 100%) using performance rakes, unsteady wallpressure arrays, tip-clearance and stagger-angle measurements. Radial profiles of intake boundary layer and rotor-exit conditions at selected conditions complete the full validation dataset for steady and unsteady aerodynamic simulations. Results are discussed in comparison to blind-test RANS simulations of different international institutes. Significant predicition inaccuracies of the tip flow and corner separations of the stator are observed and reveal the requirement of real-blade-geometry measurements at running conditions. This paper is accompanied by a publication with a focus on aeroelastic instabilities observed near the stability limit. The results represent a comprehensive dimensional benchmark dataset and allow method validation on multiple levels of fidelity for the aerodynamic and aeroelastic research community.

Abstract Research of the past decades has shown that the operating range of modern fans and compressors is often limited by aeroelastic phenomena before the onset of pure aerodynamic instability. Prediction of these mechanisms is challenging for state-of-the-art numerical methods, particularly for configurations with flexible wide-chord blades. To provide a benchmark configuration for the community, the composite-material fan stage ECL5, representative of near future Ultra-High-Bypass Ratio architectures, has been designed at Ecole Centrale de Lyon and recently shared as an open-test-case. In research program CATANA, different configurations with variable tuning and intake geometries are investigated experimentally, and here we present a comprehensive aeroelastic study of the tuned reference configuration. The study encompasses the investigation of the whole subsonic and transonic operating range using multi-physical instrumentation. A characterization of structural properties under running conditions is analyzed in comparison to individual blade measurements and FEM-predictions. The stability limit is investigated at different speedlines. At transonic conditions, rotating stall occurred without aeroelastic precursors. Severe non-synchronous-vibrations were observed at subsonic speeds and limited the operating range before the onset of rotating stall. Through a detailed analysis of the aeroelastic coupling mechanism, a full characterization of interacting modes is presented. The challenging prediction of this coupled phenomenon and the discrepancy to aeroelastic simulations are discussed. The results are a promising benchmark for future method development, particularly involving high-fidelity methods.

Abstract The onset of non-synchronous-vibrations have been predicted for a composite open-test-case UHBR fan geometry by time-linearized simulations at part-speed conditions. In the current study, time-accurate simulations with harmonic blade oscillations have been conducted to investigate the non-linear behaviour. Results for different operating conditions show the evolution of aeroelastic stability. The lock-in of convected aerodynamic disturbances with structural vibration is analysed for different vibration amplitudes and frequencies. The simulations show the development of multiple wave-numbers, mode scattering and a non-linear dependency on vibration amplitude. The results indicate the possibility of limit-cycle prediction and the necessity of strongly-coupled methods for the assessment of NSV.

Abstract A novel test facility for transonic fans has been constructed and commissioned at École Centrale de Lyon (ECL) within the Project PHARE-2. The facility is instrumented with multi-physical measurement systems to deeply investigate aeroelastic and aeroacoustic phenomena. To enable long-term fundamental research, the composite material open-test-case rotor ECL5 is currently under development, which shall be established as a new reference case for method development. Within the present publication, the project objectives, the current rotor design, ECL5v2, and details on the test facility are presented. With the goal to establish future academic collaborations, the authors aim to initiate a discussion in the research community in an early stage of the test case development to receive constructive feedback on the design and research approach.

Abstract This work concerns the numerical modeling of geometric nonlinear vibrations of slender structures in rotation using an original reduced order model based on the use of dual modes along with the implicit condensation method. This approach is an improvement of the classical ICE method in the sense that the membrane stretching effect is taken into account in the dynamic resolution. The dynamics equations are firstly presented and the construction of the reduced order model (ROM) is then proposed. The second part of the paper deals with numerical applications using the finite element method, first for a 3D cantilever beam, then for an Ultra High Bypass Ratio (UHBR) fan blade. In the applications considered, the proposed method predicts more accurately the geometrically nonlinear behavior than the ICE method.

Abstract Purpose The purpose of this study was to create 123I-FP-CIT reference values for ultra-high-resolution fan beam collimators (UHR-FB) from a sample of subjects without dopaminergic degeneration and to compare them to a normal database -PPMI database- of a commercial software (DaTQUANT) obtained using high-resolution parallel-hole collimators (HR-PH). Methods A striatal phantom study was performed to compare UHR-FB with HR-PH and to obtain a correction factor between collimators. Normal 123I-FP-CIT studies from 177 subjects acquired using UHR-FB were retrospectively selected on the basis of visual and semi-quantitative analysis as well as of the neurological follow-up (range of 2–9 years). SPECT images were reconstructed using the same parameters of DaTQUANT normal database and SBR values were obtained for striatal structures. Correction factor was applied to the UHR-FB database to test differences against DaTQUANT database. Results Correction factor obtained from the phantom study was 0.84. Uncorrected SBR values of the local database were significantly higher than PPMI database values, but no significant differences were found using corrected values. Coefficients of variations of SBR values were significantly lower in a local database than PPMI database (15% vs 20%). Significant effects of age on SBR were observed in both databases with a reduction rate for a decade of 6% in the PPMI database and 4.5% in the local database. In the latter, women had slightly higher SBR values and a steeper decline with advancing age compared to men, whereas no significant gender differences were found in the PPMI database. Conclusion The SBR values obtained using UHR-FB have an age-related distribution comparable to that of healthy subjects but with lower variability. The reduction rate per decade was similar between the two databases but the gender effect was found only in the local database, probably related to the better performance of UHR-FB.

Objectives The aim of this study was to investigate potential benefits of ultra-high resolution (UHR) over standard resolution scan mode in ultra-low dose photon-counting detector CT (PCD-CT) of the lung. Materials and Methods Six cadaveric specimens were examined with 5 dose settings using tin prefiltration, each in UHR (120 × 0.2 mm) and standard mode (144 × 0.4 mm), on a first-generation PCD-CT scanner. Image quality was evaluated quantitatively by noise comparisons in the trachea and both main bronchi. In addition, 16 readers (14 radiologists and 2 internal medicine physicians) independently completed a browser-based pairwise forced-choice comparison task for assessment of subjective image quality. The Kendall rank coefficient (W) was calculated to assess interrater agreement, and Pearson's correlation coefficient (r) was used to analyze the relationship between noise measurements and image quality rankings. Results Across all dose levels, image noise in UHR mode was lower than in standard mode for scan protocols matched by CTDIvol (P < 0.001). UHR examinations exhibited noise levels comparable to the next higher dose setting in standard mode (P ≥ 0.275). Subjective ranking of protocols based on 5760 pairwise tests showed high interrater agreement (W = 0.99; P ≤ 0.001) with UHR images being preferred by readers in the majority of comparisons. Irrespective of scan mode, a substantial indirect correlation was observed between image noise and subjective image quality ranking (r = −0.97; P ≤ 0.001). Conclusions In PCD-CT of the lung, UHR scan mode reduces image noise considerably over standard resolution acquisition. Originating from the smaller detector element size in fan direction, the small pixel effect allows for superior image quality in ultra-low dose examinations with considerable potential for radiation dose reduction.

BackgroundPsychotic transition (PT) is a crucial stage in schizophrenia. The Comprehensive Assessment of At-Risk Mental States (CAARMS) scale can be used to identify individuals at ultra-high risk (UHR) for psychosis and to evaluate their risk of PT. Many environmental and genetic factors have been identified as contributing to the development and decompensation of schizophrenia. This study aimed to determine if the quality of family functioning is associated with PT risk in UHR individuals aged between 11 and 25 years after 1 year of follow-up.MethodsFrom January to November 2017, 45 patients aged 12 to 25 consulting for psychiatric reasons were included. Twenty-six were classified as UHR of PT at the CAARMS. Family functioning was assessed by the Family Assessment Device—Global Functioning (FAD-GF). Thirty-seven of these patients (30% men, mean age 16 ± 2.5) were reassessed at 8–14 months of recruitment. Survival analysis was used to examine the impact of family functioning on PT risk.ResultsA total of 40% of UHR patients were classified as psychotic at reassessment. Survival analysis showed that better family functioning is a significant protective factor for PT in this population.DiscussionThis result suggests that the global family functioning has an impact at 1 year on the risk of PT in the population of adolescents and young adults who consult the hospital for psychiatric reasons. A family intervention may be effective in reducing PT risk in this population and should be considered as a potential therapeutic option.

Purpose The decrease in specific thrust achieved by Ultra-High Bypass Ratio (UHBPR) aero-engines allows for a reduction in specific fuel consumption. However, the typical associated larger fan size might increase the nacelle drag, weight and the detrimental interference effects with the airframe. Consequently, the benefits from the new UHBPR aero-engine cycle may be eroded. This paper aims to evaluate the potential improvement in the aerodynamic performance of compact nacelles for installed aero-engine configuration. Design/methodology/approach Drooped and scarfed non-axisymmetric compact and conventional nacelle designs were down selected from a multi-point CFD-based optimisation. These were computationally assessed at a set of installation positions on a contemporary wide-body, twin-engine transonic aircraft. Both cruise and off-design conditions were evaluated. A thrust and drag accounting method was applied to evaluate different aircraft, powerplant and nacelle performance metrics. Findings The aircraft with the compact nacelle configuration installed at a typical installation position provided a reduction in aircraft cruise fuel consumption of 0.44% relative to the conventional architecture. However, at the same installation position, the compact design exhibits a large flow separation at windmilling conditions that is translated into an overall aircraft drag penalty of approximately 5.6% of the standard cruise net thrust. Additionally, the interference effects of a compact nacelle are more sensitive to deviations in mass flow capture ratio (MFCR) from the nominal windmilling diversion condition. Originality/value This work provides a comprehensive analysis of not only the performance but also the aerodynamics at an aircraft level of compact nacelles compared to conventional configurations for a range of installations positions at cruise. Additionally, the engine-airframe integration aerodynamics is assessed at an off-design windmilling condition which constitutes a key novelty of this paper.

Det har skjedd en revolusjon innen bachelorutdanningene i økonomi og administrasjon (BØA) hva angår tematikken etikk, samfunnsansvar og bærekraft (ESAB), som i løpet av få år har fått mye oppmerksomhet og større plass i utdanningen. ESAB er nå løftet fram som eget fagområde på lik linje med bedriftsøkonomiske, administrative, samfunnsøkonomiske og metoderelaterte fag. Universitets- og høgskolerådets strategiske enhet for utdanning i økonomi og administrasjon (UHR-ØA) presenterte i 2018 nye minimumskrav til BØA-utdanningen. I denne artikkelen gjennomgås læringsutbyttebeskrivelsene i institusjonenes emnebeskrivelser, og basert på dem stiller jeg spørsmål til om dagens utdanning oppfyller minimumskravene og ruster studenter i BØA-utdanningen til å ta ansvar for dagens samfunnsbehov uten samtidig å ødelegge andre menneskers muligheter til å dekke sine behov, både de som lever i dag, og framtidens generasjoner. Artikkelen gir grunnlag for en videre samtale om hva som er institusjonenes ansvar for å ruste studentene som ansvarlige og verdibevisste arbeidstakere.

Знание величины коэффициента теплопроводности полупроводникового материала необходимо для оценки возможности использования его в качестве термоэлектрика. Абсолютным стационарным методом продольного теплового потока в интервале 50–300 K исследована теплопроводность природных минералов галенита (PbS), халькопирита (CuFeS2), а также керамики ZnS.Образцы были однородными, имели малое содержание примесей (химический состав образцов контролировался ренгенофлюоресцентным методом) и характеризовались высокими значениями удельного электрического сопротивления (r > 9·10–2 Ом·м при комнатной температуре). Это соответствует электронной составляющей теплопроводности ke < 1·10–4 Вт/(м·К). Результаты измерений теплопроводности представлены графически и в табулированном виде. Все зависимости являются убывающими. Величины теплопроводности (Вт/(м·К)) при 50 К составляют 10.9 для PbS, 62 для CuFeS2 и 73–98 для ZnS. При 300 К соответствующие величины равны 2.48, 10.5 и 18.6–18.8 Вт/(м·К).Все исследованные материалы значительно хуже проводят тепло, чем пирит FeS2. Проведено сравнение полученных данных с литературными. Температурная зависимость теплопроводности галенита является слабой, его низкая теплопроводность благоприятна для термоэлектрических приложений. Выявленная в настоящей работе теплопроводность халькопирита оказалась наивысшей из соответствующих литературных данных. Высокая теплопроводность сульфида цинка коррелирует с ее широкой вариабельностью в зависимости от структурных особенностей материала. Рассчитаны температурные зависимости средней длины свободного пробега фононов. Оцененные для температуры плавления значения этой характеристики для PbS и особенно для ZnS значительно превосходят размеры элементарной кристаллической ячейки, что необычно. ЛИТЕРАТУРА Самофалова Т. В., Семенов В. Н., Нитута А. Н., Звягина О. В., Проскурина Е. Ю. 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