Relevant bibliographies by topics / UHBR fan

Academic literature on the topic 'UHBR fan'

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Published: 7 September 2024

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Journal articles on the topic "UHBR fan"

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Natale, N., T. Egger, J. Friedrichs, and S. Russo. "Aerodynamic Analysis of a scaled UHBR Fan." IOP Conference Series: Materials Science and Engineering 1226, no. 1 (February 1, 2022): 012007. http://dx.doi.org/10.1088/1757-899x/1226/1/012007.

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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.
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Pagès, Valdo, Pierre Duquesne, Stéphane Aubert, Laurent Blanc, Pascal Ferrand, Xavier Ottavy, and Christoph Brandstetter. "UHBR Open-Test-Case Fan ECL5/CATANA." International Journal of Turbomachinery, Propulsion and Power 7, no. 2 (May 31, 2022): 17. http://dx.doi.org/10.3390/ijtpp7020017.

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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.
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Duquesne, Pierre, Quentin Rendu, Stephane Aubert, and Pascal Ferrand. "Choke flutter instability sources tracking with linearized calculations." International Journal of Numerical Methods for Heat & Fluid Flow 30, no. 9 (January 14, 2019): 4155–66. http://dx.doi.org/10.1108/hff-06-2018-0281.

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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.
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Paletta, N., J. Flüh, J. Lindemann, J. Seume, J. Goessling, J. Friedrichs, T. Eggers, et al. "The preliminary design of a scaled Composite UHBR Fan for a wind tunnel test campaign." IOP Conference Series: Materials Science and Engineering 1226, no. 1 (February 1, 2022): 012041. http://dx.doi.org/10.1088/1757-899x/1226/1/012041.

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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.
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Goessling, Jan, and Joerg R. Seume. "High-speed Digital Image Correlation (DIC) for measuring deformation and vibration of fast rotating fan blades." Journal of Physics: Conference Series 2526, no. 1 (June 1, 2023): 012075. http://dx.doi.org/10.1088/1742-6596/2526/1/012075.

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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.
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Eggers, Torben, Jens Friedrichs, Jan Goessling, Joerg R. Seume, Jan Flüh, Jens Lindemann, and Nicola Paletta. "Effect of 3D blade design on the aerodynamic, aeroelastic and structural behavior of a scaled UHBR fan." Journal of Physics: Conference Series 2526, no. 1 (June 1, 2023): 012032. http://dx.doi.org/10.1088/1742-6596/2526/1/012032.

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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.
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Mennicken, M., D. Schoenweitz, M. Schnoes, and R. Schnell. "Fan design assessment for BLI propulsion systems." CEAS Aeronautical Journal 13, no. 1 (October 4, 2021): 3–19. http://dx.doi.org/10.1007/s13272-021-00532-8.

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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.
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Mennicken, M., D. Schoenweitz, M. Schnoes, and R. Schnell. "Fan design assessment for BLI propulsion systems." CEAS Aeronautical Journal 13, no. 1 (October 4, 2021): 3–19. http://dx.doi.org/10.1007/s13272-021-00532-8.

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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.
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Stuermer, Arne. "DLR TAU-Code uRANS Turbofan Modeling for Aircraft Aerodynamics Investigations." Aerospace 6, no. 11 (November 3, 2019): 121. http://dx.doi.org/10.3390/aerospace6110121.

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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.
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Schneider, Alexandra P., Benoit Paoletti, Xavier Ottavy, and Christoph Brandstetter. "Experimental monitoring of vibrations and the problem of amplitude quantification." Journal of Physics: Conference Series 2511, no. 1 (May 1, 2023): 012017. http://dx.doi.org/10.1088/1742-6596/2511/1/012017.

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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.
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Dissertations / Theses on the topic "UHBR fan"

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Schneider, Alexandra Patrizia. "Aerodynamic and aeroelastic investigation of a composite fan for ultra-high-bypass-ratio aircraft engines." Electronic Thesis or Diss., Ecully, Ecole centrale de Lyon, 2024. http://www.theses.fr/2024ECDL0018.

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Les fans modernes à faible vitesse de rotation à très haut taux de dilution (Ultra-High Bypass Ratio, UHBR) opèrent principalement sur la partie plate de la caractéristique de compression, ont des lon-gueurs de l'entrée d'air plus courtes et sont constitués d'aubes en composites flexibles et légères. Ces changements favorisent l'évolution de différents types d'instabilités avec des interactions multi-physiques telles que les vibrations non-synchrones convectives (NSV). Pour permettre de nouvelles avancées technologiques, des données de référence expérimentales sur des géométries représenta-tives sont nécessaires. Dans ce contexte, le projet européen CATANA a été initié à l'Ecole Centrale de Lyon. Le fan ECL5 a été conçu comme une configuration ouverte selon les directives industrielles et testé expérimentalement sur le banc d'essai ECL-B3. Cette thèse présente les résultats expérimen-taux du projet CATANA. L'investigation expérimentale de la configuration de référence ECL5 montre que les objectifs de conception ont été atteints. La machine est opérationnelle sur une large plage de fonctionnement et les performances aérodynamiques au point de design coïncident exactement avec les prédictions numériques. En revanche, les mécanismes d'instabilité sont plus complexes que ceux prédits. Par l'application d'une instrumentation multi-physique synchronisée, l'interaction fluide-structure complexe impliquée est résolue. L'analyse de l'influence des conditions d'entrée et de la symétrie géométrique et structurel du système permet d'identifier la sensibilité des caractéristiques aérodynamiques et structurelles ainsi que du comportement près de la limite de stabilité. L'investiga-tion d'une deuxième configuration de rotor présentant un désaccordage structurel met en lumière l'importance des variations géométriques d'aube à aube. Elles provoquent une asymétrie du champ aérodynamique en tête d'aube et suppriment des perturbations aérodynamiques se propageant de manière cohérente, retardant le NSV. Les résultats présentés dans cette thèse offrent une caractéri-sation complète du fan ECL5 et servent de jeu de données de référence pour la validation des simula-tions numériques
Modern low-speed Ultra-High Bypass Ratio (UHBR) fans operate predominantly on the flat part of the compression characteristic, have shorter intake lengths, and employ flexible, lightweight, composite blades. These changes promote the evolution of different types of instabilities with multi-physical interactions such as convective non-synchronous vibration (NSV). To enable further technological ad-vancements, experimental benchmark data on representative geometries required. Within this con-text, the European project CATANA was initiated at Ecole Centrale de Lyon. The open-test-case fan stage ECL5 was designed, following industrial guidelines, and tested experimentally on the facility ECL-B3. This thesis presents the experimental results of the CATANA project. The experimental investiga-tion of the ECL5 reference configuration shows that all design goals have been reached. The machine is operational in a wide range and aerodynamic performance at design condition is exactly coincident with the numerical prediction. In contrast, instability mechanisms are more complex than predicted by the employed numerical methods. Through application of synchronized multi-physical instrumenta-tion, the involved complex fluid-structure interaction is resolved. The analysis of the influence of in-flow conditions and geometrical and structural system symmetry allows to identify the sensitivity of aerodynamic and structural characteristics and the behavior close to the stability limit. The investiga-tion of a second rotor configuration featuring structural mistuning highlights the importance of geo-metrical blade-to-blade variations. They cause an asymmetry of the aerodynamic field at the blade tip and suppress coherently propagating aerodynamic disturbances resulting in a delayed onset of NSV. The results presented in this thesis provide a comprehensive multi-physical characterization of the ECL5 fan stage and serve as a benchmark data set for the validation of numerical simula-tions
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Books on the topic "UHBR fan"

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Y, Ho Patrick, Mani Ramani, and United States. National Aeronautics and Space Administration., eds. UHB engine fan broadband noise reduction study. [Washington, DC]: National Aeronautics and Space Administration, 1995.

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Steiger, Diego. Zeitreise Time Travel Uhr Kalender 2021: Jahreskalender Für Zeitreise und Science-Fiction Fans. Independently Published, 2020.

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Steiger, Diego. Zeitreise Time Travel Uhr Studienplaner 2020/21: Semesterplaner Für Zeitreise und Science-Fiction Fans. Independently Published, 2020.

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Notizbücher, Luftsport. Terminplaner 2019-2020: Für Drachenfliegen Fans Juli 2019 Bis Dezember 2020 Wochentage Unterteilt Von 7. 00 Bis 21. 00 Uhr Mit Den Wichtigsten Feiertagen Deutschlands. Independently Published, 2019.

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Book chapters on the topic "UHBR fan"

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Duquesne, Pierre, Stéphane Aubert, Quentin Rendu, and Pascal Ferrand. "Effect of Frozen Turbulence Assumption on the Local Blades Vibration on the Choke Flutter Instability in Transonic UHBR Fan." In Notes on Numerical Fluid Mechanics and Multidisciplinary Design, 339–52. Cham: Springer International Publishing, 2021. http://dx.doi.org/10.1007/978-3-030-55594-8_29.

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Conference papers on the topic "UHBR fan"

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Eggers, Torben, Jens Friedrichs, Jan Goessling, Joerg R. Seume, Nunzio Natale, Jan Peter Flüh, and Nicola Paletta. "Composite UHBR Fan for Forced Response and Flutter Investigations." In ASME Turbo Expo 2021: Turbomachinery Technical Conference and Exposition. American Society of Mechanical Engineers, 2021. http://dx.doi.org/10.1115/gt2021-58941.

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Abstract In the CA3ViAR (Composite fan Aerodynamic, Aeroelastic, and Aeroacoustic Validation Rig) project, a composite low-transonic fan is designed and tested. The aim is a scaled ultra-high bypass ratio (UHBR) fan with state-of-the-art aerodynamic performance and composite rotor blades, which features aeroelastic phenomena, e.g. forced response by inlet distortions and flutter, under certain operating points within the wind tunnel. In this paper, the aerodynamic and aeroelastic design process starting from the overall performance specifications to a threedimensional numerical model is described. A target of eigen-frequency and twist-to-plunge ratio is specified such that flutter occurs at desired operating conditions with a sufficient margin with respect to the working line. Different materials and layups of the composite blade are analyzed to reach the structural target. The fan should serve as an open test case to advance the future research on aerodynamic, aeroelastic, and aeroacoustic performance investigations in a wide range of operating conditions. A preliminary fan stage design is presented in this paper.
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Benini, Ernesto, Chetankumar Mistry, and Aspi R. Wadia. "Historical Developments in Fan Technologies for Aeroengines." In ASME Turbo Expo 2023: Turbomachinery Technical Conference and Exposition. American Society of Mechanical Engineers, 2023. http://dx.doi.org/10.1115/gt2023-101639.

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Abstract This paper reports on the evolution of fan aerodynamics starting with turbofan engines featuring moderate by-pass ratios (between 4 and 6) up to Ultra-High-By-pass-Ratio (UHBR) configurations which are currently being developed. The implementation of key enabling technologies for fan blades are discussed from a historical perspective, spanning from high-aspect ratio fan blades with part span shrouds (or snubber) to wide chord fan blades, from un-ducted (UDF) and propfan open rotors to highly swept blades. With continuous requirements for higher thrust and lower fuel consumption, bypass ratio demand has also increased leading to UHBR configurations (by-pass ratios higher than 13). Almost all engine companies have responded to these challenges by reducing the number of fan blades. To meet future performance and stability requirements of lower fan pressure ratios, new fan architectures are discussed.
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Rodrigues, Martin, Laurent Soulat, Benoit Paoletti, Xavier Ottavy, and Christoph Brandstetter. "Aerodynamic Investigation of a Composite Low-Speed Fan for UHBR Application." In ASME Turbo Expo 2020: Turbomachinery Technical Conference and Exposition. American Society of Mechanical Engineers, 2020. http://dx.doi.org/10.1115/gt2020-14915.

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Abstract A composite fan stage representative of a modern 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. A detailed analysis on 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 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 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 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.
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Zillmann, Jörgen, and U. Tapken. "Tonal Noise Radiation from UHBR Fan - Active Control of Radiation Characteristic." In 15th AIAA/CEAS Aeroacoustics Conference (30th AIAA Aeroacoustics Conference). Reston, Virigina: American Institute of Aeronautics and Astronautics, 2009. http://dx.doi.org/10.2514/6.2009-3226.

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Schuff, Matthias, and Jannik Reisberg. "Flutter Analysis of a Flexible UHBR Fan at Different Flight Conditions." In ASME Turbo Expo 2018: Turbomachinery Technical Conference and Exposition. American Society of Mechanical Engineers, 2018. http://dx.doi.org/10.1115/gt2018-76930.

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A flexible UHBR fan is investigated at different flight conditions with a focus on static deflections and aeroelastic stability. Operating points at varying inlet conditions, which are comparable according to the Mach similarity principle, are investigated. However, not all the aerodynamic characteristics remain identical and aerodynamic damping of mode shape vibrations is changed. When steady deformations of the fan blades are taken into account, the deviation between different inlet conditions increases further. This is mainly due to torsional deflections, changing the effective angle of attack and causing a general shift of the compressor map. Even though the subsequent changes in flutter predictions are not severe for most parts of the compressor map, the behavior at the boundaries is sensitive to the real flight condition. As shown, the Mach similarity principle is not suitable for investigating aeroelastic stability throughout the whole flight envelope, especially when the static blade deformation is not neglectable. The reason for this can be found in the complex interaction between dimension-less numbers (Mach, Reynolds), sized values (pressure difference or aerodynamic loading, natural frequency) and their dependency on each other.
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Brandstetter, Christoph, Alexandra P. Schneider, Anne-Lise Fiquet, Benoit Paoletti, and Xavier Ottavy. "Experiments on Structurally Mistuned UHBR Open-Test-Case Fan ECL5/CATANA." In ASME Turbo Expo 2024: Turbomachinery Technical Conference and Exposition. American Society of Mechanical Engineers, 2024. http://dx.doi.org/10.1115/gt2024-129163.

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Abstract The operational capabilities of turbofan engines encounter limitations due to instabilities arising from tightly coupled interactions among aerodynamics, acoustics, and structural mechanics. Modern fans and compressors exhibit Non-Synchronous Vibration (NSV), leading to safety-critical blade oscillations. In contrast to self-excited phenomena such as flutter, NSV stems from the convection of aerodynamic disturbances that synchronize with blade eigenmodes. Understanding this phenomenon is challenging, as its intricate interaction patterns and the occurrence of flow separations constrain the predictive capabilities of current state-of-the-art methods. To establish a comprehensive benchmark dataset on the aeroelastic behavior of modern Ultra-High Bypass Ratio (UHBR) architectures, the European CleanSky-2 project CATANA aimed to examine a carbon composite fan stage, ECL5, utilizing multiphysical instrumentation. Recently, experiments on a structurally tuned reference configuration were conducted, revealing highamplitude Non-Synchronous Vibration (NSV) at multiple subsonic speedlines. The observed interaction modes and instability onset differed significantly from numerical predictions using both LRANS and URANS with prescribed harmonic blade motion. In an effort to enhance the dataset, two additional fan configurations with identical blade profile geometries were investigated: one featured a structurally mistuned rotor with approximately doubled frequency variation of all eigenmodes compared to the reference, and the other involved a case with locally increased tip clearance on individual blades. This paper presents the experimental results of a sensitivity study and explores the influence of structural mistuning and tip clearance variation associated with manufacturing tolerances. Contrary to the intended outcome, it will be demonstrated that the mistuned case exhibited higher blade vibration amplitudes than the reference case during NSV. Detailed instrumentation reveals that the mistuning pattern was effectively transferred to the rotating system, but aerodynamic mistuning, particularly concerning tip clearance, emerged as a dominant factor. The non-synchronous forced-response nature of NSV during highly throttled operation ultimately dictates the observed response levels under different conditions, necessitating a thorough analysis to evaluate the robustness of a specific configuration. These results contribute valuable insights to the open dataset for the ECL5 configuration, benefiting the research community. Particularly noteworthy is the detailed capture of blade-to-blade variations in this research, which will prove instrumental in validating numerical methods.
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Pereira, Antonio, Edouard Salze, Josselin Regnard, Fernando Gea-Aguilera, and Mathieu Gruber. "New modular fan rig for advanced aeroacoustic tests - Modal decomposition on a 20" UHBR fan stage." In 25th AIAA/CEAS Aeroacoustics Conference. Reston, Virginia: American Institute of Aeronautics and Astronautics, 2019. http://dx.doi.org/10.2514/6.2019-2604.

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Neuhaus, Lars, Ulf Tapken, Lars Enghardt, Gerd Enders, and Jörgen Zillmann. "Reduction of UHBR fan blade tones by flow induced secondary sound sources." In 22nd AIAA/CEAS Aeroacoustics Conference. Reston, Virginia: American Institute of Aeronautics and Astronautics, 2016. http://dx.doi.org/10.2514/6.2016-2891.

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Weckmüller, Christian, Sebastien Guerin, and Graham Ashcroft. "CFD/CAA Coupling Applied to DLR UHBR-Fan: Comparison to Experimantal Data." In 15th AIAA/CEAS Aeroacoustics Conference (30th AIAA Aeroacoustics Conference). Reston, Virigina: American Institute of Aeronautics and Astronautics, 2009. http://dx.doi.org/10.2514/6.2009-3342.

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Fiquet, Anne-Lise, Alexandra P. Schneider, Benoit Paoletti, Xavier Ottavy, and Christoph Brandstetter. "Experiments on Tuned UHBR Open-Test-Case Fan ECL5/CATANA: Stability Limit." In ASME Turbo Expo 2023: Turbomachinery Technical Conference and Exposition. American Society of Mechanical Engineers, 2023. http://dx.doi.org/10.1115/gt2023-102537.

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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. This paper is accompanied by a detailed aerodynamic study, and together a complete dataset including measurements of aerodynamic performance, radial flow profiles, blade-individual tip-clearance, stagger angle, vibration amplitudes and unsteady pressure fields at the rotor tip are provided. The results are a promising benchmark for future method development, particularly involving high-fidelity methods.
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