The Experts below are selected from a list of 6576 Experts worldwide ranked by ideXlab platform
Hao Yong - One of the best experts on this subject based on the ideXlab platform.
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Fatigue Life Analysis of Fluid-structure Coupling Characteristics for Hollow Wide-chord Fan Blade
Computer Simulation, 2009Co-Authors: Hao YongAbstract:The hollow wide-chord Fan Blade is one of the new techniques employed by the aero engine.Two fluid-structure interaction numerical methods including indirect coupling and direct coupling were implemented for the hollow wide-chord Fan Blade undertaking air flow field,and the fatigue life of the Fan Blade was analyzed.The fatigue life of the Fan Blade obtained by the two numerical methods was compared.Computational results show that the maximum stress is increased less than 10% with the direct coupling method compared with the indirect coupling one.The using coefficient of the fatigue life is almost zero under the von mises stress amplificatory level of 2 for hollow wide-chord Fan Blade using either of the two methods.Compared with the indirect numerical method,the coefficient of the fatigue life continuously increases with the increasing period under the von mises stress amplificatory level of 3.
Anjenq Wang - One of the best experts on this subject based on the ideXlab platform.
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numerical investigation of rub induced composite Fan Blade vibrations and abradable coating removals
Composite Structures, 2019Co-Authors: Jiaguangyi Xiao, Hua Ouyang, Jie Tian, Yong Chen, Anjenq WangAbstract:Abstract Composite Blade vibrations, removal of abradable coating, and Blade stress resulting from Blade/casing rubs are investigated. Composite Fan Blade models with different stacking sequences and a metal Blade are created and calculated through a three-dimensional finite element method. Centrifugal stiffness, damping of composite structures, B-spline surfaces, and abradable coating are included in the calculations. The results show that the maximum vibration amplitudes of composite Blades at different rotational speeds could be affected by stacking sequences. The responses of metal Blade are more sensitive to the natural frequencies of the second to the fifth Blade modes than those of the composite Blades. Abradable coating removals are highly related to Blade vibration amplitudes. Considerably more coatings are removed by the metal Blade than by the composite Blades at the design speed, particularly in the axial direction. Moreover, according to the stress results, the metal Blade is more vulnerable to rub-induced vibrations than the composite Blades at the design speed. Larger vibration amplitudes in the composite Blades do not necessarily lead to lower failure margins because of the complexity of composite structures. The strategy established can be utilized to aid in the initial designs of state-of-the-art composite Blades and reduce potential rub-induced problems.
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Investigation of Vibration Characteristics of Titanium Wide-Chord Fan Blade
Journal of Vibration Engineering & Technologies, 2019Co-Authors: Zhonglin Wang, Yong Chen, Hua Ouyang, Anjenq WangAbstract:The vibration characteristics of a wide-chord Fan Blade affect the safety, reliability, and operability of high-bypass ratio turboFan engines. In this study, the vibration characteristics of a Fan Blade were investigated using numerical and experimental methods. First, the natural frequencies and mode shapes were obtained and verified. Then, the rotating speed and frequency margins were employed to analyze the stability of the Blade. The critical crossings in the Campbell diagram were indicated and evaluated. Next, the strain energy density index and weaklink were used to evaluate the dangerous locations for the high-cycle fatigue characteristics of the Blade. Finally, single- and multi-axis random-excitation tests were performed. Results indicated that low-order bending modes were dominant under circumferential- and axial-direction excitations, while the torsional mode response was higher under radial-direction excitation. The weaklinks for different excitation directions exhibited different characteristics. This work presents a comprehensive understanding of the Fan-Blade vibration and response characteristics.
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Investigation on the Dynamic Response of a Wide-Chord Fan Blade Under Ground Vortex Ingestion
International Journal of Aeronautical and Space Sciences, 2019Co-Authors: Zhonglin Wang, Yong Chen, Hua Ouyang, Anjenq WangAbstract:This paper presents a computational study of the dynamic response of the Fan Blade owing to the excitations from the ingested ground vortex when the turboFan engine is operating on the ground or during the takeoff run. Firstly a numerical method consisting of static, modal and transient analyses is proposed to investigate the dynamic vibration characteristics of a Fan Blade model with pre-vibration. Modal analysis is conducted to find the critical speed of Blade resonances, and the intersection of the fourth engine order and the second bending mode is identified for the study. Secondly, transient analyses of the vortex ingestion are carried out to investigate the resulting Blade responses. Various parameters, including different ingestion timings, rotating speeds, ingestion positions and modes of pre-vibration are discussed. Results of dynamic displacement and stress illustrate that the effect of the ingested vortex is significant. Especially when the Fan Blade is working at the critical speed where engine orders intersect with the dynamic frequencies, the stress is amplified by 276.6% and the displacement is amplified by 156.7%. This paper demonstrates a preliminary method to connect the flow excitations of the ground-ingested vortex and the Fan Blade vibration characteristics, and provides a helpful reference to the further study of the Fan Blade vibration.
Leye M. Amoo - One of the best experts on this subject based on the ideXlab platform.
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On the design and structural analysis of jet engine Fan Blade structures
Progress in Aerospace Sciences, 2013Co-Authors: Leye M. AmooAbstract:Progress in the design and structural analysis of commercial jet engine Fan Blades is reviewed and presented. This article is motivated by the key role Fan Blades play in the performance of advanced gas turbine jet engines. The fundamentals of the associated physics are emphasized. Recent developments and advancements have led to an increase and improvement in Fan Blade structural durability, stability and reliability. This article is intended as a high level review of the Fan Blade environment and current state of structural design to aid further research in developing new and innovative Fan Blade technologies.
Mehdi Vahdati - One of the best experts on this subject based on the ideXlab platform.
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Effect of geometry variability on transonic Fan Blade untwist
International Journal of Turbomachinery Propulsion and Power, 2019Co-Authors: Bharat Lad, Sina Stapelfeldt, J. S. Green, Mehdi VahdatiAbstract:Due to manufacturing tolerance and deterioration during operation, Fan Blades in the same engine exhibit geometric variability. The absence of symmetry will inevitably exacerbate and contribute to the complexities of running geometry prediction as the Blade variability is bound to be amplified by aerodynamic and centrifugal loading. In this study, we aim to address the Fan Blade untwist related phenomenon known as alternate passage divergence (APD). As the name suggests, APD manifests as alternating passage geometry (and hence alternating tip stagger pattern) when the Fan stage is operating close to/at peak efficiency condition. APD can introduce adverse influence on Fan performance, aeroacoustics behaviour, and high cycle fatigue characteristics of the Blade. The main objective of the study is to identify the parameters contributing to the APD phenomenon. In this study, the APD behaviours of two transonic Fan Blade designs are compared.
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Improving the Flutter Margin of an Unstable Fan Blade
Volume 7C: Structures and Dynamics, 2018Co-Authors: Sina Stapelfeldt, Mehdi VahdatiAbstract:The aim of this paper is to introduce design modifications which can be made to improve the flutter stability of a Fan Blade. A rig Fan Blade, which suffered from flutter in the part-speed range and for which good quality measured data in terms of steady flow and flutter boundary is available, is used for this purpose. The work is carried out numerically using the aeroelasticity code AU3D. Two different approaches are explored; aerodynamic modifications and aero-acoustic modifications. In the first approach, the Blade is stabilized by altering the radial distribution of the stagger angle based on the steady flow on the Blade. The re-staggering patterns used in this work are therefore particular to the Fan Blade under investigation. Moreover, the modifications made to the Blade are very simple and crude and more sophisticated methods and/or an optimization approach could be used to achieve the above objectives with a more viable final design. This paper, however, clearly demonstrates how modifying the steady Blade aerodynamics can prevent flutter. In the second approach, flutter is removed by drawing bleed air from the casing above the tip of the Blade. Only a small amount of bleed (0.2% of the total inlet flow) is extracted such that the effect on the operating point of the Fan is small. The purpose of the bleed is merely to attenuate the pressure wave which propagates from the trailing edge to the leading edge of the Blade. The results show that extracting bleed over the tip of the Fan Blade can improve the flutter margin of the Fan significantly.
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Influence of Intake on Fan Blade Flutter
Journal of Turbomachinery, 2015Co-Authors: Mehdi Vahdati, Nigel Smith, Fanzhou ZhaoAbstract:The main aim of this paper is to study the influence of upstream reflections on flutter of a Fan Blade. To achieve this goal, flutter analysis of a complete Fan assembly with an intake duct and the downstream outlet guide vanes (OGVs) (whole low pressure (LP) domain) is undertaken using a validated computational fluid dynamics (CFD) model. The computed results show good correlation with measured data. Due to space constraints, only upstream (intake) reflections are analyzed in this paper. It will be shown that the correct prediction of flutter boundary for a Fan Blade requires modeling of the intake and different intakes would produce different flutter boundaries for the same Fan Blade. However, the “Blade only” and intake damping are independent and the total damping can be obtained from the sum of the two contributions. In order to gain further insight into the physics of the problem, the pressure waves created by Blade vibration are split into an upstream and a downstream traveling wave in the intake. The splitting of the pressure wave allows one to establish a relationship between the phase and amplitude of the reflected waves and flutter stability of the Blade. By using this approach, a simple reflection model can be used to model the intake effects.
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Influence of Intake on Fan Blade Flutter
Volume 7B: Structures and Dynamics, 2014Co-Authors: Mehdi Vahdati, Nigel Smith, Fanzhou ZhaoAbstract:The main aim of this paper is to study the influence of upstream reflections on flutter of a Fan Blade. To achieve this goal, flutter analysis of a complete Fan assembly with an intake duct and the downstream OGVs (whole LP domain) is undertaken using a validated CFD model. The computed results show good correlation with measured data. Due to space constraints, only upstream (intake) reflections are analyzed in this paper. It will be shown that the correct prediction of flutter boundary for a Fan Blade requires modeling of the intake and different intakes would produce different flutter boundaries for the same Fan Blade. However, the ‘Blade only’ and intake damping are independent and the total damping can be obtained from the sum of the two contributions.In order to gain further insight into the physics of the problem, the pressure waves created by Blade vibration are split into an upstream and a downstream traveling wave in the intake. The splitting of the pressure wave allows one to establish a relationship between the phase and amplitude of the reflected waves and flutter stability of the Blade. By using this approach, a simple reflection model can be used to model the intake effects.Copyright © 2014 by Rolls-Royce plc
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mechanisms for wide chord Fan Blade flutter
Journal of Turbomachinery-transactions of The Asme, 2011Co-Authors: Mehdi Vahdati, George Simpson, M ImregunAbstract:This paper describes a detailed wide-chord Fan Blade flutter analysis with emphasis on flutter bite. The same Fan was used with three different intakes of increasing complexity to explain flutter mechanisms. Two types of flutter, namely, stall and acoustic flutters, were identified. The first intake is a uniform cylinder, in which there are no acoustic reflections. Only the stall fiutter, which is driven by flow separation, can exist in this case. The second intake, based on the first one, has a "bump" feature to reflect the Fan's forward pressure wave at a known location so that detailed parametric studies can be undertaken. The analysis revealed a mechanism for acoustic flutter, which is driven by the phase of the reflected wave. The third intake has the typical geometric features of a flight intake. The results indicate that flutter bite occurs when both stall and acoustic flutters happen at the same speed. It is also found that Blade stiffening has no effect on aero-acoustic flutter.
Yong Chen - One of the best experts on this subject based on the ideXlab platform.
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numerical investigation of rub induced composite Fan Blade vibrations and abradable coating removals
Composite Structures, 2019Co-Authors: Jiaguangyi Xiao, Hua Ouyang, Jie Tian, Yong Chen, Anjenq WangAbstract:Abstract Composite Blade vibrations, removal of abradable coating, and Blade stress resulting from Blade/casing rubs are investigated. Composite Fan Blade models with different stacking sequences and a metal Blade are created and calculated through a three-dimensional finite element method. Centrifugal stiffness, damping of composite structures, B-spline surfaces, and abradable coating are included in the calculations. The results show that the maximum vibration amplitudes of composite Blades at different rotational speeds could be affected by stacking sequences. The responses of metal Blade are more sensitive to the natural frequencies of the second to the fifth Blade modes than those of the composite Blades. Abradable coating removals are highly related to Blade vibration amplitudes. Considerably more coatings are removed by the metal Blade than by the composite Blades at the design speed, particularly in the axial direction. Moreover, according to the stress results, the metal Blade is more vulnerable to rub-induced vibrations than the composite Blades at the design speed. Larger vibration amplitudes in the composite Blades do not necessarily lead to lower failure margins because of the complexity of composite structures. The strategy established can be utilized to aid in the initial designs of state-of-the-art composite Blades and reduce potential rub-induced problems.
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Investigation of Vibration Characteristics of Titanium Wide-Chord Fan Blade
Journal of Vibration Engineering & Technologies, 2019Co-Authors: Zhonglin Wang, Yong Chen, Hua Ouyang, Anjenq WangAbstract:The vibration characteristics of a wide-chord Fan Blade affect the safety, reliability, and operability of high-bypass ratio turboFan engines. In this study, the vibration characteristics of a Fan Blade were investigated using numerical and experimental methods. First, the natural frequencies and mode shapes were obtained and verified. Then, the rotating speed and frequency margins were employed to analyze the stability of the Blade. The critical crossings in the Campbell diagram were indicated and evaluated. Next, the strain energy density index and weaklink were used to evaluate the dangerous locations for the high-cycle fatigue characteristics of the Blade. Finally, single- and multi-axis random-excitation tests were performed. Results indicated that low-order bending modes were dominant under circumferential- and axial-direction excitations, while the torsional mode response was higher under radial-direction excitation. The weaklinks for different excitation directions exhibited different characteristics. This work presents a comprehensive understanding of the Fan-Blade vibration and response characteristics.
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Investigation on the Dynamic Response of a Wide-Chord Fan Blade Under Ground Vortex Ingestion
International Journal of Aeronautical and Space Sciences, 2019Co-Authors: Zhonglin Wang, Yong Chen, Hua Ouyang, Anjenq WangAbstract:This paper presents a computational study of the dynamic response of the Fan Blade owing to the excitations from the ingested ground vortex when the turboFan engine is operating on the ground or during the takeoff run. Firstly a numerical method consisting of static, modal and transient analyses is proposed to investigate the dynamic vibration characteristics of a Fan Blade model with pre-vibration. Modal analysis is conducted to find the critical speed of Blade resonances, and the intersection of the fourth engine order and the second bending mode is identified for the study. Secondly, transient analyses of the vortex ingestion are carried out to investigate the resulting Blade responses. Various parameters, including different ingestion timings, rotating speeds, ingestion positions and modes of pre-vibration are discussed. Results of dynamic displacement and stress illustrate that the effect of the ingested vortex is significant. Especially when the Fan Blade is working at the critical speed where engine orders intersect with the dynamic frequencies, the stress is amplified by 276.6% and the displacement is amplified by 156.7%. This paper demonstrates a preliminary method to connect the flow excitations of the ground-ingested vortex and the Fan Blade vibration characteristics, and provides a helpful reference to the further study of the Fan Blade vibration.
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A General Ply Design for Aero Engine Composite Fan Blade
Volume 7A: Structures and Dynamics, 2017Co-Authors: Jiaguangyi Xiao, Yong Chen, Qichen Zhu, Jun LeeAbstract:Composite Fan Blade ply lay-up design, which includes ply drop-off/shuffle design and stacking sequence design, makes Fan Blade structures different from traditional composite structures. It gives designers more freedom to construct high-quality Fan Blades. However, contemporary Fan Blade profiles are quite complex and twisted, and Fan Blade structures are quite different from regular composite structures such as composite laminates and composite wings. The ply drop-off design of a Fan Blade, especially for a fully 3D Fan Blade, is still an arduous task. To meet this challenge, this paper develops a ply lay-up way with the help of a software called Fibersim. The fully 3D Fan Blade is cut into ply pieces in Fibersim. As a result, an initial ply sequence is created and ply shuffle could revise it. Because of the complexity of ply shuffling, the ply shuffle table developed in this paper mainly refers to the design experience gained from simple plate-like laminate structures and some criterion. Besides, the impact of different ply orientation patterns on the reliability of composite Fan Blade is studied through static and modal numerical analysis. The results show that this ply lay-up idea is feasible for aero engine composite Fan Blade. Under the calculated rotating speeds, the ply stacking sequence 4 (i.e.[−45°/0°/+45°/0°] with the outer seven groups are [−45°/0°/−45°/0°]) shows the greatest margin of safety compared with other stacking sequences. Modal analysis shows that plies with different angles could have relatively big different impacts on Blades vibration characteristics. The composite Fan Blade ply design route this paper presents has gain its initial success and the results in this paper might be used as basic references for composite Blade initial structural design.
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Numerical Simulation of Ice Shedding From a Fan Blade
Volume 1: Aircraft Engine; Fans and Blowers; Marine, 2015Co-Authors: Yong Chen, Wei Dong, Zhonglin WangAbstract:In turboFan engine, ice accretion on the Fan Blade may block the flow path and disturbs the inlet flow, which will cause the decrease of the thrust and the increase of the vibration amplitude of the engine. More seriously, ice shedding can damage the compressor components, which may cause serious aircraft accidents. An understanding of the mechanisms responsible for ice shedding process is necessary in order to optimize the Fan Blade design to avoid hazardous ice shedding. In this paper, a numerical ice shedding model is developed by taking the coupling of the failure of the interface between ice and Fan Blade surface and the failure of ice itself into account. The ice shedding process is predicted and analyzed. Some factors that affect the break-up and shedding of the ice are discussed, which include the mechanical properties of the ice, centrifugal loading and vibration loading. This model could be used to further study on the ice debris trajectory prediction and ice impact analysis.Copyright © 2015 by ASME
