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1
Li, Chaofeng, Shihua Zhou, Shuhua Yang, Xiang Ren e Bangchun Wen. "Dynamic Characteristics of Blade-Disk-Rotor System with Structural Mistuned Features". Open Mechanical Engineering Journal 8, n. 1 (18 aprile 2014): 138–43. http://dx.doi.org/10.2174/1874155x20140501008.
Testo completoAbstract (sommario):
The finite element method is adopted to establish the dynamical models of blade, bladed disk and blades-diskshaft assemblies. Based on the analysis of mistuned structure and the dynamic characteristics of model in different levels, it gives the vibration mode distribution of different models. The research shows that the characteristics of the bladed disk and shaft have a huge difference, where some modes are caused by the strongly split and coupled vibration. The mistuned effects are likely to cause different coupled vibrations of blades between the blades-disk model and the blades-disk-shaft model. Meanwhile, it shows the frequency separation and concentration, and misses the system mode and the local vibration, which bring some difficulties for designing the blade-rotor system. In this paper, the results may provide a certain reference for blade-rotor system design and diagnosis.
2
Xing, Zhitai, Yan Jia, Lei Zhang, Xiaowen Song, Yanfeng Zhang, Jianxin Wu, Zekun Wang, Jicai Guo e Qingan Li. "Research on Wind Turbine Blade Damage Fault Diagnosis Based on GH Bladed". Journal of Marine Science and Engineering 11, n. 6 (26 maggio 2023): 1126. http://dx.doi.org/10.3390/jmse11061126.
Testo completoAbstract (sommario):
With the increasing installed capacity of wind turbines, ensuring the safe operation of wind turbines is of great significance. However, the failure of wind turbines is still a severe problem, especially as blade damage can cause serious harm. To detect blade damage in time and prevent the accumulation of microdamage of blades evolving into severe injury, a damage dataset based on GH Bladed simulation of blade damage is proposed. Then, based on the wavelet packet analysis theory method, the MATLAB software can automatically analyze and extract the energy characteristics of the signal to identify the damage. Finally, the GH Bladed simulation software and MATLAB software are combined for fault diagnosis analysis. The results show that the proposed method based on GH Bladed to simulate blade damage and wavelet packet analysis can extract damage characteristics and identify single-unit damage, multiple-unit damage, and different degrees of damage. This method can quickly and effectively judge the damage to wind turbine blades; it provides a basis for further research on wind turbine blade damage fault diagnosis.
3
Xu, Lin, Wen Lei Sun e An Wu. "Structural Properties Analysis of Composite Wind Turbine Blade". Key Engineering Materials 522 (agosto 2012): 602–5. http://dx.doi.org/10.4028/www.scientific.net/kem.522.602.
Testo completoAbstract (sommario):
In the process of wind turbine operation, the blade needs to withstand various kinds of loads. With wind turbine power kept getting bigger, the strength requirement of the blades become higher. In order to improve the strength of the blade, lots of new composite materials are use in blade material component parts. This paper studies the geometry laminated structure, external and structural characteristics of composite blade.
4
Chetan, Mayank, Shulong Yao e D. Todd Griffith. "Flutter behavior of highly flexible blades for two- and three-bladed wind turbines". Wind Energy Science 7, n. 4 (22 agosto 2022): 1731–51. http://dx.doi.org/10.5194/wes-7-1731-2022.
Testo completoAbstract (sommario):
Abstract. With the progression of novel design, material, and manufacturing technologies, the wind energy industry has successfully produced larger and larger wind turbine rotor blades while driving down the levelized cost of energy (LCOE). Though the benefits of larger turbine blades are appealing, larger blades are prone to aeroelastic instabilities due to their long, slender, highly flexible nature, and this effect is accentuated as rotors further grow in size. In addition to the trend of larger rotors, non-traditional rotor concepts are emerging including two-bladed rotors and downwind configurations. In this work, we introduce a comprehensive evaluation of flutter behavior including classical flutter, edgewise vibration, and flutter mode characteristics for two-bladed, downwind rotors. Flutter speed trends and characteristics for a series of both two- and three-bladed rotors are analyzed and compared in order to illustrate the flutter behavior of two-bladed rotors relative to more well-known flutter characteristics of three-bladed rotors. In addition, we examine the important problem of blade design to mitigate flutter and present a solution to mitigate flutter in the structural design process. A study is carried out evaluating the effect of leading edge and trailing edge reinforcement on flutter speed and hence demonstrates the ability to increase the flutter speed and satisfy structural design requirements (such as fatigue) while maintaining or even reducing blade mass.
5
Rogge, Timo, Ricarda Berger, Linus Pohle, Raimund Rolfes e Jörg Wallaschek. "Efficient structural analysis of gas turbine blades". Aircraft Engineering and Aerospace Technology 90, n. 9 (14 novembre 2018): 1305–16. http://dx.doi.org/10.1108/aeat-05-2016-0085.
Testo completoAbstract (sommario):
Purpose The purpose of this study a fast procedure for the structural analysis of gas turbine blades in aircraft engines. In this connection, investigations on the behavior of gas turbine blades concentrate on the analysis and evaluation of starting dynamics and fatigue strength. Besides, the influence of structural mistuning on the vibration characteristics of the single blade is analyzed and discussed. Design/methodology/approach A basic computation cycle is generated from a flight profile to describe the operating history of the gas turbine blade properly. Within an approximation approach for high-frequency vibrations, maximum vibration amplitudes are computed by superposition of stationary frequency responses by means of weighting functions. In addition, a two-way coupling approach determines the influence of structural mistuning on the vibration of a single blade. Fatigue strength of gas turbine blades is analyzed with a semi-analytical approach. The progressive damage analysis is based on MINER’s damage accumulation assuming a quasi-stable behavior of the structure. Findings The application to a gas turbine blade shows the computational capabilities of the approach presented. Structural characteristics are obtained by robust and stable computations using a detailed finite element model considering different load conditions. A high quality of results is realized while reducing the numerical costs significantly. Research limitations/implications The method used for analyzing the starting dynamics is based on the assumption of a quasi-static state. For structures with a sufficiently high stiffness, such as the gas turbine blades in the present work, this procedure is justified. The fatigue damage approach relies on the existence of a quasi-stable cyclic stress condition, which in general occurs for isotropic materials, as is the case for gas turbine blades. Practical implications Owing to the use of efficient analysis methods, a fast evaluation of the gas turbine blade within a stochastic analysis is feasible. Originality/value The fast numerical methods and the use of the full finite element model enable performing a structural analysis of any blade structure with a high quality of results.
6
Liang, Zhi Chao, Jie Hong, Yan Hong Ma e Tian Yuan He. "FEM Modeling Technology and Vibration Analysis of Flexible Rotor System". Applied Mechanics and Materials 226-228 (novembre 2012): 257–61. http://dx.doi.org/10.4028/www.scientific.net/amm.226-228.257.
Testo completoAbstract (sommario):
The low-pressure spool in a high-bypass ratio turbofan engine has its unique characteristics. The slightness rotor and the large lumped mass in blade and disk are the structural characteristics while the dynamic coupling between bladed-disk and shaft is the mechanical characteristic. This paper studies on the modeling technology of a flexible rotor system based on the finite element method (FEM). The equivalent-disk method, an equivalent principle of finite element modeling, is put forward. The blades are equivalent to a disk which can not only retain the structural and mechanical characteristics but also control the scale of the model and convert the periodic geometry into axisymmetric geometry. The results show that the equivalent-disk method is helpful to improve the modeling techniques of rotor system and can be used in engineering.
7
Mignolet, M. P., A. J. Rivas-Guerra e J. P. Delor. "Identification of Mistuning Characteristics of Bladed Disks From Free Response Data—Part I". Journal of Engineering for Gas Turbines and Power 123, n. 2 (9 giugno 1999): 395–403. http://dx.doi.org/10.1115/1.1338949.
Testo completoAbstract (sommario):
The focus of the present two-part investigation is on the estimation of the dynamic properties, i.e., masses, stiffnesses, natural frequencies, mode shapes and their statistical distributions, of turbomachine blades to be used in the accurate prediction of the forced response of mistuned bladed disks. As input to this process, it is assumed that the lowest natural frequencies of the blades alone have been experimentally measured, for example, in a broach block test. Since the number of measurements is always less than the number of unknowns, this problem is indeterminate in nature. In this first part of the investigation, two distinct approaches will be investigated to resolve the shortfall of data. The first one relies on the imposition of as many constraints as needed to ensure a unique solution to this identification problem. Specifically, the mode shapes and modal masses of the blades are set to their design/tuned counterparts while the modal stiffnesses are varied from blade to blade to match the measured natural frequencies. The second approach, based on the maximum likelihood principle, yields estimates of all the structural parameters of the blades through the minimization of a specified “cost function.” The accuracy of these two techniques in predicting the forced response of mistuned bladed disks will be assessed on simple dynamic models of the blades.
8
Aleshin, Mikhail, Aleksandr Smirnov, Margarita Murzina e Yuri Boldyrev. "On Structural Optimization of The Propeller Blade". International Journal of Engineering & Technology 7, n. 4.36 (1 dicembre 2018): 1203. http://dx.doi.org/10.14419/ijet.v7i4.36.28189.
Testo completoAbstract (sommario):
The results of the structural optimization of propeller blades are presented taking into account its composite structure and pitch change mechanism of the propeller and using FSI (Fluid-Structure Interaction) approaches. The optimality criterion of the problem is the propeller thrust with optimization parameters being the characteristics of the internal structure of the propeller blade made from a composite. Together with the optimization of the blade shape, the problem is considered which concerns the reduction of the deformations caused by loads occurring during the operation of the propeller, since significant deformations of the blades lead to decreased thrust.Thus, the following optimization problem can be formulated: to find the optimal configuration of the composite material and its micro-geometrical parameters along the height of the blade to minimize deformations and increase the thrust of the propeller. At the same time, the optimization parameters are limited by the weight of the propeller and the strength characteristics.The technique presented in the paper allows us to obtain the reliable values of thrust and reduce the estimated computational time. The influence of the structure of the composite material on the mechanical properties of the blades is shown; the values of deformation of the blades under the action of centrifugal and aerodynamic loads are given.
9
Aleshin, Mikhail, Aleksandr Smirnov, Margarita Murzina e Yuri Boldyrev. "On Structural Optimization of the Propeller Blade". International Journal of Engineering & Technology 7, n. 4.36 (9 dicembre 2018): 1203. http://dx.doi.org/10.14419/ijet.v7i4.36.28212.
Testo completoAbstract (sommario):
The results of the structural optimization of propeller blades are presented taking into account its composite structure and pitch change mechanism of the propeller and using FSI (Fluid-Structure Interaction) approaches. The optimality criterion of the problem is the propeller thrust with optimization parameters being the characteristics of the internal structure of the propeller blade made from a composite. Together with the optimization of the blade shape, the problem is considered which concerns the reduction of the deformations caused by loads occurring during the operation of the propeller, since significant deformations of the blades lead to decreased thrust.Thus, the following optimization problem can be formulated: to find the optimal configuration of the composite material and its micro-geometrical parameters along the height of the blade to minimize deformations and increase the thrust of the propeller. At the same time, the optimization parameters are limited by the weight of the propeller and the strength characteristics.The technique presented in the paper allows us to obtain the reliable values of thrust and reduce the estimated computational time. The influence of the structure of the composite material on the mechanical properties of the blades is shown; the values of deformation of the blades under the action of centrifugal and aerodynamic loads are given.
10
Petukhov, A. N., e F. D. Kiselev. "THE IMPACT OF STRESS CONCENTRATORS ON THE STRUCTURAL STRENGTH OF CAST TURBINE BLADES OF AIRCRAFT ENGINES". Industrial laboratory. Diagnostics of materials 85, n. 5 (5 giugno 2019): 52–66. http://dx.doi.org/10.26896/1028-6861-2019-85-5-52-66.
Testo completoAbstract (sommario):
Assessing of the quality parameters of the blade manufacture, which can affect their operational performance, is an important step in determining the causes of turbine blade destruction. Manufacturing defects, despite their great diversity, tend to be stress concentrators. Apart from the defects listed in the specifications to be avoided upon blade manufacturing, we mean also various kinds of defects identified as concentrators that contribute to the destruction of the blades in operation. Assessment of the blade quality suggests identification and analysis of the defects, as well as determination of the technological stage at which they have been formed. For cooled turbine blades this is the foundry stage of their manufacture. Studies of the blades damaged in operation, revealed that despite the control and rejection of blades in the manufacture, the materials of the turbine blades installed on aircraft engines, contain casting defects. The revealed casting defects are shown to affect the strength characteristics and durability of turbine blades and contribute to their destruction through fatigue fracture in operation. The special features of the quality characteristics of the single-crystal turbine blades, affecting their performance, and defects that contribute to their destruction in operation are highlighted. The necessity of improving the valuation, standardization and quality control both at the stages of design and manufacture of blades is shown.
11
Lin, Yifeng, Jiandong Xiao, Conghuan Le, Puyang Zhang, Qingshan Chen e Hongyan Ding. "Bearing Characteristics of Helical Pile Foundations for Offshore Wind Turbines in Sandy Soil". Journal of Marine Science and Engineering 10, n. 7 (28 giugno 2022): 889. http://dx.doi.org/10.3390/jmse10070889.
Testo completoAbstract (sommario):
Helical pile foundations are a new foundation type for offshore wind power applications with high bearing capacity and good recovery that can be quickly and easily constructed. In this study, the finite element method was used to simulate the bearing characteristics of helical pile foundations after installation. For simulations, a blade, deeply buried in a single layer of sand, was selected. Through numerical simulations, the vertical bearing characteristics of a single helical screw pile and an ordinary pile without blades were compared, and the compression and uplift characteristics of the helical pile were revealed. In addition, the effects of pitch, blade diameter, inclination angle, number of blades, and blade spacing on the bearing characteristics of a single helical pile were analyzed. The results show that the single helical pile has the highest bearing capacity and bearing efficiency when the pitch is 0.02 times the blade buried depth, the blade diameter is 2.5 times the pile diameter, the multi-blade spacing is more than two times the blade diameter, and the number of blades is less than or equal to three. However, compared with the straight pile, the vertical bearing capacity of the single inclined helical pile did not improve significantly.
12
Zhu, Jie, Xin Cai, Pan Pan e Rong Rong Gu. "Static and Dynamic Characteristics Study of Wind Turbine Blade". Advanced Materials Research 383-390 (novembre 2011): 1895–900. http://dx.doi.org/10.4028/www.scientific.net/amr.383-390.1895.
Testo completoAbstract (sommario):
Structural analysis of wind turbine blade is a necessary part in the process of blade design. Based on the ANSYS software, the stress and strain distribution analysis of a kind of 1500kW horizontal axis wind turbine blade is carried out at the action of ultimate flapwise loads, the vibration mode shapes of this blade are also analyzed in this paper, thus providing some reference value for the larger-scale wind turbine blade on structural design.
13
Zhu, Jie, Xin Cai, Pan Pan e Rong Rong Gu. "Static and Dynamic Characteristics Study of Wind Turbine Blade". Advanced Materials Research 433-440 (gennaio 2012): 438–43. http://dx.doi.org/10.4028/www.scientific.net/amr.433-440.438.
Testo completoAbstract (sommario):
Structural analysis of wind turbine blade is a necessary part in the process of blade design. Based on the ANSYS software, the stress and strain distribution analysis of a kind of 1500kW horizontal axis wind turbine blade is carried out at the action of ultimate flapwise loads, the vibration mode shapes of this blade are also analyzed in this paper, thus providing some reference value for the larger-scale wind turbine blade on structural design．
14
Zhu, Shi Fan, e Ibrohim Rustamov. "Structural Design and Finite Element Analysis of Composite Wind Turbine Blade". Key Engineering Materials 525-526 (novembre 2012): 225–28. http://dx.doi.org/10.4028/www.scientific.net/kem.525-526.225.
Testo completoAbstract (sommario):
This paper presents structural studies of a medium scale composite wind turbine blade construction made of epoxy glass fiber for a 750kW rated power stall regulated horizontal axis wind turbine system. The complex geometry of the blade with a skin-spar foam sandwich structure was generated by utilizing commercial code ANSYS finite element package. Dimensions of twist, chord and thickness were developed by computer program. NREL S-series airfoils with different chord thickness are used along current blade cross-sections. The current design method uses blade element momentum (BEM) theory to complete satisfactory blade design and can be carried out using a spreadsheet, lift and drag curves for the chosen aerofoil. According to composite laminate theory and finite element method, optimal blade design was obtained. The focus is on the structural static strength of wind turbine blades loaded in flap-wise direction and methods for optimizing the blade cross-section to improve structural reliability. Moreover, the natural frequencies and modal shapes of the rotor blade were calculated for defining dynamic characteristics. Structural analysis was performed by using the finite element method in order to evaluate and confirm the blade to be sound and stable under various load conditions.
15
Wang, Xu Dong, Li Cun Wang, Xian Ming Zhang e Jun Feng. "Flexible and Vibration Characteristics Simulation for the Large Megawatt Size Wind Turbine Blades". Advanced Materials Research 217-218 (marzo 2011): 363–67. http://dx.doi.org/10.4028/www.scientific.net/amr.217-218.363.
Testo completoAbstract (sommario):
In the development of new large megawatt size wind turbines, aerodynamic and structural reserch is interesting and important for study wind turbine performace and boost the development of wind power. In this paper, the aerodynamic and aeroelastic characteristic of blades is investigated and presented based on Blade Element Momentum and Hamilton theory. Then the flexible characteristics of balde is researched with the aerodynamic and aeroelastic model of the rotor. The flapwise and edgewise displacements, velocities and accelerations of blade tip are simulated and plotted to validate the model which is presented in this paper. The results have very important significance to investigate the vibration and fatigue lifetime of the wind turbine blades.
16
Rivas-Guerra, A. J., M. P. Mignolet e J. P. Delor. "Identification of Mistuning Characteristics of Bladed Disks From Free Response Data— Part II". Journal of Engineering for Gas Turbines and Power 123, n. 2 (9 giugno 1999): 404–11. http://dx.doi.org/10.1115/1.1338950.
Testo completoAbstract (sommario):
The focus of the present two-part investigation is on the estimation of the dynamic properties, i.e., masses, stiffnesses, natural frequencies, mode shapes and their statistical distributions, of turbomachine blades to be used in the accurate prediction of the forced response of mistuned bladed disks. As input to this process, it is assumed that the lowest natural frequencies of the blades alone have been experimentally measured, for example in a broach block test. Since the number of measurements is always less than the number of unknowns, this problem is indeterminate in nature. In this second part of the investigation, the maximum likelihood method (ML) will first be revisited and a thorough assessment of its reliability in a wide variety of conditions, including the presence of measurement noise, different distributions of blade structural properties, etc., will be conducted. Then, a technique that provides a bridge between the two identification methods introduced in Part I, i.e., the random modal stiffnesses (RMS) and maximum likelihood (ML) approaches, will be presented. This technique, termed the improved random modal stiffnesses (IRMS) method is based on the maximum likelihood concepts but yields a mistuning model similar to that of the random modal stiffnesses technique. Finally, the accuracy of the RMS, ML, and IRMS methods in predicting the forced response statistics of mistuned bladed disks will be investigated in the presence of close blade alone natural frequencies.
17
Jebieshia, T. R., Senthil Kumar Raman e Heuy Dong Kim. "Aerodynamic and Structural Characteristics of a Centrifugal Compressor Impeller". Applied Sciences 9, n. 16 (19 agosto 2019): 3416. http://dx.doi.org/10.3390/app9163416.
Testo completoAbstract (sommario):
The present study focuses on the aerodynamic performance and structural analysis of the centrifugal compressor impeller. The performance characteristics of the impeller are analyzed with and without splitter blades by varying the total number of main and splitter blades. The operating conditions of the compressor under centrifugal force and pressure load from the aerodynamic analysis are applied to the impeller blade and hub to perform the one-way Fluid–Structure Interaction (FSI). For the stress assessment, maximum equivalent von Mises stresses in the impeller blades are compared with the maximum allowable stress of the impeller material. The effects of varying the pressure field on the deformation and stress of the impeller are also calculated. The aerodynamic and structural performance of the centrifugal compressor at 73,000 rpm are investigated in terms of the efficiency, pressure ratio, equivalent von Mises stress, and total deformation of the impeller.
18
Li, Bei, De Tian, Xiaoxuan Wu, Huiwen Meng e Yi Su. "The Impact of Bend–Twist Coupling on Structural Characteristics and Flutter Limit of Ultra-Long Flexible Wind Turbine Composite Blades". Energies 16, n. 15 (6 agosto 2023): 5829. http://dx.doi.org/10.3390/en16155829.
Testo completoAbstract (sommario):
Flutter is an instability phenomenon that can occur in wind turbine blades due to fluid–structure interaction, particularly for longer and more flexible blades. Aeroelastic tailoring through bend–twist coupling is an effective method to enhance the aeroelastic performance of blades. In this study, we investigate the impact of bend–twist coupling on the structural performance and flutter limit of the IEA 15 MW blade, which is currently the longest reference wind turbine blade, and determine the optimal layup configuration that maximizes the flutter speed. The blade is modeled by NuMAD and iVABS, and the cross-section properties are obtained by PreComb and VABS. The accuracy of the blade model is verified in terms of stiffness and frequency. The bend–twist coupling is implemented by changing the fiber angle of the skin and spar cap considering symmetric and asymmetric layups. The flutter limits of both the baseline and the bend–twist coupled blade are evaluated based on HAWC2. The results show that the angle of spar cap carbon fiber has a greater effect on the blade’s structural properties and flutter speed than the skin fiber. Varying the spar cap carbon fiber angle increases the flutter speed, with the effect being more significant for the symmetric layup, up to 9.66% at a fiber angle of 25 degrees. In contrast, the variation in skin fiber angle has a relatively small impact on flutter speed—within ±3%.
19
Loss, Theresa, e Alexander Bergmann. "Vibration-Based Fingerprint Algorithm for Structural Health Monitoring of Wind Turbine Blades". Applied Sciences 11, n. 9 (10 maggio 2021): 4294. http://dx.doi.org/10.3390/app11094294.
Testo completoAbstract (sommario):
Monitoring the structural health of wind turbine blades is essential to increase energy capture and operational safety of turbines, and therewith enhance competitiveness of wind energy. With the current trends of designing blades ever longer, detailed knowledge of the vibrational characteristics at any point along the blade is desirable. In our approach, we monitor vibrations during operation of the turbine by wirelessly measuring accelerations on the outside of the blades. We propose an algorithm to extract so-called vibration-based fingerprints from those measurements, i.e., dominant vibrations such as eigenfrequencies and narrow-band noise. These fingerprints can then be used for subsequent analysis and visualisation, e.g., for comparing fingerprints across several sensor positions and for identifying vibrations as global or local properties. In this study, data were collected by sensors on two test turbines and fingerprints were successfully extracted for vibrations with both low and high operational variability. An analysis of sensors on the same blade indicates that fingerprints deviate for positions at large radial distance or at different blade sides and, hence, an evaluation with larger datasets of sensors at different positions is promising. In addition, the results show that distributed measurements on the blades are needed to gain a detailed understanding of blade vibrations and thereby reduce loads, increase energy harvesting and improve future blade design. In doing so, our method provides a tool for analysing vibrations with relation to environmental and operational variability in a comprehensive manner.
20
Bae, Sung-Youl, e Yun-Hae Kim. "Structural design and analysis of large wind turbine blade". Modern Physics Letters B 33, n. 14n15 (28 maggio 2019): 1940032. http://dx.doi.org/10.1142/s0217984919400323.
Testo completoAbstract (sommario):
This paper presents a new design procedure for large wind turbine blades, which can be used in various case studies. The structural design of 2MW CFRP blade was performed using a verified 2MW GFRP blade model. The structural integrity assessment of the CFRP model demonstrated that the design criteria for tip deformation, buckling failure, and laminate failure in normal wind turbine operating conditions were met. The existing aero-elastic analysis code was not used to estimate the blade load, but the blade’s surface pressure was calculated using CFD. The conventional load analysis code necessitates the establishment of a turbine system and the input of structural characteristics with changes in the structural design specifications. However, when CFD was used to estimate the load, the turbine system was not required and the structure was evaluated against various design cases, making this a useful approach in preliminary design. This new structural design and evaluation procedure for wind blades can be used to review diverse design specifications in the initial design stage.
21
Zhang, Yuquan, Zhiqiang Liu, Chengyi Li, Xuemei Wang, Yuan Zheng, Zhi Zhang, Emmanuel Fernandez-Rodriguez e Rabea Jamil Mahfoud. "Fluid–Structure Interaction Modeling of Structural Loads and Fatigue Life Analysis of Tidal Stream Turbine". Mathematics 10, n. 19 (7 ottobre 2022): 3674. http://dx.doi.org/10.3390/math10193674.
Testo completoAbstract (sommario):
Developing reliable tidal-energy turbines of a large size and capacity links to preservation of the structural safety and stability of the blades. In this study, a bidirectional fluid–structure coupling method was applied to analyze the hydrodynamic performance and structural characteristics of the blade of a tidal-stream turbine. Analyses were conducted on the transient and stable structural stresses, fatigue, and deformations under the influence of water depth and turbine rotational speed. The performance predictions with and without fluid–structure coupling are similar to measurements. The water-depth change has little effect on the stress and deformation change of the blade, while the turbine-speed change has the most significant effect on it. When the turbine just starts, the blade will be subject to a sudden change load. This is due to the increase in turbine speed, resulting in the sudden load. Similar to the trend of blade stress, the blade safety factor is lower near the root of the blade, and the turbine-speed change has a more significant impact on the blade structure’s safety. However, the number of stress cycles in the blade at different rotational speeds is within the safety range.
22
Lian, Xiaolong, Bo Zhou, Chuan Wang, Bin Li, Yingju Pei e Qiyu Dong. "Study on hydraulic characteristics and internal flow mechanism of composite blade disc pump". Journal of Physics: Conference Series 2256, n. 1 (1 aprile 2022): 012015. http://dx.doi.org/10.1088/1742-6596/2256/1/012015.
Testo completoAbstract (sommario):
Abstract Disc pump is widely used in difficult-pump-medium transportation such as petroleum and chemical industry. Discontinuous blade impellers play an important role in the passability and energy efficiency of disk pump. The research of design and internal flow mechanism are particularly important. Based on the structural characteristics and the internal flow mechanism of the original model, the improved design of the blade structure is carried out. Through the experimental verification and the numerical analysis of multiple working conditions, the influence law of the new composite blade on the hydraulic characteristics and internal flow mechanism of the disc pump is obtained. The results show that the error of energy efficiency characteristics of simulation and experiment under different flow conditions is within 5%, and the accuracy of simulation results meets the requirements; The hydraulic characteristics of the improved model are about 5.8% higher than that of the original model. The driving force of the new composite blade is more sufficient and the flow field is improved more obviously; The low pressure is located in the center of the impeller and gradually increases to the outlet of the impeller. There is obvious energy and mass conversion between the bladed region and bladeless region. The research results can provide a reference for the structural design of disc pump composite blade and the analysis of internal flow mechanism.
23
Li, Linling, e Qibai Huang. "Research on the Mechanism of Fan Blade Shape Effect on its Noise". Journal of Low Frequency Noise, Vibration and Active Control 24, n. 1 (marzo 2005): 59–69. http://dx.doi.org/10.1260/0263092054037720.
Testo completoAbstract (sommario):
The fan blade configuration affects its efficiency and sound pressure level—(SPL). This paper analyzes the fan blade noise components and studies the aerodynamic characteristics of fan blades. The bar theory and moving soundfield characteristics are used in the theoretical analysis. Nonlinear aerodynamics theory is used to analyze the blade force. A mathematical model of fan blade noise is developed and simulated by the precision Gauss-Legendre method. The model simulation and the experiment results are analyzed in the frequency domain. The simulation results are in reasonable agreement with the measured data. Our model and the Fukano model are compared for different rotational speeds of the fan. This paper then studies the change of SPL when the blade parameters (number of blades, rotation speed of fan, chord of fan, and blade profile etc.) vary. The major factors affecting the fan noise are analyzed. Our model is derived from the viewpoint of blade design, so the result can be used to study the aerodynamic characteristics of fan blades quantitatively. The study is considered as a prerequisite to designing fans of high quality, since it provides a theoretical basis for noise prediction and noise control.
24
Yang, Zhenya, e Chaofeng Li. "Influence of Fir-Tree Tenon Blade Parameters on Blade Dynamic Characteristics". Shock and Vibration 2023 (17 giugno 2023): 1–19. http://dx.doi.org/10.1155/2023/5553183.
Testo completoAbstract (sommario):
In this paper, based on the theory of elastic structure analysis, considering the rotational softening and centrifugal stiffening of the blade, the dynamic model of the fir-tree rotating blade and the macroslip hysteresis model of the dry friction on the contact surface of fir-tree tenon are established. Based on elastic mechanics, the pressure distribution model of fir-tree tenon is innovatively established and the relationship between fit clearance and contact pressure has been derived. After the blade is discretized by the finite element method, the dynamic equation of the blade is solved iteratively by the Newmark-β numerical integration method. According to the dynamic equation of the blade, the influence of the change of the tenon angle on the forced response and contact stress of the blade is derived. Finally, some novel conclusions are obtained by analyzing the influence of pressure distribution, tenon angle, friction coefficient, rotational speed, and aerodynamic excitation on blade vibration characteristics. It provides a scheme and relevant basis for the design and development of tenon blades with the most damping effect at different speeds in industrial practice.
25
Shi, Lijian, Changxin Wu, Li Wang, Tian Xu, Yuhang Jiang, Yao Chai e Jun Zhu. "Influence of Blade Angle Deviation on the Hydraulic Performance and Structural Characteristics of S-Type Front Shaft Extension Tubular Pump Device". Processes 10, n. 2 (8 febbraio 2022): 328. http://dx.doi.org/10.3390/pr10020328.
Testo completoAbstract (sommario):
When the axial-flow pump is running, the blade angle is not fully adjusted or there are errors in the manufacture of the blades, which will lead to inconsistent blade placement angles during operation, and which will reduce the efficiency of the axial-flow pump. This paper uses the research methods of numerical simulation and model experiments to analyze the hydraulic performance and impeller structure characteristics of each flow components under different schemes when the angles of each blade of the S-type front shaft extension tubular pump device are inconsistent. The research phenomenon is that the guide vane greatly recovers the flow velocity circulation at the impeller outlet, reduces the hydraulic loss of guide vane, and widens the best efficiency range with an increase in guide vane blade angle. When the blade angle deviation occurs, the flow field of each blade channel affects each other, and the maximum decrease in the best efficiency is up to 7.78%, mainly due to the increased hydraulic loss in the outlet channel. The blade angle deviation will also affect the maximum equivalent stress and maximum deformation of the impeller, which is more obvious in large flow conditions. Inconsistent blade angles seriously affect the operating efficiency of the water pump and water pump device, and make the structural characteristics of the impeller worse.
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Гребеников, А. Г., Ю. В. Дьяченко, В. В. Коллеров, В. Ю. Коцюба, И. В. Малков, В. А. Урбанович e И. А. Воронько. "АНАЛІЗ КОНСТРУКТИВНО-ТЕХНОЛОГІЧНИХ ОСОБЛИВОСТЕЙ ЛОПАТЕЙ НЕСУЧИХ ГВИНТІВ ВАЖКИХ ТРАНСПОРТНИХ ВЕРТОЛЬОТІВ". Open Information and Computer Integrated Technologies, n. 93 (19 novembre 2021): 59–103. http://dx.doi.org/10.32620/oikit.2021.93.04.
Testo completoAbstract (sommario):
The analysis of the design and technological features of the rotor blades of heavy transport helicopters is carried out. The main performance characteristics of heavy helicopters are presented. General requirements to helicopter main rotor blades design and specifications for their production are formulated. The design and force diagram of heavy helicopter main rotor blades is considered. The features of structural materials for the main rotor blades of heavy transport helicopters are marked. The main rotor blades differ in their design due to different approaches to materials, manufacturing and layout of blade elements. The main rotor blades of an all-metal design, for design and technological reasons, are divided into two groups: a frame structure with a tubular steel spar and an aluminum extruded spar. As a result of a number of design and technological measures the service life of the main rotor blade of helicopter Mi-6 was brought from 50 hours to 1500 hours. The principal peculiarity of the steel tubular spar of the main rotor blade of the Mi-26 helicopter is the absence of the shaft lug. The features of mixed design main rotor blades are presented. The method of parametric modeling of helicopter main rotor blades is presented. The application of the three-dimensional parametric models of structural elements in practice of designing and construction enables to perform numerical calculations of aerodynamic and strength characteristics both of separate aggregates, units and details and of the helicopter as a whole by means of the finite element method. The method of parametric modeling of the main rotor blade of the transport helicopter with the computer system CATIA V5 is a modification of the method of integrated designing of the elements of aviation constructions. Parametric master geometry of the main rotor blade is a linear surface, created by basic profiles of the blade. On the basis of parametric master geometry a space distribution model is created that determines the position of axial planes of the power set of the blade for further creation of the blade detail models. Technological flowchart of main rotor blade manufacturing is presented, manufacturing and surface hardening technology of steel tubular spar is considered. The technology of manufacturing and molding the nose part of the blade of the main rotor mixed design. The technological features of slipway assembly-gluing of the main rotor blade are considered, the content of off-slipway work is given.These materials can be useful in theoretical and experimental studies to extend the service life of the rotor blades of Mi-26 helicopters, which are currently in operation in Ukraine.
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HUYNH, THANH NGOC, TOẢN QUỐC TRẦN e QUYẾT THÀNH PHẠM. "Research on aerodynamic characteristics through airflow clearances in compressor blades of gas turbine engine". Science & Technology Development Journal - Engineering and Technology 3, SI3 (27 dicembre 2020): first. http://dx.doi.org/10.32508/stdjet.v3isi3.640.
Testo completoAbstract (sommario):
Reducing the loss in the airflow clearance among the compressor blades of the rotor disk and stationary blades (guide vanes) is an urgent issue. Furthermore, additional losses of airflow through the clearances among the blades and airfoil losses are the main cause of reducing the efficiency of an axial flow compressor, especially the blade height is small. With a view towards the efficiency improvement of a multistage axial compressor with a high-pressure ratio, it is necessary to manufacture a highly economical compressor with a variety of compression stages. Airflow in the circulation clearances alternating among compressor blades has viscosity, unstable compression, and quite complex flow structure. This needs to be researched into the design with the assistance of modern software (ANSYS CFX, FlowER, etc.). Although this is an important step in the current design orientation, it requires additional practical elements to perform, especially the problem of optimizing the outer rim, the level, and the number of compression stages in the whole compressor. In this paper, authors have used the method of creating three-dimensional (3D) models for blade profiles in a compressor based on analyzing the flow in three-dimensional form and studying their parameters. This paper deals with the geometry problems of the row of rotating blades (cascade) by proposing the structural arrangement of stacking blades in the circular direction and the blade profile formed the S-shape. Investigating and calculating the aerodynamic properties of the airflow through clearances of compressor blades by using ANSYS is one of the new methods. The researched result showed the dependence between the camber angle as the rotating blade formed an S-shape profile rotates regarding the stagger angle of the airfoil and the incident angle of airflow. Some characteristics of aerodynamic properties are distributed according to the blade height in conducting with different curved profiles of the rotating blades on the rotor disk and stationary blades.
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Zhao, Tianyu, Yuxuan Wang, Xinze Cui e Xin Wang. "Analytical Solution for Forced Vibration Characteristics of Rotating Functionally Graded Blades under Rub-Impact and Base Excitation". Materials 15, n. 6 (15 marzo 2022): 2175. http://dx.doi.org/10.3390/ma15062175.
Testo completoAbstract (sommario):
This paper presents an analytical investigation on the forced vibration characteristics of a rotating functionally graded material (FGM) blade subjected to rub-impact and base excitation. Based on the Kirchhoff plate theory, the rotating blade is modelled theoretically. The material properties of the FGM blade are considered to vary continuously and smoothly along the thickness direction according to a volume fraction power-law distribution. By employing Hamilton’s principle, the equations of motion are derived. Then, the Galerkin method and the small parameter perturbation method are utilized to obtain the analytical solution for the composite blade under a combined action of radial force, tangential force and displacement load. Finally, special attention is given to the effects of power-law index, rub-impact location, friction coefficient, base excitation amplitude and blade aspect ratio on the vibration characteristics of the FGM structure. The obtained results can play a role in the design of rotating FGM blades to achieve significantly improved structural performance.
29
Chen, Yiming, Rongsheng Zhu, Yonggang Lu, Zhenjun Gao e Junjun Kang. "Study on Flow Field and Rotor Safety Characteristics of MSPs Based on Flow Thermo-Coupling". Processes 7, n. 10 (8 ottobre 2019): 711. http://dx.doi.org/10.3390/pr7100711.
Testo completoAbstract (sommario):
In order to obtain the structural intensity under the operation conditions of MSP (molten salt pump), the rotor component of MSP is taken as the research object. In this paper, the influence of material properties change on the structural performance of MSP at different temperatures is analyzed. The stress distribution and strain distribution of MSP rotor components under different loads are investigated, and the intensity calculation of MSP rotor system is carried out to explore whether it meets the intensity requirements under high temperature operation, which lays a foundation for the high temperature test of MSP. The results show that the maximum deformation position of the blade working face appears at the outer edge of the impeller. When the fluid-structure coupling is applied, the blade strain law and the strain law during thermo-coupling are similar. The effect of the temperature field on the degree of blade deformation is not significant, provided that other factors remain the same. The position where the impeller equivalent stress is the largest is mainly concentrated in the area where the blade is in contact with the front and rear cover plates at the outlet of the impeller. Different degrees of stress concentration occur in the area where the blade is in contact with the impeller hub. The distribution law of the equivalent stress on the surface of the impeller cover plate is that the equivalent stress value changes periodically along the circumferential direction of the impeller, and the number of change cycles is equal to the number of impeller blades. This study can provide a reference for the structural design of MSPs.
30
van Rijswijk, K., S. Joncas, H. E. N. Bersee, O. K. Bergsma e A. Beukers. "Sustainable Vacuum-Infused Thermoplastic Composites for MW-Size Wind Turbine Blades—Preliminary Design and Manufacturing Issues". Journal of Solar Energy Engineering 127, n. 4 (21 giugno 2005): 570–80. http://dx.doi.org/10.1115/1.2037107.
Testo completoAbstract (sommario):
This paper addresses the feasibility of using innovative vacuum infused anionic polyamide-6 (PA-6) thermoplastic composites for MW-size wind turbine blades structures. To compare the performance of this fully recyclable material against commonly used less sustainable thermoset blade materials in a baseline structural MW-size blade configuration (box-spar/skins), four different blade composite material options were investigated: Glass/epoxy, carbon/epoxy, glass/PA-6, and carbon/PA-6. Blade characteristics such as weight, costs, and natural frequencies were compared for rotor blades ranging between 32.5 and 75m in length, designed according to both stress and tip deflection criteria. Results showed that the PA-6 blades have similar weights and natural frequencies when compared to their epoxy counterpart. For glass fiber blades, a 10% reduction in material cost can be expected when using PA-6 rather than epoxy while carbon fiber blades costs were found to be similar. Considering manufacturing, processing temperatures of PA-6 are significantly higher than for epoxy systems; however, the associated cost increase is expected to be compensated for by a reduction in infusion and curing time.
31
Xu, Lei. "A Study on the Structural Characteristics of the Blades of Wind Turbines under Static Load Condition". Journal of Physics: Conference Series 2474, n. 1 (1 aprile 2023): 012043. http://dx.doi.org/10.1088/1742-6596/2474/1/012043.
Testo completoAbstract (sommario):
Abstract The study of the structural strength and stiffness of wind turbine blades is an important foundation and guarantee for analyzing the stability and reliability of the complete wind turbine. By analyzing the results of static load experiments and finite element calculation, the stress, strain and deflection of blades can be more precisely determined so as to assess the structural characteristics of blades. We conducted static load tests on the medium-size experimental blades developed by the Institute of Engineering Thermophysics, Chinese Academy of Sciences, and obtained the deflection conditions of flap-wise and edgewise bendings, as well as the analytic results on the strain of the main beams and trailing edges. Meanwhile, a finite element model of blades was built using ANSYS to analyze the maximum deformation, stress, and strain. The corresponding results were compared with those of static load experiments. Then the strain and bending properties of blades under the static load were investigated, and the characteristics of the safety application of blades were verified. The results show that: 1)Within the range of 100% design load, the deflection of edgewise and flapwise directions presented a linear relationship with the applied loads. 2) After the loads in the flapwise direction exceeded 100% design load, a non-linear relationship between the blade bending and the applied loads were found. 3)The blade beam and trailing edge retain good stiffness properties under big strain conditions, and the maximum deformation appeared at the maximum chord length of the trailing edge of the blades. Our results on the static load experiments were basically consistent with the finite element model simulation, which verified the accuracy of the results of the static load experiment and finite element simulation of blades.
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Zhou, Peng Zhan, e Fang Sheng Tan. "Stress Characteristics Analysis on a Composite Wind Turbine Blade". Advanced Materials Research 602-604 (dicembre 2012): 111–14. http://dx.doi.org/10.4028/www.scientific.net/amr.602-604.111.
Testo completoAbstract (sommario):
The stress characteristics on a composite wind turbine blade are analyzed by using a finite element method. The whole stress level of the spar cap and the blade root is higher than that of the shear web and the airfoil plate, so the spar cap and the blade root are the main force-supporting parts. If the stress concentration point on the interface corner between the blade root and the shear web is neglected, the stress of the spar cap is higher than that of the blade root, and its maximum stress and mean stress are 211 MPa and 180 MPa respectively. The maximum stress of the blade is only 34.8% of the tensile stress of the glass-fiber/epoxy composites. It indicates that the laminate structural design of the blade is inclined to be safety.
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Algolfat, Amna, Weizhuo Wang e Alhussein Albarbar. "The Sensitivity of 5MW Wind Turbine Blade Sections to the Existence of Damage". Energies 16, n. 3 (28 gennaio 2023): 1367. http://dx.doi.org/10.3390/en16031367.
Testo completoAbstract (sommario):
Due to the large size of offshore wind turbine blades (OWTBs) and the corrosive nature of salt water, OWTs need to be safer and more reliable that their onshore counterparts. To ensure blade reliability, an accurate and computationally efficient structural dynamic model is an essential ingredient. If damage occurs to the structure, the intrinsic properties will change, e.g., stiffness reduction. Therefore, the blade’s dynamic characteristics will differ from those of the intact ones. Hence, symptoms of the damage are reflected in the dynamic characteristics that can be extracted from the damaged blade. Thus, damage identification in OWTBs has become a significant research focus. In this study, modal model characteristics were used for developing an effective damage detection method for WTBs. The technique was used to identify the performance of the blade’s sections and discover the warning signs of damage. The method was based on a vibration-based technique. It was adopted by investigating the influence of reduced blade element rigidity and its effect on the other blade elements. A computational structural dynamics model using Rayleigh beam theory was employed to investigate the behaviour of each blade section. The National Renewable Energy Laboratory (NREL) 5MW blade benchmark was used to demonstrate the behaviour of different blade elements. Compared to previous studies in the literature, where only the simple structures were used, the present study offers a more comprehensive method to identify damage and determine the performance of complicated WTB sections. This technique can be implemented to identify the damage’s existence, and for diagnosis and decision support. The element most sensitive to damage was element number 14, which is NACA_64_618.
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Dalli, Uğbreve;ur, e Şcedilefaatdin Yüksel. "Identification of Flap Motion Parameters for Vibration Reduction in Helicopter Rotors with Multiple Active Trailing Edge Flaps". Shock and Vibration 18, n. 5 (2011): 727–45. http://dx.doi.org/10.1155/2011/675791.
Testo completoAbstract (sommario):
An active control method utilizing the multiple trailing edge flap configuration for rotorcraft vibration suppression and blade loads control is presented. A comprehensive model for rotor blade with active trailing edge flaps is used to calculate the vibration characteristics, natural frequencies and mode shapes of any complex composite helicopter rotor blade. A computer program is developed to calculate the system response, rotor blade root forces and moments under aerodynamic forcing conditions. Rotor blade system response is calculated using the proposed solution method and the developed program depending on any structural and aerodynamic properties of rotor blades, structural properties of trailing edge flaps and properties of trailing edge flap actuator inputs. Rotor blade loads are determined first on a nominal rotor blade without multiple active trailing edge flaps and then the effects of the active flap motions on the existing rotor blade loads are investigated. Multiple active trailing edge flaps are controlled by using open loop controllers to identify the effects of the actuator signal output properties such as frequency, amplitude and phase on the system response. Effects of using multiple trailing edge flaps on controlling rotor blade vibrations are investigated and some design criteria are determined for the design of trailing edge flap controller that will provide actuator signal outputs to minimize the rotor blade root loads. It is calculated that using the developed active trailing edge rotor blade model, helicopter rotor blade vibrations can be reduced up to 36% of the nominal rotor blade vibrations.
35
Sanliturk, K. Y., D. J. Ewins, R. Elliott e J. S. Green. "Friction Damper Optimization: Simulation of Rainbow Tests". Journal of Engineering for Gas Turbines and Power 123, n. 4 (1 marzo 1999): 930–39. http://dx.doi.org/10.1115/1.1391278.
Testo completoAbstract (sommario):
Friction dampers have been used to reduce turbine blade vibration levels for a considerable period of time. However, optimal design of these dampers has been quite difficult due both to a lack of adequate theoretical predictions and to difficulties in conducting reliable experiments. One of the difficulties of damper weight optimization via the experimental route has been the inevitable effects of mistuning. Also, conducting separate experiments for different damper weights involves excessive cost. Therefore, current practice in the turbomachinery industry has been to conduct so-called “rainbow tests” where friction dampers with different weights are placed between blades with a predefined configuration. However, it has been observed that some rainbow test results have been difficult to interpret and have been inconclusive for determining the optimum damper weight for a given bladed-disk assembly. A new method of analysis—a combination of the harmonic balance method and structural modification approaches—is presented in this paper for the analysis of structures with friction interfaces and the method is applied to search for qualitative answers about the so-called “rainbow tests” in turbomachinery applications. A simple lumped-parameter model of a bladed-disk model was used and different damper weights were modeled using friction elements with different characteristics. Resonance response levels were obtained for bladed disks with various numbers of blades under various engine-order excitations. It was found that rainbow tests, where friction dampers with different weights are used on the same bladed-disk assembly, can be used to find the optimum damper weight if the mode of vibration concerned has weak blade-to-blade coupling (the case where the disk is almost rigid and blades vibrate almost independently from each other). Otherwise, it is very difficult to draw any reliable conclusion from such expensive experiments.
36
Jones, D. I. G., e A. Muszynska. "Structural Modification of Advanced Turbomachine Blading by Dynamic Stiffness Matrix Operations". Journal of Vibration and Acoustics 110, n. 4 (1 ottobre 1988): 450–55. http://dx.doi.org/10.1115/1.3269549.
Testo completoAbstract (sommario):
This paper examines the application of matrix transformations from the experimentally obtained receptance matrix to the dynamic stiffness matrix to determine changes of blade stiffness and/or mass characteristics which will achieve desired modifications of blade dynamic behavior. Results for a specific turbine blade configuration are used to illustrate the approach.
37
Bai, Yalei, e Donglei Wu. "Study on Fatigue Characteristics of Axial-Flow Pump Based on Two-Way Fluid–Structure Coupling". Energies 15, n. 23 (27 novembre 2022): 8965. http://dx.doi.org/10.3390/en15238965.
Testo completoAbstract (sommario):
When an axial-flow pump is running, there is a very complex flow inside the runner. Based on the two-way fluid–structure coupling method, this paper simulated the forward and reverse operating conditions of an axial-flow pump and calculated the dynamic stress distribution on the blade surface. The stress load spectrum was loaded onto the blade, and fatigue characteristic analysis was carried out to obtain the fatigue life and damage of the blade. This research shows the following: under different working conditions, the dynamic stress is concentrated at the root of the blade, and its amplitude decreases with the increase in the flow rate; at the same time, the change in stress with time shows a periodic change law. Under the working conditions of the turbine, the main frequency is the rotational frequency, and the secondary frequency is composed of multipliers of the rotational frequency, which is obviously affected by the number of blades; the fatigue damage and stress distribution are consistent, and the damage is the most serious at the stress concentration point. The research results of this paper can provide theoretical guidance for the structural design and safe operation of axial-flow pumps.
38
Muyan, Can, e Demirkan Coker. "Finite element simulations for investigating the strength characteristics of a 5 m composite wind turbine blade". Wind Energy Science 5, n. 4 (20 ottobre 2020): 1339–58. http://dx.doi.org/10.5194/wes-5-1339-2020.
Testo completoAbstract (sommario):
Abstract. Full-scale structural tests enable us to monitor the mechanical response of the blades under various loading scenarios. Yet, these tests must be accompanied by numerical simulations so that the physical basis of the progressive damage development can be better interpreted and understood. In this work, finite element analysis is utilized to investigate the strength characteristics of an existing 5 m RÜZGEM composite wind turbine blade under extreme flapwise, edgewise and combined flapwise plus edgewise loading conditions. For this purpose, in addition to a linear buckling analysis, Puck's (2D) physically based phenomenological model is used for the progressive damage analysis of the blade. The 5 m RÜZGEM blade is found to exhibit sufficient resistance against buckling. However, Puck's damage model indicates that laminate failure plays a major role in the ultimate blade failure. Under extreme flapwise and combined load cases, the internal flange at the leading edge and the trailing edge are identified as the main damaged regions. Under edgewise loading, the leading edge close to the root is the failure region. When extreme load case is applied as a combination of edgewise and flapwise loading cases, less damage is observed compared to the pure flapwise loading case.
39
Ye, Daoxing, Hao Li, Qiuyan Ma, Qibiao Han e Xiulu Sun. "Numerical Investigation of Performance Improvement and Erosion Characteristics of Vortex Pump Using Particle Model". Shock and Vibration 2020 (6 marzo 2020): 1–10. http://dx.doi.org/10.1155/2020/5103261.
Testo completoAbstract (sommario):
Vortex pump has characteristics of low efficiency and serious surface erosion of blade, which seriously affects service life. Therefore, it is particularly important to improve the efficiency of vortex pump and reduce erosion of blade surface. In this investigation, the design of experiment was used to determine the test plan and the number of samples tested. The relationship between geometric factors of vortex pump and efficiency and erosion rate of blade was established using the kriging approximation model. The genetic algorithm solved the multiobjective optimization and obtained the Pareto front solution using NSGA-II. The results showed that the width of nonblade cavity of the vortex pump is reduced by 18.93%, the number of blades of the impeller is increased by one, and the outlet width of the blade is increased by 19.81%. The performance after optimization is significantly improved compared with the original prototype. At design flow rate, the efficiency of the vortex pump increases by 3.24%, while the efficiency increases by 2.59% and 6.24% at 0.8Qd and 1.2Qd, respectively. The maximum erosion rate of blade surface 8.52 × 10−4 kg/(m2·s) is reduced to 7.18 × 10−4 kg/(m2·s) at 1.0Qd by optimization, which is reduced by 15.73%. The blade erosion after optimization is significantly controlled, and the angle of particle hitting blade surface is reduced.
40
Kumar, M. Rohin, e C. Venkatesan. "Effects of blade configuration parameters on helicopter rotor structural dynamics and whirl tower loads". Aeronautical Journal 120, n. 1224 (febbraio 2016): 271–90. http://dx.doi.org/10.1017/aer.2015.11.
Testo completoAbstract (sommario):
ABSTRACTThe influence of the blade geometric parameters on the structural dynamic characteristics, response and loads of a helicopter rotor under hover condition in a whirl tower was investigated. A general geometry was considered for the rotor blade which included configuration parameters like root offset, torque offset, pre-twist, pre-cone, pre-droop, pre-sweep, tip-sweep and tip-anhedral. The option of placing concentrated masses at any location on the blade was also included. Natural frequencies and the corresponding mode shapes of the rotating blade were obtained by solving the linear, undamped structural dynamics model in the finite element domain. For calculating the response and loads on the rotor, the complete aeroelastic equation was solved in modal space. Aerodynamic models used in the aeroelastic loads calculations were Peters-He dynamic wake theory for inflow and themodifiedONERA dynamic stall theory for airloads calculations. From the study, the blade structural dynamic characteristics are found to be sensitive to variation in blade geometric parameters. Tip-sweep was found to have significant effects on root oscillatory moments. The moments at the tip junction with the straight portion of the blade were found to be substantially affected by tip-sweep and tip-anhedral.
41
Xu, Hailong, Zhongsheng Chen, Yongmin Yang, Limin Tao e Xuefeng Chen. "Effects of Crack on Vibration Characteristics of Mistuned Rotated Blades". Shock and Vibration 2017 (2017): 1–18. http://dx.doi.org/10.1155/2017/1785759.
Testo completoAbstract (sommario):
Rotated blades are key mechanical components in turbine and high cycle fatigues often induce blade cracks. Meanwhile, mistuning is inevitable in rotated blades, which often makes it much difficult to detect cracks. In order to solve this problem, it is important and necessary to study effects of crack on vibration characteristics of mistuned rotated blades (MRBs). Firstly, a lumped-parameter model is established based on coupled multiple blades, where mistuned stiffness with normal distribution is introduced. Next, a breathing crack model is adopted and eigenvalue analysis is used in coupled lumped-parameter model. Then, numerical analysis is done and effects of depths and positions of a crack on natural frequency, vibration amplitude, and vibration localization parameters are studied. The results show that a crack causes natural frequency decease and vibration amplitude increase of cracked blade. Bifurcations will occur due to a breathing crack. Furthermore, based on natural frequencies and vibration amplitudes, variational factors are defined to detect a crack in MRBs, which are validated by numerical simulations. Thus, the proposed method provides theoretical guidance for crack detection in MRBs.
42
Bezjazychnyj, V. F., K. A. Vinogradov e O. V. Vinogradova. "DETERMINATION OF GEOMETRICAL PARAMETERS OF GAS TURBINE BLADES BASED ON COORDINATE MEASUREMENT BY STRUCTURAL AND PARAMETRIC ANALYSIS METHODS". Spravochnik. Inzhenernyi zhurnal, n. 277 (aprile 2020): 31–37. http://dx.doi.org/10.14489/hb.2020.04.pp.031-037.
Testo completoAbstract (sommario):
A method for determining the parameters of the turbine blades geometry (angles of the inlet and outlet edges, thickness, etc.), as well as the coordinates of the centers of gravity of the blades (height) according to the coordinate measurements of the profiles is proposed. These parameters are used to evaluate the gas-dynamic efficiency of the blade row and the strength characteristics of the turbine blades on the basis of one-dimensional and two-dimensional models widely used in engineering practice.
43
Bezjazychnyj, V. F., K. A. Vinogradov e O. V. Vinogradova. "DETERMINATION OF GEOMETRICAL PARAMETERS OF GAS TURBINE BLADES BASED ON COORDINATE MEASUREMENT BY STRUCTURAL AND PARAMETRIC ANALYSIS METHODS". Spravochnik. Inzhenernyi zhurnal, n. 277 (aprile 2020): 31–37. http://dx.doi.org/10.14489/hb.2020.04.pp.031-037.
Testo completoAbstract (sommario):
A method for determining the parameters of the turbine blades geometry (angles of the inlet and outlet edges, thickness, etc.), as well as the coordinates of the centers of gravity of the blades (height) according to the coordinate measurements of the profiles is proposed. These parameters are used to evaluate the gas-dynamic efficiency of the blade row and the strength characteristics of the turbine blades on the basis of one-dimensional and two-dimensional models widely used in engineering practice.
44
Nan, Guofang, Jianyang Lou, Chuanchong Song e Min Tang. "A New Approach for Solving Rub-Impact Dynamic Characteristics of Shrouded Blades Based on Macroslip Friction Model". Shock and Vibration 2020 (14 gennaio 2020): 1–9. http://dx.doi.org/10.1155/2020/8147143.
Testo completoAbstract (sommario):
Based on the macroslip friction model, a new dynamic model of the shrouded blades for rotating machinery is developed to study the impact vibration between the adjacent blades. Unlike the traditional analytical method of the shrouded blade based on the simple Coulomb friction model, a new approach is developed that the macroslip friction model is used to represent a more accurate rubbing behavior (more closer to reality) between the shrouds. By means of the harmonic balance method, the friction force and the normal pressure are translated into the equivalent stiffness and the equivalent damping. The Galerkin method is adopted to reduce the dimension of the equation to obtain the 1-DOF equation of motion, and the dynamic response of the shrouded blade is solved by Runge–Kutta numerical method. The effects of parameters such as the gap of shrouds, the mass of the tip, the contact angle, and the normal stiffness between the shrouded blades on the damping characteristics are discussed. The results show that the gap of tips has a significant effect on the vibration amplitude of the blade. Within a certain range, with the decrease of the gap, the amplitude of the blade tip is getting smaller while the resonant speed is increasing. The mass of the shroud has little effect on the damping characteristics, while the contact angle has a great influence on the equivalent stiffness and damping. Increasing the contact angle to a certain extent can effectively reduce the vibration amplitude of the blade, and the normal contact stiffness also has an important influence in reducing the vibration. The research results based on the new method in this paper are compared with the published articles and agree well. The research work is important to the accurate calculations and design and control of the shrouded blades for rotating machinery.
45
Wang, Shuo, Liaojun Zhang e Guojiang Yin. "Numerical Investigation of the FSI Characteristics in a Tubular Pump". Mathematical Problems in Engineering 2017 (2017): 1–9. http://dx.doi.org/10.1155/2017/7897614.
Testo completoAbstract (sommario):
Flow condition was simulated in a shaft tubular pump by using the Shear-Stress Transport (SST) k-ω turbulence model with high quality structured grids in design condition. Corresponding structural vibration characteristics were then analyzed based on two-way coupled Fluid-Structure Interaction (FSI) method. Fluid results showed that flow in the outlet flow passage was a combination of the axial flow and circumferential rotation motion. Time and frequency domain analysis of pressure pulsation of typical measure points indicated that larger pulsation amplitudes appeared in the tip of the blades and the main vibration source was the pressure pulsation induced by rotation of the blades. The fluid pulsation amplitudes decreased gradually along the flow direction, which can be ascribed to the function of fixed guide vane. Structural analysis of the blades in both pressure and suction side indicated that significant stress concentration was formed at the blade and hub connection near the leading edge. Maximum effective stress of the blades varied periodically, so prevention measures of the fatigue of blades should be taken. This research can provide important reference for the design of the tubular pump.
46
Belan, Juraj, Lenka Kuchariková, Magdalena Mazur, Eva Tillová e Patrícia Hanusová. "The Quality Assurance of Cast and Wrought Aero Jet Engine Components Made from Ni-base Superalloys with Using of Quantitative Metallography Methods and Alloys Lifetime Prediction". Quality Production Improvement - QPI 1, n. 1 (1 luglio 2019): 222–29. http://dx.doi.org/10.2478/cqpi-2019-0030.
Testo completoAbstract (sommario):
Abstract The Ni-base superalloys are used in the aircraft industry for the production of aero engine most stressed parts, turbine blades or turbine discs. Quality of aero jet engine components has a significant influence on the overall lifetime of a jet engine as itself as well as the whole airplane. From this reason a dendrite arm spacing, grain size, morphology, number and value of γ′-phase are very important structural characteristics for blade or discs lifetime prediction. The methods of quantitative metallography are very often used for evaluation of structural characteristics mentioned above. The high-temperature effect on structural characteristics and application of quantitative methods evaluation are presented in this paper. The two different groups of Ni-base alloys have been used as experimental material: cast alloys ZhS6K and IN713LC, which are used for small turbine blades production and wrought alloys EI 698VD and EI 929, which are used for turbine disc production. Selected alloys have been evaluated in the starting stage and after applied heat-treatment at 850°C for 24 hrs. This applied heat-treatment causes structural changes in all alloys groups. In cast alloy dendritic structure is degraded and gamma prime average size has grown what has a negative influence on turbine blade creep rupture life. Wrought alloys show partially grain boundary melting and grain size changed due to recrystallization what causes mechanical properties decreasing – ultimate tensile strength mainly.
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Wang, Quan, Pan Huang, Di Gan e Jun Wang. "Integrated Design of Aerodynamic Performance and Structural Characteristics for Medium Thickness Wind Turbine Airfoil". Applied Sciences 9, n. 23 (2 dicembre 2019): 5243. http://dx.doi.org/10.3390/app9235243.
Testo completoAbstract (sommario):
The currently geometric and aerodynamic characteristics for wind turbine airfoils with the medium thickness are studied to pursue maximum aerodynamic performance, while the interaction between blade stiffness and aerodynamic performance is neglected. Combining the airfoil functional integration theory and the mathematical model of the blade cross-section stiffness matrix, an integrated design method of aerodynamic performance and structural stiffness characteristics for the medium thickness airfoils is presented. The aerodynamic and structural comparison of the optimized WQ-A300 airfoil, WQ-B300 airfoil, and the classic DU97-W-300 airfoil were analyzed. The results show that the aerodynamic performance of the WQ-A300 and WQ-B300 airfoils are better than that of the DU97-W-300 airfoil. Though the aerodynamic performance of the WQ-B300 airfoil is slightly reduced compared to the WQ-A300 airfoil, its blade cross-sectional stiffness properties are improved as the flapwise and edgewise stiffness are increased by 6.2% and 8.4%, respectively. This study verifies the feasibility for the novel design method. Moreover, it also provides a good design idea for the wind turbine airfoils and blade structural properties with medium or large thickness.
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Montagner, Denise Baptaglin, Marta Gomes da Rocha, Teresa Cristina Moraes Genro, Fernando Luiz Ferreira de Quadros, Juliano Roman e Dalton Roso. "Sward structural characteristics and ingestive behaviour of beef heifers in a Pearl Millet pasture". Revista Brasileira de Zootecnia 38, n. 9 (settembre 2009): 1668–74. http://dx.doi.org/10.1590/s1516-35982009000900005.
Testo completoAbstract (sommario):
Ingestive behaviour of beef heifers and sward structural characteristics of Pearl Millet (Pennisetum americanum (L.) Leeke) were evaluated. The experiment was carried out in a randomized complete design following a repeated measure arrangement (three experimental periods) with three replications of two leaf blade masses (600 and 1,000 kg/ha DM), which were maintained using continuous grazing with variable stocking rate. The variables measured were sward height, herbage mass, leaf blade and stem bulk density in sward vertical strata (sward structural characteristics), grazing, idling, rumination time and bite rate of heifers (ingestive behaviour). Bite rate was modified by pasture management and was lower when the leaf blade mass was 1,000 kg/ha DM. The daily grazing, rumination and idling time of beef heifers were similar for both leaf blade masses. Structural variation of the sward, during the experimental period, altered the grazing, rumination and idling time of heifers, and affected the bite rate. In Southern Brazil, the beef heifers concentrate their grazing activities in the 12 p.m. to 6:00 p.m. period, decreasing the grazing between 12 a.m. and 6:00 a.m., even in the hottest season of the year.
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Guo, Haonan, Yongmin Yang, Fengjiao Guan, Haifeng Hu, Guoji Shen, Suiyu Chen e Zifang Bian. "A Torsional Vibration Measurement Method for Rotating Blades Based on Blade Tip Timing". Shock and Vibration 2021 (11 ottobre 2021): 1–14. http://dx.doi.org/10.1155/2021/9950269.
Testo completoAbstract (sommario):
During the working process of the turbine, some types of faults can cause changes in the vibration characteristics of the blades. The real-time vibration monitoring of the blades is of great significance to the stable operation and state-based maintenance. Torsional vibration is a kind of blade vibration modes and results in failures such as cracks easily. Thus, it is important to measure it due to the harmfulness of torsional vibration. Firstly, the principle of blade tip timing (BTT) is introduced, and the models of the blade are built to analyze the characteristics of torsional vibration. Then, the compressed sensing theory is introduced, and its related parameters are determined according to the measurement requirements. Next, based on the condition that the blade rigidity axis is not bent and bent, respectively, the layout method of sensors is proposed and the numerical simulation of the measurement process is performed. The results of the above two types of numerical simulation verify the proposed measurement method. Finally, by analyzing the influencing factors of measurement uncertainty, the optimization method of sensors’ layout is further proposed. This study can provide important theoretical guidance for the measurement of blade torsional vibration.
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Pei, Hansheng, e Xuemin Wang. "Optimization of cavitation characteristics of axial flow submersible pump". Journal of Physics: Conference Series 2365, n. 1 (1 novembre 2022): 012006. http://dx.doi.org/10.1088/1742-6596/2365/1/012006.
Testo completoAbstract (sommario):
Abstract In view of the problem that the actual performance of axial-flow pump is less than the theoretical design value, Taking the axial-flow pump with a designed flow rate of 350L/s as the research object. The theoretical relationship between impeller head and outlet installation angle was studied. The influence of different blade angles on the external characteristics of the impeller was analyzed. Through the analysis of different external characteristics corresponding to different blade outlet installation angles, the influence of blade installation angles on shaft oil pump performance is verified, and the theoretical basis for the structural optimization of axial flow pump is provided.