The Experts below are selected from a list of 294 Experts worldwide ranked by ideXlab platform
Ray M. Chi - One of the best experts on this subject based on the ideXlab platform.
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An unsteady lifting surface theory for ducted Fan Blades
Journal of Turbomachinery, 1993Co-Authors: Ray M. ChiAbstract:A frequency domain lifting surface theory is developed to predict the unsteady aerodynamic pressure loads on oscillating Blades of a ducted subsonic Fan. The steady baseline flow as observed in the rotating frame of reference is the helical flow dictated by the forward flight speed and the rotational speed of the Fan. The unsteady perturbation flow, which is assumed to be potential, is determined by solving an integral equation that relates the unknown jump in perturbation velocity potential across the lifting surface to the upwash velocity distribution prescribed by the vibratory motion of the blade. Examples of unsteady pressure distributions are given to illustrate the differences between the three-dimensional lifting surface analysis and the classical two-dimensional strip analysis. The effects of blade axial bending, bowing (i.e., circumferential bending), and sweeping on the unsteady pressure load are also discussed.
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An Unsteady Lifting Surface Theory for Ducted Fan Blades
Volume 5: Manufacturing Materials and Metallurgy; Ceramics; Structures and Dynamics; Controls Diagnostics and Instrumentation; Education; IGTI Scholar, 1991Co-Authors: Ray M. ChiAbstract:A frequency domain lifting surface theory is developed to predict the unsteady aerodynamic pressure loads on oscillating Blades of a ducted subsonic Fan. The steady baseline flow as observed in the rotating frame of reference is the helical flow dictated by the forward flight speed and the rotational speed of the Fan. The unsteady perturbation flow, which is assumed to be potential, is determined by solving an integral equation that relates the unknown jump in perturbation velocity potential across the lifting surface to the upwash velocity distribution prescribed by the vibratory motion of the blade. Examples of unsteady pressure distributions are given to illustrate the differences between the three dimensional lifting surface analysis and the classical two dimensional strip analysis. The effects of blade axial bending, bowing (i.e., circumferential bending) and sweeping on the unsteady pressure load are also discussed.Copyright © 1991 by ASME
A. Jahangiri - One of the best experts on this subject based on the ideXlab platform.
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failure analysis of gas turbine generator cooling Fan for 14 and 19 Blades angle of attack
Journal of Mechanical Science and Technology, 2013Co-Authors: A. Jahangiri, S.e. Moussavi Torshizi, S.m. Yadavar NikraveshAbstract:In gas turbine power plants, a Fan is used as a cooling system to dissipate generated heat in coils (copper conductors) and generator electric circuits at the end sides of its rotor. In some cases, fracture of Blades causes short circuit between rotor and stator and consequently generator explosion and made lot of financial problems. The fracture of cooling Fan Blades has been occurred five times at the turbine side of the generator in our case of study, just 100 hr after resuming operation after overhaul. Using numerical analysis as well as laboratory investigation — includes visual inspections, metallography and SEM — can help better finding failure problems that cause blade failures. A series of numerical analysis was performed to diagnose the cause of failure possibility. CFD analysis is used to study the airflow distribution in order to observe probable separation phenomenon and pressure forces that they are imposed to Fan Blades due to operation. A finite element method was utilized to determine the stresses and dynamic characteristics of the Fan blade (natural frequencies, stresses and vibrations).
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Failure analysis of gas turbine generator cooling Fan for 14° and 19° — Blades angle of attack
Journal of Mechanical Science and Technology, 2013Co-Authors: A. Jahangiri, S.e. Moussavi Torshizi, S.m. Yadavar NikraveshAbstract:In gas turbine power plants, a Fan is used as a cooling system to dissipate generated heat in coils (copper conductors) and generator electric circuits at the end sides of its rotor. In some cases, fracture of Blades causes short circuit between rotor and stator and consequently generator explosion and made lot of financial problems. The fracture of cooling Fan Blades has been occurred five times at the turbine side of the generator in our case of study, just 100 hr after resuming operation after overhaul. Using numerical analysis as well as laboratory investigation — includes visual inspections, metallography and SEM — can help better finding failure problems that cause blade failures. A series of numerical analysis was performed to diagnose the cause of failure possibility. CFD analysis is used to study the airflow distribution in order to observe probable separation phenomenon and pressure forces that they are imposed to Fan Blades due to operation. A finite element method was utilized to determine the stresses and dynamic characteristics of the Fan blade (natural frequencies, stresses and vibrations).
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Failure analysis of gas turbine generator cooling Fan Blades
Engineering Failure Analysis, 2009Co-Authors: S.e. Moussavi Torshizi, S.m. Yadavar Nikravesh, A. JahangiriAbstract:Abstract Since the optimum operation of a generator is highly affected by increasing in temperature, a cooling system is used to control the temperature. Employing a Fan as a cooling system for the generator at the end sides of its rotor is a practical method [Montazer Ghaem Gas Turbine Power Plant. Gas turbine generator manual, Iran, 2004]. In some cases, fracture of Blades causes short circuit between rotor and stator and consequently generator explosion and huge financial loss. Since fracture in cooling Fan Blades has been occurred five times in our case study, in this research, the emphasis has been placed on failure analysis and preventing methods from the fracture in this generator’s Fan Blades. Survey and analysis of the above-mentioned problem have been conducted in different ways, which the main titles results are as follows: • All of these failures have been happened after the first operation of gas turbine or at the early after operation 100 h after gas turbine repairs [Alsthom Company. Failure report for gas turbine Fan Blades, 1997]. • Metallurgical and structural analyses on the failed Blades have not shown any microstructure degradation. • Studies on the ruptured surfaces using scanning electron microscope (SEM) have shown that fracture has been happened as a results of high cycle fatigue (hcf). • Calculation of alternative stresses has indicated that this stress is less than fatigue endurance limit of blade material and none of these stresses and forces could result in fracture. • Modal analysis of blade has indicated that the Blades natural frequency has been limited too close to the Blades operational frequency. It means that making changes in Blades installation conditions; blade natural frequency approaches the operational frequency and consequently causes the resonance. Analysis results show that the final fracture of Blades is due to fatigue conditions in resonance state and growth of existent tiny probable cracks.
S.m. Yadavar Nikravesh - One of the best experts on this subject based on the ideXlab platform.
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failure analysis of gas turbine generator cooling Fan for 14 and 19 Blades angle of attack
Journal of Mechanical Science and Technology, 2013Co-Authors: A. Jahangiri, S.e. Moussavi Torshizi, S.m. Yadavar NikraveshAbstract:In gas turbine power plants, a Fan is used as a cooling system to dissipate generated heat in coils (copper conductors) and generator electric circuits at the end sides of its rotor. In some cases, fracture of Blades causes short circuit between rotor and stator and consequently generator explosion and made lot of financial problems. The fracture of cooling Fan Blades has been occurred five times at the turbine side of the generator in our case of study, just 100 hr after resuming operation after overhaul. Using numerical analysis as well as laboratory investigation — includes visual inspections, metallography and SEM — can help better finding failure problems that cause blade failures. A series of numerical analysis was performed to diagnose the cause of failure possibility. CFD analysis is used to study the airflow distribution in order to observe probable separation phenomenon and pressure forces that they are imposed to Fan Blades due to operation. A finite element method was utilized to determine the stresses and dynamic characteristics of the Fan blade (natural frequencies, stresses and vibrations).
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Failure analysis of gas turbine generator cooling Fan for 14° and 19° — Blades angle of attack
Journal of Mechanical Science and Technology, 2013Co-Authors: A. Jahangiri, S.e. Moussavi Torshizi, S.m. Yadavar NikraveshAbstract:In gas turbine power plants, a Fan is used as a cooling system to dissipate generated heat in coils (copper conductors) and generator electric circuits at the end sides of its rotor. In some cases, fracture of Blades causes short circuit between rotor and stator and consequently generator explosion and made lot of financial problems. The fracture of cooling Fan Blades has been occurred five times at the turbine side of the generator in our case of study, just 100 hr after resuming operation after overhaul. Using numerical analysis as well as laboratory investigation — includes visual inspections, metallography and SEM — can help better finding failure problems that cause blade failures. A series of numerical analysis was performed to diagnose the cause of failure possibility. CFD analysis is used to study the airflow distribution in order to observe probable separation phenomenon and pressure forces that they are imposed to Fan Blades due to operation. A finite element method was utilized to determine the stresses and dynamic characteristics of the Fan blade (natural frequencies, stresses and vibrations).
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Failure analysis of gas turbine generator cooling Fan Blades
Engineering Failure Analysis, 2009Co-Authors: S.e. Moussavi Torshizi, S.m. Yadavar Nikravesh, A. JahangiriAbstract:Abstract Since the optimum operation of a generator is highly affected by increasing in temperature, a cooling system is used to control the temperature. Employing a Fan as a cooling system for the generator at the end sides of its rotor is a practical method [Montazer Ghaem Gas Turbine Power Plant. Gas turbine generator manual, Iran, 2004]. In some cases, fracture of Blades causes short circuit between rotor and stator and consequently generator explosion and huge financial loss. Since fracture in cooling Fan Blades has been occurred five times in our case study, in this research, the emphasis has been placed on failure analysis and preventing methods from the fracture in this generator’s Fan Blades. Survey and analysis of the above-mentioned problem have been conducted in different ways, which the main titles results are as follows: • All of these failures have been happened after the first operation of gas turbine or at the early after operation 100 h after gas turbine repairs [Alsthom Company. Failure report for gas turbine Fan Blades, 1997]. • Metallurgical and structural analyses on the failed Blades have not shown any microstructure degradation. • Studies on the ruptured surfaces using scanning electron microscope (SEM) have shown that fracture has been happened as a results of high cycle fatigue (hcf). • Calculation of alternative stresses has indicated that this stress is less than fatigue endurance limit of blade material and none of these stresses and forces could result in fracture. • Modal analysis of blade has indicated that the Blades natural frequency has been limited too close to the Blades operational frequency. It means that making changes in Blades installation conditions; blade natural frequency approaches the operational frequency and consequently causes the resonance. Analysis results show that the final fracture of Blades is due to fatigue conditions in resonance state and growth of existent tiny probable cracks.
Cheng Yang - One of the best experts on this subject based on the ideXlab platform.
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Fatigue life prediction of centrifugal Fan Blades in the ventilation cooling system of the high-speed-train
2020Co-Authors: Pengfei Feng, Li Tan, Tong Pang, Yi Chen, Cheng YangAbstract:The centrifugal Fan Blades of the high-speed train ventilation and cooling system are subjected to cyclic loading which will shorten the life of Fan Blades. It could cause an accident of the high-speed-train in service. In this study, a modified method based on the nominal stress method was proposed and developed for the fatigue life prediction of centrifugal Fan Blades. The finite element model was firstly used to analyze the mode and the stress of Fan Blades based on the typical material property. The fatigue life was predicted based on the physical curve, using the Miner’s cumulative damage rule to calculate total damage. In order to verify the effectiveness of this method, the experimental tests were conducted on Fan Blades using a fatigue bench system, which were the typical structure of the ventilation cooling system of the high-speed-train. The damage mechanisms of Blades was deduced from the fracture fractographs. The ventilation good correlation was achieved between the prediction model and the actual experimental results, testifying the practicability and effectiveness of this proposed method. Thus, the research result can reduce the probability of accidents caused by the Fan blade damage and improve the reliability of the ventilation cooling system of the high-speed train.
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Fatigue life prediction of centrifugal Fan Blades in the ventilation cooling system of the high-speed-train
Engineering Failure Analysis, 1Co-Authors: Peifu Feng, Tong Pang, Ligang Tan, Y.z. Chen, Cheng YangAbstract:Abstract The centrifugal Fan Blades of the high-speed train ventilation and cooling system are subjected to cyclic loading which will shorten the life of Fan Blades. It could cause an accident of the high-speed-train in service. In this study, a modified method based on the nominal stress method was proposed and developed for the fatigue life prediction of the centrifugal Fan Blades. The finite element model was firstly used to analyze the mode and the stress of Fan Blades based on the typical material property. The fatigue life was predicted based on the physical curve, using the Miner’s cumulative damage rule to calculate total damage. In order to verify the effectiveness of this method, the experimental tests were conducted on Fan Blades using a fatigue bench system, which were the typical structure of the ventilation cooling system of the high-speed-train. The damage mechanisms of Blades was deduced from the fracture fractographs. The ventilation good correlation was achieved between the prediction model and the actual experimental results, testifying the practicability and effectiveness of this proposed method. Thus, the research result can reduce the probability of accidents caused by the Fan blade damage and improve the reliability of the ventilation cooling system of the high-speed train.
S.e. Moussavi Torshizi - One of the best experts on this subject based on the ideXlab platform.
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failure analysis of gas turbine generator cooling Fan for 14 and 19 Blades angle of attack
Journal of Mechanical Science and Technology, 2013Co-Authors: A. Jahangiri, S.e. Moussavi Torshizi, S.m. Yadavar NikraveshAbstract:In gas turbine power plants, a Fan is used as a cooling system to dissipate generated heat in coils (copper conductors) and generator electric circuits at the end sides of its rotor. In some cases, fracture of Blades causes short circuit between rotor and stator and consequently generator explosion and made lot of financial problems. The fracture of cooling Fan Blades has been occurred five times at the turbine side of the generator in our case of study, just 100 hr after resuming operation after overhaul. Using numerical analysis as well as laboratory investigation — includes visual inspections, metallography and SEM — can help better finding failure problems that cause blade failures. A series of numerical analysis was performed to diagnose the cause of failure possibility. CFD analysis is used to study the airflow distribution in order to observe probable separation phenomenon and pressure forces that they are imposed to Fan Blades due to operation. A finite element method was utilized to determine the stresses and dynamic characteristics of the Fan blade (natural frequencies, stresses and vibrations).
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Failure analysis of gas turbine generator cooling Fan for 14° and 19° — Blades angle of attack
Journal of Mechanical Science and Technology, 2013Co-Authors: A. Jahangiri, S.e. Moussavi Torshizi, S.m. Yadavar NikraveshAbstract:In gas turbine power plants, a Fan is used as a cooling system to dissipate generated heat in coils (copper conductors) and generator electric circuits at the end sides of its rotor. In some cases, fracture of Blades causes short circuit between rotor and stator and consequently generator explosion and made lot of financial problems. The fracture of cooling Fan Blades has been occurred five times at the turbine side of the generator in our case of study, just 100 hr after resuming operation after overhaul. Using numerical analysis as well as laboratory investigation — includes visual inspections, metallography and SEM — can help better finding failure problems that cause blade failures. A series of numerical analysis was performed to diagnose the cause of failure possibility. CFD analysis is used to study the airflow distribution in order to observe probable separation phenomenon and pressure forces that they are imposed to Fan Blades due to operation. A finite element method was utilized to determine the stresses and dynamic characteristics of the Fan blade (natural frequencies, stresses and vibrations).
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Failure analysis of gas turbine generator cooling Fan Blades
Engineering Failure Analysis, 2009Co-Authors: S.e. Moussavi Torshizi, S.m. Yadavar Nikravesh, A. JahangiriAbstract:Abstract Since the optimum operation of a generator is highly affected by increasing in temperature, a cooling system is used to control the temperature. Employing a Fan as a cooling system for the generator at the end sides of its rotor is a practical method [Montazer Ghaem Gas Turbine Power Plant. Gas turbine generator manual, Iran, 2004]. In some cases, fracture of Blades causes short circuit between rotor and stator and consequently generator explosion and huge financial loss. Since fracture in cooling Fan Blades has been occurred five times in our case study, in this research, the emphasis has been placed on failure analysis and preventing methods from the fracture in this generator’s Fan Blades. Survey and analysis of the above-mentioned problem have been conducted in different ways, which the main titles results are as follows: • All of these failures have been happened after the first operation of gas turbine or at the early after operation 100 h after gas turbine repairs [Alsthom Company. Failure report for gas turbine Fan Blades, 1997]. • Metallurgical and structural analyses on the failed Blades have not shown any microstructure degradation. • Studies on the ruptured surfaces using scanning electron microscope (SEM) have shown that fracture has been happened as a results of high cycle fatigue (hcf). • Calculation of alternative stresses has indicated that this stress is less than fatigue endurance limit of blade material and none of these stresses and forces could result in fracture. • Modal analysis of blade has indicated that the Blades natural frequency has been limited too close to the Blades operational frequency. It means that making changes in Blades installation conditions; blade natural frequency approaches the operational frequency and consequently causes the resonance. Analysis results show that the final fracture of Blades is due to fatigue conditions in resonance state and growth of existent tiny probable cracks.
