scholarly journals Rotordynamic Analysis of the AM600 Turbine-Generator Shaftline

Energies ◽  
2018 ◽  
Vol 11 (12) ◽  
pp. 3411 ◽  
Author(s):  
Tshimangadzo Mudau ◽  
Robert Murray Field
Keyword(s):  
Finite Element ◽  
Nuclear Power ◽  
Natural Frequencies ◽  
Three Dimensional ◽  
Low Pressure ◽  
Lumped Mass ◽  
Damage Potential ◽  
Turbine Generator ◽  
Element Analysis ◽  
Low Pressure Turbine

The AM600 represents the conceptual design and layout of a Nuclear Power Plant Turbine Island intended to address challenges associated with emerging markets interested in nuclear power. When coupled with a medium sized nuclear reactor plant, the AM600 is designed with a unit capacity that aligns with constraints where grid interconnections and load flows are limiting. Through design simplification, the baseline turbine-generator shaftline employs a single low-pressure turbine cylinder, a design which to date has not been offered commercially at this capacity. Though the use of a ‘stiffer’ design, this configuration is intended to withstand, with a margin, the damage potential of torsional excitation from the grid-machine interface, specifically due to transient disturbances and negative sequence currents. To demonstrate the robust nature of the design, torsional rotordynamic analysis is performed for the prototype shaftline using three dimensional finite element modelling with ANSYS® software. The intent is to demonstrate large separation of the shaftline natural frequencies from the dominant frequencies for excitation. The analysis examined both welded drum and monoblock type Low Pressure Turbine rotors for single cylinder and double cylinder configurations. For each, the first seven (7) torsional natural frequencies (ranging from zero–190 Hz) were extracted and evaluated against the frequency exclusion range (i.e., avoidance of 1× and 2× grid frequency). Results indicate that the prototype design of AM600 shaftline has adequate separation from the dominant excitation frequencies. For verification of the ANSYS® modelling of the shaftline, a simplified lumped mass calculation of the natural frequencies was performed with results matching the finite element analysis values.

Finite Element Analysis of Elliptical Chord

2013 ◽  
Vol 3 (4) ◽  
pp. 44-61
Author(s):  
K. S. Narayana ◽  
R. T. Naik ◽  
R. C. Mouli ◽  
L. V. V. Gopala Rao ◽  
R. T. Babu Naik
Keyword(s):  
Finite Element ◽  
Natural Frequencies ◽  
Three Dimensional ◽  
Compressive Load ◽  
Dynamic Strength ◽  
Element Analysis ◽  
T Joints ◽  
Shell Elements ◽  
Tubular Joints ◽  
Plane Bending

The work presents the Finite element study of the effect of elliptical chords on the static and dynamic strength of tubular T-joints using ANSYS. Two different geometry configurations of the T-joints have been used, namely Type-1 and Type-2. An elastic analysis has been considered. The Static loading conditions used are: axial load, compressive load, In-plane bending (IPB) and Out-plane bending (OPB). The natural frequencies analysis (dynamic loading condition) has also been carried out. The geometry configurations of the T-joints have been used, vertical tubes are called brace and horizontal tubes are called chords. The joint consists of brace joined perpendicular to the circular chord. In this case the ends of the chord are held fixed. The material used is mild steel. Using ANSYS, finite element modeling and analysis of T-joint has been done under the aforementioned loading cases. It is one of the most powerful methods in use but in many cases it is an expensive analysis especially due to elastic–plastic and creep problems. Usually, three dimensional solid elements or shell elements or the combination of two types of elements are used for generating the tubular joints mesh. In tubular joints, usually the fluid induced vibrations cause the joint to fail under resonance. Therefore the natural frequencies analysis is also an important issue here. Generally the empirical results are required as guide or comparison tool for finite element investigation. It is an effective way to obtain confidence in the results derived. Shell elements have been used to model the assembled geometry. Finite element ANSYS results have been validated with the LUSAS FEA and experimental results, that is within the experimentation error limit of ten percentage.

scholarly journals The Analysis and Resolution of a Fatigue Failure of a Low Pressure Turbine Blade Caused by the Excitation of a Bladed Disc Mode of Vibration

1997 ◽  
Author(s):  
Malcolm C. Staddon ◽  
Paul R. Box ◽  
Barry Barnett ◽  
Tony Horton ◽  
Geoff H. Ballans
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Turbine Blade ◽  
Fatigue Failure ◽  
Strain Gauge ◽  
High Frequency ◽  
Low Pressure ◽  
Dynamic Strain ◽  
Element Analysis ◽  
Low Pressure Turbine

A high cycle fatigue failure of a low pressure turbine blade was investigated. Strain gauge tests of a running engine indicated a high dynamic response of the blade at the nozzle passing frequency. This could be attributed to the excitation of a bladed disc mode of vibration. A Finite Element analysis of the low pressure turbine blades and discs, together with bench testing of the complete structure, confirmed the existence of a high frequency 2nd Nodal Diameter mode of vibration. The levels of dynamic strain determined through strain gauge tests were found to be sufficient enough to explain the failure at the given location. Having understood the problem, the situation was resolved through the use of Finite Element analysis with a short term modification to the original blade aerofoil to prevent the mode from being excited. An aero/mechanical re-design of both the low pressure turbine rotor and the stator was undertaken to resolve the problem by both returning the blade to avoid high frequency excitation, and also by reducing the forcing effect of the nozzle passing frequency. The new design has been validated through strain gauge tests and endurance tests. A further improvement in performance was also obtained.

Modal Analysis of Marine Propeller Submerged in Fluid

2014 ◽  
Vol 1030-1032 ◽  
pp. 1201-1205
Author(s):  
Hong Ren ◽  
Fan Chun Li ◽  
Tian Yu Zhao
Keyword(s):  
Finite Element ◽  
Modal Analysis ◽  
Natural Frequencies ◽  
Three Dimensional ◽  
Secondary Development ◽  
Marine Propeller ◽  
Fluid Inertia ◽  
Element Analysis ◽  
Dimensional Finite Element ◽  
Three Dimensional Finite Element

The present work is aimed to free vibration characteristics of marine propeller in fluid, and analyze the influence of fluid inertial effect on propeller. The fully coupled three dimensional finite element method is applied, and the commercial finite element code, ANSYS WORKBENCH, has been used to perform modal analysis for both wet and dry configurations via fluid-structure interaction APDL commands for secondary development. On this basis, analyze a marine propeller in air and in fluid with finite element analysis, then the differences of natural vibration frequencies and vibration modes of the propeller for different boundary conditions are discussed. In addition, the natural frequencies curves are presented. Results show that the natural frequencies of propeller in fluid are significantly lower than those in air, the fluid inertia effect also has some influences on vibration mode.

scholarly journals Finite Element Analysis and Experimental Evaluation of Residual Stress of Zr-4 alloys Processed through Swaging

Metals ◽  
2020 ◽  
Vol 10 (10) ◽  
pp. 1281 ◽  
Author(s):  
Gaurav Singh ◽  
Bijit Kalita ◽  
K. I. Vishnu Narayanan ◽  
Umesh Kumar Arora ◽  
Manas M. Mahapatra ◽  
...  
Keyword(s):  
Residual Stress ◽  
Finite Element ◽  
Nuclear Power ◽  
Zirconium Alloy ◽  
True Strain ◽  
Three Dimensional ◽  
Element Model ◽  
Hole Drilling ◽  
Element Analysis ◽  
Hole Drilling Method

Zirconium alloy has been extensively used as a cladding material in nuclear power reactors due to its low neutron absorption cross section, excellent mechanical properties, and corrosion resistance. The influence of the swaging parameter, feed rate (0.7, 1.25, 2 m/min) on residual stress induced in Zr-4 alloy is investigated in the present work. A three-dimensional finite element model was implemented in the Deform 3D software to simulate the rotary swaging (RS) process over a circular rod of Zr-4 alloy. The simulation results based on the 3D framework provide a detailed insight of residual stress, true stress versus true strain and force applied over the rod during the multiple pass swaging process; the results are compared with experimental results. The experimental hole drilling method is used to determine the residual stresses on swaged zirconium alloy at different feed rates (0.7, 1.25, and 2 m/min). A similar trend of residual stress between experimental and numerical results from the surface to the center on the swaged rod samples is observed. The same magnitude of residual stress at the surface of the swaged Zr-4 rod is also observed. It is found to be compressive at the surface and tensile in the center of the samples, as observed in the present work.

A Comparative Study of Valve Natural Frequency Estimation Using Finite Element Analysis (FEA), Raleigh’s Principles and Laboratory Tests

2014 ◽  
Author(s):  
L. Ike Ezekoye ◽  
Preston A. Vock ◽  
Ronald S. Farrell ◽  
Richard J. Gradle
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Natural Frequency ◽  
Natural Frequencies ◽  
The Other ◽  
Test Results ◽  
Lumped Mass ◽  
Element Analysis ◽  
Valve Body ◽  
Other Hand

The natural frequency of valves is an important design requirement to ensure that valves do not go into resonance during operation and consequently fail structurally or fail to perform their design and safety related functions. Besides its impact on operability, valve resonance can initiate piping vibration that could damage pipes and their supports; which is undesirable. As important as equipment natural frequency is to valve operability, one would expect that testing should be the de facto method for confirming its value. Ideally, this should be the case, however, cost considerations limit the extent to which testing is used. On the other hand, testing does have some issues with respect to accuracy such as the effect of supporting structure flexibility resulting in a conservatively lower natural frequency measurement. In addition, the multiplicity of valves in nuclear power plants with different designs, sizes and safety classes limit the use of testing to establish valve natural frequencies except when required in the equipment specifications. Frequently, valve natural frequencies are determined by analysis either using finite element techniques (FEA) or by first principles of beam and mass models; the latter being more frequently used. This paper presents the studies performed to correlate valve natural frequency test results to the results derived from analytical techniques using Raleigh’s energy principle and from finite element analysis (FEA) methods. In a previous paper on valve natural frequency [1], Ezekoye et al. presented a model for estimating valve natural frequency by incorporating mass inertia of the valve structures with the more traditional methods that are based on a lumped mass model to determine displacements. In the process, the flexibility of the extended structure (otherwise referred to as the superstructure) and the valve body itself are considered. Using limited test data, Ezekoye et al. showed that there is merit in using their enhanced analysis model. Their correlation was promising. The finite element analysis, on the other hand, is a well-established technique for solving complex structural mechanics problems and should be expected to provide reasonable results comparable to actual valve tests provided the boundary conditions provide a reasonable representation of the actual valves tested. In this paper, ANSYS Version 12.1 was used to model valve natural frequencies. Additionally, a more extensive testing of valves for natural frequency was performed in this paper than was reported in Reference 1. The results of both the FEA and the Raleigh’s principle model as presented in Ezekoye et al. are compared against the test results. By comparing the three results, strengths and weaknesses of each method become apparent. The choice of whether or not one chooses to test or perform analysis depends on the valve specification requirement and the preference of the designer.

Vibration Characteristics of a Containing Liquid Cylindrical Pipe with Lumped Mass

2012 ◽  
Vol 184-185 ◽  
pp. 641-644
Author(s):  
Bing Li ◽  
Yu Lan Wei ◽  
Qi Bo Yan ◽  
Yue Zhan Wang
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Natural Frequencies ◽  
Vibration Characteristics ◽  
Experimental Results ◽  
Vibration Modes ◽  
Lumped Mass ◽  
Cylindrical Pipe ◽  
Element Analysis ◽  
Lumped Masses

The liquid within a cylindrical pipe affects the vibration characteristics of the pipe. Furthermore, these vibration characteristics are affected by lumped mass on the pipe. The natural frequencies and the vibration modes of the cylindrical pipe with different lumped masses can be obtained by finite element analysis. The natural frequencies of the containing liquid cylindrical pipe are obtained by experiments. The experimental results show that the natural frequencies of the containing liquid pipe are affected by the lumped mass. The greater the lumped mass is, the smaller the natural frequencies of the pipe are.

Influence of Lumped Mass on the Natural Frequency of Cylindrical Pipe

2012 ◽  
Vol 532-533 ◽  
pp. 403-407
Author(s):  
Bing Li ◽  
Yu Lan Wei ◽  
Dan Zhang ◽  
Qing Huang
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Natural Frequency ◽  
Natural Frequencies ◽  
Vibration Modes ◽  
Lumped Mass ◽  
Cylindrical Pipe ◽  
Bending Vibration ◽  
Element Analysis ◽  
Lumped Masses

The lumped mass on the cylindrical pipe affects the natural frequency of the cylindrical pipe. The first-three order natural frequencies and vibration modes of the cylindrical pipe with different lumped masses are analyzed by the bending vibration theory and finite element analysis, respectively. The results with different lumped masses are obtained by experiments. As shown in the results, the natural frequencies of the cylindrical pipe with lumped mass are lower than those without lumped mass. The greater the lumped mass is, the smaller the natural frequencies of the pipe are.

Modal and harmonic analysis of three-dimensional wind turbine models

2016 ◽  
Vol 40 (6) ◽  
pp. 518-527 ◽  
Author(s):  
Takwa Sellami ◽  
Hanen Berriri ◽  
A Moumen Darcherif ◽  
Sana Jelassi ◽  
M Faouizi Mimouni
Keyword(s):  
Finite Element ◽  
Wind Turbine ◽  
Natural Frequencies ◽  
Equations Of Motion ◽  
Three Dimensional ◽  
Operating Conditions ◽  
Dynamic Responses ◽  
Mode Shapes ◽  
Element Analysis ◽  
Micro Turbine

In this article, the dynamic responses of wind turbine systems are analytically and numerically investigated. For this purpose, analytic differential equations of motion of wind turbine components subjected to vibration (the blades, the nacelle, and the tower) are solved. This allows determining their dynamic characteristics, mode shapes, and natural frequencies. Two models of two three-dimensional (3D) micro-turbine that are created by the finite element method are set up using the new version of the academic finite element analysis software ANSYS. The first wind turbine is a standard micro three-bladed turbine and the second one is a micro six-bladed Rutland 504. Their natural frequencies and mode shapes are identified based on the modal analysis principle to check the validity of designed models. Dynamic behaviors at several operating conditions of wind turbines are established. Then, spectrum graphs of the structures along x-, y- and z-axis are analyzed.

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