Effect of Material Damping of Steam Turbine Vane on Flutter Suppression

2012 ◽  
Author(s):  
Yasutomo Kaneko ◽  
Kazushi Mori ◽  
Hiroharu Ohyama
Keyword(s):  
Steam Turbine ◽  
Aerodynamic Force ◽  
Working Fluid ◽  
Material Damping ◽  
Element Analysis ◽  
Flutter Suppression ◽  
Aerodynamic Damping ◽  
Turbine Vane ◽  
3D Fea ◽  
The Stability

The vane used in a low pressure end of steam turbine is usually fixed to shroud and casing by welding both ends. In such a vane structure, the damping in loading operation is comprised of the material damping and the aerodynamic damping, because the structural damping is very small. In this paper, first, the vane is modeled by the uniform beam fixed at both ends, and the effect of the material damping on the vane flutter is studied. In the stability analysis, the simple one-degree-of-freedom model is applied, where the linear aerodynamic model is used. In other words, it is assumed that the aerodynamic force due to the working fluid is proportional to the vane velocity and the negative damping coefficient does not change with amplitude. The allowable aerodynamic damping for the vane flutter is calculated and compared for the solid vane and the hollow vane. In addition, the vibration analysis of the actual steam turbine vane is carried out by 3D FEA (Finite Element Analysis), and the material damping of the solid and hollow vane is calculated by use of the results by FEA. The stability of the solid vane and the hollow vane on the flutter is also evaluated by use of the results calculated by FEA. From these results, the material damping characteristics of the steam turbine vane are clarified, as well as the effect of the material damping of the steam turbine vane on the flutter suppression.

Analysis and Verification Test of Damping Characteristics of Steam Turbine Hollow Vane With Friction Damper

2014 ◽  
Author(s):  
Yasutomo Kaneko ◽  
Hiroyuki Yamashita ◽  
Hiroharu Ooyama
Keyword(s):  
Steam Turbine ◽  
High Capacity ◽  
Analysis Method ◽  
Structural Damping ◽  
Friction Damper ◽  
Flat Plates ◽  
Aerodynamic Damping ◽  
Damping Characteristics ◽  
Excited Vibration ◽  
Turbine Vane

A vane used in a low pressure end of a steam turbine is usually fixed to a shroud and a casing by welding both ends. In such a vane structure, the damping in loading operation is comprised of the material damping and the aerodynamic damping, because the structural damping is very small. In the blade and vane of high-capacity steam turbine units, the aerodynamic damping may become negative under the high loading operation, and some papers reported the self-excited vibration of the blade and vane caused by the negative aerodynamic damping. Recently, in order to increase the reliability of the steam turbine vane, a hollow vane with a friction damper has been proposed. In such a steam turbine vane, the curved damper piece made of the thin plate is inserted into the hollow vane, and the structural damping is added by use of the friction between the damper piece and the vane. In this paper, for the purpose of clarifying the damping characteristics of the hollow vane with the friction damper, first, the excitation test of the model vane is carried out. In the excitation test of the model vane, the damping characteristics of the model vane consisting of two flat plates and the thin curved damper piece are measured, changing the excitation force. Second, the analysis method for predicting the damping characteristics of the hollow vane with the friction damper, which utilizes the conventional modal analysis method and the harmonic balance method, is proposed. The validity of the analysis method is verified by comparing the measured damping with the calculated ones. After verifying the analysis method, the actual steam turbine hollow vane with the friction damper is also analyzed, and the effect of the damper stiffness on the damping characteristics is examined. Finally, the actual hollow vane with the friction damper for the high-capacity steam turbine unit is designed and manufactured, and the excitation test of the actual hollow vane is carried out. From these results, the damping characteristics of the hollow vane with the friction damper are clarified.

scholarly journals Inlay-Retained Dental Bridges—A Finite Element Analysis

2021 ◽  
Vol 11 (9) ◽  
pp. 3770
Author(s):  
Monica Tatarciuc ◽  
George Alexandru Maftei ◽  
Anca Vitalariu ◽  
Ionut Luchian ◽  
Ioana Martu ◽  
...  
Keyword(s):  
Finite Element ◽  
Young Patients ◽  
Maximum Pressure ◽  
Class Iii ◽  
Element Analysis ◽  
Dental Prostheses ◽  
Abutment Teeth ◽  
Fixed Dental Prostheses ◽  
Implant Therapy ◽  
The Stability

Inlay-retained dental bridges can be a viable minimally invasive alternative when patients reject the idea of implant therapy or conventional retained full-coverage fixed dental prostheses, which require more tooth preparation. Inlay-retained dental bridges are indicated in patients with good oral hygiene, low susceptibility to caries, and a minimum coronal tooth height of 5 mm. The present study aims to evaluate, through the finite element method (FEM), the stability of these types of dental bridges and the stresses on the supporting teeth, under the action of masticatory forces. The analysis revealed the distribution of the load on the bridge elements and on the retainers, highlighting the areas of maximum pressure. The results of our study demonstrate that the stress determined by the loading force cannot cause damage to the prosthetic device or to abutment teeth. Thus, it can be considered an optimal economical solution for treating class III Kennedy edentation in young patients or as a provisional pre-implant rehabilitation option. However, special attention must be paid to its design, especially in the connection area between the bridge elements, because the connectors and the retainers represent the weakest parts.

scholarly journals Experimental Investigation on Stability, Viscosity, and Electrical Conductivity of Water-Based Hybrid Nanofluid of MWCNT-Fe2O3

Nanomaterials ◽  
2021 ◽  
Vol 11 (1) ◽  
pp. 136
Author(s):  
Solomon O. Giwa ◽  
Mohsen Sharifpur ◽  
Mohammad H. Ahmadi ◽  
S. M. Sohel Murshed ◽  
Josua P. Meyer
Keyword(s):  
Electrical Conductivity ◽  
Visual Inspection ◽  
Volume Concentration ◽  
Working Fluid ◽  
Hybrid Nanofluid ◽  
Multiwalled Carbon ◽  
Transmission Electron ◽  
Hybrid Nanofluids ◽  
Uv Visible ◽  
The Stability

The superiority of nanofluid over conventional working fluid has been well researched and proven. Newest on the horizon is the hybrid nanofluid currently being examined due to its improved thermal properties. This paper examined the viscosity and electrical conductivity of deionized water (DIW)-based multiwalled carbon nanotube (MWCNT)-Fe2O3 (20:80) nanofluids at temperatures and volume concentrations ranging from 15 °C to 55 °C and 0.1–1.5%, respectively. The morphology of the suspended hybrid nanofluids was characterized using a transmission electron microscope, and the stability was monitored using visual inspection, UV–visible, and viscosity-checking techniques. With the aid of a viscometer and electrical conductivity meter, the viscosity and electrical conductivity of the hybrid nanofluids were determined, respectively. The MWCNT-Fe2O3/DIW nanofluids were found to be stable and well suspended. Both the electrical conductivity and viscosity of the hybrid nanofluids were augmented with respect to increasing volume concentration. In contrast, the temperature rise was noticed to diminish the viscosity of the nanofluids, but it enhanced electrical conductivity. Maximum increments of 35.7% and 1676.4% were obtained for the viscosity and electrical conductivity of the hybrid nanofluids, respectively, when compared with the base fluid. The obtained results were observed to agree with previous studies in the literature. After fitting the obtained experimental data, high accuracy was achieved with the formulated correlations for estimating the electrical conductivity and viscosity. The examined hybrid nanofluid was noticed to possess a lesser viscosity in comparison with the mono-particle nanofluid of Fe2O3/water, which was good for engineering applications as the pumping power would be reduced.

On real-time creep damage prediction for steam turbine

2022 ◽  
pp. 014233122110689
Author(s):  
Yongjian Sun ◽  
Bo Xu
Keyword(s):  
Finite Element ◽  
Steam Turbine ◽  
Real Time ◽  
Creep Damage ◽  
Element Model ◽  
Turbine Rotor ◽  
Theoretical Research ◽  
Element Analysis ◽  
Damage Prediction ◽  
Time Calculation

In this paper, in order to solve the calculation problem of creep damage of steam turbine rotor, a real-time calculation method based on finite element model is proposed. The temperature field and stress field of the turbine rotor are calculated using finite element analysis software. The temperature data and stress data of the crucial positions are extracted. The data of temperature, pressure, rotational speed, and stress relating to creep damage calculation are normalized. A real-time creep stress calculation model is established by multiple regression method. After that, the relation between stress and damage function is analyzed and fitted, and creep damage is calculated in real-time. A creep damage real-time calculation system is constructed for practical turbine engineering. Finally, a numerical simulation experiment is designed and carried out to verify the effectiveness of this novel approach. Contributions of present work are that a practical solution for real-time creep damage prediction of steam turbine is supplied. It relates the real-time creep damage prediction to process parameters of steam turbine, and it bridges the gap between the theoretical research works and practical engineering.

Comparative study of finite element analysis of steel silos with rectangular and I stiffeners

2021 ◽  
Vol 10 (1) ◽  
pp. 9
Author(s):  
Prasad Lakshmi ◽  
Neethu Elsa Anil
Keyword(s):  
Reinforced Concrete ◽  
Element Analysis ◽  
Plate Structures ◽  
Steel Reinforced Concrete ◽  
Wide Range ◽  
Earthquake Load ◽  
The Stability ◽  
Dynamic Loading Conditions ◽  
Steel Silos ◽  
Static And Dynamic Loading

Silos are used by a wide range of industries to store bulk solids in quantities ranging from a few tones to hundreds or thousands of tones. They can be constructed of steel or reinforced concrete. Steel bins range from heavily stiffened flat plate structures to efficient unstiffened shell structures. They can be closed or open. They are subjected to many different static and dynamic loading conditions, mainly due to the unique characteristics of stored materials. Wind and earthquake load often undermine the stability of the silos. A steel silo with and without stiffeners is adopted and static structural analysis and dynamic analysis is done. The analysis is done by idealizing geometry, material and boundary conditions. Keywords: steel, reinforced concrete, silos.

Finite Element Analysis of Metal Flow of Finishing Groove in Hot Continuous Rolling Bar

2012 ◽  
Vol 510 ◽  
pp. 667-672
Author(s):  
Jia Lin Zhou ◽  
Chen Gang Pan ◽  
Xiao Yong Zhang
Keyword(s):  
Strain Distribution ◽  
Metal Flow ◽  
Dimensional Accuracy ◽  
Stress And Strain ◽  
Fe Model ◽  
Element Analysis ◽  
Iron And Steel ◽  
Expansion Angle ◽  
The Stability ◽  
Stress And Strain Distribution

This article established 3D FE model of dual-radius arc finishing groove and tangent expansion angle finishing groove using ANSYS / LS-DYNA software for Wuhan Iron and Steel plant Ф16 hot continuous bar, and analyzed metal flow pattern, stress and strain distribution of two types finishing grooves. The results show that surface stress and strain distribution of dual-radius arc finishing groove have better uniform than them of tangent expansion angle finishing groove, and dual-radius arc finishing groove ensures the stability of the rolled piece in finishing groove, improve the dimensional accuracy and surface quality of rolled finishing product.

scholarly journals Flexural-Torsional Vibration of Thin-Walled Beams Subjected to Combined Initial Axial Load and End Bending Moment: Application to the Design of Saw Tooth Blades

2019 ◽  
Vol 2019 ◽  
pp. 1-11
Author(s):  
Van Binh Phung ◽  
Anh Tuan Nguyen ◽  
Hoang Minh Dang ◽  
Thanh-Phong Dao ◽  
V. N. Duc
Keyword(s):  
Boundary Conditions ◽  
Axial Load ◽  
Stability Boundary ◽  
Bending Moment ◽  
Element Analysis ◽  
The Finite Element Analysis ◽  
Rayleigh Method ◽  
Thin Walled ◽  
The Stability ◽  
Fixed End

The present paper analyzes the vibration issue of thin-walled beams under combined initial axial load and end moment in two cases with different boundary conditions, specifically the simply supported-end and the laterally fixed-end boundary conditions. The analytical expressions for the first natural frequencies of thin-walled beams were derived by two methods that are a method based on the existence of the roots theorem of differential equation systems and the Rayleigh method. In particular, the stability boundary of a beam can be determined directly from its first natural frequency expression. The analytical results are in good agreement with those from the finite element analysis software ANSYS Mechanical APDL. The research results obtained here are useful for those creating tooth blade designs of innovative frame saw machines.

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