Vibration Response Analysis of Mistuned Bladed Disk With Under-Platform Damper: Effect of Variation of Contact Condition on Vibration Characteristics

2017 ◽  
Author(s):  
Yasutomo Kaneko
Keyword(s):  
Gas Turbine ◽  
Direct Method ◽  
Contact Condition ◽  
Vibration Response ◽  
Response Analysis ◽  
Friction Damper ◽  
Mass Model ◽  
Contact Conditions ◽  
Manufacturing Tolerance ◽  
Bladed Disk

Blades with a friction damper have been used in a steam turbine and a gas turbine to improve the blade reliability. In particular, for a gas turbine blade of the upstream stage, under-platform dampers have been widely used, where the damper pieces with various geometries are inserted into the platforms of the adjacent blades. The damper piece is designed so that its surface contacts the platform surface uniformly. However, the contact conditions of the damper piece (in other words, the equivalent stiffness and the damping caused by the damper piece) may change appreciably blade by blade because of the likes of manufacturing tolerance, blade deformation in operation, and wear of the damper piece. Therefore, it is essential to consider the mistuning effect caused by the variation of the contact condition of the damper piece in evaluating the vibration response of the bladed disk with the under-platform damper. In this study, a mistuned bladed disk with under-platform dampers is represented by the equivalent spring-mass model. Frequency response analysis and random response analysis are carried out using the direct method and Monte Carlo simulation. Carrying out an extensive parametric study, the effect of the variation of the contact condition caused by the damper piece on the vibration response of the bladed disk is clarified.

scholarly journals Study on Vibration Characteristics of Mistuned Bladed Disk(Vibration Response Analysis by Reduced Model FMM)

2013 ◽  
Vol 7 (4) ◽  
pp. 328-342 ◽  
Author(s):  
Yasutomo KANEKO ◽  
Ryota NAKANISHI ◽  
Kazushi MORI ◽  
Hiroharu OHYAMA
Keyword(s):  
Vibration Characteristics ◽  
Vibration Response ◽  
Reduced Model ◽  
Response Analysis ◽  
Bladed Disk

Study on Transient Vibration of Mistuned Bladed Disk Passing Through Resonance

2013 ◽  
Author(s):  
Yasutomo Kaneko
Keyword(s):  
Vibration Analysis ◽  
Response Analysis ◽  
Analysis Method ◽  
Frequency Response Analysis ◽  
Transient Vibration ◽  
Mass Model ◽  
Bladed Disk ◽  
Acceleration Rate ◽  
Start Up ◽  
Speed Engine

In a variable speed engine, it is impossible to avoid the resonance during operation. In a constant speed engine, the resonance during start-up or shut-down also cannot be avoided. Therefore, the increase of the acceleration rate in passing through the resonance has been considered as one of the effective methods for reducing the vibratory stress of the blade and increasing the reliability of the turbomachinery. In this study, the transient vibration analysis of the mistuned bladed disk passing through the resonance is carried out, using the conventional modal analysis method and the numerical integration method. First, the mistuned bladed disk is modeled by the equivalent spring-mass model, and the steady frequency response analysis is carried out by the Monte Carlo simulation, in order to obtain the worst mistuning pattern. Second, for the mistuned bladed disk of the worst mistuning pattern, the transient vibration analysis in passing through the resonance is carried out, and the effect of the acceleration rate and the blade damping on the transient vibration response is examined in detail. From these results, it is concluded that the larger the acceleration rate is, the smaller the mistuning effect is.

Nonlinear Dynamics Analysis of Mistuned Turbine Bladed Disks With Damped Shrouds

2017 ◽  
Author(s):  
Wei Zhao ◽  
Di Zhang ◽  
Lei Sun ◽  
Yonghui Xie
Keyword(s):  
Dry Friction ◽  
Normal Load ◽  
Forced Response ◽  
Vibration Response ◽  
Amplification Coefficient ◽  
Response Analysis ◽  
Friction Damping ◽  
Friction Forces ◽  
Bladed Disk ◽  
The Impact

This paper deals with the real dynamics characteristics of a mistuned steam turbine bladed disk subjected to dry friction forces to better understand the nonlinear mistuning phenomenon. Normal load, which directly affects contact stiffness between interfaces, is chosen as the mistuning parameter. Based on Mindlin model, a forced response analysis of the finite element model of mistuned bladed disk with damped shrouds is performed in ANSYS. Compared with results of other simplified models, a real and complicated nonlinear behavior are observed here. A mass of qualitative analysis is also performed to assess the impact of the mistuning magnitude and excitation level on the vibration. The result shows that, vibration response of bladed disk is affected by excitation and mistuning level significantly. Local amplification coefficient of vibration response in the cases of different mistuning levels is obtained by introducing 10 random mistuned patterns. In addition, frequency splitting phenomena even appears at one of the blades by the contribution of high mistuning levels. According to the calculated results for different excitation levels, the curve of modal damping varying with response amplitude is gained. Lastly, rigidity mistuning is introduced and a combined analysis is performed to investigate the influence of friction damping mistuning on rigidity mistuning in the same 10 random mistuning patterns. The arrangement of dry friction damping mistuning also could be controlled to reduce the local vibration amplification originating from structure mistuning. However, further statistical investigations should be made to gain more information. (CSPE)

Effects of Damping and Varying Contact Area at Blade-Disk Joints in Forced Response Analysis of Bladed Disk Assemblies

2005 ◽  
Vol 128 (2) ◽  
pp. 403-410 ◽  
Author(s):  
E. P. Petrov ◽  
D. J. Ewins
Keyword(s):  
Large Scale ◽  
Normal Load ◽  
Forced Response ◽  
Response Analysis ◽  
Finite Element Models ◽  
Bladed Disks ◽  
Contact Conditions ◽  
New Approach ◽  
Bladed Disk ◽  
Unilateral Contacts

An approach is developed to analyze the multiharmonic forced response of large-scale finite element models of bladed disks taking account of the nonlinear forces acting at the contact interfaces of blade roots. Area contact interaction is modeled by area friction contact elements which allow for friction stresses under variable normal load, unilateral contacts, clearances, and interferences. Examples of application of the new approach to the analysis of root damping and forced response levels are given and numerical investigations of effects of contact conditions at root joints and excitation levels are explored for practical bladed disks.

Vibration Response Analysis of a Small Gas Turbine Rotor

2010 ◽  
Vol 13 (3) ◽  
pp. 18-23
Author(s):  
Young-Cheol Kim ◽  
Jin-Woong Ha ◽  
Ji-Ho Myung
Keyword(s):  
Gas Turbine ◽  
Turbine Rotor ◽  
Vibration Response ◽  
Response Analysis
Sign in / Sign up

Export Citation Format

Share Document