Nonlinear Vibration by Asynchronous Excitation Force in Friction Damper of Turbine Blade

2021 ◽  
Author(s):  
Ryuichi Umehara ◽  
Haruko Shiraishi ◽  
Naoki Onozato ◽  
Tetsuya Shimmyo
Keyword(s):  
Nonlinear Vibration ◽  
Turbine Blade ◽  
Friction Damper ◽  
Excitation Force

Nonlinear Vibration by Asynchronous Excitation Force in Friction Damper of Turbine Blade

2018 ◽  
Vol 2018 (0) ◽  
pp. 432
Author(s):  
Ryuichi UMEHARA ◽  
Haruko SHIRAISHI ◽  
Tetsuya SHIMMYO ◽  
Naoki ONOZATO ◽  
Hiroki KITADA ◽  
...  
Keyword(s):  
Nonlinear Vibration ◽  
Turbine Blade ◽  
Friction Damper ◽  
Excitation Force

Nonlinear Vibration by Asynchronous Excitation Force in Friction Damper of Turbine Blade

2020 ◽  
Author(s):  
Ryuichi Umehara ◽  
Haruko Shiraishi ◽  
Naoki Onozato ◽  
Tetsuya Shimmyo
Keyword(s):  
Nonlinear Vibration ◽  
Turbine Blade ◽  
Gas Turbines ◽  
Turbine Blades ◽  
Harmonic Balance Method ◽  
Time History ◽  
Harmonic Excitation ◽  
Friction Damper ◽  
Excitation Force ◽  
Force Components

Abstract Turbine blades are now being used under increasingly severe conditions in order to increase the thermal efficiency of gas turbines. Friction dampers are often used to reduce the vibration of the blade and improve the plant reliability. This is a general study dealing with resonance passing where the natural frequency of the turbine blade coincides with the frequency of specific harmonic excitation forces while increasing the turbine rotation speed. Asynchronous components of excitation forces are also considered in addition to the synchronous components caused by specific harmonic excitation forces. In this study, a new method for predicting the characteristics of nonlinear vibration under excitation force including both synchronous and asynchronous force components is developed. In order to investigate the effect of additional asynchronous loading, time history response analyses considering nonlinear vibration using simulated turbine blades were conducted. Results showed that friction damper slip can be induced by the presence of the additional asynchronous excitation force components even for low values of synchronous excitation force. It is shown that it is possible to use a calibration factor to predict vibration characteristics considering friction slipping by estimating the ratio of the total excitation force to the single harmonic excitation force. To verify the effect of asynchronous excitation force and the validity of the proposed correction method, verification tests were conducted experimentally. The experimental results show that friction slipping occurred under small harmonic excitation force when there was asynchronous excitation force and show good agreement with the numerical results. Moreover, the validity of the proposed method which corrects the dynamic characteristics obtained using of the first order harmonic balance method is confirmed.

Detection of a Rotor Crack Based on the Nonlinear Vibration Diagnosis Using Periodic Excitation

2005 ◽  
Author(s):  
Yukio Ishida ◽  
Tsuyoshi Inoue
Keyword(s):  
Nonlinear Vibration ◽  
Equations Of Motion ◽  
Frequency Component ◽  
Dominant Frequency ◽  
Vibration Characteristics ◽  
Periodic Excitation ◽  
Cracked Rotor ◽  
On Line ◽  
Linear And Nonlinear ◽  
Excitation Force

Detection of a rotor crack based on the nonlinear vibration diagnosis using periodic excitation force is investigated. Due to the open-close mechanism of the crack, the equations of motion of a cracked rotor have linear and nonlinear parametric terms. When a periodic excitation force is applied to the cracked rotor, various kinds of resonances due to the unique vibration characteristics of a crack. Furthermore, types of resonances, resonance points and dominant frequency component of these resonances are clarified theoretically and experimentally. These results enable us to detect a crack on-line without stopping the system.

Study on Unsteady Aerodynamic Force of Turbine Blade With Different Mass Flow

2008 ◽  
Author(s):  
Jibing Lan ◽  
Yonghui Xie ◽  
Di Zhang
Keyword(s):  
Turbine Blade ◽  
Mass Flow ◽  
Aerodynamic Force ◽  
Incidence Angle ◽  
Wake Flow ◽  
Unsteady Aerodynamic ◽  
Design Case ◽  
Excitation Force ◽  
Unsteady Aerodynamic Force ◽  
Flow Case

The traditional turbomachinery design systems are always based on the assumption of steady or quasi-steady flows. However, unsteady flows such as wake flow, separated flow and shedding vortices are the main factors inducing the excitation force on turbine blade which leads to high cycle fatigue failure of blade. In this paper, the three-dimensional, time dependent, Reynolds-Averaged Navier-Stokes (RANS) equations were resolved using a commercial program CFX based on finite volume method. The unsteady flow fields of three mass flow cases (design case, 110% design mass flow and 85% design mass flow) in a one-and-a-half stage axial turbine (stator/rotor/stator) were investigated in detail and then the unsteady aerodynamic force on the rotational blade was obtained. Frequencies of unsteady disturbances and excitation force factors were obtained by spectrum analysis. It can be seen clearly that the excitation factors at 110% mass flow case are larger than that at the design case. On the other side, the unsteady aerodynamic force on the rotational blade at 85% mass flow case is quite different from the design case. There are two peaks during a stator passing period and the dominate frequency of the tangential blade force is 6000Hz due to large amount of negative incidence angle. The 6000Hz component tangential aerodynamic force amplitude is 6.533N, which is 5.93 times of that at design case and 2.92 times of that at 110% mass flow case. Because of the large amplitude, the unsteady aerodynamic force at small mass flow case is necessary to be taken into account in the forced vibration analysis of blade.

Nonlinear Model and Simulation Experiment Research of Vibratory Rollers

2011 ◽  
Vol 121-126 ◽  
pp. 2121-2125
Author(s):  
Yuan Hao ◽  
Zhao Hui Ren ◽  
Feng Wen
Keyword(s):  
Nonlinear Vibration ◽  
Simulation Experiment ◽  
Response Characteristic ◽  
Soil Mass ◽  
System Model ◽  
System Response ◽  
Experiment Research ◽  
System Parameters ◽  
Model And Simulation ◽  
Excitation Force

On the basis of the relation between force and deformation when the plastic deformation of soil mass is studied, nonlinear vibration roller model is built. Based on one type vibratory rollers select the system parameters and calculate the natural frequency. And according to the selected numerical value proceed the numerical simulation with different excitation force frequencies. Meanwhile, obtain and analyze the experimental data according to the vibratory roller experiment. Then the system response characteristic of nonlinear vibration roller is obtained, and the availability of system model is checked. All above provide the valuable theoretical basis for the research of vibrating compacting.

Detection of a Rotor Crack Using a Harmonic Excitation and Nonlinear Vibration Analysis

2006 ◽  
Vol 128 (6) ◽  
pp. 741-749 ◽  
Author(s):  
Yukio Ishida ◽  
Tsuyoshi Inoue
Keyword(s):  
Power Series ◽  
Nonlinear Vibration ◽  
Piecewise Linear ◽  
Equations Of Motion ◽  
Excitation Frequency ◽  
Harmonic Excitation ◽  
Crack Model ◽  
Cracked Rotor ◽  
Nonlinear Resonances ◽  
Excitation Force

Detection of a rotor crack based on the nonlinear vibration diagnosis using harmonic excitation force is investigated. The open-close mechanism of crack is firstly modeled by a piecewise linear function. In addition, another approximation crack model using a power series function that is convenient for the theoretical analysis is used. When the power series function crack model is used, the equations of motion of a cracked rotor have linear and nonlinear parametric terms. In this paper, a harmonic excitation force is applied to the cracked rotor and its excitation frequency is swept, and the nonlinear resonances due to crack are investigated. The occurrence of various types of nonlinear resonances due to crack are clarified, and types of these resonances, their resonance points, and dominant frequency component of these resonances are clarified numerically and experimentally. Furthermore, nonlinear theoretical analyses are performed for these nonlinear resonances, and it is clarified that the amplitudes of these nonlinear resonances depend on the nonlinear parametric characteristics of rotor crack. These results enable us to detect a rotor crack without stopping the system during on-line operation.

Modelling and design of friction damper used for the control of vibration in a gas-turbine blade - a microslip approach

2007 ◽  
Vol 221 (8) ◽  
pp. 887-895
Author(s):  
P V Ramaiah ◽  
G Krishnaiah
Keyword(s):  
Mathematical Model ◽  
Turbine Blade ◽  
Experimental Test ◽  
Contact Region ◽  
Modal Parameters ◽  
Second Phase ◽  
Rigid Surface ◽  
Friction Damper ◽  
The Third ◽  
Third Phase

The paper deals with modelling and design of a friction damper. This has been done in four phases. In the first phase, modal analysis is performed to determine the modal parameters of turbine blade. In the second phase, a mathematical model for the contact region of damper and rigid surface has been developed using microslip approach. This model has the ability to account for microslip in the contact region. In the third phase, a mathematical model for the combined blade with damper is developed and in the fourth phase the damper is designed. The results of the combined blade with damper model are confirmed by experimental test.

Nonlinear Vibration Analysis of the Wind Turbine Blade (Occurrence of the Superharmonic Resonance in the Out of Plane Vibration of the Elastic Blade)

2012 ◽  
Vol 134 (3) ◽  
Author(s):  
Tsuyoshi Inoue ◽  
Yukio Ishida ◽  
Takashi Kiyohara
Keyword(s):  
Wind Turbine ◽  
Nonlinear Vibration ◽  
Turbine Blade ◽  
Vibration Analysis ◽  
Gravitational Force ◽  
Clean Energy ◽  
Wind Turbine Blade ◽  
Turbine Generator ◽  
Superharmonic Resonance ◽  
Wind Turbine Generator

The use of wind turbine generator has rapidly spread as a one of the foremost clean energy sources. Recently, as the size of the wind turbine generator has become larger, its maintenance has become more difficult. However, there are few studies on the vibration analysis and its suppression in the conventional researches. The wind turbine is a special type of rotating machinery which has a long heavy blade rotating in the vertical plane under the action of the gravitational force. The wind power acting on the wind turbine blade varies periodically because of the height-dependent characteristic of the wind. Therefore, the dynamical design and analysis of the wind turbine blade requires a more thorough study. This paper investigates the fundamental vibration characteristic of an elastic blade of the wind turbine. The nonlinear vibration analysis of the superharmonic resonance is performed, and its characteristics are explained. Furthermore, the effect of the interaction of both the gravitational force and the wind force on the superharmonic resonance is clarified.

A Vibration Damping Analysis Method of Turbine Blade Shroud Dampers Based on a Given Eigen-Mode

2018 ◽  
Author(s):  
Zhao Jiazhe ◽  
Wang Yanrong ◽  
Luo Yanbin ◽  
Zhang Xiaojie
Keyword(s):  
Turbine Blade ◽  
Damping Ratio ◽  
Twist Angle ◽  
Vibration Damping ◽  
Design Parameters ◽  
Slip Model ◽  
Analysis Method ◽  
Friction Damper ◽  
Analysis And Design ◽  
Eigen Mode

High cycle fatigue damage caused by resonance and forced vibration can significantly affect the life and reliability of turbine rotor blades in aero-engines. The friction damper has been widely used to reduce the resonant stress of blades, on which the turbine blade shroud dampers are highly used. In order to solve the problems of vibration damping analysis and design of shrouded blades dampers, an analytical method without complex and time-consuming nonlinear vibration response has been proposed based on a given eigen-mode in this paper. For the serrated shrouded damper, two typical friction models, namely macro-slip model, and micro-slip model, have been introduced. Additionally, a complete set of damping analysis method has been introduced by the energy method, based on the vibration dynamics principle and eigen-mode analyzed by finite element method. Combined with the analysis of the natural vibration characteristics of the shrouded turbine blade, the law of the damping ratio with the relevant design parameters, such as the vibration stress, the pre-twist angle, the friction coefficient and the nodal diameter, was obtained through a calculation example. The method can also provide an important reference for the parameterized design of dampers.

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