Numerical Investigation of Creep–Fatigue Behavior in a Steam Turbine Inlet Valve Under Cyclic Thermomechanical Loading

2017 ◽  
Vol 139 (11) ◽  
Author(s):  
Weizhe Wang ◽  
Sihua Xu ◽  
Yingzheng Liu
Keyword(s):  
Steam Turbine ◽  
Contact Stress ◽  
Damage Mechanics ◽  
Fatigue Behavior ◽  
Thermomechanical Loading ◽  
Inlet Valve ◽  
Valve Body ◽  
Turbine Inlet ◽  
Creep Fatigue ◽  
Cyclic Thermomechanical Loading

The aim of this study was to investigate the cyclic creep–fatigue interaction behavior in a steam turbine inlet valve under cyclic thermomechanical loading conditions. Three years and nine iterations of idealized startup–steady-state operation–shutdown process were chosen. The Ramberg–Osgood model, the Norton–Bailey law, and continuum damage mechanics were applied to describe the stress–strain behavior and calculate the damage. The strength of the steam valve revealed that significant stress variation mainly occurred at the joint parts between the valve diffuser and the adjust valve body, due to the combination of the enhanced turbulent flow and assembly force at these areas. The contact stress at the region of component assembly was sensitive to the cyclic loading at the initial iterations. The maximum decrease amplitude in the normalized contact stress between the second and the fourth iterations reached 0.12. The damage analysis disclosed that the notch of the deflector in the adjust valve had the maximum damage due to the stress concentration.

Analysis of Multi-Axial Creep–Fatigue Damage on an Outer Cylinder of a 1000 MW Supercritical Steam Turbine

2014 ◽  
Vol 136 (11) ◽  
Author(s):  
Weizhe Wang
Keyword(s):  
Steam Turbine ◽  
Fatigue Damage ◽  
Damage Mechanics ◽  
Hydrostatic Stress ◽  
Fatigue Behavior ◽  
Axial Stress ◽  
Outer Cylinder ◽  
Continuum Damage Mechanics ◽  
Transfer Coefficients ◽  
Creep Fatigue

A multi-axial continuum damage mechanics (CDM) model was proposed to calculate the multi-axial creep–fatigue damage of a high temperature component. A specific outer cylinder of a 1000 MW supercritical steam turbine was used in this study, and the interaction of the creep and fatigue behavior of the outer cylinder was numerically investigated under a startup–running–shutdown process. To this end, the multi-axial stress–strain behavior of the outer cylinder was numerically studied using Abaqus. The in-site measured temperatures were provided to validate the heat transfer coefficients, which were used to calculate the temperature field of the outer cylinder. The multi-axial mechanics behavior of the outer cylinder was investigated in detail, with regard to the temperature, Mises stress, hydrostatic stress, multi-axial toughness factor, multi-axial creep strain, and damage. The results demonstrated that multi-axial mechanics behavior reduced the total damage.

Internal leakage analysis and experiment in hydraulic control system of steam turbine inlet valve

2020 ◽  
pp. 095440892097311
Author(s):  
Ying Liu ◽  
Qimin Wang ◽  
Xiaoxiao Li ◽  
Liming Wang
Keyword(s):  
Control System ◽  
Steam Turbine ◽  
Simulation Software ◽  
Hydraulic Control ◽  
Inlet Valve ◽  
Proportional Valve ◽  
Hydraulic Simulation ◽  
Turbine Inlet ◽  
Control Switch ◽  
Hydraulic Control System

In this paper, the transformation of steam turbine regulating system from mechanical hydraulic regulation to electro-hydraulic regulation is realized. And the internal leakage mechanism of the hydraulic control switch valve and the electro-hydraulic proportional valve in the system is analyzed. With the use of hydraulic simulation software AMESim, the mathematical model of the electro-hydraulic control system after transforming is established. The parameters of the hydraulic control switch valve and the electro-hydraulic proportional valve in the hydraulic control system of steam turbine inlet valve are studied under different internal leakage locations and different leakage degree, such as piston regulating time, steady position of piston, oil pressure and leakage flow flux. The fault characteristic table of internal leakage is obtained. An experimental platform for simulating internal leakage is built. The experimental curves of several physical quantities under different internal leakage conditions are obtained. The experimental results prove that the internal leakage has a great impact on the performance of the electro-hydraulic control system. The results of internal leakage experiment are consistent with those of internal leakage simulation.

Creep-Fatigue Behavior of a Newly Developed Ultra-Supercritical Steam Turbine Grade Nickel-Based Superalloy, HAYNES 282

2021 ◽  
Vol 10 (2) ◽  
pp. 20200167
Author(s):  
Shreya Mukherjee ◽  
Kaustav Barat ◽  
Soumitra Tarafder ◽  
S. Sivaprasad ◽  
Sujoy Kumar Kar
Keyword(s):  
Steam Turbine ◽  
Fatigue Behavior ◽  
Nickel Based Superalloy ◽  
Creep Fatigue

Multiaxial Creep-Fatigue Life Prediction on the Rotor of a 1000MW Supercritical Steam Turbine

2012 ◽  
Author(s):  
Jianfeng Mao ◽  
Weizhe Wang ◽  
Yingzheng Liu ◽  
Junhui Zhang
Keyword(s):  
High Temperature ◽  
Steam Turbine ◽  
Damage Mechanics ◽  
Continuum Damage Mechanics ◽  
Continuum Damage ◽  
Mechanics Model ◽  
Creep Fatigue ◽  
Damage Accumulation Model ◽  
Multiaxial Creep ◽  
Comparison Of The Results

Damage of a high temperature rotor subjected to the creep-fatigue interaction was numerically investigated. Toward that end, a high temperature rotor of a 1000MW supercritical steam turbine was chosen for the study. A continuum damage mechanics model (CDM), which depicts the fatigue-creep interaction, was developed in the present paper. During the practical startup and shutdown processes, the influence of the multiaxial creep-fatigue interaction on strength of the rotor was analyzed in terms of stress, strain and damage. Comparison of the results from linear damage accumulation model (LDA) and CDM demonstrated that CDM was more reasonable to predict the lifetime of the rotor due to the multiaxial creep-fatigue interaction.

A Continuum Damage Mechanics-Based Viscoplastic Model of Adapted Complexity for High-Temperature Creep–Fatigue Loading

2016 ◽  
Vol 138 (9) ◽  
Author(s):  
Weizhe Wang ◽  
Patrick Buhl ◽  
Andreas Klenk ◽  
Yingzheng Liu
Keyword(s):  
Damage Mechanics ◽  
Fatigue Behavior ◽  
Continuum Damage Mechanics ◽  
Fatigue Loading ◽  
Material Model ◽  
Material Behavior ◽  
Continuum Damage ◽  
Loading Test ◽  
Constitutive Material Model ◽  
Creep Fatigue

A continuum damage mechanics (CDM) based viscoplastic constitutive model is established in this study to describe the fully coupling of creep and fatigue behavior. The most significant improvement is the introduction of a continuum damage variable into the constitutive equations, instead of considering creep damage and fatigue damage separately. The CDM-based viscoplastic constitutive material model is implemented using a user-defined subroutine (UMAT). A standard specimen is used for carrying out uniaxial creep, fatigue, and creep–fatigue interaction tests to validate the material model. In addition, to further demonstrate the capability of the material model to predict the complex material behavior, a complex strain-control loading test is performed to validate the material model. The simulated and measured results are in good agreement at different temperatures and loadings, in particular for rapid cyclic softening behavior following crack initiation and propagation.

Creep-Fatigue Life Prediction of Stop and Regulating Valves on the Intermediate-Pressure Section of a 1000MW Steam Turbine

2013 ◽  
Author(s):  
Jianfeng Mao ◽  
Junhui Zhang ◽  
Weizhe Wang ◽  
Yingzheng Liu
Keyword(s):  
Fatigue Life ◽  
Steam Turbine ◽  
Life Prediction ◽  
Damage Mechanics ◽  
Continuum Damage Mechanics ◽  
Complex Stress ◽  
Fatigue Life Prediction ◽  
Temperature Fields ◽  
Intermediate Pressure ◽  
Creep Fatigue

The stop&regulating integrated valve on the intermediate-pressure (IP) section of a 1000MW steam turbine is presented in this paper. A multiaxial model based on continuum damage mechanics (CDM) is applied to life prediction of the valve. The transient stress and the temperature fields of the valve in a 1000MW supercritical steam turbine are investigated by using finite element method (FEM) for fatigue-creep. Since the turbine typically runs 120 days between starts, a simplified mission profile for a 120-day block was created. Accordingly, the 120-day loading block with plasticity and creep was run repetitively to achieve a 22 years creep-fatigue life prediction. The interaction between creep and fatigue was considered in total damage in proper order. Due to highly complex stress and structure, the multiaxial factors for fatigue and creep are assessed from the temporal and spatial points of view respectively. Furthermore, the creep-fatigue damage of the integrated valve is discussed in relation to the multiaxial factors. The results drawn from the multiaxial CDM model give a satisfactory life prediction on the valve.

Design, simulation, and experiment research on fast control system of steam turbine inlet valve

2021 ◽  
pp. 095440892110439
Author(s):  
Ying Liu ◽  
Xiaoju Yin ◽  
Yunlong Yi ◽  
Xiaoxiao Li ◽  
Liming Wang
Keyword(s):  
Control System ◽  
Steam Turbine ◽  
Simulation Software ◽  
Servo Motor ◽  
Closing Time ◽  
Inlet Valve ◽  
Turbine Inlet ◽  
Simulation Results ◽  
Fast Control ◽  
First Time

In this paper, a new fast control system of steam turbine inlet valve is designed, which is composed of the fast closing system and the fast opening system. For the first time, this paper proposes that the fast closing system is designed by means of the special structure of the slide valve in an oil servo motor on the basis of the transformation of the hydraulic control system of steam turbine inlet valve. For the first time, a differential oil discharge fast opening system is designed by use of two cartridge valves. The mathematical model of electro-hydraulic fast control system is presented. With the use of simulation software Advanced Modeling Environment for Simulation of engineering systems , the curves of parameters such as piston displacement, piston velocity, oil pressure of upper and nether cavities of oil servo motor, and flow flux of upper and nether cavities of oil servo motor are obtained. The fast closing time of the piston for whole journey from the simulation results is 0.36 s. The fast opening time of the piston for whole journey from the simulation results is 1.55 s. According to the designed structure of the fast control system, the fast control experiment system is built. The fast closing time of the piston for whole journey from the experiment results is 0.22 s. The fast opening time of the piston for the whole journey from the experiment results is 1.97 s. The simulation and experimental results show that the designed fast control system can realize the fast closing and fast opening of the inlet valve. The fast closing time of the fast control system is <0.5 s, and the fast opening time of the fast control system is <3 s, which meets the fast control time requirement of the steam turbine inlet valve. Compared with the existing fast control system products, the fast control system and the inlet valve servo regulation system share a set of oil sources. And the fast control system has the advantages of low cost, simple structure, easy implementation, etc.

Sign in / Sign up

Export Citation Format

Share Document