Fatigue Life Evaluation for Turbine Rotor Using Green's Function

Song, Geewook; Kim, Bum-Shin; Chang, Sung-Ho

doi:10.1016/j.proeng.2011.04.379

Cited by 18 publications

(16 citation statements)

References 4 publications

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“…Assuming that the steam temperature is described by Heaviside's function H(t), the boundary condition (8) can be written in the form [10]: λ r ðÞ ∂Xr ; t ðÞ ∂n ¼Àα r ðÞHt ðÞÀXr ; t ðÞ ðÞ (9) where X(r, t) is Green's function for temperature. Using Green's function X(r, t), we can calculate the metal temperature for arbitrary variation of steam temperature employing Duhamel's theorem [20]:…”

Section: Green's Function Methodsmentioning

confidence: 99%

“…The major issue in using Green's function and Duhamel's integral method in modeling transient thermal stresses in steam turbine components is the time dependence of material physical properties and heat transfer coefficients affecting proper evaluation of Green's functions and making the problem nonlinear. There are known approaches assuming the determination of the influence functions at constant values of these quantities [9]. The inclusion of temperature-dependent physical properties proposed by Koo et al [10] relies on determining the weight functions for steady-state and transient operating conditions.…”

Section: Introductionmentioning

confidence: 99%

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Practical Methods for Online Calculation of Thermoelastic Stresses in Steam Turbine Components

Banaszkiewicz¹,

Badur²

2018

Selected Problems of Contemporary Thermomechanics

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This chapter presents two practical methods of thermoelastic stress calculation suitable for application in online monitoring systems of steam turbines. Both methods are based on the Green function and Duhamel integral and consider the effect of variable heat transfer coefficient and material physical properties on thermal stresses. This effect is taken into account either by using an equivalent steam temperature determined with a constant heat transfer coefficient or by applying an equivalent Green's function determined with variable heat transfer coefficient and physical properties. The effectiveness of both methods was shown by comparing their predictions with the results of exact three-dimensional (3D) calculations of a steam turbine valve.

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Section: Green's Function Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Practical Methods for Online Calculation of Thermoelastic Stresses in Steam Turbine Components

Banaszkiewicz¹,

Badur²

2018

Selected Problems of Contemporary Thermomechanics

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“…The results showed that the fatigue mechanism derived from the stress field generated by the frequent start-up and the blade fixing method [11]. Based on the thermal stress analysis of a turbine rotor at transient condition, the fatigue life of the rotor was obtained by solving the Green function [12]. A nonlinear damage model was established to analyze the fatigue damage of a rod-fastened rotor under the start-up condition [13].…”

Section: Introductionmentioning

confidence: 99%

Transient Analysis and Design Improvement of a Gas Turbine Rotor Based on Thermal‐Mechanical Method

Liu

Yuan

Zhu

et al. 2018

Shock and Vibration

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The rotor is the core component of a gas turbine, and more than 80% of the failures in gas turbines occur in the rotor system, especially during the start-up period. Therefore, the safety assessment of the rotor during the start-up period is essential for the design of the gas turbine. In this paper, the transient equivalent stress of a gas turbine rotor under the cold start-up condition is investigated and the novel tie rod structure is introduced to reduce the equivalent stress. Firstly, a three-dimensional finite element model of the gas turbine rotor is built, and nonlinear contact behaviors such as friction are taken into account. Secondly, the convective heat transfer coefficients of the gas turbine rotor under the cold start-up condition are calculated using thermal dynamic theory. The transient analysis of the gas turbine rotor is conducted considering the thermal load, the centrifugal load, and the pretightening force. The temperature and stress distributions of the rotor under the cold start-up condition are shown in detail. In particular, the generation mechanism of maximum equivalent stress for tie rods and the change tendency of the pretightening force are illustrated in detail. The tie rod holes of the rear shaft and the turbine tie rod are the dangerous locations during the startup period. Finally, a novel tie rod is proposed to reduce the maximum equivalent stress at the dangerous location. The maximum equivalent stress at this location is decreased by 15%. This paper provides some reference for the design of the gas turbine rotor.

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“…The zone of rotor which is more exposed to highest temperatures is the Curtis stage [9]. Song et al [10] use Green's function to calculate the thermal stress and the remaining life of steam turbine rotors. In the case of a geometrical model like hollow cylinders, Irfan and Chapman [11] investigate the thermal stresses in radiant tubes caused by axial, circumferential and radial temperature distributions and they conclude that radial temperature gradients cause the major thermal stress.…”

Section: Introductionmentioning

confidence: 99%

Effect of Rotor Diameter on the Thermal Stresses of a Turbine Rotor Model

Dávalos

García

Urquiza

et al. 2016

International Journal of Turbo &Amp; Jet-Engines

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Thermal stresses in a simplified steam turbine rotor model during a cold startup are analyzed using finite element analysis (FEA). In order to validate the numerical model, an experimental array is developed in which a hollow cylinder is heated with hot air in the external surface. At the thick wall of the cylinder, temperature distribution is measured in real time, while at the same time an algorithm computes thermal stresses. Additional computational fluid dynamics (CFD) calculations are made to obtain magnitudes of velocity and pressure in order to compute convective heat transfer coefficient. The experimental results show good agreement with the FEA computations. To evaluate the effect of rotor diameter size, FEA computations with variation in external and internal diameters are performed. Results show that thermal stresses are proportional to rotor diameter size. Also, zones of higher stress concentration are found in the external and internal surfaces of the rotor.

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Fatigue Life Evaluation for Turbine Rotor Using Green's Function

Cited by 18 publications

References 4 publications

Practical Methods for Online Calculation of Thermoelastic Stresses in Steam Turbine Components

Practical Methods for Online Calculation of Thermoelastic Stresses in Steam Turbine Components

Transient Analysis and Design Improvement of a Gas Turbine Rotor Based on Thermal‐Mechanical Method

Effect of Rotor Diameter on the Thermal Stresses of a Turbine Rotor Model

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