High-temperature fatigue behavior of a steam turbine rotor under flexible operating conditions with variable loading amplitudes

Hong, Hui; Wang, Weizhe; Liu, Yingzheng

doi:10.1016/j.ijmecsci.2019.105121

Cited by 22 publications

(5 citation statements)

References 18 publications

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“…Often, 3D thermoelastic stress data in the elastic regime can provide the essential input parameters in subsequent shakedown and creep-fatigue life calculations [23,[32][33][34][35][36][37][38][39][40]. Such calculations provide the means for improving and/or balancing thermodynamic cycle efficiency and service life, in high temperature double wall components in gas turbines [40,41] as well as other technologies [15,[42][43][44].…”

Section: Introductionmentioning

confidence: 99%

2D and 3D thermoelastic phenomena in double wall transpiration cooling systems for gas turbine blades and hypersonic flight

Skamniotis

Cocks

2021

Aerospace Science and Technology

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Section: Introductionmentioning

confidence: 99%

2D and 3D thermoelastic phenomena in double wall transpiration cooling systems for gas turbine blades and hypersonic flight

Skamniotis

Cocks

2021

Aerospace Science and Technology

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“…The temperature distribution obtained from the heat transfer analysis is read as an input for stress analysis in the truncated model. It has been shown in previous studies (Hong et al, 2019;Wang and Liu, 2018;Wang et al, 2016a) that such an idealization has very less effect on the results for localized region of rotor inlet. The mechanical forces include the rotational body force caused by the angular speed x rpm and the blade centrifugal loads applied as external forces F x 1 for the 1 st blade stage and F x 2;3;4 for stages 2-4.…”

Section: Model and Loading Conditionsmentioning

confidence: 94%

“…Viscoplastic constitutive laws have been applied for the analysis of steam turbine rotors (Liu and Wang, 2020; Wang et al., 2016a, 2016b) with fifteen cold start and shutdown sequences. Such operating modes are shown to cause radial temperature gradients within the rotor (Hong et al., 2019; Liu and Wang, 2020; Wang and Liu, 2018; Wang et al., 2016a, 2016b). The non-linear structural analysis of steam turbine rotors with thermal stress relief groove at the inlet section using the unified constitutive models under the obtained temperature profiles showed significant viscoplastic strain and damage accumulation at the inlet thermal stress relief groove and portions of the first blade groove.…”

Section: Introductionmentioning

confidence: 99%

“…The non-linear structural analysis of steam turbine rotors with thermal stress relief groove at the inlet section using the unified constitutive models under the obtained temperature profiles showed significant viscoplastic strain and damage accumulation at the inlet thermal stress relief groove and portions of the first blade groove. A combination of operating modes (Hong et al., 2019) where a sequence of one cold start, three warm and sixteen hot starts was chosen, and the considered loading conditions showed a fast warm start can be equally or more damaging than a cold start. Using a principal stress measure instead of a von Mises stress measure showed (Liu and Wang, 2020) that further optimization of the inlet groove is possible.…”

Section: Introductionmentioning

confidence: 99%

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Continuum damage mechanics of cyclic viscoplasticity using asymptotic numerical method

Sen,

Patel

2023

International Journal of Damage Mechanics

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Conscious efforts on reduction of greenhouse gas emissions have led to an energy transition to renewable energy, however uncertainties of renewable energy production have resulted in higher thermal cycling demands from conventional power plants. Thermal load cycling at high temperature regions of steam turbine components leads to enhanced creep-fatigue damage accumulation. It is well established that such damage mechanism is numerically best predicted by unified constitutive modeling including damage as a variable as per the formalism of continuum damage mechanics at an expense of considerable computational efforts using finite element analysis. In this paper, the non-iterative Asymptotic Numerical Method (ANM), currently limited to partial cycle analysis with linear hardening plasticity model, is proposed for the first time to address cyclic viscoplasticity problems including damage capable of handling multiple cycles and most generalized loading conditions. Regularization techniques additionally necessary to implement loading-unloading-reloading criteria and advanced constitutive models etc. are presented. The constitutive model chosen for the formulation includes the non-linear multiple back stress variable modified Chaboche model to include damage combined with modified Chaboche-Rousselier isotropic hardening model to include damage, power law for viscoplasticity, Lemaitre’s damage potential and Kachanov-Rabotnov’s creep damage law. The method is verified with defined error measures and then applied to two high pressure steam turbine rotors, one with and another without thermal stress relief groove (TSRG) at the inlet under service type loading conditions to study the beneficial effect of the TSRG on creep-fatigue damage evolution. The accumulated errors of the proposed ANM and computational time are compared to a conventional Newton-Raphson solution.

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“…Baseload thermal power plants must operate under variable loads due to wind and solar energy share. Steam turbines are subject to severe operating conditions [5,6], and rotor last stage blades can operate in a compressor mode delivering energy to the working fluid in low volume flow conditions [7]. Concepts of a dynamic power plant and solutions for an operational flexibility enhancement appear more often in the literature [8][9][10][11][12].…”

Section: Introductionmentioning

confidence: 99%

Analysis of Geometric Errors of Throat Sizes of Last Stage Blades in a Mid-Size Steam Turbine

Eret¹,

Hoznedl²

2022

Journal of Machine Engineering

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Steam turbine technology with enhanced flexibility will continue to participate in electric power supply mixes. Last stage blades secure the reliability of a steam turbine and require high precision manufacturing and assembly. This case study presents a statistical analysis of geometric errors of the throat sizes of the last stage blades in a mid-size steam turbine. A 3D optical scanner is employed to capture detailed geometries of rotor blades and a half of assembled nozzle diaphragm. Unrolled cylinder cross-sections are used to evaluate 2D geometrical features such as blade throats and areas at three different diameters, and the results are compared to intended designs. In addition, linear correlations between the throat size and blade pitch, area and trailing edge thickness are established, and blade throat position shifts are quantified. Such a comprehensive study is presented for the first time, and some useful conclusions can be retrieved from this case study.

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High-temperature fatigue behavior of a steam turbine rotor under flexible operating conditions with variable loading amplitudes

Cited by 22 publications

References 18 publications

2D and 3D thermoelastic phenomena in double wall transpiration cooling systems for gas turbine blades and hypersonic flight

2D and 3D thermoelastic phenomena in double wall transpiration cooling systems for gas turbine blades and hypersonic flight

Continuum damage mechanics of cyclic viscoplasticity using asymptotic numerical method

Analysis of Geometric Errors of Throat Sizes of Last Stage Blades in a Mid-Size Steam Turbine

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