DOI: https://doi.org/10.32347/2410-2547.2018.101.103-110

Influence of temperature regimes on stress-strain state of design details

Vladyslav Valer, Sergey Pyskunov

Abstract


Details of turbomachines come in direct contact with gases, which are at the peak of their temperature. There is a heterogeneous temperature distribution across the detail as a result of changes in temperature and external influences. As is known, the temperature stresses in materials are due to temperature gradients and boundary conditions. However, when designing and determining the bearing capacity of turbomachinery structural elements, other factors, including the heating regime, must be taken into account. The greatest temperature stresses develop during the cycles of heating and cooling. At the same time, the greatest values of temperature gradients and stresses arise in a fairly short period of time, which in turn can cause a temperature fatigue of the material. In addition, high temperatures contribute to the development of creep deformations, which reduce the length of the life cycle of the detail. One of the factors that determines the occurrence of thermal stresses is the nature of the temperature change during the start-up process, which is determined by the start-up curve of the turbine or machine. Start-up curve is the dependence between rotor speed or gas temperature and time. It is especially important for such parts as turbine blades and roots of the blades. Considering that turbomachinery parts must withstand a significant number of start-up cycles, both temperature and mechanical analysis is required. The purpose of this work is to study the effect of the nature of the change of external temperature (start-up curves) on the change in the parameters of the stress-strain state of the fir-tree root of the gas turbine blade under thermoelastoplastic deformation, taking into account the nonhomogenous temperature distribution. The effect of heating regimes on the development of temperature stresses is considered in the paper. The initial relations of the problem of transient thermal conductivity and the problem of thermoelastoplasticity are given. An analysis of the effect of the selection of the start-up curve on the approximated geometry of fir-tree root of the blade was carried out.


Keywords


start-up curve; transient thermal conductivity; thermoelastoplasticity; plane body; fir-tree root; blade

References


Oscar Tenango-Pirin, J. C. García, L. Castro-Gómez, J. A. Rodríguez, F. Sierra, O. De Santiago, J. M. Rodríguez-Lelis.Effect of the modification of the start-up sequence on the thermal stresses for a microgas turbine / International journal of rotating machinery – Volume 2016 – Article ID 5834172.

G. Nowak, A. Rusin. Lifetime deterioration of turbine components during start-ups / Operation Maintenance and Materials Issues, vol. 3, no. 1, pp. 1–10, 2004.

T.S. Kim, D.K. Lee, S.T.Ro. Analysis of thermal stress evolution in the steam drum during start-up of a heat recovery steam generator / Applied Thermal Engineering. - Vol. 20. No. 11, 2000. - PP. 977–992.

Kovalenko A.D. Osnovy termouprugosti (The foundations of thermal conductivity) / A.D. Kovalenko. – K. : Nauk. dumka, 1970. – 204 p.

Hulyar O.I. Algoritm rozvyazannya visesymetrichnyh zadach nestatzionarnoi teploprovidnosti ( An algoritm for solving the axisymmetric problem of transient heat transfer) / O.I. Hulyar, S.O. Pyskunov, Yu.V. Maksymyuk, V.P. Andriyevskyy // Opir materíalív í teoríya sporud. – 2015. – Volume 95. – pp. 64-72.

Blokh V.I. Teoriya uprugosti (Theory of elasticity) / V.I. Blokh. – Kh. : Izd. Khar'kovsk. Gos. Universiteta, 1964. – 484 p.

Zenkevich O. Metod konechnykh elementov v tekhnike (Finite element method in technique) . M., Mir, 1975.

Pyskunov S.O., Valer V.V. Postanovka zadach deformuvannya ploskih s visesymetrichnih til v umovah nestatzionarnoi teploprovidnosti (Formulation of problems of deformation of planar and axisymmetric bodies under transient thermal conditions) // Matematicheskie problem tehnicheskoy mechaniki. – 2017. Abstracts, Part 2. Dnipro, Kamyanske.

Kachanov L.M. Teoriya polzuchesti (Theory of creep) – M.: Fizmatgiz, 1960. -456 p.

Rabotnov Yu.N. Polzuchest' elementov konstruktsiy (Creep of elements of structure). – M.: Nauka, 1966. – 732 p.

Pyskunov S.O., Valer V.V. Postanovka dvovymirnich zadach deformuvannya i contynualnogo ruynuvannya v nestatzionarnomu temperaturnomu poli (Formulation of twodimensional problems of deformation and continual fracture in nonhomogenous temperature field) // Opir materíalív í teoríya sporud. – 2016. – Volume 97. – pp 194 – 205.


Refbacks

  • There are currently no refbacks.


Copyright (c) 2019 Vladyslav Valer, Sergey Pyskunov