Naslov
Modelling of Non-Stationary Temperature Stresses in Steam Turbine Casings

Autori
Guzović, Zvonimir ; Matijašević, Branimir ; Tuković, Željko

Vrsta, podvrsta i kategorija rada
Radovi u zbornicima skupova, cjeloviti rad (in extenso), znanstveni

Izvornik
CD Proceedings of The Dubrovnik Conference on Sustainable Development of Energy, Water and Environment Systems / Duić, Neven - Zagreb : Energetika marketing, 2002, 1-13

Skup
Dubrovnik Conference on Sustainable Development of Energy, Water and Environment Systems

Mjesto i datum
Dubrovnik, Hrvatska, 02.06.2002. - 07.06.2002

Vrsta sudjelovanja
Predavanje

Vrsta recenzije
Međunarodna recenzija

Ključne riječi
numerical modelling; non-stationary temperature stresses; steam turbine casings

Sažetak
All the more extensive usage of steam turbines for ensuring variable part of electric load is characterised by requirements for high manoeuvrability of operation (rapid starting, stopping and change of power). In these conditions both at elaborating new designs of steam turbines and in their operation, the additional attention is dedicated to thermally most loaded thick-walled parts, as steam turbine casings, stop and governing valves of high pressure, in which the intense space and time dependent temperature gradients cause high non-stationary temperature stresses. Therefore at the design of new steam turbines are solved different problems, which relate to casings, e.g. the stator design optimization in order to realize uniform temperature field and restrict thermal stresses with regard to the axes of the casings, the turbine casings fastening to the foundation frame and the related axial and radial clearances in turbines determination, etc. Also, the safe work of steam turbines of large power is not possible without the usage of different expert systems for on-line control (e.g. for the estimation of strength margin and the remaining useful life of parts). Solving of provisorily mentioned problems demands knowledge about temperature stresses state in steam turbine casings, separately about non-stationary temperature stresses. In the present time non-stationary temperature stresses (clearly as well as the state of total stresses) are efficiently calculated by modelling by means of the user software programs (of software packages), which are based on numerical methods. The paper presents the procedure and the results of non-stationary temperature stresses modelling in steam turbine casing by means of the user software package. Also for modelling of temperature stresses (i.e. of temperature fields and deformations) along with the mechanical boundary conditions it is necessary to known thermal boundary conditions &#8211 ; the convective heat transfer coefficients. Because the calculation accuracy of the temperature stresses (i.e. of the temperature fields) strongly depends on the validity applied thermal boundary conditions, the special attention is dedicated to defining and determination of the convective heat transfer coefficients on surfaces of different spaces inside the turbine casings (e.g. in inlet casings, in exhaust casings, in spaces betwenn external and internal casings, in channels of system for preheating of flange joint, in spaces of steam extractions and cross-over pipelines, in spaces inside valves). Also, in the paper are presented the original generalized statistical correlations for determining of the convective heat transfer coefficients on provisorily mentioned locations. These correlations were just used at calculations which results are shown in the paper.

Izvorni jezik
Engleski

Znanstvena područja
Strojarstvo

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