The Efficiency Increase of the Steam Turbine Low Pressure Cylinder Last Stage by the Blades Spatial Profiling

Journal Journal of Mechanical Engineering – Problemy Mashynobuduvannia
Publisher A. Podgorny Institute for Mechanical Engineering Problems
National Academy of Science of Ukraine
ISSN 0131-2928 (Print), 2411-0779 (Online)
Issue Vol. 23, no. 1, 2020 (March)
Pages 6-14
Cited by J. of Mech. Eng., 2020, vol. 23, no. 1, pp. 6-14



Andrii V. Rusanov, A. Podgorny Institute of Mechanical Engineering Problems of NASU (2/10, Pozharskyi St., Kharkiv, 61046, Ukraine), e-mail:, ORCID: 000-0003-1345-7010

Viktor L. Shvetsov, Joint-Stock Company Turboatom (199, Moskovskyi Ave., Kharkiv, 61037, Ukraine), e-mail: ORCID: 0000-0002-2384-1780

Svitlana V. Alyokhina, A. Podgorny Institute of Mechanical Engineering Problems of NASU (2/10, Pozharskyi St., Kharkiv, 61046, Ukraine), V. N. Karazin Kharkiv National University, (4, Svobody Sq., Kharkiv, 61022, Ukraine), e-mail:, ORCID: 0000-0002-2967-0150

Natalia V. Pashchenko, A. Podgorny Institute of Mechanical Engineering Problems of NASU, (2/10, Pozharskyi St., Kharkiv, 61046, Ukraine), e-mail:, ORCID: 0000-0002-3936-7331

Roman A. Rusanov, A. Podgorny Institute of Mechanical Engineering Problems of NASU (2/10, Pozharskyi St., Kharkiv, 61046, Ukraine), e-mail:, ORCID: 0000-0003-2930-2574

Mykhailo H. Ishchenko, Joint-Stock Company Turboatom (199, Moskovskyi Ave., Kharkiv, 61037, Ukraine), e-mail:, ORCID: 0000-0003-2251-5104

Liubov O. Slaston, Joint-Stock Company Turboatom (199, Moskovskyi Ave., Kharkiv, 61037, Ukraine), e-mail:, ORCID: 0000-0002-9268-8134

Riza B. Sherfedinov, Joint-Stock Company Turboatom (199, Moskovskyi Ave., Kharkiv, 61037, Ukraine), e-mail:, ORCID: 0000-0002-5947-7802



The paper presents an option of the steam condensing turbine K-325-23.5 (K-300 series) low pressure cylinder flow part improvement due to the last stage modernization. The K-325-23.5 turbine is designed to replace the outdated K-300 series turbines, which together with the K-200 series turbines form the basis of Ukraine’s thermal energy. In the modernized flow part, new last stage guide apparatus blades with a complex circular lean near the hub are used. The purpose of the modernization was to increase the low-pressure cylinder efficiency in the “bad” condenser vacuum to ensure that it did not “decrease” its efficiency at rated operating modes. The modernized low-pressure cylinder flow part is developed with the usage of modern methods of the viscous three-dimensional flow calculation based on the numerical integration of the Reynolds-averaged Navier-Stoks equations. For the turbulent effects, a two-parameter differential SST Menter turbulence model is applied, and for the hydraulic fluid real properties, the IAPWS-95 state equation is used. To construct the axial blades three-dimensional geometry, the original method, the initial data for which was the limited number of parameterized quantities, was used. The applied methods of gas-dynamic calculations and design of flow turbomachines are implemented in the IPMFlow software package, which is the development of the FlowER and FlowER-U software packages. The researched low-pressure cylinder flow part is limited by the last two stages (4th and 5th). A difference grid with a total element volume of more than 3 million is used to construct the calculation area. The research examined more than 20 options of the last stage stator blades. In the modernized flow part of the low-pressure cylinder last stage at rated operating mode, the gain of the efficiency coefficient (efficiency) is 0.9% and power – 0.61 MW. In the mode of “bad” condenser vacuum (with high pressure) a significant increase is achieved: efficiency – by 11.5%, power increased by almost 2 MW.


Keywords: spatial profiling, numerical modeling, spatial flow, gas-dynamic efficiency, steam turbine, last stage.


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Received 24 February 2020

Published 30 March 2020