Aerodynamic interaction effects from upstream and downstream on the down-flow type exhaust diffuser performance in a low pressure steam turbine

Tadashi Tanuma, Yasuhiro Sasao, Satoru Yamamoto, Yoshiki Niizeki, Naoki Shibukawa, Hiroshi Saeki

Research output: Chapter in Book/Report/Conference proceedingConference contribution

11 Citations (Scopus)

Abstract

The purpose of this paper is to explain aerodynamic interaction effects from upstream and downstream on the down-flow type exhaust diffuser performance in a low pressure steam turbine. To increase exhaust diffuser performance, design data related to the aerodynamic interaction effects from upstream turbine stages and downstream exhaust hood geometry on the exhaust diffuser performance would be very useful. This paper presents numerical investigation of three dimensional wet steam flows in a down-flow type exhaust diffuser with non-uniform inlet flow from a typical last stage with long transonic blades designed with recent aerodynamic and mechanical design technology. Previous studies show that small scale model tests and CFD analyses of exhaust diffusers with uniform inlet flow conditions are not enough to investigate diffuser efficiency and detail diffuser flow mechanism because inlet flow structures including tip leakage flows and blade wakes superimposed from a last stage and several other upstream turbine stages in low pressure turbines affect flow separations that reduce the exhaust diffuser performance. Recent studies by the authors show that the introduction of radial distributions of velocities and flow angles at the inlet section of exhaust diffuser measured in a full scale development steam turbine increased the accuracy of numerical analysis of diffuser flow. In the present study, the computational domain was enhanced and the method of boundary condition definition was improved to increase the accuracy of boundary layer separation and separation vortex generation in wet steam flows. Using the improved method, the calculation results explained the aerodynamic interaction effects from upstream and downstream on the down-flow type exhaust diffuser performance.

Original languageEnglish
Title of host publicationASME Turbo Expo 2013
Subtitle of host publicationTurbine Technical Conference and Exposition, GT 2013
DOIs
Publication statusPublished - 2013 Dec 17
EventASME Turbo Expo 2013: Turbine Technical Conference and Exposition, GT 2013 - San Antonio, Tx, United States
Duration: 2013 Jun 32013 Jun 7

Publication series

NameProceedings of the ASME Turbo Expo
Volume5 B

Other

OtherASME Turbo Expo 2013: Turbine Technical Conference and Exposition, GT 2013
CountryUnited States
CitySan Antonio, Tx
Period13/6/313/6/7

ASJC Scopus subject areas

  • Engineering(all)

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