Numerical investigation of steam turbine exhaust diffuser flows and their three dimensional interaction effects on last stage efficiencies

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 present the methodology for high accurate aerodynamic numerical analysis and its design application of steam turbine down-flow type exhaust diffusers including their three dimensional flow interaction effects on last stage efficiencies. Down-flow type exhaust diffusers are used in large scale steam turbines from 200MW to 1400MW class units for power generation plants mainly. The axial length of typical 1000MW class large scale steam turbines is about 30-40m and its four low pressure (LP) down-flow type exhaust diffusers occupy a large amount of space. The axial lengths and diameters of these exhaust diffusers contribute significantly to the size, weight, cost, and efficiency of the turbine system. The aerodynamic loss of exhaust hoods is nearly the same as that of stator and rotor blading in LP steam turbines, and there remains scope for further enhancement of steam turbine efficiency by improving the design of LP exhaust hoods. In the design process of last stages, the average static pressure in the last stage exit is introduced accurately using numerical analysis and experimental data of model steam turbines and model diffusers. However the radial and circumferential unsteady aerodynamic interaction effects between last stages and their exhaust diffusers are still need to be investigated to increase the accuracy of the interaction effect on the last stage efficiencies. This paper presents numerical investigation of three dimensional wet steam flows including three dimensional flow interaction effects on last stage efficiencies 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.

Original languageEnglish
Title of host publicationMarine; Microturbines, Turbochargers and Small Turbomachines; Steam Turbines
PublisherAmerican Society of Mechanical Engineers (ASME)
ISBN (Electronic)9780791845585
DOIs
Publication statusPublished - 2014 Jan 1
EventASME Turbo Expo 2014: Turbine Technical Conference and Exposition, GT 2014 - Dusseldorf, Germany
Duration: 2014 Jun 162014 Jun 20

Publication series

NameProceedings of the ASME Turbo Expo
Volume1B

Other

OtherASME Turbo Expo 2014: Turbine Technical Conference and Exposition, GT 2014
CountryGermany
CityDusseldorf
Period14/6/1614/6/20

ASJC Scopus subject areas

  • Engineering(all)

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