0
research-article

Improvement of Steam Turbine Stage efficiency by Controlling Rotor Shroud Leakage Flows: Part I ? Design Concept and Typical Performance of a Swirl Breaker

[+] Author and Article Information
Takanori Shibata

Research & Innovation Center, Mitsubishi Heavy Industries, Ltd., 2-1-1 Shinhama, Arai-cho, Takasago, Hyogo, 676-8686, Japan
takanori_shibata@mhi.co.jp

Hisataka Fukushima

Turbomachinery Headquarters, Mitsubishi Hitachi Power Systems, Ltd., 2-1-1 Shinhama, Arai-cho, Takasago, Hyogo, 676-8686, Japan
hisataka_fukushima@mhps.com

Kiyoshi Segawa

Turbomachinery Headquarters, Mitsubishi Hitachi Power Systems, Ltd., 3-1-1 Saiwai-cho, Hitachi, Ibaraki, 317-8585, Japan
kiyoshi_segawa@mhps.com

1Corresponding author.

ASME doi:10.1115/1.4041650 History: Received August 24, 2018; Revised September 10, 2018

Abstract

In high and intermediate pressure (HIP) steam turbines with shrouded blades, it is well known that shroud leakage losses contribute significantly to overall losses. Shroud leakage flow with a large tangential velocity creates a significant aerodynamic loss due to mixing with the mainstream flow. In order to reduce this mixing loss, two distinct ideas for rotor shroud exit cavity geometries were investigated using computational fluid dynamics (CFD) analyses and experimental tests. One idea was an axial fin placed from the shroud downstream casing to reduce the axial cavity gap, and the other was a swirl breaker placed in the rotor shroud exit cavity to reduce the tangential velocity of the leakage flow. In addition to the conventional cavity geometry, three types of shroud exit cavity geometries were designed, manufactured and tested using a 1.5-stage air model turbine with medium aspect ratio blading. Test results showed that the axial fin and the swirl breaker raised turbine stage efficiency by 0.2% and 0.7%, respectively. The proposed swirl breaker was judged to be an effective way to achieve highly efficient steam turbines because it not only reduces the mixing losses but also improves the incidence angle distribution onto the downstream blade row. This study is presented in two papers. The basic design concept and typical performance of the proposed swirl breaker are presented in this Part I, and the effect of axial distance between a swirl breaker and rotor shroud on efficiency improvement is discussed in Part II [8].

Copyright (c) 2018 by ASME
Your Session has timed out. Please sign back in to continue.

References

Figures

Tables

Errata

Some tools below are only available to our subscribers or users with an online account.

Related Content

Customize your page view by dragging and repositioning the boxes below.

Related Journal Articles
Related eBook Content
Topic Collections

Sorry! You do not have access to this content. For assistance or to subscribe, please contact us:

  • TELEPHONE: 1-800-843-2763 (Toll-free in the USA)
  • EMAIL: asmedigitalcollection@asme.org
Sign In