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].
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April 2019
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
Takanori Shibata,
Takanori Shibata
Research & Innovation Center,
Mitsubishi Heavy Industries, Ltd.,
2-1-1 Shinhama, Arai-cho,
Takasago 676-8686, Hyogo, Japan
e-mail: takanori_shibata@mhi.co.jp
Mitsubishi Heavy Industries, Ltd.,
2-1-1 Shinhama, Arai-cho,
Takasago 676-8686, Hyogo, Japan
e-mail: takanori_shibata@mhi.co.jp
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Hisataka Fukushima,
Hisataka Fukushima
Turbomachinery Headquarters,
Mitsubishi Hitachi Power Systems, Ltd.,
Takasago 676-8686, Hyogo, Japan
e-mail: hisataka_fukushima@mhps.com
Mitsubishi Hitachi Power Systems, Ltd.,
2-1-1 Shinhama, Arai-cho
,Takasago 676-8686, Hyogo, Japan
e-mail: hisataka_fukushima@mhps.com
Search for other works by this author on:
Kiyoshi Segewa
Kiyoshi Segewa
Turbomachinery Headquarters,
Mitsubishi Hitachi Power Systems, Ltd.,
Ibaraki 317-8585, Japan
e-mail: kiyoshi_segawa@mhps.com
Mitsubishi Hitachi Power Systems, Ltd.,
3-1-1 Saiwai-cho, Hitachi
,Ibaraki 317-8585, Japan
e-mail: kiyoshi_segawa@mhps.com
Search for other works by this author on:
Takanori Shibata
Research & Innovation Center,
Mitsubishi Heavy Industries, Ltd.,
2-1-1 Shinhama, Arai-cho,
Takasago 676-8686, Hyogo, Japan
e-mail: takanori_shibata@mhi.co.jp
Mitsubishi Heavy Industries, Ltd.,
2-1-1 Shinhama, Arai-cho,
Takasago 676-8686, Hyogo, Japan
e-mail: takanori_shibata@mhi.co.jp
Hisataka Fukushima
Turbomachinery Headquarters,
Mitsubishi Hitachi Power Systems, Ltd.,
Takasago 676-8686, Hyogo, Japan
e-mail: hisataka_fukushima@mhps.com
Mitsubishi Hitachi Power Systems, Ltd.,
2-1-1 Shinhama, Arai-cho
,Takasago 676-8686, Hyogo, Japan
e-mail: hisataka_fukushima@mhps.com
Kiyoshi Segewa
Turbomachinery Headquarters,
Mitsubishi Hitachi Power Systems, Ltd.,
Ibaraki 317-8585, Japan
e-mail: kiyoshi_segawa@mhps.com
Mitsubishi Hitachi Power Systems, Ltd.,
3-1-1 Saiwai-cho, Hitachi
,Ibaraki 317-8585, Japan
e-mail: kiyoshi_segawa@mhps.com
1Corresponding author.
Manuscript received August 24, 2018; final manuscript received September 10, 2018; published online November 1, 2018. Editor: Jerzy T. Sawicki.
J. Eng. Gas Turbines Power. Apr 2019, 141(4): 041002 (9 pages)
Published Online: November 1, 2018
Article history
Received:
August 24, 2018
Revised:
September 10, 2018
Citation
Shibata, T., Fukushima, H., and Segewa, K. (November 1, 2018). "Improvement of Steam Turbine Stage Efficiency by Controlling Rotor Shroud Leakage Flows—Part I: Design Concept and Typical Performance of a Swirl Breaker." ASME. J. Eng. Gas Turbines Power. April 2019; 141(4): 041002. https://doi.org/10.1115/1.4041650
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