0

Full Content is available to subscribers

Subscribe/Learn More  >

Design and Performance Assessments of a Partial Admission Axial Turbine Using Supercritical Carbon Dioxide

[+] Author Affiliations
Young-Seok Kang, Jae-Sung Huh

Korea Aerospace Research Institute, Daejeon, Republic of Korea

Junhyun Cho, Hyungki Shin, Young-Jin Baik

Korea Institute of Energy Research, Daejeon, Republic of Korea

Paper No. FEDSM2016-7734, pp. V01AT09A010; 8 pages
doi:10.1115/FEDSM2016-7734
From:
  • ASME 2016 Fluids Engineering Division Summer Meeting collocated with the ASME 2016 Heat Transfer Summer Conference and the ASME 2016 14th International Conference on Nanochannels, Microchannels, and Minichannels
  • Volume 1A, Symposia: Turbomachinery Flow Simulation and Optimization; Applications in CFD; Bio-Inspired and Bio-Medical Fluid Mechanics; CFD Verification and Validation; Development and Applications of Immersed Boundary Methods; DNS, LES and Hybrid RANS/LES Methods; Fluid Machinery; Fluid-Structure Interaction and Flow-Induced Noise in Industrial Applications; Flow Applications in Aerospace; Active Fluid Dynamics and Flow Control — Theory, Experiments and Implementation
  • Washington, DC, USA, July 10–14, 2016
  • Conference Sponsors: Fluids Engineering Division
  • ISBN: 978-0-7918-5028-2
  • Copyright © 2016 by ASME

abstract

Power density of a super-critical carbon dioxide cycle is very high due to its fluid-like density. For this reason, generally size of turbines are very compact compared to that of the air Brayton cycle. However, such an advantage sometimes becomes a challenge for aerodynamic design, because low volume flow rate of the turbine requires design point at a very low specific speed. One of the solution for the challenge is to design a turbine stage as a partial admission stage in which flow enters the turbine nozzle over only a portion of its annulus. Then it secures a sufficient turbine inlet area, even though performance degradation should be taken in to account.

In this study, aerodynamic design of an axial turbine has been carried out and its performance has been assessed with numerical simulations. One of design requirements for the axial turbine was to minimize rotor inlet and outlet pressure difference to avoid potential axial thrust. In spite of a small amount of expansion ratio in the turbine stage, the absolute pressure difference could cause severe damage to rotor dynamic system and require complicated bearing system. For this reason, in this study, the turbine was designed as impulse type axial turbine with partial admission.

Required rotating speed and resultant low volume flow rate restricted mean diameter and blade height at the stage inlet. The final design has a very low aspect ratio, less than unity. The number of nozzle and rotor are 12 and 34, respectively. The rotating speed of the rotor is 45,000 rpm. The ratio of nozzle arc to blade pitch is approximately 3, which determines efficiency deterioration due to the partial admission.

During the numerical simulations, to implement real gas property, Redlich-Kwong-Aungier cubic equation was used. As the turbine operating point is far from its critical point, the Redlich-Kwong-Aungier cubic equation showed a good agreement with real supercritical gas property.

To assess full and partial admission turbine performance, steady state numerical simulations have been performed. The full annulus CFD domain was constructed for the partial admission stage. At the design condition, there was 15% isentropic efficiency drop in case of the partial admission stage relative to the full admission stage. Also similar amount of power output penalty was investigated from the partial admission case. As the nozzle was choked at the design condition, the mass flow rate was conserved regardless of the admission type. Then in the flowing region, design velocity triangle in front of the rotor well established, while additional loss was generated along the circumferential direction over non flowing region.

Copyright © 2016 by ASME

Figures

Tables

Interactive Graphics

Video

Country-Specific Mortality and Growth Failure in Infancy and Yound Children and Association With Material Stature

Use interactive graphics and maps to view and sort country-specific infant and early dhildhood mortality and growth failure data and their association with maternal

NOTE:
Citing articles are presented as examples only. In non-demo SCM6 implementation, integration with CrossRef’s "Cited By" API will populate this tab (http://www.crossref.org/citedby.html).

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 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