In this paper, the effects of axial gap distance between the first stage stator and rotor blades and multiblocking on aerodynamics and performance of partial admission turbines are analyzed numerically. The selected test case is a two stage axial steam turbine with low reaction blades operating with compressed air. The multiblocking effect is studied by blocking the inlet annulus of the turbine in a single arc and in two opposing blocked arcs, each having the same admission degree. The effect of axial gap distance between the first stage stator and rotor blades is studied while varying the axial gap by 20% compared with the design gap distance. Finally, full admission turbine is modeled numerically for comparison. Performance of various computational cases showed that the first stage efficiency of the two stage partial admission turbine with double blockage was better than that of the single blockage turbine; however, the extra mixing losses of the double blockage turbine caused the efficiency to deteriorate in the downstream stage. It was shown that the two stage partial admission turbine with smaller axial gap than the design value had better efficiency of the first stage due to lower main flow and leakage flow interactions; however, the efficiency at the second stage decreased faster compared with the other cases. Numerical computations showed that the parameters, which increased the axial force of the first stage rotor wheel for the partial admission turbine, were longer blocked arc, single blocked arc, and reduced axial gap distance between the first stage stator and rotor blades.
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July 2011
Research Papers
Effects of Multiblocking and Axial Gap Distance on Performance of Partial Admission Turbines: A Numerical Analysis
Narmin Baagherzadeh Hushmandi,
Narmin Baagherzadeh Hushmandi
Department of Energy Technology,
Royal Institute of Technology (KTH)
, SE 100 44, Stockholm, Sweden
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Torsten H. Fransson
Torsten H. Fransson
Department of Energy Technology,
Royal Institute of Technology (KTH)
, SE 100 44, Stockholm, Sweden
Search for other works by this author on:
Narmin Baagherzadeh Hushmandi
Department of Energy Technology,
Royal Institute of Technology (KTH)
, SE 100 44, Stockholm, Sweden
Torsten H. Fransson
Department of Energy Technology,
Royal Institute of Technology (KTH)
, SE 100 44, Stockholm, SwedenJ. Turbomach. Jul 2011, 133(3): 031028 (9 pages)
Published Online: February 28, 2011
Article history
Received:
October 26, 2009
Revised:
June 3, 2010
Online:
February 28, 2011
Published:
February 28, 2011
Citation
Hushmandi, N. B., and Fransson, T. H. (February 28, 2011). "Effects of Multiblocking and Axial Gap Distance on Performance of Partial Admission Turbines: A Numerical Analysis." ASME. J. Turbomach. July 2011; 133(3): 031028. https://doi.org/10.1115/1.4002415
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