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Loss reduction in a 1.5 stage axial turbine by computer-driven stator hub contouring

journal contribution
posted on 2020-03-30, 10:34 authored by H Obaida, A Rona, J Gostelow
Improvements in stage isentropic efficiency and reductions in total pressure loss are sought in a 1.5 stage axial turbine. This is representative of power generation equipment used in thermal power cycles, which deliver about 80% of the 20 trillion kWh world-wide electricity. Component-level improvements are therefore timely and important towards achieving carbon dioxide global emission targets. Secondary flow loss reduction is sought by applying a non-axisymmetric endwall design to the turbine stator hub. A guide groove directs the pressure side branch of the horseshoe vortex away from the airfoil suction side, using a parametric endwall hub surface, which is defined as to obtain first-order smooth boundary connections to the remainder of the passage geometry. This delays the onset of the passage vortex and reduces its associated loss. The Automatic Process and Optimization Workbench (APOW) generates a Kriging surrogate model from a set of Reynolds Averaged Navier-Stokes (RANS) simulations, which is used to optimize the hub surface. The three-dimensional steady RANS model with an axisymmetric hub is validated against reference experimental measurements from Rheinisch-Westfälische Technische Hochschule Aachen. Comparative computational fluid dynamics predictions with an optimized non-axisymmetric hub show a decrease in the total pressure loss coefficient and an increase in the isentropic stage efficiency at and off design conditions.

Funding

On-going research on endwall contouring is undertaken under the auspices of the GE Power –University of Leicester framework agreement. Advice from Dr. N. Z. Ince and colleagues from the Methodologies for Tools group, GE Power, is gratefully acknowledged. Obaida’sPhD in Engineeringat the University of Leicester wassupported by the Ministry of Higher Education and Scientific Research of Iraq, award number S1632. The authors wish to acknowledge the insightful guidance on OpenFOAMby Prof. Hrvoje Jasak, Wikki. This research used the ALICE2 high performance computing facility at the University of Leicester. Graphical rendering software licenses were originally acquired with EPSRC support on Grant GR/N23745/01. The supply of experimental data for the 1.5 stage axial flow turbine “Aachen Turbine” under license by RWTH Aachen is gratefully acknowledged

History

Citation

Obaida, H. M. B., Rona, A., and Gostelow, J. P. (January 29, 2019). "Loss Reduction in a 1.5 Stage Axial Turbine by Computer-Driven Stator Hub Contouring." ASME. J. Turbomach. June 2019; 141(6): 061009. https://doi.org/10.1115/1.4042305

Author affiliation

/Organisation/COLLEGE OF SCIENCE AND ENGINEERING/Department of Engineering

Version

  • AM (Accepted Manuscript)

Published in

Journal of Turbomachinery

Volume

141

Issue

6

Pagination

061009

Publisher

American Society of Mechanical Engineers

issn

0889-504X

Acceptance date

2018-12-11

Copyright date

2019

Available date

2019-01-29

Publisher version

https://asmedigitalcollection.asme.org/turbomachinery/article-abstract/141/6/061009/368663

Editors

Hall, K

Language

en

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