Research Papers

Aerothermal Optimization of Fully Cooled Turbine Blade Tips

[+] Author and Article Information
Valeria Andreoli

Zucrow Laboratories,
Purdue University,
West Lafayette, IN 47907
e-mail: vale.andreoli@gmail.com

James Braun

Zucrow Laboratories,
Purdue University,
West Lafayette, IN 47907
e-mail: jamesbraun91@gmail.com

Guillermo Paniagua

Zucrow Laboratories,
Purdue University,
West Lafayette, IN 47907
e-mail: gpaniagua@me.com

Cis De Maesschalck

Rolls-Royce plc,
Derby DE24 8BJ, UK
e-mail: cis.demaesschalck@gmail.com

Matthew Bloxham

Rolls-Royce Corporation,
Indianapolis, IN 46225
e-mail: Matthew.Bloxham@rolls-royce.com

William Cummings

Rolls-Royce Corporation,
Indianapolis, IN 46225
e-mail: william.cummings2@rolls-royce.com

Lawrence Langford

Rolls-Royce Corporation,
Indianapolis, IN 46225
e-mail: lawrence.langford@rolls-royce.com

1Corresponding author.

Contributed by the International Gas Turbine Institute (IGTI) of ASME for publication in the JOURNAL OF TURBOMACHINERY. Manuscript received October 21, 2018; final manuscript received November 7, 2018; published online January 21, 2019. Editor: Kenneth Hall.

J. Turbomach 141(6), 061007 (Jan 21, 2019) (10 pages) Paper No: TURBO-18-1299; doi: 10.1115/1.4041961 History: Received October 21, 2018; Revised November 07, 2018

Optimal turbine blade tip designs have the potential to enhance aerodynamic performance while reducing the thermal loads on one of the most vulnerable parts of the gas turbine. This paper describes a novel strategy to perform a multi-objective optimization of the tip geometry of a cooled turbine blade. The parameterization strategy generates arbitrary rim shapes around the coolant holes on the blade tip. The tip geometry performance is assessed using steady Reynolds-averaged Navier–Stokes simulations with the k–ω shear stress transport (SST) model for the turbulence closure. The fluid domain is discretized with hexahedral elements, and the entire optimization is performed using identical mesh characteristics in all simulations. This is done to ensure an adequate comparison among all investigated designs. Isothermal walls were imposed at engine-representative levels to compute the convective heat flux for each case. The optimization objectives were a reduction in heat load and an increase in turbine row efficiency. The multi-objective optimization is performed using a differential evolution strategy. Improvements were achieved in both the aerodynamic efficiency and heat load reduction, relative to a conventional squealer tip arrangement. Furthermore, this work demonstrates that the inclusion of over-tip coolant flows impacts the over-tip flow field, and that the rim–coolant interaction can be used to create a synergistic performance enhancement.

Copyright © 2019 by ASME
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Rotor mesh strategy

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Fig. 4

Rim parameterization

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Fig. 5

Fluid domain creation

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Fig. 7

Validation of the Nusselt number on the overtip casing [12]

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Fig. 8

Postprocessing details

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Fig. 10

Pareto front evolution

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Fig. 11

Results of optimization—geometry details

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Fig. 12

Details of turbine aerodynamics

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Fig. 13

Contours of relative total pressure 50% cax downstream of trailing edge

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Fig. 14

Radial distributions of relative total pressure of the baseline (black lines), optimal efficiency (red lines), and optimal heat flux (blue lines) tip geometries

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Fig. 15

Tip leakage characteristics

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Fig. 16

Details of rotor heat flux

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Fig. 17

Effect of tip coolant on blade top heat transfer

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Fig. 18

Tip clearance sensitivities to turbine efficiency for the baseline, optimal efficiency, and optimal heat flux

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Fig. 19

Tip clearance sensitivity to tip heat flux for the baseline, optimal efficiency, and optimal heat flux



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