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research-article

EXPERIMENTAL AND NUMERICAL INVESTIGATION OF OPTIMIZED BLADE TIP SHAPES - PART I: TURBINE RAINBOW ROTOR TESTING AND CFD METHODS

[+] Author and Article Information
Bogdan C. Cernat

von Karman Institute for Fluid Dynamics, Rhode Saint Genèse, Brussels BE-1640, Belgium
cernat@vki.ac.be

Marek Paty

von Karman Institute for Fluid Dynamics, Rhode Saint Genèse, Brussels BE-1640, Belgium
marek.paty@seznam.cz

Cis De Maesschalck

von Karman Institute for Fluid Dynamics, Rhode Saint Genèse, Brussels BE-1640, Belgium
cis.demaesschalck@gmail.com

Sergio Lavagnoli

von Karman Institute for Fluid Dynamics, Rhode Saint Genèse, Brussels BE-1640, Belgium
lavagnoli@vki.ac.be

1Corresponding author.

ASME doi:10.1115/1.4041465 History: Received August 22, 2018; Revised September 08, 2018

Abstract

The clearance between stationary and rotating parts in turbine stages generates unsteady tip leakage ?ows that reduce the engine ef?ciency and can cause thermally induced blade failures. An improved understanding of the tip ?ows is essential to re?ne the engine design strategies and increase the turbine aerothermal performance. While past studies have focused on conventional tips, the open literature suffers from a lack of data on advanced rotor tip con?gurations. This work presents a numerical and experimental investigation on the ?ow ?eld of a HP turbine adopting three different blade tips. The aerothermal characteristics of two novel high-performance tip geometries, one with a fully contoured shape and the other presenting a multi-cavity squealer tip with partially open external rims, are compared against the performance of a regular squealer geometry. The turbine stage is tested at engine-representative conditions in the high-speed turbine facility of the von Karman Institute. A rainbow rotor is mounted for simultaneous testing of multiple blade tip geometries, with the blades arranged in sectors operating at two different clearance levels. Full-stage simulations are conducted to model the secondary ?ows development and identify the tip loss and heat transfer mechanisms. In the ?rst part, we describe the experimental setup, instrumentation and data processing techniques used to measure the unsteady over-tip aerothermal ?eld. We report the time-average and time-resolved static pressure and heat transfer measured on the shroud of the turbine rotor, comparing the experimental data against CFD predictions.

Copyright (c) 2018 by ASME
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