Indexing Effect

Jan Krysinski

Institute of Turbomachinery, Technical University of Lodz krysinski@p. lodz. pl

Robert Blaszczak Jaroslaw

Institute of Turbomachinery, Technical University of Lodz blaszczk@p. lodz. pl

Antoni Smolny

Institute of Turbomachinery, Technical University of Lodz asmo1948@p. lodz. pl

Abstract The results of the stator-to-stator clocking effect in a two-stage low-pressure tur­bine are presented. The main goal is focused on a detailed investigation of the shape and its position of the stator wake after the first stage and the correlation between different parameters including acoustic signal levels. The numerical calculations confirmed the image of the flaw field obtained during the measure­ments.

Keywords: axial turbine, clocking effect, measurements, flow field, acoustics

1. Introduction

In order to improve performance and prediction methods accuracy for mul­tistage axial turbomachines, understanding of the unsteady fhw is essential. A number of experimental and numerical studies have been carried out in recent years to investigate these fhw phenomena [e. g. Arnone et al. 2000, 2002; Dorney et al. 1999, Eulitz 2000; Haldeman et al., 2003; He et al. 2002, Howel et al. 2001, Huber 1996, Hummel 2002; Jouini et al. 2003; Reinmoeller et al.


K. C. Hall et al. (eds.),

Unsteady Aerodynamics, Aeroacoustics and Aeroelasticity of Turbomachines, 615-626. © 2006 Springer. Printed in the Netherlands.

2002, Saren et al. 2002]. The experimental work presented herein is the con­tinuation of our earlier studies, starting from mid-nineties [e. g. Krysinski et al. 1995 – 2002; Smolny, Blaszczak 1997] and it is still in progress at the Insti­tute of Turbomachinery (Technical University of Lodz, Poland). The objective of the present test program is to experimentally investigate vane-indexing ef­fects (so called also the clocking effects) on the performance of the two-stage low-pressure turbine test rig. Special clocking mechanisms were designed to allow the first stage vanes to be moved circumferentially relative to the second stage vanes independently of the casing. This allows changing the clocking positions of the first and the second stator vanes during the tests without stop­ping the turbine and dismantling it. Herein, some unsteady fbw measurement results, wall pressure above the rotor blades and the external characteristics for different circumferential positions of the stator vanes are described.

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