Title: Aerodynamic character of partial squealer tip arrangements in an axial flow turbine. Part I: Detailed aerodynamic field modifications via three dimensional viscous flow simulations around baseline tip

Authors: Levent Kavurmacioglu, Debashis Dey, Cengiz Camci

Addresses: Faculty of Mechanical Engineering, Istanbul Technical University, 34437 Istanbul, Turkey. ' GE Corporate Research and Development Center, Schenectady, NY, USA. ' Department of Aerospace Engineering, Pennsylvania State University, 223 Hammond Bldg., University Park PA 16802, USA

Abstract: This paper deals with the viscous flow simulations of the complex tip leakage flow in Axial Flow Turbine Research Facility (AFTRF). Special attention is paid to the 3D structure of the tip leakage flow mechanisms in a baseline tip configuration with no desensitisation. Although past experimental studies provide much insight into the physical understanding of the tip region aerodynamics, there are still many areas of the flow-field in which experiments are extremely difficult to perform. Fine details of the entrance flow near the pressure side where the tip leakage jet starts to form, the leakage jet formation between the tip surface and outer casing, the re-circulatory flow zone very near the pressure side corner, the interaction area of the tip vortex with the conventional passage flow, the influence of the relative motion of the outer casing and leakage flow reversal can be visualised with excellent resolution. After the presentation of the measured inlet boundary conditions and a grid independency study, the baseline tip flow simulations are discussed in detail.

Keywords: tip leakage flow; computational fluid dynamics; CFD; flow visualisation; aerodynamics; squealer tip arrangements; axial flow turbines; aerodynamic field modifications; viscous flow; 3D simulation; baseline tip; leakage jet formation.

DOI: 10.1504/PCFD.2007.014959

Progress in Computational Fluid Dynamics, An International Journal, 2007 Vol.7 No.7, pp.363 - 373

Published online: 28 Aug 2007 *

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