NDLI: Effect of Common Blade Tip Squealer Designs in Terms of Tip Clearance Loss Control

Content Provider	The American Society of Mechanical Engineers (ASME) Digital Collection
Author	Lomakin, N. Granovskiy, A. Belkanov, V. Szwedowicz, J.
Copyright Year	2013
Abstract	The increase of new gas turbine’s efficiency is connected with further rise of turbine inlet temperature and sometimes as well pressure. In these conditions, first cooled turbine stages of a gas turbine engine usually consist of freestanding airfoils, which do not use an integrated shroud, to avoid risk of shroud overheating. In order to better control the radial gap leakage flow between the rotating blade tip and turbine casing, special design features of the airfoil tip need to be considered in the design process to meet the best possible stage performance. In the general engineering practice, a blade tip squealer provides opportunities to control tip clearance loss. In this paper several simplified types of the tip squealer design are investigated to determine the most effective loss control. At this stage of the investigation, blade tip cooling was not taken into account, but aerodynamic effects were analysed in detail. Based on the most common designs of the blade tip in the literature, four geometry types were investigated: (i) a flat tip design as the reference baseline solution, (ii) full tip squealer, (iii) partial squealer along the pressure side (PS) wall with a cut-out at the pressure side near the trailing edge (TE) and (iv) partial squealer along the suction side (SS) wall with a cut-out at the suction side near TE. All these cases have been compared among each other for two relative radial gaps (gap to blade height) of 0.6% and 1.36%. The flow calculations were done with a full 3D Navier-Stokes CFD code. For the flat tip and for full squealer designs, numerical results were validated against well-known experimental data measured on the GE-E3 blade cascade test rig found in the open literature. By using the 3D numerical data, the special attention was considered to confirm reliability and predictive credibility of the blade tip flow obtained from the analytical model. The obtained loss values and flow details were compared for all studied cases, providing insight into turbine stage aerodynamics with respect to minimal and maximal radial clearance.
Sponsorship	International Gas Turbine Institute
File Format	PDF
ISBN	9780791856079
DOI	10.1115/TBTS2013-2040
Conference Proceedings	ASME 2013 Turbine Blade Tip Symposium
Language	English
Publisher Date	2013-09-30
Publisher Place	Hamburg, Germany
Access Restriction	Subscribed
Subject Keyword	Suction Temperature Cooling Blades Computational fluid dynamics Cascades (fluid dynamics) Rotating blades Clearances (engineering) Airfoils Aerodynamics Risk Flow (dynamics) Pressure Design Geometry Gas turbines Leakage flows Reliability Turbines
Content Type	Text
Resource Type	Article

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