Turbine Stator-well flow modelling

Abstract

In axial gas turbines, hot air from the main annulus path tends to be ingested into the turbine disc cavities. This leads to overheating which will reduce the disc’s life time or lead to serious damage. Often, to overcome this problem, some air is extracted from the compressor to cool the rotor discs. This also helps seal the rim seals and to protect the disc from the hot annulus gas. However, this will deteriorate the overall efficiency. A detailed knowledge of the flow interaction between the main gas path and the disc cavities is necessary in order to optimise thermal effectiveness against overall efficiency due to losses of the cooling air from the main gas path. The aim of this study is to provide better understanding of the flow in a turbine stator-well, and evaluate the use of different CFD methods for this complex, 3-dimensional unsteady flow. This study presents CFD results for a 2-stage turbine. The stator-well cavity for the second row of stationary vanes is included in the calculation and results for both turbine performance and stator-well sealing efficiency are presented.

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