One-Stage Power Turbine Preliminary Design and Analysis

Design and development of gas turbine components are a complex multidisciplinary process. At the beginning of the power class definition and engine configuration it is necessary to conduct a market study. The results obtained are used in gas turbine thermodynamic cycle calculations and analysis in order to define the gas turbine design point. Several possible design points are evaluated during this procedure. After this step, the gas turbine components are designed, including: compressor, combustion chamber and turbine. For industrial gas turbine purposes, it is common to use a free turbine after the gas generator, also commonly named power turbine. In this work, a power turbine was initially designed by meanline techniques, considering internal loss mechanisms, to obtain the main dimensions. The geometries of the components were generated in a 3-D environment to make possible the mesh generation, process to discretize the physical domain into a computational domain and use a 3-D Computational Fluid Dynamics tool. The results from the meanline approach and from the 3-D turbulent flow numerical simulations were compared to verify the turbine operational conditions and its predictions at design and off-design conditions. The gas turbine under study is a project, derived from a low thrust turbojet previously developed by Instituto de Aeronautica e Espaco. The power turbine project uses the same turbojet gas generator, already designed and currently under tests.