CFD Application in Design of GT Structural Components

Currently CFD is extensively used in turbine and compressor blading design and analysis with numerous examples of CFD applications to be found in literature. At the same time, there are no reports about CFD simulation of secondary flows inside the turbomachine (e.g. cooling air transit, purge, etc). One probable reason is that the amount of air/gas involved in these flows is typically too small to have a direct impact on the engine performance. However, these secondary flows have a big impact on the heat transfer in cavities between structural components, and as a result have an impact on the thermal state, life of structural components, and clearances in the main flowpath. Therefore, the proper prediction of the flow between structural components is also an important part of the design procedure. In spite of the recent progress in computational hardware and software development, CFD simulation of flow between structural components remains still a challenging task due to very complex geometries, 3D turbulent flow structure with separations, reattachments and vortices. In addition to this, to be applied in design practice, the CFD code should satisfy certain important requirements, for instance the ability to automate the calculations in order to execute the analysis within a reasonable time and cost. Only recently has it become possible to satisfy this requirement, and now CFD starts to penetrate into design practices. This paper presents the experience accumulated within ALSTOM during the last few years in CFD simulation of flow between different structural components using commercial and in-house software. The following issues are presented: • Validation of numerical models; • Automation of numerical calculation; • Application examples (the flow in different cavities between casings and in rotor cavity).Copyright © 2005 by ASME