Conceptual design tool for radial turbines

Abstract

The aim of this thesis is to develop a method to automate the set up process of a CFD simulation and study the flow of a generic fluid radial turbine design. This method could then be used to verify the coherence between an in-house mean line design performance code and 3D CFD simulations in a robust and simple way. The method can be used as a conceptual design tool for radial turbines and supports most fluids included in the refpropTM software database. To show the capability of the method developed, without going into full analysis with mesh dependent study and as high quality mesh as possible, a comparison is made between the performance code and the 3D CFD simulations. The turbine analysis is carried out using the methods of Computational Fluid Dynamics (CFD) and Finite Element Analysis (FEA) for structural analysis. Two methods have been developed for the simulations: one rapid Single Blade Passage (SBP) model as well as a more detailed Full Turbine (FT) model. The macro based methodology described in the report has proven to reduce the set up time for the simulation of the radial turbine extracted from the performance code. Two cases are used for comparison between the performance code and the 3D CFD simulations. The first one is based on an experimental report from NASA, a cold performance evaluation of a 6.02 inch radial inflow turbine with Argon fluid. The efficiency given in the report is similar to the result from the performance code and the CFD simulation. The other case is an Organic Rankine Cycle (ORC) turbine with refrigerant R143a as a working fluid. The efficiency in the CFD simulations is slightly lower than the performance code possibly due to partly choked flow. Both test cases show similar behaviour with respect to flow separation and highlight possible improvements in the performance code. A number of programs from ANSYSTM are used to carry out the thesis work. The programs are DesignModelerTM and ICEM CFDTM for CAD modeling, TurboGridTM and ICEM CFDTM for meshing, CFXTM is used as the CFD solver and MechanicalTM for structural analysis.