Development of CFD Capability for the Optimisation of Radial-inflow Turbine Geometry

Geothermal power generation is a promising technology for the supply of baseload power in Australia, due to the existence of a vast and exploitable hot rock resource. The application of geothermal power can be achieved through the use of an Engineered Geothermal System, and aspects of this technology are currently under development at the Queensland Geothermal Energy Centre of Excellence. Within the Centre, there is a need for the development of the tools and expertise in designing high performance radial-inflow turbines for these systems.This report presents the results of an investigation into the modelling and analysis of radial-inflow turbines for the use in Engineered Geothermal Systems. Firstly, verification and validation assessments were conducted using the Eilmer3 fluid simulation software which has been proposed for use in turbomachinery design and analysis. The numerical simulation results of the Standard Configuration 10 turbine cascade test case gave an excellent agreement with published numerical simulation results. By contrast, only a fair agreement was found with the experimental results of the planar turbine cascade test case presented by Kiock et al. (1986), however improvements can be achieved through the use of a viscous simulation. This thesis is important as it improves the usability and confidence of using the Eilmer3 software for turbomachinery design and optimisation.To undertake the design and optimisation of a radial-inflow turbine blade, a three dimensional parameter driven model of this blade has been constructed. It has been found that the complex, three dimensional geometry of a radial-inflow turbine blade can be completely described by three planar control graphs. The control points defining the Bezier curves in these planar control graphs have then been used to drive the three dimensional geometry of a radial-inflow turbine blade. The aim of developing the tools to parametrically model a radial-inflow turbine blade has been achieved, but the large project still requires further work to construct a mesh for use with the Eilmer3 CFD software package.The development of a parameter driven radial-inflow turbine blade model will allow engineers at the Queensland Geothermal Energy Centre of Excellence to develop and implement a turbine blade profile optimisation capability, to effectively and more quickly obtain an optimum radial-inflow turbine design. This, in turn, will enable higher performance turbomachinery to be used in power generation cycles and will allow a more rapid approach to feasible geothermal energy in Australia.