Turbine film cooling modelling through a hybrid 1D-3D approach using Flownex and Ansys CFX

1D-3D approach for modelling turbine film cooling Since their inception, gas turbines have revolutionized industries worldwide. Their ability to convert the energy of burning fuel into mechanical power or thrust has been essential in a multitude of applications across many sectors. Initially conceived for aviation propulsion during World War II, gas turbines rapidly found their place in the realm of power generation, where they became pivotal, especially considering the sustainable transition we are currently facing. Enhancing fuel efficiency and reducing emissions, or investigating the viability of different kind of fuels, such as biofuels, hydrogen or synthetic fuels, has driven research and investments in the past few years. It is worth to highlight, anyway, that gas turbine systems became widely used only when it became possible to achieve higher turbine inlet temperatures (TIT) and compression ratios ($\beta$). So, if we want to maximize the work produced by the Joule cycle, we are strictly limited by the maximum value of TIT. Structural materials, such as titanium or nickel, typically cannot withstand temperatures higher than 1300K. However, blade cooling techniques, including film cooling, allow us to raise T to even higher values, improving efficiency and increasing power or thrust output. Film cooling involves bleeding relatively cool air from the compressor and discharging it through small holes in the blade walls. This creates a protective layer of cooler air on the surface of the blades, preventing them from overheating. Accurate computational fluid dynamics (CFD) modelling has been instrumental in obtaining precise results for complex engineering problems, such as blade cooling, especially considering the limitations in applying experimental procedures in this field. However, these simulations often demand significant computational resources and time. This is why it becomes crucial to explore novel modelling approaches that strike a balance between accuracy and computational efficiency, especially during a preliminary design phase. In this thesis project, we combine two CFD software tools — Ansys CFX and FLOWNEX SE — to model film cooling more rapidly. The main idea is to create a 1D network for modelling blade internal channels, coupling hole exit boundary conditions with injection regions applied to the external surface of the blade modelled in CFX. This hybrid 1D-3D approach for turbine film cooling modelling revealed to be in line with full 3D simulation results, achieving a good balance between accuracy and computational efficiency. By leveraging the strengths of both Ansys CFX and Flownex SE, we were able to create a model that provided reliable predictions in a fraction of the time required by fully resolved simulations. This method shows great potential for use in preliminary design phases, where rapid iteration is crucial. However, further studies are needed to optimize the 1D-3D coupling between the softwares, or for applying this method to other components of the gas turbine.