Application of Immersed Boundary Method on Instrumented Turbine Blade With LES

Leading edge instrumentation used in compressor and turbine blades for jet-engine test rigs can cause significant obstruction and lead to a marked increase in downstream pressure loss. Typical instrumentation used in such a scenario could be a Kiel-shrouded probe with either a thermocouple or pitot-static tube for temperature/pressure measurement. High fidelity analysis of a coupled blade and probe would require the generation of a high quality mesh which can take a significant amount of an engineers time. The application of Immersed Boundary Method (IBM) and Large Eddy Simulation is shown in this paper to enable the use of an extremely simple mesh to observe the primary flow features generated due to the blade and probe interaction effects, as well as quantify downstream pressure loss to within a high level of accuracy. IBM is utilised to approximately model the probe, while fully resolving the blade itself through a series of LES simulations. This method has shown to be able to capture downstream loss profiles as well as integral quantities compared to both experiment and fully wall-resolved LES without the need to spend a significant amount of time generating the ideal mesh. Additionally, it is also able to capture the turbulence anisotropy surrounding the probe and blade regions.

Considering the time spent on the wall-resolved instrumented blade mesh being in the order of months, and the approximate run time being 1 month per case, the time taken for the generating the IBM mesh is 1 day with approximately 1.5 months of run time. Hence, the time taken to mesh the wall-resolved case is enough to both mesh and run the IBM case twice, with modifications to the IBM modelled geometry being as simple as re-running the search-based distance generator which is itself only takes a few minutes.