Assessment of SAS and DDES predictive capability of trailing edge cutback coolant ejection

In this numerical study two hybrid RANS-LES methods such as Scale Adaptive Simulation (SAS) and Delayed Detached Eddy Simulation (DDES) have been applied to trailing edge cutback film cooling in a high pressure turbine nozzle guide vane, for a coolant-to-mainstream mass flow ratio value of MFR = 1.05%, under incompressible-flow assumption. The geometry here considered features a pressure side cutback with 8 film cooling slots. Cooling air is also ejected through two rows of cooling holes placed on the pressure side, upstream of the cutback. Attention was drawn to the predictive capability of vortex structures that are formed behind the cutback lip and convected downstream along the vane surface since they are primarily responsible for determining the thermal coverage at the trailing edge. Results from SAS and DDES were compared against each other on equal terms to highlight any different behavior coming closer to experiments. Vortex shedding was well predicted in shape and magnitude, but with a lower frequency, by both models. The DDES method yielded slightly more accurate predictions of cutback film cooling as well as larger resolved turbulent content.