| The fluid mechanics in gas-turbine endwalls is quite complicated with horseshoe, passage, and corner vortices. These secondary flows adversely affect performance and reliability of gas turbines. This is because secondary flows get their energy from the main flow, and so is a source of aerodynamic loss. Also, they entrain higher-temperature gas in the main flow to the airfoils and the endwalls and this can increase surface heat transfer. On film cooling, secondary flows can advect and lift film-cooling jets away from surfaces that they are intended to protect. These detrimental effects can be especially severe for low-aspect ratio, high-pressure turbines and highly loaded, low-pressure turbines.; The objective of this research is to assess the usefulness of existing turbulence models in predicting the complicated flow and heat transfer in the endwall region of the first-stage stator. The following models will be evaluated: (1) the realizable k-epsilon model, (2) the shear stress transport k-o model with the two-layer model in the near-wall region, (3) Durbin's v2-f model, (4) the Reynolds-stress model with the two-layer model in the near-wall region, and (5) the Spalart-Allmaras model. The evaluation will be performed in two steps. First, a grid sensitivity study will be performed. Afterwards, predictions will be compared with experimental measurements. |
