Detached Eddy Simulation Analysis of Pak-B Low Pressure Turbine Blade

Abstract : Two cases were computationally investigated using the detached eddy simulation (DES) turbulence model: an unmodified Pak-B blade and a Pak-B blade with a dimple located at 65% of axial chord. Both cases were created so that they simulated an infinite span with an infinite number of dimples. The cases were run for an inlet Reynolds number of 25,000. The computed results were used to resolve the location of separation and reattachment, visualize the streamlines for the dimpled case, build velocity magnitude contour and vector plots, and map the thickness of the boundary layer. The results were then compared to previous computational and experimental studies in order to validate the detached eddy simulation model for future research into the effect of dimples on low pressure turbine flow fields. For the unmodified blade, the performance of the DES model compared favorably to other available viscous and turbulence models. For the dimpled blade, preliminary results also compare favorably to other models although further development of the flow field is needed to verify this. Based on these results, future researchers studying dimples on turbine blades should strongly consider using the DES turbulence model.