Tip-Shroud Cutbacks in a Low-Pressure Gas Turbine Stage

This paper presents an experimental and computational study of tip-shroud modifications in a low-pressure gas turbine. Partial shrouds are a viable option to reduce the static stresses in high-speed stages compared to full shrouds while still benefiting from superior aerodynamic efficiency compared to unshrouded blades. Three different tip-shroud platform cutbacks have been tested experimentally in a low-aspect-ratio 1.5-stage low-pressure axial turbine and are compared to a full-shroud baseline. A detailed analysis of the fluid dynamics is carried out to provide a starting point for shroud optimizations. The leading- and trailing-edge platforms are cut back separately to isolate the effect of each modification. The final rotor then features a combined partial shroud on both leading and trailing edge, with the same material reduction as the shroud leading-edge cutback. The time-resolved flowfield and pressure measurements are accompanied by three-dimensional, unsteady Reynolds-averaged Navier–Stokes simul...