Improving Turbine Aerodynamics
Turbulent Junction Flow
The horseshoe vortex system is a highly dynamic flow feature that contributes to high heat transfer, shear stress, and unsteady pressure loading in the junction region of wall mounted bluff-bodies. A project funded by the Office of Naval Research investigated the effect of changes in Reynolds number and turbulence intensity on the dynamics of the horseshoe vortex system. Stereo-particle image velocimetry (SPIV) measurements were made in front of a single symmetric wing at varying freestream conditions turbulence and Reynolds number conditions. High Reynolds number led to an increase in the unsteadiness of vortex motions and endwall backflow due to a more generally turbulent incoming boundary layer. High freestream turbulence intensity led to increased unsteadiness in vortex motions at low Reynolds number, but little effect at high Reynolds number.
High speed measurements of the vorticity in the flow upstream of a wall-mounted wing
Effect of Leakage Gaps on Endwall Flow
Gas turbines have many interfaces between stationary and rotating components, which must be supplied with purge air. This air can change the behavior of the complex endwall secondary flow and reduce the overall turbine efficiency as well as the local heat transfer.
Measurements of the total pressure loss downstream of a turbine,
with leakage flow through a gap between components.