3-DIMENSIONAL BLADE BOUNDARY-LAYER AND ENDWALL FLOW DEVELOPMENT IN THE NOZZLE PASSAGE OF A SINGLE-STAGE TURBINE

The three-dimensional viscous flow field development in the nozzle pas sage of an axial flow turbine stage was measured using a ''x'' hot-wir e probe. The measurements were carried out at two axial stations on th e endwall and vane surfaces and at several spanwise and pitchwise loca tions. Static pressure measurements and flow visualization, using a fl uorescent oil technique, were also performed to obtain the location of transition and the endwall limiting streamlines. The boundary layers on the vane surface were found to be very thin and mostly laminar, exc ept on the suction surface downstream of 70 percent axial chord. Stron g radial pressure gradient, especially close to the suction surface, i nduces strong radial flow velocities in the trailing edge regions of t he blade. On the endwalls, the boundary layers were much thicker, espe cially near the suction corner of the casing surface, caused by the se condary flow. The secondary flow region near the suction surface-casin g corner indicated the presence of the passage vortex detached from th e vane surface. The boundary layer code accurately predicts the three- dimensional boundary layers on both vane surfaces and endwall in the r egions where the influence of the secondary flow is small.