Detailed experimental and numerical studies have been performed in a s
ubsonic, axial-flow turbine stage to investigate the secondary flow fi
eld, the aerodynamic loss generation, and the spanwise mixing under a
stage environment. The experimental study includes measurements of the
static pressure distribution on the rotor blade surface and the rotor
exit flow field using three-dimensional hot-wire and pneumatic, probe
s. The rotor exit flow field was measured with an unsteady hot-wire pr
obe, which has high temporal and spatial resolution. Both steady and u
nsteady numerical analyses were performed with a three-dimensional Nav
ier-Stokes code for the multiple blade rows. Special attention was foc
used on how well the steady multiple-blade-row calculation predicts th
e rotor exit flow field and how much the blade interaction affects the
radial distribution of flow properties at the stage exit. Detailed co
mparisons between the measurement and the steady calculation indicate
that the steady multiple-blade-row calculation predicts the overall ti
me-averaged pow field very well. However, the steady calculation does
not predict the secondary flow at the stage exit accurately. The curre
nt study indicates that the passage vortex near the hub of the rotor i
s transported toward the midspan due to the blade interaction effects.
Also, the structure of the secondary flow field at the exit of the ro
tor is significantly modified by the unsteady effects. The time-averag
ed secondary flow field and the radial distribution of the flow proper
ties, which are used for the design of the following stage, can be pre
dicted more accurately with the unsteady flow calculation.