Rj. Goldstein et al., THE INFLUENCE OF SECONDARY FLOWS NEAR THE ENDWALL AND BOUNDARY-LAYER DISTURBANCE ON CONVECTIVE-TRANSPORT FROM A TURBINE BLADE, Journal of turbomachinery, 117(4), 1995, pp. 657-665
A naphthalene sublimation technique is used to investigate convective
transport from a simulated turbine blade in a stationary linear cascad
e. In some of the tests undertaken, a trip wire is stretched along the
span of the blade near the leading edge. The disturbance produced by
tripping the boundary layers on the blade near the leading edge causes
early boundary layer transition, creates high mass transfer rate on t
he pressure side and in the laminar flow region on the suction side, b
ut lowers the transfer rate in the turbulent flow region on the suctio
n side. Comparison is made with other heat and mass transfer studies i
n the two-dimensional region far from the endwall and good agreement i
s found. Near the endwall, flow visualization indicates a strong secon
dary flow pattern. The impact of vortices initiated near the endwall o
n the laminar-turbulent transition extends three-dimensional effects t
o about 0.8 chord lengths on the suction side and to about 0.2 chord l
engths on the pressure side away from the endwall. The effect of the p
assage vortex and the new vortex induced by the passage vortex on mass
transfer is clearly seen and can be traced along the suction surface
of the blade. Close to the endwall the highest mass transfer rate on t
he suction surface is not found near the lending edge. It occurs at ab
out 27 percent of the curvilinear distance from the stagnation line to
the trailing edge where a strong main flow and the secondary passage
flow from the pressure side of the adjacent blade interact. The influe
nces of some small but very intense corner vortices and the passage vo
rtex on mass transfer are also observed on both surfaces of the blade.