Effect of vane/blade relative position on heat transfer characteristics in a stationary turbine blade: Part 1. Tip and shroud

This study was carried out to investigate the effect of relative blade position on heat transfer in a stationary blade and shroud. A low speed wind tunnel with a single stage stationary annular turbine cascade was used. The test section is composed of sixteen guide plates and sixteen blades. The chord length of the blade is 150 mm and the mean tip clearance of the blade is 2.5% of the blade chord. Detailed mass transfer measurements were conducted for the stationary blade fixed at six different relative blade positions within a single pitch using a naphthalene sublimation method. The Reynolds number based on blade inlet velocity and chord length ranged between 1.0 × 10⁵ and 2.3 × 10⁵ and mean turbulence intensity was about 3%. As the blade position changed, the incoming flow field condition also changed significantly due to a blockage effect. As a result, the heat transfer on the tip and the shroud was significantly affected by the blade position because the incoming flow condition is changed. Especially, the mass transfer coefficients in the upstream region of the tip vary up to ± 25% of their average values. On the shroud, the size and the level of peak regions due to flow acceleration, transition and tip leakage vortex were strongly affected by the relative blade position.