Measurement of Turbine Blade-Tip Rotordynamic Excitation Forces

摘要: This paper presents results of a program to investigate the magnitude, origin, and parametric variations destabilizing forces that arise in high power turbines due blade-tip leakage effects. Five different unshrouded turbine configurations one configuration shrouded with labyrinth seal were tested static offsets shaft. The along perpendicular offset measured directly dynamometer also inferred from velocity triangles pressure distributions obtained detailed flow surveys. These two routes yielded values fair agreement all cases. For turbines, cross-forces are seen originate mainly (∼ 2/3) classical Alford mechanism (nonuniform work extraction varying blade efficiency tip gap) about 1/3 slightly skewed hub pattern. direct (3/4) this pattern, rest slight skewness mechanism. nonuniformity (lower pressures near widest is large-scale redistribution as it approaches eccentric turbine. cross-fbrces found increase substantially when gap reduced 3.0 1.9 percent height, probably viscous between stator rotor decreases. force coefficient decreases operating coefficient. In case turbine, most nonuniform pressures. includes 80 transverse forces. appears come uneven (Alford mechanism). Their level 50 higher than