In this experimental and numerical study rotors of various blade skews, namely, axial,
circumferential and axial-circumferential types, are studied and their aerodynamic
performances are compared to those of the baseline radial rotors of two types, namely,
constant chord and varying chord. The skew in a blade can be considered as
combination of sweep and dihedral. The skew change from the circumferential to axial
type causes reversal of dihedral induced radial blade force and hence a reversal of
meridional streamline curvature which in turn reverses the modulation of the end-wall
loads. The inherent forward sweep in the forward skewed blades also modulates hub
and tip loads. Thus, in a forward axial skew blade the forward sweep and positive
dihedral combine favorably to unload the tip and to upload the hub. In the forward
circumferentially skewed blades, forward sweep and the negative dihedral have
mutually countering effects on end-wall load modulation. The highlight of this study is
that it has demonstrated experimentally the unloading of the tip in the forward axially
skewed blades which resulted in reduced losses and better performance including
increased stall margin. Reduced tip loading was also verified from the casing pressure
sensor measurements which showed weakening of tip vortex. The relative influence of
sweep and dihedral on performance was additionally demonstrated in the axially
circumferentially skewed rotor of the constant chord type, with improvements
attributable to higher sweep.