The aerodynamic performance of blade affects the vibration characteristics
and stable operation of turbomachinery closely. The aerodynamic performance
of turbine stage can be improved by using swept blade. In this paper, the
RANS method and the RNG k-? turbulence mode were adopted to investigate the
unsteady flow characteristics and excitation force of swept blade stage.
According to the results, for the swept blade, the fluid of boundary layer
shifts in radial direction due to the influence of geometric construction. It
is observed that there is similar wake development for several kinds of
stators, and the wake has a notable effect on the boundary layer of the rotor
blades. When compared with straight blade, pressure fluctuation of
forward-swept blade is decreased while the pressure fluctuation of
backward-swept blade is increased. The axial and tangential fundamental
frequency excitation force factors of 15?forward-swept blade are 0.139 and
0.052 respectively, which are the least, and all excitation force factors are
in the normal range. The excitation factor of the forward-swept blade is
decreased compared with straight blade, and the decreasing percentage is
closely related to the swept angle. As for backward-swept blades, the
situation is the other way around. Additionally, the change of axial
excitation factor is more obvious. So the vibration reduction performance of
forward-swept blade is better.
Innovation in Vertical Axis Hydrokinetic Turbine – Straight Blade Cascaded (VAHT-SBC) design and testing for low current speed power generation