Abstract:
Performance prediction and design of a straight-bladed vertical-axis Darrieus Wind Turbine is
done with the cascade theory. In this prediction model the effect of dynamic stall and flow
curvature is taken into consideration with blade pitching.
For dynamic stall consideration, Boeing-Vertol stall model with modification is taken into
account. An empirical relation is used to determine the drag characteristics. In the prestall
condition, the ECN stall model is followed to calculate the lift characteristics.
For the flow curvature effect the lift values are corrected only by a factor that is determined using
the thin airfoil theory. However, the drag values are modified for the effect of chord-radius ratio,
thus further correction of them due to the effect of flow curvature is not necessary. The finite
aspect ratio effect is also incorporated in the prediction model.
Incorporation of blade pitching with dynamic stall and flow curvature effects in the performance
prediction model is the prime objective of the thesis. Different important parameters, like normal
and tangential forces, power coefficients, torque coefficients, drag coefficients etc. at different
fixed pitch angles are obtained in this investigation and they are presented in graphical form.
Also design of a I KW straight-bladed vertical axis Darrieus wind turb.ine is done with mean wind
velocity for the coastal regions of Bangladesh. The design wind speed is taken as 5 m/s and cutout
wind speed as 15 m/s. The effect of dynamic stall and flow curvature is taken into consideration
with fixed and variable blade pitching.
