Estimation of performances of a HAWT with passive pitch-angle control system using fiber-reinforced rubber

A passive pitch-angle control system for a small horizontal axis wind turbine (HAWT) has been proposed in our previous study. The main component of the system is the rubber pipe reinforced by metal fibers arranged with oblique angle, and the system is installed at the root of the blade. When the rubber pipe is subjected to centrifugal force due to the rotation of the rotor, the oblique fibers cause the torsional deformation of the pipe and the change in the pitch-angle of the blade. In this study, FEM analyses for the fiber-reinforced rubber pipe are carried out, and the influences of the structural specifications on the torsional deformation are examined. Additionally the electric power generation of the turbine with the system is estimated in order to confirm the effectiveness of the proposed system for the prevention of the overspeed of the turbine. Through the study, it is found that the fiber-angle of the fiber-reinforced rubber pipe affects the torsional deformation remarkably, and the influences of the dimensions of the rubber pipe on the torsional behavior can be simply shown as a relation between the average stress and the average shear strain. It is also confirmed that the proposed pitch-angle control system prevents the overspeed of the turbine in the strong wing condition and the stall control is more effective than the feather control.