Investigation of self-starting mechanism on the performance of darrieus rotor

Abstract

Currently, the Darrieus rotor is receiving more interest as it can be more favorable and perform better in low wind speed regimes. However, the symmetrical NACA airfoil suffers from low starting torque. Thus, in the present study, a passive method is adopted to enhance the self-starting difficulties while improving the performance of the rotor. Four typical conditions were studied including a rotor with six semicircle PVCs (case 4), a rotor with three semicircle PVCs at the bottom arms of the rotor (case 3), a rotor with three semicircle PVCs at the top arm (case 2) and a rotor without any semicircle PVCs (case 1). The results indicated a significant improvement in terms of self-start characteristic and performance output. Case 3 showed the highest output, while, case 4 showed the least with regard to the cases with PVCs. The system has also enhanced the self-starting behavior by allowing the model to self-start at a wind speed of as low as 5 m/s and increased to 8 m/s without any semicircle PVCs. Such improvement of the proposed approach confirms the effectiveness of this method and could hopefully provide a simple and low-cost mechanism of enhancing self-starting difficulties in Darrieus H-type VAWTs.