On the self starting of darrieus turbine : An experimental investigation with secondary rotor

Abstract

Darrieus type vertical axis wind turbines are preferred for the small scale distributed power generation for their distinctive advantages, yet these lift based turbines suffers from poor self-starting capability. As a potential solution, a Dual rotor Darrieus Turbine (DD) with secondary rotor in addition to the primary rotor has been proposed to improve the self-starting characteristics and to enhance the low wind speed performance. The current study experimentally evaluates the proposed rotor with two set of blades as a possible means of achieving higher static torque and thus promoting self-starting capability. Albeit, the design parameters for the secondary rotor such as solidity, appropriate airfoil, secondary rotor diameter, secondary rotor offset with respect to primary rotor requires extensive optimization, the current preliminary study is focused on the feasibility check of the DD turbine. Power coefficient, dynamic and static torque coefficient are obtained through wind tunnel test and compared with Conventional Darrieus (CD) turbine (only with primary rotor). The results indicate the novel dual rotor do improve the self-starting capability at the expense of reduced power performance.