Design, Development and Testing of A Combined Savonius and Darrieus Vertical Axis Wind Turbine

With a growing focus on renewable energy, interest in design of wind turbines has also been expanding. in today’s market, the horizontal axis (windmill) turbine is the most common type in use; but, vertical axis (darrieus) turbines have certain advantages. darrieus turbines, which are lift-driven, have a higher power potential than the horizontal, or drag-driven turbines. the main flaw with their design is their inability to self-start. darrieus turbines require an external energy source to bring the device to a minimum rotational speed. this paper presents design, construction and testing of a vertical axias (darrieus) wind turbine with 3 blades, starting solely from the low energy of the wind. a separate drag device (savonius type turbine) on the top of an existing darrieus turbine was mounted to make the turbine self start at low wind speed. the cut-in speed of the turbine was 3 m/s, cut-off speed was 20 m/s and power obtained was 50 watts at wind velocity of 6 m/s. the testing with primiarly available permanent magnetic generator sponsored by industry resulted in 35 watts at 9m/s.