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Keywords:

  • ducted wind turbines;
  • diffuser;
  • nozzle

Abstract

Ducted wind turbines are known to exceed the Betz limit for the power that may be extracted from free currents per unit cross-sectional area of their rotors. The present study points to another advantage: the fact that the turbine rotor (and the associated subassemblies) need not be lifted up on the air and rotated to align with the wind. They can function just as effectively by installing them on the ground and sucking air inside it. The analysis evaluates the efficiency of a ducted wind turbine plant, exhausting into the wake of a bluff body, under both ideal and realistic component performance. The results indicate that there exists a strong need to develop diffusers with a very low loss coefficient (e.g. by employing suction or transpiration techniques). Under such conditions and by employing the above exhaust assist techniques, the ducted wind turbine concept may deliver efficiencies more than an order of magnitude larger than those of the conventional plants. Copyright © 2009 John Wiley & Sons, Ltd.