Diffusers placed around wind turbines may augment its power for a given wind speed. Based upon experimental velocity augmentations found at the nozzle of such diffusers enormous power augmentations are sometimes claimed for DAWT's. By application of straightforward momentum theory it is shown that the linear - cube relation between wind speed and power is not valid for the high velocities obtained inside the diffuser. A considerable (negative) back pressure results at the exit of a diffuser However this is equivalent to the pressure in the near wake of an ordinary wind turbine. The theory shows that the achievable DAWT performance is comparable to the performance of a standard HAWT (horizontal axis wind turbine) having a diameter equal to the exit diameter of the diffuser. By introduction of an extra back pressure at the exit may however increase the performance to some extent.
|Conference||1999 ASME Fluids Engineering Division Summer Meeting (FEDSM 1999)|
|Abbreviated title||FEDSM '99|
|Period||18/07/99 → 23/07/99|