Shrouded wind turbine research in Israel

Experimental results are presented which demonstrate that enclosing a turbine inside a specially designed shroud will increase its power output by a factor of two; with the prospect of augmentation factors as high as four resulting from the use of coaxial annular trailing flaps and boundary layer laminarization techniques such as surface suction. The power-augmenting characteristics of shrouds are due to (1) the inviscid wake-recovery effect, which produces a sub-atmospheric pressure region at the shroud exit plane, and (2) the conversion of kinetic energy to a rise in pressure inside the rear part of the shroud. Preliminary economic studies indicate that the shrouded turbine would have lower specific power costs than conventional turbines in at least two power-rating regimes.