Research and development for shrouded wind turbines.

In order to exploit wind power as economically as possible, it was suggested that a wind turbine should be enclosed inside a specially designed shroud. Various geometries are discussed. It is shown that with a fairly compact shroud a significant power augmentation can be achieved. For improving the shroud performance, the use of a ring shaped flap or boundary layer control technique is introduced. It is shown that up to 80% improvement in the shroud power augmentation can be obtained by the use of an appropriate ring shaped flap while proper bleeding of the shroud's external flow into its inner rear part will increase its power augmentation by about 25%. Based on the reported research with shrouds, a pilot plant producing 1 hp at 5 m/s with a 3 m diameter turbine was built. Its preliminary field test results are also included in the review. (A)