Compact Wind Acceleration Turbine - Flodesign

Flodesign

Flodesign's MEWT (mixer-ejector wind turbine, another CWAT variation) is differentiated from previous DAWT's by using a lobed two stage diffuser (Grumman and Vortec machine were also two stage, but conical instead of lobed) to equalize the pressure over the exit area of the diffuser. The theory is that creating a uniform pressure distribution with the lobes and the injection of external flow will prevent boundary layer separation in the diffuser thereby allowing the maximum acceleration through rotor. Werle and Presz's (Flodesign's chief scientists) paper, AAIA technical note Ducted Water/Wind turbines revisited - 2007, details the theory behind their design. Maximum acceleration detailed in their paper is 1.8× the ambient velocity from which they derive that 3-5 times more power is available at the rotor than for an unshrouded turbine. When referred to exit area this multiple drops to between parity and 2.1 times the HAWT power. Flodesign's turbine based on released images and CAD's appears to be substantially similar to the Vortec and Grumman machines except for the lobed inner annulus. This would indicate that its drag characteristics can be expected to be similar.