Performance of a Rooftop Wind Turbine System Having a Wind Deflecting Structure, Experimental Results

This work presents the results of an experimental work on a novel design for wind tower system. The system is intended for areas of low wind speeds. The wind tower consists of four rooftop turbines mounted alongside a cylindrical structure that acts as a Wind Deflecting Structure (WDS). This arrangement results in lowering of the cut-in wind speed for the turbine; the system allows the turbine rotors to operate in the areas that have normally low wind speeds, as low as 3 m/s. The nameplate rating of each of the turbines is 1.65. The four turbine system was installed on the rooftop of a five story building in downtown Cleveland, Ohio. A fifth stand-alone wind turbine was installed on the rooftop of the same building as the reference in order to examine. Orientation of the four wind turbines is controlled by a close-loop active direction control sub-system using a double worm-gear reduction as its actuator. The output of the worm-gear unit has a spur gear pinion that meshes with an external gear that is an integral part of the outer race of the bearing that in turn supports the arm to which the four turbines are attached to. The wind power data from five turbines (four turbines on the tower & one reference turbine) were recorded by PLC's. The data was updated and recorded every 10 seconds. This means that in every hour there were 360 data points for each of the turbines. For each day the number of data points for each turbine is 24 x 360 = 8640. The other information that is recorded every 1 second includes: the wind direction, wind speed, time, date and an index number. The experimental results show that the power output of the each of the turbines installed on the proposed system may be increased by an average factor of about 4 times compared to the power generated by the stand-alone turbine under the same wind flow condition.