Wind Tunnel-1

To establish and test the superior efficiency of the GURV design concept a controlled wind flow was required. It was decided to fabricate a wind tunnel which could generate wind flow of few KMPH to above 100 KMPH.

We started with an over ambitious size of wind tunnel size of 10’x14′ to drive a GURV wind turbine of Blade size of 4’x8′ with a capacity to generate 15 KVA at low wind speeds. The tunnel design consisted of 31 no’s of 24″ exhaust fan blades mounted in a panel formation and driven by 31 no’s of 1.5 KW DC motors. These wind drivers were designed to reach speeds above 3000 RPM. A custom built drive system using IGBT controls was fabricated to drive all the 31 motors at the same speed with single remote control.

An floor based structure was created to link GURV turbine and the flow of the wind tunnel with firm floor mountings. Due to space limitations the length of the tunnel was kept to 12′, which proved limitation in smooth flow of air. Another lesson learned was that the tunnel fan drive should have been based on suction rather than forced flow. Drive motor power rating, also proved under estimated leading to reach only 45 KMPH peak wind speed. Overall the tunnel and turbine combination could not meet its desired goals hence had to be abandoned.

WIND Tunnel -2

Learning from experience of wind tunnel -1 a new wind tunnel with manageable proportions is fabricated for testing of a smaller (less than 1 sq. meter) wind turbine. This time fins type aerodynamically balanced impeller blade panels are used. these blades are total 7 in numbers with individual diameter of 13″and total tunnel cross section of tunnel is 48″x48″. this time the tunnel is configured on suction based drive with all the 7 motors driven by synchronous dive.

The tunnel fabrication is done for inside use with wooden/steel frame and ply wood panelling covering it on 4 sides. The tunnel is 16′ long with turbine mounted half way. all the 7 motors driving the suction blades are symmetrically placed on one side of the tunnel with necessary control and monitoring devices mounted on top conveniently.

New Wind turbine -4

Target for this design was revised to establish maximum power generation capacity of the system practically, hence openable sub blades are not part of design. Necessary coupling with generator mounted outside of tunnel on either side has provision for connecting a gear box. To achieve optimum power at low rpm of the wind turbine in the range of 8-10 rpm the gear set increases generator rpm by25 times.

Low power Generator

Finding a suitable low power generator was another challenge. Many options were evaluated but available small generators needed 3000 rpm to perform. Auto motive alternators were tried but proved inefficient for the purpose. finally team decided to design and build a permanent magnet generator. Initial trial design with 36 pole generator provided a reasonable alternative.