On 7-10-2015, the VIRYA-1.65 with the Chinese axial flux generator as described in public report KD 595, has been installed. This windmill has a 2-bladed stainless steel rotor with a design tip speed ratio of 5.5. For the head, the slightly modified head of the VIRYA-1.8 is used. The modification includes a smaller and lighter 2 mm aluminium vane blade and clamps and sheets for mounting of the generator shaft. The 2 m long stainless steel tower pipe is connected to the 12 m free standing 3-legs tower of the VIRYA-4.2 windmill, such creating a total tower height of about 14 m. The generator is loaded by a voltage controller and dump load which is adjusted at a voltage of 13.5 V, such simulating a 12 V battery load.

The added oil seal resulted in a friction torque of the generator of about 0.13 Nm and this torque gives a starting wind speed of about 3.5 m/s. It could be seen that about this wind speed is required for about half a minute to make the rotor accelerate up to a rather high rotational speed. However, once the rotor is rotating, it keeps running even at very low wind speeds. The rotor is running unloaded as long as a voltage of 13.5 V isn’t reached. An unloaded rotor makes some noice because the angle of attack isn’t optimal. The noice is reduced at higher wind speeds when the generator load reduces the tip speed ratio to values closer to the design tip speed ratio. During the first hour of rotation it was checked if vibrations caused by the gyroscopic moment could be felt in the tower foot but nothing was felt. There wasn’t much wind during the first hour so the generated power was nothing or very low. The tower is provided with a cup anemometer at a height of 10 m but the wind speed can not yet be read because the control box needs a 230 V, 50 Hz power supply and this isn’t available in the shed where the electronics of the windmill are installed.

Photo VIRYA-1.65 VIRYA-1.65 (0.25)