Batteryless Bluetooth Anemometer employing 2 cm Axial Turbine as both Power Source and Wind Speed Transducer

We report a miniature, self-powered wireless anemometer in which a 2 cm-diameter axial turbine acts as both the power source and the wind speed transducer. The device is cylindrical with an outside diameter of 3.2 cm and a length of 5.5 cm. The turbine is a simple, low-cost device fabricated mainly by 3D printing. Wind speed measurements are made by temporarily removing the electrical load from the turbine and then measuring its rotation rate and angular acceleration. With these data, and an analytical model of the turbine dynamics, an estimate of the wind speed can be obtained. Control electronics has been developed that adjusts the interval between measurements to suit the available wind power and applies parasitic loading at higher wind speeds to prevent turbine overspeed. Wind speed and temperature data are sent via a Bluetooth Low Energy wireless link to a data collection node. Wind tunnel tests indicate that the anemometer can operate at wind speeds down to 3 m/s and provide measurements with an average lying within ±0.17 m/s of the true wind speed and a worst case standard deviation of 0.41 m/s for wind speeds in the range 3 to 9 m/s.