An aerodynamically efficient sphere anemometer with integrated hot-film sensors for 2-D environmental airflow monitoring

This paper reports a novel anemometer configuration for airflow measurement. The flow over a sphere provides an ideal flow geometry. Four micro hot-film sensors are orthogonally mounted on the circumference of a sphere. The airflow speed distribution on the sphere as well as flow separation point will affect heat dissipation of the hot-film sensors, and result in variance of resistance of the sensors. By using the information from four positions, 2-D airflow speed and direction can be reconstructed. The micro hot-film sensor die was first designed and fabricated, and then packaged and assembled into a plastic sphere. The wind tunnel testing of the sensor prototype reveals good sensitivity and directivity, indicating it is feasible for environmental airflow measurement.