Ultrasonic anemometry for the spatial distributed measurement of rotor wakes

Abstract

The Institute of Aerodynamics and Flow Technology of the German Aerospace Center (DLR), in Göttingen is investigating the outwash of single and multirotor aircraft hovering in ground effect. Due to the complex nature of the outwash, especially in the case of multirotor aircraft, a spacial distributed measuring system is needed to investigate the outwash. A suitable measurement technique is an array of ultrasonic anemometers, due to their low complexity and ability to measure even low velocities accurately. Commercially available sensors are costly and do not feature a method for synchronization. Another challenge is the size requirement of under 100 mm×100 mm×100 mm. A 2D ultrasonic anemometer with the required features is developed. The sensor is tested in a wind tunnel campaign and calibrated. The occurring measurement errors are examined and if possible corrected. It has been found that building a small scale ultrasonic anemometer is viable but that some errors occur due to the reduced size of the sensor