Applying an Icing Wind Tunnel for Drone Propeller Research, Validation of New Measurement Instrument

Unmanned aerial vehicles have increased in popularity in recent years, especially the numbers of small multicopters. At the same time, icing research of such systems has been left behind, and results especially for propellers in this scale and in VTOL configuration are few. While the numbers of such systems have grown, also their usage in cold and icing conditions has increased.

A lot of research has been conducted for full-size airplanes and rotorcraft, but for drones the Reynolds numbers are relatively low in comparison. For this reason, it is important to research these systems in order to develop anti-icing methods and operate drones safely in all weather conditions. Also, currently used numerical tools are developed and validated for high Reynolds number conditions, but such validation has not yet been conducted for low Reynolds number flows.

VTT has operated an icing wind tunnel since 2009 primarily for experimental research in wind power technologies. Part of this line of research, methods for preventing icing of wind turbine blades, has been developed, and numerical tools developed in-house have been validated.

For developing the icing wind tunnel capabilities, a propeller dynamometer was added as a research instrument. This provides the means to research propellers used in drones to be researched in the wind tunnel. During the commissioning of the instrument, experiments in warm and dry conditions were conducted for validation and repeatability purposes. Experiments showed that the thrust measurements were accurate and repeatable, but torque measurement requires more development.