Flight Physics of Propellers in Crossflow Conditions

Propellers in Crossflow Conditions

The best way to overcome the issue of high uncertainty in modeling and simulation is measurement.

The unique test truck of AVILUS allows a high frequency recording of all propeller forces and moments under hover and crossflow conditions. Our equipment provides a setup with variable angles of attack from pure crossflow down to pure positive and negative axial flow. Furthermore, our customers can choose in between a single and a coaxial setup with adjustable axial spacing.  

Propeller aerodynamics of axial flow are well understood, can be easily modeled by readily available tools or could simply be measured on static test rigs. In contrast, the aeroelastic behavior of propellers under crossflow conditions is highly complex to predict. Crossflow occurs e.g. during transition of lift and cruise vehicles or during forward flight of multicopters. The complexity of prediction in this working state arises from uncertainties in structural dynamic excitations, strongly non-uniform inflow and effects of compressibility. The uncertainty is even increased when it comes coaxial units due to the mutual interactions of the tilted wakes. The figure displays simulation results of the propeller pitching moment for different structural stiffnesses of the blades.

Propeller aerodynamics of crossflow.