Investigation of small-scale propellers under non-axial inflow conditions

Abstract Small-scale propellers, especially those used on conventional multicopter configurations or in the context of urban air mobility, may experience high inflow angles. In order to improve their aerodynamic efficiency, a better understanding of the flow-fields that occur under non-axial inflow conditions is required. Therefore, both isolated and ducted small-scale fixed-pitch propellers are analyzed at a range of inflow angles from zero to 180 degrees, to investigate their steady and temporal resolved loads. Furthermore, the influence of the inflow angle on the flow field is investigated. The load data is also used to simulate the efficiency of different configurative propulsion concepts. The aerodynamics coefficients obtained experimentally, as well as the flow field analysis by particle image velocimetry (PIV), are in close agreement with the unsteady numerical results obtained by URANS calculations.