Experimental Investigation Of The Vortex Ring State For Side-By-Side Tandem Propellers

Abstract

The present paper describes an experimental wind tunnel campaign aimed at investigating the aerodynamic interactions between two side-by-side eVTOL propeller models in vortex ring state conditions. Load measurements and Particle Image Velocimetry (PIV) were employed in the comprehensive test campaign considering several configurations with different lateral distance between the propellers in side-by-side configuration, i.e. with aligned propeller disks, in both co-rotating and counter-rotating configurations. Tests results enabled to characterise the influence of the mutual aerodynamic influence between the two side-by-side propellers, providing insight into the loss of performance occurring on the propellers when entering in such descent flight condition. Moreover, PIV measurements enabled to get a detailed characterization of the velocity flow field and the vortical structures dimensions associated with vortex ring state occurrence in the different configurations tested.