Parametric Study on an Annular Airfoil Geometry for Collector Electrodes in Electrohydrodynamic Propulsion Systems

This project investigates the effect of collector electrode geometry on the thrust of single-stage electrohydrodynamic (EHD) thrusters. EHD thrusters are silent and feature no moving parts, which makes them promising alternatives to small-scale drone propellers. However, their low thrust density remains a major hurdle. A significant contributor to this inefficiency is the aerodynamic drag generated by the collector electrode, which acts against the generated thrust. The thrust was measured using a customized low-friction force measurement setup. Different geometrical parameters of collector electrodes were tested, with a focus on the annular airfoil shape. The thruster was tested with a constant voltage of 8 kV, at a constant electrode gap of 25.4 mm. A negative correlation was observed between thrust and the thickness, camber and convergence angle of the annular airfoil. A net decrease in thrust of up to 32% was measured over the tested parameter ranges. These findings suggest that a slimmer airfoil shape improves aerodynamics and minimizing the collector's aerodynamic profile remains critical for maximizing EHD propulsion efficiency.