Electrohydrodynamic thrust density using positive corona-induced ionic winds for in-atmosphere propulsion

Abstract

ResearchCite this article: Gilmore CK, Barrett SRH. 2015 Electrohydrodynamic thrust density using positive corona-induced ionic winds for in-atmosphere propulsion. Proc. R. Soc Previous work has characterized electrohydrodynamic (EHD) thruster performance, determining that thrust-to-power ratios are comparable with that of conventional propulsion at the laboratory scale. Achievable thrust density of EHD propulsion has yet to be experimentally quantified and could be a limiting factor in its application. In this paper, we quantify the achievable thrust density for a wire-to-cylinder electrode geometry using positive corona discharges for electrode pairs operating in parallel and in series. Geometric parameters, including the non-dimensional inter-pair and stage spacings, are varied, and the effect on current and thrust is measured. We estimate a maximum thrust per unit area of 3.3 N m −2 and a maximum thrust per unit volume of 15 N m −3 , which we compare with the characteristic thrust density of a range of aircraft. We find that trade-offs exist between thrust density and the achieved thrust-to-power ratio, where increases in the former through either increased power input or pair packing density lead to decreases in the latter. We conclude that EHD propulsion has the potential to be viable from both an energy efficiency perspective (our previous study) and a thrust density perspective (this paper), with the greatest likelihood of viability for smaller aircraft such as unmanned aerial vehicles.

Electrohydrodynamic Thrust for In-Atmosphere Propulsion

“…Those results are general and do not depend on the electric field shape [27]. More precisely, thrust and thrust-to-power of one current tube do not depend on the ion path (electric field lines) but only on the projection d drift of this path along the thruster axis; see Fig.…”

“…In previous studies [24][25][26][27], increasing the gap between the electrodes at fixed net thrust allowed to reach higher thrust-to-power ratio, but it automatically led to higher voltages. On a practical point of view, our results show that, at fixed thrust density, the distance between the electrodes plays a secondary role.…”

“…These studies concluded that the thrust density was too low to propel conventional aircraft and that the efficiency would strongly decrease with altitude. However, significant improvements are possible [5,[24][25][26][27] using adequate electrode shapes and arrangements. Furthermore, Masuyama and Barret [24] recently highlighted the fact that one relevant parameter for comparing in-atmosphere propulsive systems is the specific power consumption.…”

“…The flux of force is therefore conserved in a current tube. Gilmore and Barrett [27] use this property to compute the force and the thrust-topower ratio of one current tube, starting from the emitter and ending at the collector:…”

Electrohydrodynamic ionic wind, force field, and ionic mobility in a positive dc wire-to-cylinders corona discharge in air

“…This phenomenology has been known for a long time, and analyzed in many studies [1][2][3][4][5][6][7][8][9][10]. Recent investigations have revived interest in the possible propulsion capabilities of ionic wind, which were previously disregarded [11][12][13][14][15]. Nevertheless, many details concerning the ionic wind are still poorly understood, e.g., the precise chemical composition of the unipolar charges, the spatial dependence of charge ejection out of the corona discharge due to the geometrical configuration of the electrodes, and the possible influence of unsteady wake effects downstream.…”