On the performance of electrohydrodynamic propulsion

Abstract

Partially ionized fluids can gain net momentum under an electric field, as charged particles undergo momentum-transfer collisions with neutral molecules in a phenomenon termed an ionic wind. Electrohydrodynamic (EHD) thrusters generate thrust by using two or more electrodes to ionize the ambient fluid and create an electric field. We characterize the performance of EHD thrusters of single-(SS) and dual-stage (DS) configurations. SS thrusters refer to a geometry using one emitter electrode, an air gap and a collector electrode with large radius of curvature relative to the emitter. DS thrusters add a collinear intermediate electrode. SS thruster performance was shown to be consistent with a one-dimensional theory. Increasing the gap length requires a higher voltage for thrust onset, generates less thrust per input voltage, generates more thrust per input current and most importantly generates more thrust per input power. A thrust-to-power ratio as high as approximately 100 N kW −1 was obtained. DS thrusters were shown to be more effective than their SS counterparts at producing current, leading to a smaller total voltage necessary for producing equal thrust. However, losses involving ion collection at the intermediate electrode led to reduced thrust-per-power compared with the SS thruster of equal length.

Electrohydrodynamic Thrust for In-Atmosphere Propulsion

“…Recent experiments [5,24,25] widely confirm the trends of the EHD propulsion theory derived by Christenson and Moller [21] in 1967. Inside the drift region, the charge density ρ is only due to ions.…”

“…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.…”

“…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. Simple experimental EHD thrusters were then found to reach more than 20 mN∕W [24], a value compatible with operating conditions of electrical aircraft, which reopened the issue of EHD propulsion practical interest.…”

“…With ambient flowfield u 50 m∕s, the thrust-to-power ratio reaches 4 N ⋅ kW −1 with a 20% efficiency. As a comparison, according to Masuyama and Barrett [24], typical turbojet engines deliver 2.5 N ⋅ kW −1 effectiveness at sea level, where the input power is derived from the specific fuel consumption. Our experimental measurements for zero ambient flow speed (u 0) have shown that Θ can reach more than 20 N ⋅ kW −1 at low voltage, but this is obviously at the cost of low thrust.…”

Electrohydrodynamic Thrusters: An Examination of the Biefeld-Brown Effect and its Influence on its Surroundings

“…This brings up further work in investigating the Biefeld-Brown effect. Dual stage lifters were also tested and noted to be less efficient but more powerful [5]. The paper gave an in-depth explanation of the forces at work and how differing geometries, specifically gap distance, changed the efficiency of the lifter.…”