Optimization of surface dielectric barrier discharge ion sources for electroaerodynamic propulsion

Abstract

Surface dielectric barrier discharges (SDBDs) are a type of asymmetric dielectric barrier discharge (DBD) that can be used to generate ions and produce aerodynamic forces in air. They have been studied for aerodynamic flow control and proposed for small aircraft propulsion as both direct sources of thrust and as ion sources for "decoupled" electroaerodynamic (EAD) propulsion, in which decoupling ionization from ion-acceleration provides performance and control advantages. SDBDs can also be integrated into aircraft surfaces without introducing additional drag. A challenge for these aerospace applications is minimizing the power draw (or maximizing the efficiency) of these actuators. Optimizing SDBD actuators requires a robust model for SDBD electrical power draw as a function of geometric, material, and electrical properties.

Existing approaches use empirical power law fits to estimate the power of a specific DBD configuration at certain electrical operating points; they are challenging to use in engineering design and optimization as they require experimental measurements for each individual configuration. This thesis proposes the first physics-based model for surface DBD power consumption. The proposed model is based on established models for parallel-plate or "volume" DBDs, and it incorporates the effect of changing plasma length that is specific to SDBDs. This thesis examines SDBDs of three materials, eleven thicknesses, and 394 unique electrical operating points and finds a correlation with R² = 0.99 (n = 394) between experimentally-measured power and model-predicted power. SDBD power measurements extracted from four other experiments from the literature are analyzed with a correlation of R² = 0.97 (n = 101), demonstrating that the model is generalizable to other SDBD constructions.

Ionization rate is also measured to facilitate optimization for use in decoupled EAD thrusters. This work enables the quantitative design and optimization of SDBDs for EAD propulsion and other applications in aerospace and beyond.