Electrostatic forces acting on particle image velocimetry tracer particles in a plasma actuator flow

Abstract

Dusty plasma effects were investigated for the results of plasma actuator particle image velocimetry experiments. Two particle charging theories, partially collisional and fully collisional theories, are used to estimate the charge on the particles. Secondary aerodynamic forces are shown to be weak in comparison to Stokes drag, and secondary dusty plasma effects are also weak compared to the electrostatic force. It is shown that the true air velocity can be calculated by extrapolating to the 0-nm particle size. Using the difference in velocity between the air and the particles, the Stokes drag force is calculated and found to be between 1 and 200 pN depending on particle size. The electrostatic force is also calculated and found to be almost equal and opposite to Stokes drag, but the charge and electric field components cannot be separated. Based on assumptions from published simulation results, the theories are shown to be within a factor of two in predicting the charge on a particle in a high pressure plasma.