Structural characteristics of electrohydrodynamic jets induced by a blade-plane actuator subjected to highly non-uniform electric fields: Parametric investigation through the particle image velocimetry techniques

This study set out to systematically investigate the structural characteristics of plane electrohydrodynamic jets through the particle image velocimetry (PIV) techniques. Due to the wide range of applied voltages and electrode gaps under various experimental conditions, an assessment of the image quality and a statistical analysis of the velocity fields are first performed to ensure the validity of the PIV measurements, which were originally applied purely to fluid mechanics. The results indicate that the time interval between two consecutive images should be pre-adjusted to reduce the number of uncorrelated vector fields. Moreover, the minimum number of instantaneous fields should be achieved for an accurate calculation of the time-averaged fields. An equivalent electric field criterion adapted to the asymmetric electrode configuration is defined to find similarities in flow structures under different voltage and electrode gap conditions. As the applied electric field increases, three injection regimes are identified and the current increases almost linearly, indicating a large conduction current component. The decrease in charge density due to recombination proves to be relevant in all cases of this study. Analogous to the parametric analysis approach for classical jets and thermal plumes, the evolution of the coefficients of axial velocity, half-width and turbulence intensity are investigated.