Background-oriented schlieren measurement of near-surface density field in surface dielectric-barrier-discharge

Surface dielectric-barrier-discharge (DBD) is widely utilized for flow control actuators called DBD plasma actuator (DBDPA). With the aim of ensuring an accurate background-oriented schlieren (BOS) measurement of the near-surface density field in surface DBD, we investigate the effects of the depth of field (DoF), the wall surface and the background image deformation on measurement results. Experiments using a glass plate as the measurement target reveal that there is no appreciable effect of whether the DoF includes the measurement target. Additionally, the DoF should be shallow from the viewpoint of the error introduced by the wall surface. Moreover, it is found that the error introduced by the wall surface and the dot deformation can be characterized by specific dimensionless parameters. Finally, we conduct the BOS measurement of the DBDPA. We confirm that the density field is qualitatively valid from a physical respect, and we present the density field while discussing specific measurement errors.