In this study, a proposed method for selecting a tracer for PIV measurement in EHD flows was developed. To begin with, several published studies were identified that exploit different tracers; such as oil smoke, cigarette smoke, and TiO 2. An assortment of tracers was then selected based on comparisons with conventional dimensionless numbers; Stokes number (St), Archimedes number (Ar) and electrical mobility ratio (M). Subsequently, an experimental study for testing tracers was developed, which enabled the velocity profile of an ionic wind generated by a needle/ring configuration to be measured. Air velocity measurements carried out with a Pitot tube, considered as the reference measurements, were compared to PIV measurements for each tracer. In addition, the current-voltage curves and the evolution of the current during seeding were measured. All the experimental results show that TiO 2 , SiO 2 microballoons and incense smoke are the ideal tracers in the series of tracers investigated.

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