Flow visualization and image analysis of gas-phase AC corona discharge induced electrohydrodynamic liquid flow in a stratified fluid

A phenomenon of AC gas-phase needle-plate corona discharge induced electrohydrodynamic (EHD) liquid flow in a stratified fluid has been investigated experimentally. The flow visualization of flow pattern is carried out by a fluorescent dielectric liquid tracer, where the steady EHD liquid motion induced by the corona discharge is presented in visual impressions. The results show that the EHD liquid flow direction on an electrode axis is not from needle to plate electrodes axis when the needle position was above the liquid layer. For the case of the needle electrode tip immersed into the dielectric liquid, it is well known that the dielectric liquid flows in anticlockwise rotation by contraries. The flow velocity distribution is experimentally obtained by a particle image velocimetry with image processing, where the measurement system takes sequential digital images of flow field illuminated by a laser light sheet for computed tomography. The mechanistic model based on interfacial momentum transfer effects on liquid-phase fluid motion is discussed in detail.