Plasma-induced unconventional shock waves on oil surfaces

Abstract

Electric corona discharge in a multi-phase system results in complex electro-hydrodynamic phenomena. We observed unconventional shock wave propagation on an oil thin film sprayed over a polymer-coated conductor. A hair-thin single shock wave arose when the high voltage bias of an overhung steel needle was abruptly removed. However, such solitary waves possess neither interference nor reflection properties commonly known for ordinary waves, and also differ from the solitons in a canal or an optical fiber. We also observed time-retarded movement for dispersed oil droplets at various distances from the epicenter which have no physical contact, as if a wave propagating on a continuous medium. Such a causality phenomenon for noncontact droplets to move resembling wave propagation could not be possibly described by the conventional surface wave equation. Our systematic studies reveal a mechanism involving oil surface charges driven by reminiscent electric fields in the air when the needle bias is suddenly removed.

Time resolved study of ignition of microwave discharge in liquid hydrocarbons

“…It is known that shock waves arise in discharges during electric breakdown. [24][25][26][27][28][29][30] Sound vibrations lead to the mixing of gas components in the space over the surface of the liquid.…”

Generation and Transport of Dielectric Droplets along Microchannels by Corona Discharge

“…The flow generated is generally referred to as electric wind or ion wind. Various patterns of three-dimensional electroconvective flow induced by ion wind in dielectric liquids have been investigated [15][16][17][18][19], especially the regular static cell structures [15,20,21]. At the same time, a number of previous reports refer this to the directional driving of the electric wind exerting upon the dielectric fluid [13,22].…”

Directional motion of dielectric droplets on polymer-coated conductor driven by electric corona discharge

“…21 One of the EHD effects is the electric wind caused by corona discharge. This phenomenon observed for several centuries has induced a variety of possible applications today and even showed a peculiar phenomenon, 22 including flow enhancement, 23 heat transfer enhancement, 24 drying and evaporation, 25 and fluid pumps. 26 These applications and studies focused on a continuous fluid, and only a small number refers to the liquid droplet.…”