Effect of an upstream charge on flow electrification mechanisms of dielectric liquids

When the electric charge induced at the electrical double layer of a solid/liquid interface is transported by a liquid flow, a phenomenon known as flow electrification occurs and creates new charge to balance the interface´s electrical neutrality. In the context of an aircraft fuel tank being filled, this phenomenon is a generation source of electric charge on the tank wall. This charge is likely to accumulate if it is generated more efficiently at the walls than it relaxes to an electrical ground via an electrical path. In metallic fuel tanks, the charge relaxation is favored over the accumulation. However, the introduction of composite materials with different dielectric multilayers in the construction of future aircraft fuel tanks tends to reduce the relaxation of the charge and amplify the generation. Furthermore, the passage of the fuel through the upstream complex hydraulic and filtering circuits electrically charges the fuel before it enters the tank. This paper consists in analyzing the effects of an upstream charged liquid on the mechanisms of charge generation occurring at a downstream solid/liquid interface. This analysis is based on recent experimental observations for several solid/liquid couples within both cylindrical and rectangular laminar flow conditions.