A new electric dipole model for lightning-aircraft electrodynamics

Abstract

Purpose -As commercial and military aircraft continue to be subject to direct lightning flashes, there is a great need to characterize correctly the electrical currents and electric potential fluctuations on an aircraft to determine alternative design approaches to minimizing the severity of the lightning-aircraft dynamics. Moreover, with the increased severity of thunderstorms due to global warming, the need arises even more to predict and quantify electrical characteristics of the lightning-aircraft electrodynamics, which is normally not measurable, using a reliable electric model of the aircraft. Such a model is advanced here. The paper aims to discuss these issues. Design/methodology/approach -The case considered in this paper is that of an aircraft directly attached to an earth flash lightning channel. The paper develops a new approach to modelling the aircraft using electric dipoles. The model has the power to represent sharp edges such as wings, tail ends and radome for any aircraft with different dimensions by using a number of different sized dipoles. The distributed transmission line model (TLM) of the lightning return stroke incorporating the distributed aircraft model is used to determine aircraft electrical elements and finally the electric current induced on the aircraft body due to lightning's interaction with the aircraft. The model is validated by the waveform method and experimental results. Findings -The dipole model proposed is a very powerful tool for minute representation of the different shapes of aircraft frame and to determine the best geometrical shape and fuselage material to reduce electric stress. This charge simulation method costs less computer storage and faster computing time. Originality/value -The paper for the first time presents a computer-based simulation tool that allows scientists and engineers to study the dynamics of voltage and current along the aircraft surface when the aircraft is attached to a cloud to ground lightning channel.

Applying a 3D Dipole Model for Lightning Electrodynamics of Low-Flying Aircraft

“…Note that it is possible to account for the conical radome, sharp tail and wings by using dipoles that gradually decrease in distance d of charge separation. As noted in [12], the dipole model proposed and verified in that paper is a very powerful tool for minute representation of different shapes of aircraft frame to determine the best geometrical shape and fuselage material for reduced electric stress. And because that model has been validated in the laboratory with aircraft models, we feel confident extending its use here in this paper.…”

“…These models are used to simulate and to find the airframe resonances, dynamic currents and charges on the aircraft for studying aircraft-lightning electrodynamics. An electric circuit model which yields results validated when compared to laboratory tests of model aircraft has been recently presented [12] which we extend here through a simple matrix formulation.…”

“…Following the description and methodology in [12], the aircraft's body is subdivided into a number of dipoles, each directed along the z-axis and placed along the y-axis with induced positive charge at the top pole and equivalent negative charge at the bottom of the aircraft fuselage as shown in Figure 1 [12]. The radome, wings and the tail of the aircraft are the most prominent edges to get struck by lightning strikes due to more charges accumulating at these edges.…”

“…The aircraft geometry used in this research simulation model is the Airbus A380 passenger aircraft with a fuselage approximately 72-m long, and 6-m high, the same as in [12]. Following the description and methodology in [12], the aircraft's body is subdivided into a number of dipoles, each directed along the z-axis and placed along the y-axis with induced positive charge at the top pole and equivalent negative charge at the bottom of the aircraft fuselage as shown in Figure 1 [12].…”

“…where e 0 is the permittivity of air; A Cyl is the surface area of the cylindrical Gaussian surface of diameter 200 m and height 500 m; d dis is the distance between the dipole segments on the aircraft surface; d sep is the length of the dipoles which is the height of the aircraft; A altop is the distance from ground to the top of the aircraft; D i self is the surface area of line charge forming the dipole on the aircraft surface; V Cl is the cloud voltage which is assumed to be a negative flash of ¡50 MV [12]; and V is the unknown aircraft potential we seek.…”