Development of Algorithms for Quantitative Analysis of Long Electrical Arcs in Crossflows

Abstract

A single lightning strike can deliver a steady current of hundreds of amps during its attachment to an aircraft. Therefore, it is imperative to have an adequate lightning protection system in the aircraft to minimize the probability of catastrophic accidents. Current guidelines for lightning protection systems are based on prior service experience and historical data, which might become insufficient with future generation aircraft. These often adopt novel and unconventional aircraft designs, often deviating significantly from current designs. Therefore, efforts are underway to update these guidelines with novel methods such as designs aided by numerical simulation that can accurately model the behavior of lightning attachment and the subsequent swept-stroke phase. To aid in the development of these numerical methods, ample data of not only the electrical arcs but also their interactions with the surrounding flow are necessary for validation. However, most studies on long electrical arcs lack a detailed investigation of the coupling between the electrical arcs and the surrounding flow field. For that purpose, teams from the Massachusetts Institute of Technology (MIT), ONERA, and Universitat Politècnica de Catalunya (UPC) conducted an extensive experimental campaign in April 2024 that investigates this coupling in detail for the first time. Data gathered from this experiment include electrical properties of the arc, high-speed video of the arc column, and the velocity field of the surrounding flow. Approximately 200 cases were conducted with various geometrical and electrical configurations. To meaningfully analyze all the data, a set of algorithms was developed to automatically process, analyze, and visualize these data. Detailed analysis of the root and column behavior was performed; electrical properties were verified to be consistent with literature values; and coupling between the velocities of the arc column and the flow field was determined by simultaneous visualization of both data forms.