Researchers have developed a unique computational model to simulate how lightning could strike an aircraft.
The insights the researchers at the Indian Institute of Science (IISc), Bengaluru, have gleaned from this model can help design better lightning protective measures for aircraft.
Lightning strikes can be dangerous for aircraft.
However, studying this phenomenon in the field is quite difficult.
Lightning strikes can damage the aircraft surface, lead to temporary disruptions in electrical and electronic systems or even cause permanent damage, and in extreme cases, cause ignition of the fuel-air mixture around the engine, leading to an explosion.
“Usually, an aircraft gets struck by lightning once every 1,000 hours,” said Udaya Kumar, Professor at the Department of Electrical Engineering, IISc, whose lab has been investigating this phenomenon in recent years.
“There have been a lot of incidents in the last century where things have been very catastrophic,” said Kumar.
The study has been published in the journal Atmosphere.
According to the study, the first step in protecting aircraft from lightning is identifying the most common regions on the aircraft where lightning can attach or hit.
Kumar and his team realised that current approaches to this identification were grossly oversimplified, and set out to develop a more comprehensive computational model, the study said.
In the usual downward cloud-to-ground lightning, leaders – precursors to lightning arcs – are initiated at the cloud, which propagate towards the ground.
However, field data, as well as the model developed, clearly showed that in more than 90 per cent of the cases, the leader discharges are initiated at the aircraft, the study said.
The model developed by the IISc team is applied to two different aircraft geometries: a DC10 passenger aircraft and the SDM fighter aircraft model. It involves extensive computation of the electric field around the aircraft and suitable modelling of the electrical discharges, the study said.
With the model, the scientists were able to obtain estimates of the minimum ambient electric field required for initiation of lightning leader discharges from the aircraft.
These values, the researchers said, are in good agreement with measured data from instrumented aircraft flown through thunderstorms, such as NASA’s Storm Hazard Program.
Moreover, the aircraft is not perfectly parallel to the ground during take-off and landing, and the model is able to simulate how these changes in orientation can affect the electric field, the study said.
The role of atmospheric conditions such as humidity and air pressure are also taken into account in the model. It also showed that aircraft at higher altitudes had a greater affinity for lightning strikes, the study said.
Kumar’s lab has been studying lightning protection for the past few years.
In the current study as well as in ongoing work, they have focused on modelling how lightning impacts aircraft.
Kumar and his team suggest that such studies can aid in reliable quantification of the lightning threat, and enable optimised design of lightning protective measures.
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