Carbon nanotube-based anti-icing coating proves itself in wind tunnel testing
There are numerous types of systems designed to prevent ice forming on aircraft surfaces during flight. Some reroute hot air produced by jet engines, others generate their own heat, others knock ice off through mechanical force, while others still release antifreeze chemicals onto the wing. Battelle has recently tested its carbon nanotube-base HeatCoat technology that it claims is lighter and less power hungry than such systems. It also has no moving parts and could easily be retrofitted to existing aircraft.
We've seen a number of new technologies that take differing approaches to the problem of de-icing. The first involves the use of superhydrophobic surfaces that repel water so effectively that even tiny drops of condensation or frost slide off and prevent ice sheets building up. The second involves using carbon nanotubes to heat the aircraft surface, which is the approach that Battelle researchers have taken with the HeatCoat system.
Designed for unmanned aerial vehicles (UAVs), but potentially for use in larger aircraft, the HeatCoat technology consists of a series of layers that can be sprayed onto the aircraft surface like paint or applied as a laminate sheet. The first layer is a primer coating, followed by the heater coating that is made up of carbon nanotubes. This is topped off by a barrier coating and an outer top coating.
When power is applied to the heater layer, heat is generated to prevent ice forming. An intelligent controller on the aircraft monitors the performance of the heater layer so that the power level, and the heat being generated, is altered dynamically to ensure the minimum amount of power level for the current conditions.
Battelle claims its system is lighter than traditional ice protection systems, has lower power requirements and is also less complex. While such attributes should be attractive to operators of manned aircraft, they are necessities for use on UAVs, in which payload and power capabilities are clearly limited.
The Battelle team recently applied the HeatCoat technology to representative wing and engine inlet test samples and subjected them to temperatures as low as -22° F (-30° C) and air speeds of up to 182 knots (337 km/h, 209 mph) in a research aero-icing tunnel. The organization says that the coating successfully performed anti-icing and de-icing functions over a four-day demonstration and testing period.
"Battelle has made a long term investment in this technology because we think it is so promising," said Ron Gorenflo, HeatCoat Systems Product Manager. "Our recent tests validated improvements we’ve made and prove that we are ready to go from a Technology Readiness Level (TRL) 6 on to a TRL 7 once we identify a key partner to help complete the next step of this process."
The video below illustrates how the HeatCoat system works.
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