Anti-icing, de-icing, and heating configuration, integration, and power methods for aircraft, aerodynamic, and complex surfaces
Anti-icing methods and aerodynamic structures having laminated resistive heaters for de-icing are described. Several of the inventive aspects utilize laminated resistive heaters comprising a carbon nanotube layer and/or capacitors to store and supply electricity. The invention also includes methods of making aerodynamic structures having de-icing or anti-icing functionality.
1. An airfoil, comprising: a channel in a surface of the airfoil wherein a surface of the channel is coated with an electrical insulator and an electrical lead is disposed in the channel;
wherein the electrical insulator electrically insulates the airfoil from the electrical lead; wherein the electrical insulator does not completely surround the electrical lead over the length of the channel;
wherein the electrical insulator is open on top of the channel area allowing for the electrical lead to contact a CNT-containing resistive heating layer, and wherein the CNT-containing resistive heating layer contacts the electrical lead in the channel; and
further comprising a second electrical lead in electrical contact with the CNT-containing resistive heating layer; wherein the CNT-containing resistive heating layer is disposed between the electrical leads and wherein, during operation, the electrical leads power the CNT-containing resistive heating layer.
2. The airfoil of claim 1 wherein the airfoil is a wing and wherein the electrical leads pass through a via in the skin of the wing and wherein the electrical leads are completely encased in the electrical insulator through the via that passes through the skin and connects to the channel.
3. The airfoil of claim 1 where the electrical insulator is made from a flexible plastic.
4. The airfoil of claim 1 wherein the channel allows for the electrical leads to remain flush with the surface when installed so as not to disrupt the aerodynamic properties of the airfoil.
5. The airfoil of claim 1 wherein the electrical insulator completely encases the electrical leads where they pass through a hole in the wing.
6. The airfoil of claim 1 wherein the electrical leads are porous which allows for capillary action to draw a CNT-fluid into contact with the lead improving the bond between carbon nanotubes and the electrical leads.
7. The airfoil of claim 1 where the electrical insulator is open on top of the channel area allowing for the electrical leads to contact with the CNT heater layer along a length of at least 10 cm.
8. The airfoil of claim 6 wherein the electrical leads comprise copper mesh or braided copper wires.
9. The airfoil of claim 1 further comprising a coating disposed over the CNT heating layer; wherein the coating has a thickness of 2 mm or less.
10. The airfoil of claim 2 wherein the CNT-containing resistive heating layer comprises at least 25 weight percent CNTs.
11. The airfoil of claim 2 wherein the CNT-containing resistive heating layer comprises 5 weight percent or less of a polymer.
12. The airfoil of claim 1 wherein the CNT-containing resistive heating layer has a thickness in the range of 0.05 μm to 100 μm.
13. The airfoil of claim 12 wherein the CNT-containing resistive heating layer has a sheet resistance of less than 500 Ω/square.
14. The airfoil of claim 1 wherein the channel is a first channel recessed in the surface of the airfoil; and
further comprising a second channel recessed in the surface of the airfoil wherein the surface of the second channel is coated with a second electrical insulator and the second electrical lead is disposed in the second channel;
wherein the second electrical insulator electrically insulates the airfoil from the second electrical lead; wherein the second electrical insulator does not completely surround the second electrical lead over the length of the second channel; and
wherein the CNT-containing resistive heating layer extends between an exposed surface of the first electrical lead in the first channel and an exposed surface of the second electrical lead in the second channel.
15. The airfoil of claim 14 wherein the first channel and the second channel each have rectangular cross-sections perpendicular to the channel length.
16. The airfoil of claim 15 comprising a polymer coating overlying the CNT heater layer and wherein the CNT-containing resistive heating layer comprises 10 mass % or less of the coating polymer.
17. The airfoil of claim 15 wherein the electrical leads have a rectangular cross-section and wherein the electrical insulator surrounds the electrical lead on three sides and is open on one side where they contact the CNT-containing resistive heating layer.