Aircraft ice protection method

• US 7,556,221 B2
• Filed: 06/28/2007
• Issued: 07/07/2009
• Est. Priority Date: 06/28/2006
• Status: Active Grant

• Current Assignee: Goodrich Corporation (Rtx Corporation)
• Original Assignee: Goodrich Corporation (Rtx Corporation)
• Inventors: Deiwert, Kyle H., Putt, James C., Hindel, James T., Dorsey, Michael J.
• Primary Examiner(s): ELDRED, JOHN W
• Application Number:
  US11/769,774
• Publication Number:
  US 20080156937A1
• Time in Patent Office: 740 Days
• Field of Search: 244/134.D, 244/134.B, 244/134.R, 219/200, 219/50, 219/202
• US Class Current: 244/134.00D
• CPC Class Codes: B64D 15/12 by electric heating electric heating elements in general H05B

Abstract

A method of removing a delay-induced ice accumulation (e.g., an ice cap) from an airfoil'"'"'s leading-edge region with a zoned electrothermal device. The method comprises delay-rectifying steps which are performed prior to routine-deicing steps. The delay-rectifying steps comprise continuously heating the parting strip (PS), continuously heating the upper fore zone (UF1), and continuously heating the lower fore zone (LF1). These steps efficiently and effectively remove the delay-induced ice accumulation, whereby routine deicing can be resumed.

Claims

1. A method of protecting an airfoil from undue ice accumulation during flight, said method comprising delay-rectifying steps for removing delay-induced ice accumulation and routine-deicing steps performed after the delay-rectifying steps;

wherein the delay-rectifying steps and the routine-deicing steps are performed by an electrothermal device comprising a parting strip (PS) and at least a first set of spanwise-aligned deicing zones, the parting strip (PS) being positioned to heat the leading edge region of the airfoil, the first zone set comprising an upper fore zone (UF1), a lower fore zone (LF1), an upper aft zone (UA1), and a lower aft zone (LA1);

wherein the delay-rectifying steps comprise;

for a first time period (t1)

continuously heating the parting strip (PS),

continuously heating the first upper fore zone (UF1),

continuously heating the first lower fore zone (LF1),

not heating the first upper aft zone (UA1),

not heating the first lower aft zone (LA1),

wherein the routine-deicing steps comprise;

continuously heating the parting strip (PS),

intermittently heating the first upper aft zone (UA1),

intermittently heating the first lower aft zone (LA1).

2. A method as set forth in claim 1, wherein the routine-deicing steps further comprise:

intermittently heating the first upper fore zone (UF1);

intermittently heating the first lower fore zone (LF1).

3. A method as set forth in claim 1, wherein the electrothermal device further comprises a second set of spanwise-aligned deicing zones, the second zone set comprising an upper fore zone (UF2), a lower fore zone (LF2), an upper aft zone (UA2), and a lower aft zone (LA2);

wherein the delay-rectifying steps further comprise;

for a second time period (t2) after the first time period (t1);

continuously heating the parting strip (PS),

continuously heating the second upper fore zone (UF2),

continuously heating the second lower fore zone (UL2),

not heating the second upper aft zone (UA2),

not heating the second lower aft zone (LA2);

wherein the routine-deicing steps further comprise;

intermittently heating the second upper aft zone (UA2),

intermittently heating the second lower aft zone (LA2).

4. A method as set forth in claim 3, wherein the routine-deicing steps further comprise:

intermittently heating the first upper fore zone (UF1),

intermittently heating the first lower fore zone (LF1),

intermittently heating the second upper fore zone (UF2),

intermittently heating the second lower fore zone (LF2).

5. A method as set forth in claim 3, wherein the delay-rectifying steps further comprise:

during the first time period (t1), not heating the second set of zones (UF2, LF2, UA2, LA2);

during the second time period (t2), not heating the first set of zones (UF1, LF1, UA1, LA1).

6. A method as set forth in claim 5, wherein the routine-deicing steps further comprise:

intermittently heating the first upper fore zone (UF1),

intermittently heating the first lower fore zone (LF1),

intermittently heating the second upper fore zone (UF2),

intermittently heating the second lower fore zone (LF2).

7. A method as set forth in claim 3, wherein the electrothermal device further comprises a third set of spanwise-aligned deicing zones, the third zone set comprising an upper fore zone (UF3), a lower fore zone (LF3), an upper aft zone (UA3), and a lower aft zone (LA3);

wherein the delay-rectifying steps further comprise;

during a third time period (t3) after the second time period (t2),

continuously heating the parting strip (PS),

continuously heating the third upper fore zone (UF3),

continuously heating the third lower fore zone (LF3),

not heating a third upper aft zone (UA3),

not heating a third lower aft zone (LA3);

wherein the routine-deicing steps further comprise;

intermittently heating the third upper aft zone (UA3),

intermittently heating the third lower aft zone (LA3).

8. A method as set forth in claim 7, wherein the routine-deicing steps further comprise:

intermittently heating the first upper fore zone (UF1),

intermittently heating the first lower fore zone (LF1),

intermittently heating the second upper fore zone (UF2),

intermittently heating the second lower fore zone (LF2),

intermittently heating the third upper fore zone (UF3),

intermittently heating the third lower fore zone (LF3).

9. A method as set forth in claim 7, wherein the delay-rectifying steps further comprise:

during the first time period (t1), not heating the second set of zones (UF2, LF2, UA2, LA2) and not heating the third set of zones (UF3, LF3, UA3, LA3);

during the second time period (t2), not heating the first set of zones (UF1, LF1, UA1, LA1) and not heating the third set of zones (UF3, LF3, UA3, LA3);

during the third time period (t3), not heating the first set of zones (UF1, LF1, UA1, LA1) and not heating the second set of zones (UF2, LF2, UA2, LA2).

10. A method as set forth in claim 9, wherein the routine-deicing steps further comprise:

intermittently heating the first upper fore zone (UF1),

intermittently heating the first lower fore zone (LF1),

intermittently heating the second upper fore zone (UF2),

intermittently heating the second lower fore zone (LF2),

intermittently heating the third upper fore zone (UF3),

intermittently heating the third lower fore zone (LF3).

11. A method as set forth in claim 1, wherein the electrothermal device further comprises chordwise strips (IP) isolating adjacent inter-set zones, and wherein these zone-isolating strips (IP) are heated continuously during the routine-deicing steps.

12. A method as set forth in claim 11, wherein the zone-isolating strips (UPS, LPS) are continuously heated during the delay-rectifying steps.

13. A method as set forth in claim 1, wherein the intermittent heatingsteps are performed so three or less zones are intermittently heated at the same time.

14. A method as set forth in claim 13, wherein the intermittent heatingsteps are performed so two or less zones are intermittently heated at the same time.

15. A method as set forth in claim 14, wherein the intermittent heatingsteps are performed so only one zone is intermittently heated at a time.

16. A method as set forth in claim 1, wherein the delay-rectifying time period (t1) is based on an outside air temperature reading.

17. A method as set forth in claim 1, wherein the parting-strip continuously heating steps are performed at a temperature T_delay during delay-rectifying steps and at a temperature T_deicing during routine-deicing steps,

wherein the delay-rectifying temperature T_delay is greater than the routine-deicing temperature T_deicing.

18. A method as set forth in claim 17, wherein the delay-rectifying temperature T_delay is greater than the routine-deicing temperature T_deicing by at least about 30°

F. and/or about 11°

C.

19. A method as set forth in claim 1, wherein the parting strip (PS) has a width of between about 0.5 inch to about 1.0 inch and/or about 12 mm to about 26 mm.