Method and device for detecting rime and/or rime conditions on a flying aircraft

• US 8,485,473 B2
• Filed: 04/09/2008
• Issued: 07/16/2013
• Est. Priority Date: 04/11/2007
• Status: Active Grant

• Current Assignee: Safran Aerotechnics SAS (Safran SA)
• Original Assignee: Intertechnique (Safran SA)
• Inventors: Picco, Nicolas, Thillays, Bruno, Portier, Philippe, Larue, Francois
• Primary Examiner(s): Dinh, Tien
• Assistant Examiner(s): Hawk, Steven
• Application Number:
  US12/594,822
• Publication Number:
  US 20100116940A1
• Time in Patent Office: 1,924 Days
• Field of Search: 244/134.R, 244/134.D, 244/134.F, 731/702.6, 731/700.2, 731/701.2
• US Class Current: 244/134.F
• CPC Class Codes: B64D 15/20 Means for detecting icing or initiating de-icing
• CPC Class Codes: G08B 19/02 Alarm responsive to formation or anticipated formation of ice

Abstract

According to the invention, the method comprises exposing a surface (3) sensitive to relative wind and monitoring the thermal flow variations between the surface (3) and the aerodynamic flow, said variations resulting from that of the forced-convection thermal exchange coefficient between the surface (3) and the aerodynamic flow depending on the rime or ice build-up, using the temperature sensor (12) under the surface (3), considering that stripping occurs by the flow of an ice layer formed on the surface (3) if it is detected, preferably after heating by at least one heater (4), that there is a brisk rise of the flow at a temperature close to 0° C., and supplying after the detection of ice stripping, a signal indicating the presence of rime or rime conditions. A cooler (5) may cool the surface (3) for anticipating the formation of ice with a heating process. The invention can be used for detecting rime and/or rime conditions on a flying aircraft.

Claims

1. A method of detecting frost and/or frosty conditions on an aircraft in flight, on which at least one free external surface, exposed to an aerodynamic flow around the aircraft, on a skin of one of the aircraft a probe projecting from the aircraft into the aerodynamic flow, is reserved as a detection-sensitive surface, on which a build-up of frost or ice is likely to be formed in flight in frosty conditions, the method including at least one cycle with at least the following steps, comprising:

monitoring variations of a thermal flux between said sensitive surface and the aerodynamic flow, which are caused by variations of a forced convection thermal exchange coefficient between said sensitive surface and the aerodynamic flow according to a build-up of frost or ice,

considering that the aerodynamic flow has caused a film of frost or ice formed on said sensitive surface to tear off if, after a time interval during which a slow or substantially zero reduction of said thermal flux is observed, an abrupt increase is detected in said thermal flux at a temperature close to the melting point of the frost or ice, and

following a detection of a tearing-off of frost or ice, delivering a signal indicating the presence of frost or frosty conditions.

2. The method as claimed in claim 1, also comprising at least one step of heating said sensitive surface by placing said sensitive surface in a thermal exchange relationship with at least one heater, so as to provoke at least a partial melting of a film of frost or ice that may be formed on said sensitive surface, during at least one prior frost or ice build-up phase.

3. The method as claimed in claim 2, wherein at least one step of heating said sensitive surface is used to defrost said sensitive surface, at least following an at least partial tearing-off of said film of frost or ice that covered said sensitive surface.

4. The method as claimed in claim 2, wherein said heating step or a last one of several heating steps is followed by a final step, which is a cooling step, enabling a faster return than by natural cooling to an appropriate temperature as an initial temperature to begin a next cycle.

5. The method as claimed in claim 1, also including a first step, which is a step of overcooling said sensitive surface, relative to the natural balance temperature, by placing said sensitive surface in a thermal exchange relationship with at least one cooler, so as to favor the formation of frost or ice on said sensitive surface in near-frosty conditions.

6. The method as claimed in claim 5, including at least one succession of at least two cycles, at least one of which comprises at least one overcooling step followed by at least one heating step, followed in turn by at least one step of cooling said sensitive surface, so as to anticipate and then detect a formation of frost or ice by detecting a tearing-off of said frost or ice, and regenerate said sensitive surface and then return the said sensitive surface to temperature conditions more favorable to the progress of a next cycle.

7. The method as claimed in claim 1, wherein a trend of said thermal flux is determined from a thermal power generated to produce said thermal flux and temperature measurements using at least one temperature sensor positioned under said sensitive surface, and by monitoring modifications of a temperature profile of said sensitive surface.

8. The method as claimed in claim 7, wherein said modifications of said temperature profile are determined by calculating a time drift of a temperature deviation or a temperature.

9. The method as claimed in claim 7, comprising a substantially continuous time tracking of a trend of the temperature of said sensitive surface, and a delivery of a signal indicating a tearing-off of frost or ice, previously deposited on said sensitive surface, said signal resulting from a detection of at least one break in the slope of a temperature curve, resulting from said time tracking.

10. The method as claimed in claim 9, further comprising at least one measurement of the duration of a level at substantially 0°

C. on said temperature curve, so as to obtain a signal indicating the severity of frosty conditions, because said duration of said level is all the longer when the thickness of a film of deposited ice or frost is thick.

11. The method as claimed in claim 2, further comprising controlling the duration of a frost or ice build-up phase prior to any heating step, said control consisting in gradually reducing the duration of said build-up phase during successive cycles, until disappearance of a detection signal is observed, to a detection limit corresponding to the longest duration of said build-up phase without obtaining a deposit of frost or ice on said sensitive surface, because frosty conditions are all the more severe when said limit duration is short.

12. The method as claimed in claim 1, using reference information comprising at least measurements of the speed of the aircraft, of total temperature and/or of static temperature, supplied by the aircraft and/or another onboard device on or in the aircraft.