Apparatus and method for detecting water or ice

Apparatus for detecting the presence of water or ice on a surface of a structure, the structure having a surface exposable to an impinging airflow, the apparatus comprising:

• a plurality of heaters coupleable to the structure exposable to an impinging airflow, the plurality of heaters being arranged adjacent one another from a region of a leading edge of the structure and extending aft of the leading edge of the structure;
• a plurality of temperature sensors each thermally coupled to a respective heater of the plurality of heaters for sensing the temperature of the respective heater and for outputting a respective temperature signal;
• a controller coupled to the heaters and the temperature sensors, for controllably applying power to the respective heaters and for receiving the respective temperature signals, the controller being configured to:
• supply each of the respective heaters with a respective power, each of the respective powers being sufficient to heat a surface of the structure at each of the respective regions associated with the respective heaters to substantially the same surface temperature;
• sense a first power being supplied to a first heater and sensing a second power being supplied to a second heater, the first heater being aft of the fore-most heater, and the second heater being fore of the aft-most heater;
• compare the first and second powers consumed by the respective first and second heaters;
• and
• detect the presence of water or ice on the surface of the structure based on the comparison of the first and second powers consumed by the respective first and second heaters, wherein water or ice is detected when the power consumed by the first heater is different to the power consumed by the second heater.

A controller for detecting the presence of water or ice on a surface of a structure, the structure having a surface exposable to an impinging airflow, and the structure having a plurality of heaters in thermal contact therewith, the plurality of heaters being arranged adjacent one another from a region of a leading edge of the structure and extending aft of the leading edge of the structure, the controller comprising:

• a plurality of outputs each being adapted to supply power respectively to a heater from the plurality of heaters, the plurality of heaters being thermally coupleable to a region of the structure exposable to an impinging airflow;
• and
• a plurality of inputs each being adapted to receive a temperature sensor signal from a respective temperature sensor, each of a plurality of temperature sensors being thermally coupleable to a respective heater of the plurality of heaters for sensing the temperature of the respective heater;
• the controller being configured to:
• supply each of the respective heaters with a respective power, each of the respective powers being sufficient to heat a surface of the structure at each of the respective regions associated with the respective heaters to substantially the same surface temperature;
• sense a first power being supplied to a first heater and sense a second power being supplied to a second heater, the first heater being aft of the fore-most heater, and the second heater being fore of the aft-most heater;
• compare the first and second powers consumed by the respective first and second heaters;
• and
• detect the presence of water or ice on the surface of the structure based on the comparison of the first and second powers consumed by the respective first and second heaters, wherein water or ice is detected when the power consumed by the first heater is different to the power consumed by the second heater.