Method and apparatus of detecting liquid water in a cloud

Patent metadata

Field	Value
Publication number	US-10343783-B2
Application number	US-201715423296-A
Country	US
Kind code	B2
Filing date	Feb 2, 2017
Priority date	Apr 28, 2016
Publication date	Jul 9, 2019
Grant date	Jul 9, 2019

Abstract

Apparatus and associated methods relate to determining liquid-water concentration in a cloud atmosphere based on a frequency of resonance of a magnetostrictive resonator and/or a temporal variation of the resonant frequency of the magnetostrictive resonator. The magnetostrictive resonator is configured to resonate at a resonant frequency indicative of a measure of ice accumulation upon an exterior surface of the magnetostrictive resonator. When in liquid-water ambient, however, the magnetostrictive resonator has a resonant frequency less than a baseline resonant frequency. When in the liquid-water ambient, the magnetostrictive resonator also has temporal variations in resonant frequency that exceed one part in ten thousand. Using one or both of these resonant-frequency responses to liquid-water ambient, a signal indicative of liquid-water content can be generated.

First claim

The invention claimed is:

1. A cloud phase detector comprising:
a magnetostrictive resonator having a baseline resonant frequency in an ice-free and liquid-water-free condition, the magnetostrictive resonator configured to resonate at a resonant frequency indicative of a measure of ice accretion upon an exterior surface of the magnetostrictive resonator;
a processor; and
computer-readable memory encoded with instructions that, when executed by the processor, cause the cloud phase detector to:
detect the resonant frequency of the magnetostrictive resonator;
detect temporal variations of the resonant frequency of the magnetostrictive resonator; and
generate a signal indicative of liquid-water content if either the detected resonant frequency is a first threshold less than the baseline resonant frequency or the detected temporal variations of the resonant frequency are greater than a second threshold.

2. The cloud phase detector of claim 1 , further comprising:
a temperature sensor configured to generate a signal indicative of a temperature of an exterior surface of the cloud phase detector.

3. The cloud phase detector of claim 2 , further comprising:
a digital communications interface configured to receive digital communications from an aircraft instrumentation bus, the received digital communications including a signal indicative of airspeed of an aircraft and a signal indicative of an angle of attack of the aircraft,
wherein the computer-readable memory is further encoded with instructions that, when executed by the processor, cause the cloud phase detector to:
calculate, based on the received signals of the airspeed and the angle of attack as well as the signal indicative of the temperature, one or more critical temperatures corresponding to one or more surface locations on the aircraft, respectively, the one or more critical temperatures indicative of a temperature below which a portion of the liquid-water content can freeze on the one or more corresponding surface locations.

4. The cloud phase detector of claim 3 , wherein the computer-readable memory is further encoded with instructions that, when executed by the processor, cause the cloud phase detector to:
calculate, based on the received signals of the airspeed and the angle of attack as well as the signal indicative of the temperature, one or more Ludlam temperatures corresponding to one or more surface locations on the aircraft, respectively, the one or more Ludlam temperatures indicative of a temperature below which all of the liquid-water content can freeze on the one or more respective surface locations.

5. The cloud phase detector of claim 1 , wherein the computer-readable memory is further encoded with instructions that, when executed by the processor, cause the cloud phase detector to:
generate a signal indicative of the liquid-water content if both the detected resonant frequency is the first threshold less than the baseline resonant frequency and the detected temporal variations of the resonant frequency are greater than the second threshold.

6. The cloud phase detector of claim 1 , wherein the computer-readable memory is further encoded with instructions that, when executed by the processor, cause the cloud phase detector to:
generate a signal indicative of a rate of the ice accretion, the signal indicative of the rate of the ice accretion based on a slope of the detected resonant frequency with respect to time.

7. The cloud phase detector of claim 6 , wherein the computer-readable memory is further encoded with instructions that, when executed by the processor, cause the cloud phase detector to:
generate a signal indicative of the liquid-water content, the generated signal indicative of the liquid-water content based on the slope of the detected resonant frequency with respect to time.

8. The cloud phase detector of claim 1 , wherein the computer-readable memory is further encoded with instructions that, when executed by the processor, cause the cloud phase detector to:
generate a signal indicative of the liquid-water content if either the detected resonant frequency is at least three ten thousandths the baseline resonant frequency less than the baseline resonant frequency and the detected temporal variations of the resonant frequency are greater than two ten thousandths of the baseline resonant frequency.

9. A liquid-water content calculator comprising:
a magnetostrictive resonator having a baseline resonant frequency in an ice-free and liquid-water-free condition, the magnetostrictive resonator configured to resonate at a resonant frequency indicative of a measure of ice accretion on an exterior surface of the magnetostrictive resonator;
an airspeed indicator configured to detect airspeed of an aircraft;
an angle-of-attack sensor configured to detect an angle of attack of the aircraft;
a processor; and
computer-readable memory encoded with instructions that, when executed by the processor, cause the liquid-water content calculator to:
detect the resonant frequency of the magnetostrictive resonator;
detect an ambient temperature;
detect temporal variations of the resonant frequency of the magnetostrictive resonator; and
generate a signal indicative of liquid-water content if either the detected resonant frequency is a first threshold less than the baseline resonant frequency or the detected temporal variations of the resonant frequency are greater than a second threshold; and

calculate, based on the detected airspeed, the detected angle of attack, the detected ambient temperature, the detected resonant frequency, and the detected temporal variations of the resonant frequency, one or more critical temperatures corresponding to one or more locations on an aircraft surface, respectively, the one or more critical temperatures indicative of a temperature below which a freezing fraction of the liquid-water content is greater than zero.

10. The liquid-water content calculator of claim 9 , wherein the computer-readable memory is further encoded with instructions that, when executed by the processor, cause the liquid-water content calculator to:
calculate, based on the received signals of the airspeed and the angle of attack as well as the signal indicative of the temperature, one or more Ludlam temperatures corresponding to one or more surface locations on the aircraft, respectively, the one or more Ludlam temperatures indicative of a temperature below which all of the liquid-water content can freeze on the one or more corresponding surface locations.

11. The liquid-water content calculator of claim 10 , wherein the computer-readable memory is further encoded with instructions that, when executed by the processor, cause the liquid-water content calculator to:
generate a signal indicative of liquid-water content if both of the detected resonant frequency is less than the baseline resonant frequency and the detected temporal variations of the resonant frequency are greater than one ten thousandth of the baseline resonant frequency.

12. The liquid-water content calculator of claim 9 , wherein the computer-readable memory is further encoded with instructions that, when executed by the processor, cause the liquid-water content calculator to:
generate a signal indicative of a rate of the ice accretion, the signal indicative of the rate of the ice accretion based on a slope of the detected resonant frequency with respect to time.

13. The liquid-water content calculator of claim 12 , wherein the computer-readable memory is further encoded with instructions that, when executed by the processor, cause the liquid-water content calculator to:
generate a signal indicat

Assignees

• Rosemount Aerospace Inc

Inventors

• Jackson Darren G

Classifications

• G01N29/4436

  with a reference signal (amplitude comparison G01N29/48) · CPC title

• G01N2291/2694

  Wings or other aircraft parts · CPC title

• G01N33/0036

  specially adapted to detect a particular component (physical analysis of gaseous biological material G01N33/497) · CPC title

• B64D15/22 Primary

  Automatic initiation by icing detector · CPC title

• G01N29/2412

  using the magnetostrictive properties of the material to be examined, e.g. electromagnetic acoustic transducers [EMAT]; (investigating the presence of flaws using eddy currents G01N27/90, magnetostrictive transducers B06B1/08, measuring magnetostrictive properties G01R33/18) · CPC title