Ice crystals and volcanic ash detection system

• US 10,336,465 B2
• Filed: 01/05/2017
• Issued: 07/02/2019
• Est. Priority Date: 01/08/2016
• Status: Active Grant

• Current Assignee: Board of Regents of the University of Michigan (University of Michigan)
• Original Assignee: Board of Regents of the University of Michigan (University of Michigan)
• Inventors: Renno, Nilton O.
• Primary Examiner(s): Chowdhury, Tarifur R
• Assistant Examiner(s): Nixon, Omar H
• Application Number:
  US15/399,088
• Publication Number:
  US 20170197728A1
• Time in Patent Office: 908 Days
• Field of Search: 356432
• CPC Class Codes: B64D 15/20 Means for detecting icing or initiating de-icing
• CPC Class Codes: B64D 15/22 Automatic initiation by icing detector
• CPC Class Codes: B64D 43/00 Arrangements or adaptations of instruments arrangements of cameras B64D47/08; aeronautical measuring instruments per se G01C
• CPC Class Codes: B64D 45/00 Aircraft indicators or protectors not otherwise provided for camouflage F41H3/00
• CPC Class Codes: G01N 2021/1793 Remote sensing
• CPC Class Codes: G01N 2021/1795 Atmospheric mapping of gases
• CPC Class Codes: G01N 21/35 using infrared light G01N21/39 takes precedence
• CPC Class Codes: G01N 21/41 Refractivity; Phase-affecting properties, e.g. optical path length G01N21/21 takes precedence
• CPC Class Codes: G01N 2201/12 Circuits of general importance; Signal processing
• CPC Class Codes: G01N 33/0036 Specially adapted to detect a particular component all the other sub-groups of G01N33/0004 take precedence
• CPC Class Codes: G01N 33/0055 for radionuclides
• CPC Class Codes: G01T 1/178 for measuring specific activity in the presence of other radioactive substances, e.g. natural, in the air or in liquids such as rain water
• CPC Class Codes: G01V 8/12 using one transmitter and one receiver
• CPC Class Codes: G01V 9/007 by detecting gases or particles representative of underground layers at or near the surface analysing earth materials G01N33/24; analysing gases per se G01N
• CPC Class Codes: Y02A 50/20 Air quality improvement or preservation, e.g. vehicle emission control or emission reduction by using catalytic converters

Abstract

Methods and systems for detecting ice crystals and volcanic ash in concentrations capable of causing power loss in aircraft jet engines. These hazard conditions are inferred from the detection of ice crystals or ash in air recently lifted from the lower atmosphere by convective updrafts. The detection systems can comprise subsystems for detecting air recently lifted from the lower troposphere by measuring radon activity along the aircrafts'"'"' flight track, as well as subsystems for detecting ice crystals or volcanic ash around the aircraft via multispectral measurements. The detection of ice crystals in air recently lifted from the lower troposphere indicates that the ice crystals are likely present in large concentration. The detection of volcanic ash in air recently lifted from lower atmosphere also indicates that volcanic ash is likely present in high concentration. These are hazards conditions that could cause power loss, jet engine flameout, and even damage jet engines.

Claims

1. A system for detecting ice crystals and/or volcanic ash in an airspace of interest along a flight path of an airborne vehicle, the system comprising:

a probe configured to collect an air sample in the airspace of interest;

a radon detection system having a radon activity sensor measuring radon activity in the air sample and outputting a radon activity signal;

a processing unit configured to determine if the radon activity is above a predetermined critical radon value for the airspace of interest, the predetermined critical radon value being greater than a non-convective background level for the airspace of interest, the processing unit configured to compare the radon activity signal to the predetermined critical value and output a radon determination signal indicative of recent convective updraft from lower troposphere;

a spectral detection system configured to determine if ice crystals and/or volcanic ash are present in the airspace of interest when the radon activity is above the predetermined critical radon value and output an ice/ash detection signal, the spectral detection system having an optical sensor configured to measure radiance, emittance, and/or reflectance at spectral bands of interest on opposing sides of at least one crossover point in the airspace of interest; and

the processing unit configured to determine a ratio of the measured radiance, emittance, and/or reflectance at the spectral bands and if the ratio is above a predetermined critical ratio value output an ice/ash determination signal indicative of the presence of ice crystals and/or volcanic ash in the airspace of interest.

2. The system according to claim 1, further comprising:

a data display system displaying an indicia in response to the determination signal.

3. The system according to claim 1, further comprising:

a system of an aircraft configured to be responsive to the determination signal.

4. The system according to claim 1, further comprising:

a flight control system of an aircraft configured to be responsive to the determination signal.

5. The system according to claim 1, further comprising:

a light source outputting light energy at the spectral bands of interest, the light source illuminating the area of interest.

6. The system according to claim 5 wherein the spectral bands of interest are in the range of about 2.05 μ

m to about 2.30 μ

m.

7. The system according to claim 5 wherein the light source is selected from the group consisting of a laser, halogen light, infrared light, and light-emitting diode.

8. A method for detecting ice crystals and/or volcanic ash in an airspace of interest along a flight path of an airborne vehicle, the method comprising:

measuring radon activity A in an airspace in which an aircraft is flying;

determining if the radon activity A is above a predetermined critical radon value A_crit for the airspace of interest, the predetermined critical radon value being greater than a non-convective background level for the airspace of interest,

if the radon activity A is above the predetermined critical radon value (A≥

A_crit) then producing a radon determination signal indicative of recent convective updraft from lower troposphere has been detected,

if the radon activity A is above the predetermined critical radon value (A≥

A_crit) then measuring radiance, emittance, and/or reflectance at spectral bands of interest on opposing sides of at least one crossover point in the airspace of interest and determining a ratio of the measured radiance, emittance, and/or reflectance at the spectral bands, and

if the ratio above a predetermined critical ratio value then output an ice/ash determination signal indicative of the presence of ice crystals and/or volcanic ash in the airspace of interest.

9. The method according to claim 8, wherein the measuring radiance, emittance, and/or reflectance at spectral bands of interest on opposing sides of at least one crossover point in the airspace of interest and determining a ratio of the measured radiance, emittance, and/or reflectance at the spectral bands comprises:

measuring a first radiance of the airspace of interest at a first spectral band on a first side of the crossover point (R<sub>λ

1</sub>);

measuring a second radiance of the airspace of interest at a second spectral band on a second opposing side of the crossover point (R<sub>λ

2</sub>); and

calculating the ratio of the first radiance and the second radiance (γ

=R<sub>λ

1</sub>/R<sub>λ

2</sub>.