Classifications

• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
  • G01N15/00—Investigating characteristics of particles; Investigating permeability, pore-volume or surface-area of porous materials
  • G01N15/10—Investigating individual particles
  • G01N15/14—Optical investigation techniques, e.g. flow cytometry
  • G01N15/1434—Optical arrangements
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B64—AIRCRAFT; AVIATION; COSMONAUTICS
  • B64D—EQUIPMENT FOR FITTING IN OR TO AIRCRAFT; FLIGHT SUITS; PARACHUTES; ARRANGEMENT OR MOUNTING OF POWER PLANTS OR PROPULSION TRANSMISSIONS IN AIRCRAFT
  • B64D15/00—De-icing or preventing icing on exterior surfaces of aircraft
  • B64D15/20—Means for detecting icing or initiating de-icing
• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01K—MEASURING TEMPERATURE; MEASURING QUANTITY OF HEAT; THERMALLY-SENSITIVE ELEMENTS NOT OTHERWISE PROVIDED FOR
  • G01K11/00—Measuring temperature based upon physical or chemical changes not covered by groups G01K3/00, G01K5/00, G01K7/00 or G01K9/00
• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
  • G01N15/00—Investigating characteristics of particles; Investigating permeability, pore-volume or surface-area of porous materials
  • G01N15/10—Investigating individual particles
  • G01N15/14—Optical investigation techniques, e.g. flow cytometry
  • G01N15/1429—Signal processing
  • G01N15/1433—Signal processing using image recognition
• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
  • G01S17/00—Systems using the reflection or reradiation of electromagnetic waves other than radio waves, e.g. lidar systems
  • G01S17/88—Lidar systems specially adapted for specific applications
  • G01S17/95—Lidar systems specially adapted for specific applications for meteorological use
• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
  • G01N15/00—Investigating characteristics of particles; Investigating permeability, pore-volume or surface-area of porous materials
  • G01N15/10—Investigating individual particles
  • G01N15/14—Optical investigation techniques, e.g. flow cytometry
  • G01N15/1434—Optical arrangements
  • G01N2015/1447—Spatial selection
  • G01N2015/145—Spatial selection by pattern of light, e.g. fringe pattern
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
  • Y02A—TECHNOLOGIES FOR ADAPTATION TO CLIMATE CHANGE
  • Y02A90/00—Technologies having an indirect contribution to adaptation to climate change
  • Y02A90/10—Information and communication technologies [ICT] supporting adaptation to climate change, e.g. for weather forecasting or climate simulation

Definitions

• the present description relates to the field of the physical and thermochemical characterization of a mist of droplets of dimensions between 1 and 500 ⁇ , in particular for quality control applications in industrial processes using liquid particle streams, particularly in the agri-food, cosmetic or pharmaceutical or icing detection field.
• a first area of application concerns quality control.
• the aim is to verify in real time the constancy of the thermochemical and physical characteristics of the liquid particles, in particular the consistency of the temperature of the liquid particles in a fog or in a misting as well as the constancy of the chemical nature of the liquid particles and the dispersion of the particles. particle sizes.
• a second area of application concerns the detection of icing conditions and, in particular, icing conditions for equipment, in particular an aircraft.
• aircraft icing can occur when atmospheric conditions result in ice formation on aircraft surfaces. In addition, this ice can also occur in the engine. The formation of ice on aircraft surfaces, engine entrances and other locations is undesirable and potentially dangerous for the use of the airplane.
• frost is a dangerous phenomenon for aircraft, taken into account on the ground as well as in flight. It has been observed in recent years that during altitude flight, this phenomenon was more frequent, perhaps due to climate change and certainly the increase in air traffic in regions of the world where the climate is favorable for the formation of air traffic. Frost at altitude.
• Frost presents a danger first of all for the engine of the aircraft. It can be formed at the compressor inlet. If the ice builds up and breaks, it can damage the engine. Frost is also likely to accumulate on certain parts of the cell: wing attack, fuselage, empennage, cockpit, etc. This accumulation can result in the increase of the mass of the aircraft and the alteration of the aerodynamics which can cause the stall of the aircraft. On fins and flaps the formation of ice can reduce their navigability; on the cockpit, visibility will be reduced.
• Pilots have techniques for defrosting.
• the mechanical technique consists of alternately inflating and deflating pneumatic tubes located at the leading edge of the wings.
• Thermal technology uses air heated by motors or electricity. Electrical means are large energy consumers and their use is reserved for some equipment such as airspeed antennas, air intakes, windshield windows and blades. The heated air is used for the leading edges of wings and empennages but also for the air inlets of the reactors.
• the inaccuracy of current detection systems makes it difficult for the pilot to make decisions about the implementation of a particular de-icing system.
• the sensor can be picked up by frost while the rest of the cell is not affected.
• Another type of sensor detects the conditions where frost forms.
• the detection systems detect the presence of frost-forming droplets in contact with the surface of the apparatus or in the reactor. These systems are intended to better manage defrost activation and will enable energy saving.
• Icing conditions may occur when drops of frozen liquid water are present.
• the water is considered to be super-cooled when the water is cooled below the freezing point indicated for water but still in liquid form.
• Icing conditions can be characterized by drop size, liquid water content, air temperature, water, and other parameters. These parameters can affect the rate and extent to which ice forms on an aircraft.
• This article inventors of which are the author authors, relates to a rainbow thermometry system using slotted apertures and a sheet of laser light, that is to say a luminous plane and not a linear beam. This system is intended to measure the size and refractive index of the droplets in the spray space.
• Chinese patent application CN105043946 is still known relating to a self-calibrating whole-field rainbow measuring method and a method of manufacturing a device based on a dual wavelength scattering angle relating to a two-phase gas-liquid flow.
• the CCD camera captures an image resulting from the interaction of the scattered beam with a cross-slit filter and two lenses.
• the goal is to characterize drops on a trajectory contained in the laser sheet.
• the image formed on the camera does not make it possible to perform a satisfactory analysis when the imaged droplet is in an intermediate state between the liquid state and the solid state, at the moment of the formation of micro-crystals inside. of the liquid drop. In this case, the image observed through the optics described and the system of two crossed slots is unusable.
• the present invention relates, in its most general sense, to an equipment for determining in real time the refractive index of the liquid droplets, with a precision sufficient to allow the temperature to be deduced therefrom.
• the invention relates in its most general sense to equipment, applications and methods that are the subject of at least one of the claims.
• the invention provides, in its most general sense, the following treatments:
• “Diffusion angle” means the angle formed between the axis of the incident light beam and the axis of the scattered beam
• FIG. 1 shows a schematic view of an equipment according to the invention.
• the equipment according to the invention consists of a monochromatic light source (1), in the example described a laser and an optical image unit (2) comprising a camera (3).
• the one-dimensional laser beam (4) is directed towards a measuring zone (5) situated in a duct (6) for circulating the particles to be controlled or situated in front of a surface (6) to be protected from icing, for example the edge attacking an airplane wing
• the optical axis (7) of the optical pickup assembly (2) forms with the optical axis (8) an angle Gamma equal to (Alpha ⁇ Beta) + Theta
• o Alpha corresponds to 180 ° minus the principal rainbow angle corresponding to the refractive index of the component of said droplets
• o Beta corresponds to the opening of the collimation optics
• o Theta is a value between 0 and 20 °.
• the optical pickup assembly comprises a lens (9) focused in the measurement zone (5), a diaphragm (10) forming a slot perpendicular to the plane defined by the optical axes (7, 8) and an output lens (11), as well as a camera (3).
• main rainbow refers to the rainbow formed by a single reflection inside the drop and thus produces the so-called “principal” rainbow that has the highest intensity.
• the main rainbow is that resulting from a first refraction of the incident ray, corresponding to the change of index between the air and the liquid forming the taste, a reflection at the liquid-air interface resulting from an angle of incidence greater than the limit angle, and a second refraction at the liquid-air interface resulting from an angle of incidence of the refracted ray inside the drop below the limit angle.
• the focal plane of the optical assembly is located at a distance of between 50 and 750 millimeters from the area to be protected from icing so as to measure the temperature of the incident particles, and to provide an real-time information on the risk of icing, to control the commissioning of heating equipment or mechanical excitation.
• the image acquired by the camera results from the refraction of the laser beam (4) in the droplets.
• the refraction angle within each droplet is primarily a function of the droplet section, the wavelength and the refractive index, which depends on the temperature of the droplet. However, the variation of the refractive index as a function of the temperature is very small, and requires a measurement of great precision. For example, for water particles: Wave length
• the image observed by the camera (3) has interference fringes with an alternation of dark bands and light bands.
• a first treatment is carried out to extract a line of pixels P lfj representative of the image, parallel to the plane defined by the axis (8) of the laser and the axis (7) of the optical assembly.
• the representative line selected is the one with the greatest contrast.
• the intensity curve corresponding to this line is recorded to determine a bell-shaped profile whose peak position determines the refractive index and the shape factor depends on the size distribution of the particles present in the measurement zone. .
• a processing consisting of a step of estimating a reference index IND ref , determined as a function of said measured distribution and the theoretical law of generic optics associating an index and a theoretical distribution and a calculation step for N classes C y of particle sizes, the number of particles P x belonging to class C y by a matrix inversion [I ⁇ ]

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• Physics & Mathematics (AREA)
• General Physics & Mathematics (AREA)
• Engineering & Computer Science (AREA)
• Chemical & Material Sciences (AREA)
• Dispersion Chemistry (AREA)
• Immunology (AREA)
• Pathology (AREA)
• General Health & Medical Sciences (AREA)
• Biochemistry (AREA)
• Health & Medical Sciences (AREA)
• Life Sciences & Earth Sciences (AREA)
• Analytical Chemistry (AREA)
• Computer Networks & Wireless Communication (AREA)
• Electromagnetism (AREA)
• Radar, Positioning & Navigation (AREA)
• Remote Sensing (AREA)
• Aviation & Aerospace Engineering (AREA)
• Signal Processing (AREA)
• Investigating Or Analysing Materials By Optical Means (AREA)

Applications Claiming Priority (3)

Publications (1)

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• 2018
  • 2018-08-14 EP EP18765955.2A patent/EP3669170A1/de not_active Withdrawn
  • 2018-08-14 WO PCT/FR2018/052061 patent/WO2019034821A1/fr not_active Ceased

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