Classifications

• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01K—MEASURING TEMPERATURE; MEASURING QUANTITY OF HEAT; THERMALLY-SENSITIVE ELEMENTS NOT OTHERWISE PROVIDED FOR
  • G01K13/00—Thermometers specially adapted for specific purposes
  • G01K13/02—Thermometers specially adapted for specific purposes for measuring temperature of moving fluids or granular materials capable of flow
  • G01K13/028—Thermometers specially adapted for specific purposes for measuring temperature of moving fluids or granular materials capable of flow for use in total air temperature [TAT] probes
• • 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
  • B64D15/12—De-icing or preventing icing on exterior surfaces of aircraft by electric heating
• • 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
  • B64D43/00—Arrangements or adaptations of instruments
  • B64D43/02—Arrangements or adaptations of instruments for indicating aircraft speed or stalling conditions
• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01K—MEASURING TEMPERATURE; MEASURING QUANTITY OF HEAT; THERMALLY-SENSITIVE ELEMENTS NOT OTHERWISE PROVIDED FOR
  • G01K13/00—Thermometers specially adapted for specific purposes
  • G01K13/02—Thermometers specially adapted for specific purposes for measuring temperature of moving fluids or granular materials capable of flow
• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01P—MEASURING LINEAR OR ANGULAR SPEED, ACCELERATION, DECELERATION, OR SHOCK; INDICATING PRESENCE, ABSENCE, OR DIRECTION, OF MOVEMENT
  • G01P13/00—Indicating or recording presence, absence, or direction, of movement
  • G01P13/02—Indicating direction only, e.g. by weather vane
  • G01P13/025—Indicating direction only, e.g. by weather vane indicating air data, i.e. flight variables of an aircraft, e.g. angle of attack, side slip, shear, yaw
• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01P—MEASURING LINEAR OR ANGULAR SPEED, ACCELERATION, DECELERATION, OR SHOCK; INDICATING PRESENCE, ABSENCE, OR DIRECTION, OF MOVEMENT
  • G01P5/00—Measuring speed of fluids, e.g. of air stream; Measuring speed of bodies relative to fluids, e.g. of ship, of aircraft
  • G01P5/14—Measuring speed of fluids, e.g. of air stream; Measuring speed of bodies relative to fluids, e.g. of ship, of aircraft by measuring differences of pressure in the fluid
  • G01P5/16—Measuring speed of fluids, e.g. of air stream; Measuring speed of bodies relative to fluids, e.g. of ship, of aircraft by measuring differences of pressure in the fluid using Pitot tubes, e.g. Machmeter
  • G01P5/165—Arrangements or constructions of Pitot tubes

Definitions

• the invention relates to a multifunction probe for aircraft, a probe making it possible in particular to measure the total pressure Pt and the total temperature Tt of an air flow surrounding the aircraft.
• the multifunction probe further comprises means for measuring the static pressure Ps and the incidence ⁇ of the air flow surrounding the aircraft. We then have all the parameters necessary to determine the module and the direction of the speed vector of the aircraft.
• French patent application FR 2 802 647 filed on December 17, 1999 in the name of THOMSON-CSF describes such a probe comprising a Pitot tube for measuring the total pressure Pt of the air flow and temperature measurement means total Tt in the form of a first channel whose air inlet orifice faces substantially the flow and of a second channel comprising a temperature sensor.
• the second channel takes part of the air circulating in the first channel.
• the Pitot tube and the first channel belonging to the means for measuring the total temperature Tt are substantially parallel and arranged in the vicinity of one another.
• the first channel is advantageously arranged above or below the pitot tube but not on one of its sides.
• This arrangement allows the total pressure measuring means Pt and the total temperature measuring means Tt not to interfere with each other when the incidence of the air flow, located in the vicinity of the probe, is modified.
• this arrangement tends to increase the projection of the probe relative to the skin of the aircraft. Indeed, it is necessary that the air inlet orifices of the pitot tube and of the first channel are both located outside of a boundary layer located in the immediate vicinity of the skin of the aircraft and in which the air is unsuitable for a good measurement of temperature or pressure.
• the increase in the projection leads to greater fragility of the probe which one would have to overcome by increasing the dimensions of the mast or of the wing carrying the Pitot tube and the first channel.
• the invention makes it possible to avoid this defect by reducing the projection of the probe.
• the probes mounted on aircraft are subjected to significant temperature variations and, sometimes, to conditions in which frost can develop, in particular inside the Pitot tube or channels allowing the total temperature measurement Tt .
• the frost disturbs the measurements and, to avoid it, the probe includes means for heating it.
• These means generally comprise a wire heating the probe by the Joule effect.
• This wire is wound in the walls of the Pitot tube and in that of the channels allowing the measurement of total temperature.
• an electrical conductor is commonly used comprising an alloy of iron and nickel coated with a mineral insulator such as alumina or magnesia. The insulator is itself coated with a nickel or inconel sheath allowing the soldering of the wire on the body of the probe.
• the heating wire is formed, for example, by winding it around cylindrical mandrels having marks allowing the heating wire to be positioned on the mandrels.
• the shape of the heating wire is produced for a probe as described in patent application FR 2 802 647, it is impossible to wind a heating wire on two parallel mandrels. It is therefore necessary to offset one of the mandrels to perform the operation of shaping the heating wire. Thereafter, the two mandrels are brought back parallel to one another to give the heating wire its final shape. This last operation of moving the mandrels is traumatic for the heating wire because it causes torsional stresses in the heating wire. These constraints risk cracking the sheath of the heating wire and consequently reduce its reliability.
• the invention makes it possible to produce a probe measuring the total pressure Pt and the total temperature Tt, a probe equipped with a single heating wire.
• the arrangement of the different elements of the probe between them makes it possible to avoid any abnormal twisting of the heating wire.
• the subject of the invention is a multifunction probe for aircraft, comprising means for measuring the total pressure and means for measuring the total temperature of an air flow surrounding the aircraft, the means for measuring the total pressure comprising a first tube said Pitot tube oriented substantially along the axis of the air flow surrounding the aircraft, the means for measuring the total temperature comprising a second tube open to the air flow and oriented substantially in the axis of the air flow, characterized in that the first tube is located inside the second tube.
• the invention also relates to a method of shaping a heating wire forming means for defrosting the multifunction probe.
• the process consists in: - winding the heating wire in a helix around a first mandrel,
• the probe described in patent application FR 2 802 647 comprises a movable pallet which is oriented in the axis of the air flow which surrounds it. It is understood that the invention can be implemented both for a probe comprising a movable pallet and for a probe not having one.
• This type of probe is known as a fixed probe and the pressure taps, Pitot tube and first channel, have a fixed position relative to the skin of the aircraft.
• FIG. 1 shows a probe comprising means for measuring the total temperature of the air flow, means for measuring the total pressure of the air flow, means for measuring the static pressure of the air flow, means for measuring the incidence of the air flow surrounding the aircraft, the plane of the figure containing the axis of the flow;
• FIG. 2 shows an enlarged partial view of the means for measuring the total pressure and the total temperature of the flow, a view whose section plane is the same as that of Figure 1;
• FIG. 3 shows the air inlet of the means for measuring the total pressure and the total temperature, seen in a plane perpendicular to the plane of Figure 1;
• FIGs 4 and 5 show the winding tools of a heating wire used for heating the probe; more specifically, the figure
• FIG. 4 shows a first mandrel in perspective, a mandrel around which the heating wire is wound and
• FIG. 5 shows two mandrels in perspective.
• the probe represented in FIG. 1 comprises a movable pallet 1 rotating around an axis 2.
• the pallet 1 comprises a wing 3 having a plane of symmetry, parallel to the plane of the figure and separating the lower surface from the upper surface.
• the profile of the wing 3 perpendicular to its leading edge 4 is for example of the OOZT type of the N.A.C.A.
• the leading edge 4 is substantially rectilinear and inclined relative to the axis 2. It is understood that other shapes of wings can be used to implement the invention.
• the pallet 1 also comprises a shaft 5 with an axis 2 which penetrates inside the skin 6 of an aircraft.
• the shaft 5 is movable in rotation relative to the aircraft for example by means of a rolling bearing 7. Due to the shape of the wing 3, the pallet 1 is naturally oriented in the axis of the air flow surrounding the movable pallet 1.
• the axis of the flow is materialized by the arrow 8 shown on Figure 1.
• the movable vane 1 further comprises means for measuring the total temperature of the air flow and means for measuring the total air pressure, means carried by the movable vane 1. These means will be better described in help of figure 2.
• the probe further comprises means for measuring the static pressure Ps and the incidence of the air flow.
• the means for measuring the static pressure Ps comprise for example two static pressure taps 9 and 10, each located on a of the faces of the movable pallet 1. In FIG. 1 only the pressure tap 9 is visible.
• the pressure tap 10 is placed on the invisible face of the movable pallet 1, in a manner substantially symmetrical to the pressure tap 9 with respect to the plane of symmetry of the wing 3. This plane of symmetry is parallel to the plane of the figure 1.
• Each pressure tap 9 and 10 may have several orifices, three are shown in FIG. 1, in particular in order to limit the section of each orifice so as to less disturb the air flow surrounding the movable pallet 1 or even to be able to carry out the pressure measurement even if one of the orifices were to be blocked.
• the two static pressure taps 9 and 10 are in communication with a chamber located inside the pallet in order to average the pressure between the two taps 9 and 10.
• the means for measuring the incidence of the flow comprise for example two incidence pressure taps 11 and 12 located, as for the static pressure taps 9 and 10, on one of the faces of the pallet also in a substantially symmetrical manner by relative to the plane of symmetry of the wing 3.
• the incidence pressure taps 11 and 12 are not in communication and it is the difference between the pressures prevailing at each tap 11 and 12 which makes it possible to determine the exact incidence of the movable pallet 1 and therefore that of the aircraft.
• the pressure taps 11 and 12 can be placed in the immediate vicinity of the leading edge 4 of the movable pallet 1.
• the orientation, thus improved, of the movable pallet 1 makes it possible in particular to improve the alignment of the means for taking the total pressure Pt and the total temperature Tt with the axis 8 of the air flow.
• FIG. 2 represents the part of the probe furthest from the skin 6 of the aircraft.
• the means for measuring the total pressure comprise a first tube 20, advantageously of circular section, said Pitot tube oriented substantially along the axis 8 of the air flow. More precisely, the tube 20 has an air inlet orifice 21 substantially facing the air flow of axis 8. At the end 22 of the tube 20, end 22 opposite to the orifice 21, the tube 20 comprises a purge hole 23 making it possible to evacuate particles liable to penetrate inside the tube 20. Still at the end 22 of the tube, a channel 24 opens in the tube 20. The channel 24 is for example connected to a pressure sensor not shown in the figure. The pressure sensor effectively measures the total pressure Pt of the air flow.
• the means for measuring the total temperature Tt comprise a second tube 25, advantageously of circular cross section, and open to the air flow at an inlet orifice 26.
• the second tube 25 also includes an outlet orifice 27 allowing air in the second tube 25 to escape in the direction of the axis 8.
• the section of the inlet orifice 26 is substantially that of the tube 25 and the section of the orifice outlet 27 is lower than that of inlet 26.
• the outlet 27 allows particles circulating in the tube 25 to be evacuated without coming into contact with a temperature sensor whose position will be described later . These particles are, for example, formed of drops of water or dust.
• the Pitot tube 20 is located inside the second tube 25.
• the Pitot tube 20 extends along an axis 28 and the second tube 25 extends along an axis 29.
• the axis 28 and axis 29 are substantially parallel.
• the inlet orifices 21 and 26 of the two tubes 20 and 25 are substantially coplanar. Thus, part of the air flow entering one of the tubes 20 or 25 does not disturb another part of the air flow entering the other tube.
• the means for measuring the total temperature Tt further include a channel 30 in which circulates part of the air circulating in the second tube 25, as well as a temperature sensor 31 fixed in the channel 30.
• the channel 30 has an inlet of air 32 located in the second tube 25. Part of the air circulating in the second tube 25 enters the channel 30 by the air inlet 32 and escapes from the channel 30 by an air outlet 33 opening to the outside downstream of the probe.
• the air circulating in the second tube 25 passes over a deflector 34 comprising an orifice 35 making it possible to evacuate to the outside of the probe air belonging to a boundary layer which develops along the wall of the Pitot tube 20 inside the second channel 25.
• the air inlet 32 is located in the vicinity of an upper wall 36 of the Pitot tube 20. More specifically, the air inlet 32 is located in the extension of the upper wall 36. This location of the air inlet 32 makes it possible to prevent air circulating in the second tube 25 and disturbed by the internal walls of the tube 25 from entering the channel 30. The disturbed air forms a boundary layer along the internal walls of the tube 25, boundary layer which it is not necessary to evacuate outside the second tube 25 upstream of the air inlet 32. This boundary layer is nevertheless evacuated from the second tube 25 in particular by the outlet orifice 27 situated at the downstream end of the second tube 25. Other outlet orifices, for example two in number, and bearing the marks 37 and 38 allow the evacuation of the boundary layer developed inside the second tube 25.
• the orifices 37 and 38 are visible in FIG. 3 and are located by pa rt and other of the Pitot tube 20.
• the fact that the air inlet 32 is located in the vicinity of the upper wall 36 of the Pitot tube 20 also makes it possible to prevent liquids entering the second tube 25 does not enter the air inlet 32. In fact, such liquids are located preferentially by gravity on the interior walls of the second tube 25 without reaching the air inlet 32.
• the position of the inlet d air 32 in the vicinity of an upper wall 36 of the pitot tube 20 is distant from the interior walls of the second tube 25 and is close to the center of the second tube 25.
• the probe comprises defrosting means making it possible to heat the probe.
• the heating means comprise a heating wire 39 which, thanks to the relative position of the Pitot tube 20 and the second tube 25 can be unique for heating the Pitot tube 20 and the second tube 25.
• the heating wire 39 is wound helically both inside the pitot tube 20 and inside the second tube 25.
• the heating wire 39 is fixed against the interior walls of the tubes 20 and 25 for example by brazing. There is no need to drown the heating wire 39 in the inner walls of the tubes 20 and 25, because it is less likely to be subjected to possible mechanical attack than if it were located outside the tubes 20 and 25.
• the fact of drowning the heating wire 39 in the interior walls of the tubes 20 and 25 requires making grooves in the walls of the tubes 20 and 25.
• the invention makes it possible to avoid these grooves.
• the fact that the air inlet 32 is located in the vicinity of the upper wall 36 of the pitot tube 20 also makes it possible to prevent the air streams entering the air inlet 32 from being disturbed, and in particular heated, by the heating wire 39
• the position of the heating wire 39 inside the tubes 20 and 25 allows the inside of the tubes 20 and 25 to be defrosted directly. This makes it possible to reduce the power required for defrosting.
• the heating wire 39 is positioned outside the tubes 20 and 25, it is necessary for the heat to be conducted through the walls of the tubes 20 and 25 to defrost the inside of the tubes 20 and 25.
• the heating wire 39 is formed before being attached to the probe. An example of a method for shaping the heating wire 39 is described with the aid of FIGS. 4 and 5.
• the heating wire 39 is first of all cut up to a length sufficient to ensure the heating of the probe, then folded in half so that its two ends are in the vicinity of one another.
• the heating wire 39 is wound in a helix around a first cylindrical mandrel 41 whose diameter is less than the inside diameter of the pitot tube 20 so that the wire thus wound in a helix can 'insert inside the pitot tube 20.
• the winding of the wire 39 around the first mandrel 40 is shown in Figure 4. Once a sufficient number of turns has been made around the first mandrel 40, this mandrel 41 is inserted inside a second hollow mandrel 42; then the helical winding of the heating wire 39 is continued around the second mandrel 42. This second phase of the winding of the heating wire 39 is visible in FIG. 5.
• the heating wire 39 having a certain elasticity, once the winding has been carried out around the two mandrels 41 and 42, it can slide along the two mandrels 41 and 42 to disengage from it. It is then possible to place the heating wire 39, thus formed, inside the two tubes 20 and 25 to be fixed there.
• the heating wire 39 may include an outer sheath of nickel or inconel. This material allows the brazing of the sheath inside the tubes 20 and 25 by heating the probe to inside which the heating wire 39 has been placed, the temperature and the heating time of the probe must be sufficient to carry out the soldering of the heating wire 39.
• heating wire 39 can be extended to heat other parts of the probe, in particular the movable pallet 1.

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• Physics & Mathematics (AREA)
• General Physics & Mathematics (AREA)
• Engineering & Computer Science (AREA)
• Aviation & Aerospace Engineering (AREA)
• Testing Or Calibration Of Command Recording Devices (AREA)
• Measuring Volume Flow (AREA)
• Measuring Fluid Pressure (AREA)
• Measuring Temperature Or Quantity Of Heat (AREA)

Applications Claiming Priority (3)

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• 2001
  • 2001-12-11 FR FR0115991A patent/FR2833347B1/fr not_active Expired - Fee Related
• 2002
  • 2002-12-10 EP EP02804605A patent/EP1454149A2/de not_active Withdrawn
  • 2002-12-10 WO PCT/FR2002/004261 patent/WO2003050496A2/fr active Application Filing
  • 2002-12-10 US US10/493,567 patent/US7124630B2/en not_active Expired - Fee Related

Non-Patent Citations (1)

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