WO2024079278A1

WO2024079278A1 - Pressure sensing probe

Info

Publication number: WO2024079278A1
Application number: PCT/EP2023/078384
Authority: WO
Inventors: Philippe REIJASSE; Jean-Charles ABART
Original assignee: Office National D'etudes Et De Recherches Aérospatiales
Priority date: 2022-10-13
Filing date: 2023-10-12
Publication date: 2024-04-18
Also published as: FR3140943A1

Abstract

The invention relates to a pressure sensing probe comprising: a wall (12) defining a tube (10) into which a fluid can enter; and a pressure tap (40) passing through the wall (12), from which tap the pressure is measured. The tube (10) is open at both ends (10A, 10B) so as to channel the flow of fluid along the tube (10). The probe (1) comprises an obstacle (30) having a front face (32) which faces the channelled flow of fluid and opposes this flow, the obstacle (30) forming a projection on the wall (12) and being dimensioned so as to create a stop region (S1) for stopping the fluid upstream and at the bottom of the front face (32), while allowing the fluid to flow around the obstacle (30), between the obstacle (30) and the wall (12). The pressure tap (40) is located in alignment with and upstream of the obstacle (30), in the stop region (S1).

Description

Pressure sensing probe

The invention relates to a pressure sensing probe. This probe is used to sense the pressure of a fluid. It can be mounted, in particular, on an aircraft to sense the pressure in a stopping region.

Background

On board an aircraft, systems are used to measure air pressure in flight, so that the aircraft's Mach number or altitude can then be calculated. These systems generally include pressure sensing probes such as Pitot probes, static probes or Pitot-static probes (also called Prandtl antennas). All these probes consist of a collection tube inside which the air flow can penetrate.

The Mach number of an aircraft is generally calculated from the measured stopping pressure and the static pressure. In fluid dynamics, stopping pressure is the pressure at a stopping point in a fluid flow. However, the measurement of the stopping pressure obtained using current probes can be distorted by various phenomena.

First, the collection tube may become clogged with debris or insects. To avoid the introduction of insects, current probes are covered when the plane is on the ground. However, insects or debris can enter the probe as soon as it is uncovered.

Then, during a flight in icing conditions or in heavy rain, despite the heating of the probe and the presence of a purge device, the measurement of the shutdown pressure can be distorted due to poor evacuation of the gas. water and crystals accumulated in the collection tube, by the purge device.

Hereinafter, for the sake of brevity, water, crystals, debris, insects and impurities present in the atmosphere, whatever they may be, are referred to jointly and individually as "impurities".

Patent FR3067115 describes a probe in which the bottom of the collection tube is blocked by a rear partition, so as to stop the flow of the fluid and allow the stopping pressure to be measured. This probe also has a drainage hole machined in the center of the rear wall of the tube (i.e. at the bottom of the tube). This small diameter hole aims to evacuate impurities to the outside. However, the drainage hole being located in the axis of symmetry of the tube, impurities risk accumulating around the hole, at the periphery of the rear partition, in the intersection zone (i.e. in the corner) between the rear bulkhead and tube.

There is therefore a need for a new pressure sensing probe to effectively evacuate impurities.

General presentation

A pressure sensing probe according to the invention comprises: a wall defining a tube inside which a fluid can penetrate; and a pressure tap passing through the wall, from which the pressure is measured. The tube is open at both ends so as to channel the flow of fluid along the tube. The probe comprises an obstacle having a front face, or upstream face, or even frontal face, which faces the channeled flow of the fluid and opposes this flow. The obstacle forms a projection on the wall and is dimensioned so as to create a fluid stopping region upstream and at the foot of the front face, while allowing the fluid to flow around the obstacle, between the obstacle and the wall. The pressure tap is located in line and upstream of the obstacle, in the stopping region.

Such a probe is simple and robust in design, and its risk of clogging by impurities is limited. In addition, its maintenance is facilitated by the fact that the tube is open at its ends.

When such a probe is mounted on an aircraft, the impurities are evacuated directly and efficiently by being entrained in the channeled flow of the fluid. This channeled flow is deflected away from the pressure tap, by the obstacle, which protects the pressure tap from impurities. Despite this, if impurities were to lodge at the foot of the obstacle, they would be quickly dislodged by a suction phenomenon drawing them into the channeled flow. This suction phenomenon is the result of a depression created by the increase in the speed of the flow around the obstacle. This increase in speed is itself created by the Venturi effect. Such a probe therefore makes it possible to effectively evacuate impurities and, thus, to avoid measurement errors linked to these particles.

In the present application, the upstream and downstream are identified in relation to the channeled flow of the fluid inside the tube. The stopping region and the pressure tap are therefore located before the obstacle, in the direction of flow.

The tube extends along a central axis. It can be of any section. Generally, the tube has the general shape of a cylinder of revolution, in which case, its central axis is the axis of revolution and its section is circular. In the present discussion, an axial direction is a direction parallel to the central axis while a radial direction is a direction perpendicular to the central axis. The alignment is assessed in an axial direction. Thus, the pressure tap and the obstacle are aligned in an axial direction.

The obstacle forms a projection on the wall in the sense that it is raised relative to the internal surface of the wall. In other words, in the particular case of a wall defining a cylindrical tube, the front face of the obstacle is located inside the cylindrical volume of mathematically infinite length delimited by the internal surface of the tube.

The obstacle extends in height, in a radial or substantially radial direction, from its lower edge which is connected to the wall to its upper edge which is free. The stopping region is located at the foot of the obstacle, i.e. along the wall at the level of the lower edge of the obstacle, and upstream of the latter. An empty space for the passage of the fluid extends between the upper edge of the obstacle and the wall which surrounds it.

In certain embodiments, the front face of the obstacle is delimited in height by an upper edge and a lower edge, and in width by side edges. The lower edge is connected to the wall. The top edge and side edges are free, so fluid can flow over the obstacle, between the top edge and the wall, and down the sides of the obstacle, between the side edges and the wall. wall. Such a configuration makes it possible to evacuate the particles more effectively by providing, on either side of the obstacle, lateral evacuation zones.

In contrast to known probes, in which the bottom of the collection tube is blocked to stop the flow of the fluid, the proposed probe has a collection tube open at its two ends so as to channel the flow of the fluid along the tube, from the upstream end to the downstream end of the tube and even beyond the downstream end. In the proposed probe, the flow of fluid is only stopped locally, in a limited region upstream of the obstacle, namely said stopping region.

In this presentation, the "minimum passage section" of the fluid is called the section delimited by the internal wall of the tube and the free edges (lateral and upper) of the obstacle. We call "maximum passage section" the surface perpendicular to the flow in the tube when there is no obstacle.

In certain embodiments, the minimum passage section located at the level of the obstacle is at least equal to 20% of the maximum passage section. The tube is therefore widely open, including at the level of the obstacle, so as to promote the flow of fluid along the tube.

Currently, an airliner can be equipped with two or three probes in order to compensate for the failure of one of the probes. The proposed probe could, for example, be used in addition to or as a replacement for one of these probes.

The invention also relates to a pressure measurement system comprising a probe as previously described and a pressure sensor pneumatically connected to the pressure tap.

The aforementioned characteristics and advantages, as well as others, will become apparent on reading the following detailed description of embodiments of the probe. This detailed description refers to the accompanying drawings.

The accompanying drawings are schematic and are not necessarily to scale; they are primarily intended to illustrate the principles of the invention. In these drawings, from one figure (fig) to another, identical elements (or parts of elements) are identified by the same reference signs.
This figure is an axial section of an example of a collection probe.
This figure is a right-hand view, according to arrow II, of the probe of the .
This figure is a detailed perspective view of the downstream end of the probe of the .
This figure is an axial section of another example of a collection probe.
This figure is a right-hand view, according to arrow V, of the probe of the .
This figure is a detailed perspective view of the downstream end of the probe of the .
This figure is a view similar to that of the , of a variant embodiment.
This figure is a view similar to that of the , of a variant embodiment.
This figure is a view similar to that of the , of a variant embodiment.
This figure is an axial section of another example of a collection probe.
This figure is a right-hand view, according to arrow XI, of the probe of the .
This figure is a detail and top view, according to arrow XII, of the downstream end of the probe of the .
This figure is a detailed view, in axial section, of the downstream end of another example of a collection probe.
This figure is a perspective view of the .
This figure is a detailed view, in axial section, of the downstream end of another example of a collection probe.
This figure is a detailed view, in axial section, of the downstream end of another example of a collection probe.
This figure represents an example of a sensing probe, in axial section, mounted on the fuselage of an aircraft.
This figure is a graph representing different measured pressures P, expressed in pascal (Pa), as a function of the Mach number of the flow M0 measured in the wind tunnel vein.
This figure is a graph representing the Mach number of the flow Mc calculated from the pressure Pi_S1 measured in the stopping region S1, as a function of the Mach number M0 measured in the vein of the wind tunnel.
This figure is a graph which represents the rectified Mach number McR resulting from the correction method described below.

detailed description

Particular embodiments of the probe of the invention are described in detail below, with reference to the examples shown in the accompanying drawings. These embodiments and examples illustrate the characteristics and advantages of the invention. However, it is recalled that the invention is not limited either to these particular embodiments or to the examples shown.

As illustrated in the drawings, the pressure sensing probe 1 comprises a wall 12 defining a tube 10, or sensing tube, inside which a fluid can penetrate. Such a probe 1 can be mounted, in particular, on a land, air or sea vehicle. In particular, the probe 1 can equip an aircraft such as an airplane. In this case, the flowing fluid is air.

The probe 1 includes a pressure tap 40 passing through the wall 12. The pressure can be measured from the pressure tap 40 by a pressure sensor P (shown in dotted lines in Figures 1 and 17). The pressure sensor P is connected to the pressure tap 40 by a pneumatic connection. In other words, the information is transmitted pneumatically from the pressure tap 40 to the sensor P which performs the pressure measurement. This pressure measurement can then serve as a basis for calculating the Mach number of the vehicle on which probe 1 is mounted.

The tube 10 is hollow and open at its two ends 10A, 10B, so as to channel the flow of the fluid along the tube 10. The current lines F of the flow are represented by arrowed lines in Figures 1, 4,10 and 13. As illustrated, the fluid rushes into the tube 10 and its flow is channeled along the tube 10. An obstacle 30 projecting relative to the wall 12 creates a stopping region S1 of the fluid in upstream and at the foot of the obstacle 30, while allowing the fluid to flow around the obstacle 30, that is to say between the obstacle 30 and the wall 12 which surrounds it. The obstacle 30 can, for example, be a protrusion or a rising step. The pressure tap 40 is located in alignment and upstream of the obstacle 30, in the stopping region S1.

The length L of the tube 10 is sufficiently large so that the incident flow is channeled and uniform before arriving at the obstacle 30. For example, the length L of the tube 10 can be greater than five times the largest dimension of its section. In the examples of the drawings, the tube 10 is of cylindrical shape and of circular section, so that the largest dimension of its section corresponds to the internal diameter d of the tube 10. Other shapes of tube could nevertheless be considered without departing from the framework of the invention. For example, the tube 10 could have a divergent frustoconical shape upstream of its length L, to limit the introduction of impurities. The leading edge of the front end 10A of the tube 10 could, moreover, be cut with a knife, or rounded, to better capture the flow of the fluid in the tube.

The obstacle 30 has a first face, called the front face 32, facing the channeled flow of the fluid and opposing this flow. The front face 32 has a height H and a width W, as marked on the . In the examples of the drawings, the obstacle 30 is of substantially constant section, but this is not necessarily the case. For example, the obstacle 30 can become thinner towards the downstream. The obstacle 30 may, moreover, have beveled or rounded edges as shown in Figures 11 and 15. Roundings 47, 48 at the edges of the front face 32 and the side edges 33 of the obstacle make it possible to promote the evacuation of the flow between the obstacle 30 and the wall 12 (Figures 11, 15 and 16).

As shown in Figures 13, 15 and 16, a rounding 39 or a corner break 49 at the junction of the front face 32 and the wall 12 makes it possible to promote the evacuation of impurities which could temporarily rush into the stopping region S1.

Generally speaking, the shape of the obstacle 30 and its front face 32 can vary. Likewise, the position of the obstacle 30 relative to the exit plane PS of the tube 10 can vary. Thus, in the example of Figures 1 to 3, the obstacle 30 is fixed to the downstream end 10B of the tube 10 so that the front face 32 of the obstacle is located in the exit plane PS of the tube 10. We then say that the obstacle 30 is located "at the exit" of the tube 10. The obstacle 30 has the shape of a plate and has a thickness E, measured in an axial direction, less than the height H and the width W of the obstacle.

The example of Figures 4 to 6 differs from that of Figures 1 to 3 in that the obstacle 30 has a greater thickness E so that it has a general shape of a rectangular parallelepiped, it being understood that the lower face of this parallelepiped is not plane since it is in contact with the wall 12 and follows the curvature of the wall 12. Furthermore, the obstacle 30 is positioned inside the tube 10 so that its rear face 36, or downstream face, is located upstream of the outlet plane PS of tube 10.

The example of the differs from that of Figures 4 to 6 in that the obstacle, although it is still positioned inside the tube 10, is closer to the exit plane PS of the tube 10. In particular, the rear face 36 of the obstacle 30 is aligned with the exit plane PS of the tube 10. The rear face 36 of the obstacle 30 could also be located outside the tube without departing from the scope of the invention.

The examples of Figures 8 and 9 differ from that of Figures 4 to 7 essentially by the shape of the obstacle 30. It is understood that the obstacle can have different shapes without departing from the scope of the invention, its front face 32 and, more generally, the cross section of the obstacle 30, which can be of generally rectangular, square, trapezoidal, polygonal, semi-circular, etc. shape, it being understood that the lower edge 35 of the front face 32 is in contact with the wall 12 and follows the curvature thereof.

The examples of Figures 10 to 16 differ from that of Figures 1 to 3 in that the obstacle 30 has the shape of a plate fixed to the downstream end 10B of the tube 10 so that the front face 32 of the obstacle is located downstream of the exit plane PS of tube 10 (and not in the exit plane PS).

In certain embodiments, as in the examples of Figures 10 to 16, the downstream end 10B of the tube is delimited by an outlet plane PS, and a portion 12B of the wall 12 extends downstream of the outlet plane PS. In particular, the portion 12B forms a tongue extending from one side of the tube 10, in the extension thereof. The obstacle 30 forms a projection on this wall portion 12B. The front face 32 of the obstacle 30 is located downstream of the exit plane PS. There are thus transverse passage zones ZT between the exit plane PS and the front face 32 of the obstacle 30, on each side of the obstacle 30. Plus the axial distance XF between the front face 32 and the exit plane PS increases, the more the size of the transverse passage zones ZT increases. The projection of the transverse passage zones ZT in an axial section plane passing through the pressure tap 40 is represented in hatched form on the .

The transverse passage zones ZT lead to a three-dimensional passage (or evacuation) surface greater than in the configurations where the front face 32 is positioned inside the tube 10 or in the outlet plane PS. The ZT transverse passage zones promote the lateral evacuation of impurities.

In certain embodiments, the front face 32 is located downstream of the outlet plane PS so that XF < 0.5 dS, where XF is the axial distance between the front face 32 and the outlet plane PS and dS is the largest dimension of the internal straight section of the tube 10 in the outlet plane PS. When the tube 10 is of circular section, the largest dimension dS of its section corresponds to its internal diameter d. Such a configuration guarantees the fact that the obstacle 30 is located in the channeled flow of the fluid. In other words, the zone downstream of the tube 10 in which the obstacle 30 is located is sufficiently close to the exit plane PS of the tube 10 so that the flow of the fluid is still channeled in this zone.

In certain embodiments, the front face 32 of the obstacle is delimited in height by an upper edge 31 and a lower edge 35, and in width by side edges 33. The lower edge 35 is connected to the wall of the tube 12 while the upper edge 31 and the side edges 33 are free in the sense that they are not connected to the wall of the tube 12, but separated from it by an empty space. There is therefore an upper surface ZA, above the obstacle 30, and lateral surfaces ZB, on either side of the obstacle 30, through which the fluid flows. These surfaces ZA and ZB are marked in Figures 2, 5 and 11. The surfaces ZA and ZB are contiguous and flat when the front face 32 of the obstacle 30 is located upstream or in the exit plane PS of the tube 10 (that is to say when the obstacle 30 is located inside or at the exit of the tube 10). These surfaces ZA and ZB are contiguous and three-dimensional, when the front face 32 of the obstacle is located downstream of the outlet plane PS of the tube 10, that is to say when there are transverse passage zones ZT.

The tube 10 delimits passage sections for the fluid. We call the passage section the surface through which the fluid flows (or is evacuated) between the obstacle 30 and the wall 12 of the tube. In certain embodiments, the tube 10 delimits a minimum passage section and a maximum passage section for the fluid, the minimum passage section being located at the level of the obstacle and being at least equal to 20% of the section of maximum passage. In the particular case of a cylindrical tube of revolution, the maximum passage section can be equal to the area of the internal circular section of the tube, i.e. π·d ² /4 where d is the internal diameter of the tube.

In the examples in the figures, the minimum passage section corresponds to the sum of the surfaces ZA and ZB which surround the obstacle.

In the embodiments where the obstacle 30 is located inside or at the exit of the tube 10, as in the examples of Figures 1 to 9, the section of the obstacle, at the level of its front face 32, measures between 20% and 80%, in particular between 30% and 70%, of the passage section of the tube 10 located just upstream of the front face 32. In the particular case of a cylindrical tube of revolution, the section of the The obstacle, at the level of its front face 32, therefore measures between 20% and 80% of the interior circular section of the tube.

In certain embodiments, the front face 32 of the obstacle 30 is substantially perpendicular to the wall 12 of the tube (in the examples of the drawings, the front face 32 of the obstacle 30 is perpendicular to the wall 12). In particular, the front face can form with the wall 12 an angle of between 60° and 120°, in particular between 70° and 110°. A lower angle risks creating an impurity retention zone at the lower edge 35 of the front face 32, while a higher angle risks reducing the size of the stopping region S1.

More precisely and with reference to the taken as an example, a stopping region S1 is created in the vicinity and upstream of the front face 32. The stopping region S1 is characterized by a zone called isobaric swirling dead water, delimited, in the cutting plane axial, by a line (shown in dotted lines on the ) connecting a point of separation A1 of the flow to the point of joining A2 of the flow. The separation point A1 is located on the wall 12 in alignment with and upstream of the obstacle 30. The separation point A2 is located towards the top of the obstacle.

The pressure tap 40 must be located in the stopping region S1, upstream of the front face 32 of the obstacle and downstream of the separation point A1. The separation point A1 is defined by a zero average friction coefficient. This separation point A1 can be obtained without particular difficulty by fluid mechanics calculations of the Navier Stokes type within the reach of those skilled in the art. The pressure tap 40 thus captures the pressure denoted Pi_S1 prevailing in the stopping region S1.

In certain embodiments, the pressure tap 40 is located upstream of the obstacle 30 so that 0.2 H ≤ X ≤ 2 H, where X is the axial distance between the pressure tap 40 and the face front 32 of the obstacle, and H the height of the front face. Below 0.2·H, the pressure tap 40 is too close to the front face, which presents a risk of temporary blockage by impurities not yet evacuated. Beyond 2·H, the pressure tap 40 risks being outside the stop region S1. To further reduce these risks, the pressure tap 40 can be located upstream of the obstacle 30 at an axial distance X such that 0.3·H ≤ X ≤ H.

Furthermore, in the stopping region S1, it is possible for a secondary vortex to form in the corner between the front face 32 of the obstacle and the wall 12 used to channel the flow, i.e. say at the level of the lower edge 35 of the front face 32. In certain embodiments, to avoid the formation of such a secondary swirl which could promote the accumulation of impurities, a corner break 49 or a rounding 39 judiciously dimensioned can be formed in the corner at the foot of obstacle 30, as illustrated in Figures 13, 15 and 16.

There illustrates an example of probe 1 mounted, via a support 93, on the fuselage 91 of an aircraft. A pneumatic connection 42 passes through the support 93 and connects the pressure tap 40 to a pressure sensor P present on board the aircraft. A heating device such as a heating resistor 95 can be integrated into the obstacle 30 in order to increase the temperature of the materials constituting the obstacle 30 and, thus, further limit the risk that condensed phases of humid or icing air do not are formed or persist in contact with the walls of the obstacle 30 and in the stopping region S1.

The pressure sensor P (connected to the pressure tap 40) measures the pressure Pi_S1 in the stopping region S1 upstream of the obstacle. It is then possible, by applying a correction law described below, to go back to the Mach number of the aircraft, if we also measure the static pressure P0. The static pressure P0 can be measured, for example, using one or more other pressure taps located elsewhere on the fuselage 91.

Compared to a Pitot probe of the prior art, the proposed probe 1 makes it possible to prevent the pressure sensing from being exposed frontally to the flow and to establish a more effective evacuation of impurities. The probe 1 can have a general shape similar to that of a Pitot probe and can be integrated in the same way into an aircraft or any other vehicle. It can therefore be mounted in place of a Pitot probe. Probe 1 can be fixedly mounted on a vehicle because it allows reliable measurement of the stopping pressure for an angle of attack or slip range of + or – 15°. Probe 1 can also be mounted on a weather vane. These characteristics respond to the constraints posed by manufacturers to re-equip existing aircraft.

The quality and reliability of the pressure measurements carried out using the proposed probe 1 were evaluated during wind tunnel tests.

These tests were carried out for several Mach numbers in the “ONERA–S3Ch” transonic wind tunnel, which includes a return circuit provided with thermal regulation and a test vein with a rectangular section of 0.80 m x 0. 76 m sides, powered by a motor developing up to 3.5 MW of power.

The probe 1 tested had a general shape identical to that of Figures 1 to 3, namely that of a hollow cylindrical tube of revolution, of length L = 120mm, and of internal diameter d = 18mm. The obstacle 30 had the shape of a rectangular plate of height H = 10mm, width W = 12mm and thickness E = 1mm. To produce a probe on a smaller scale, it is possible, for example, to carry out a scale in all the spatial directions of the probe tested.

There shows the pressure measurements taken during a test sequence, carried out for a range of Mach 0.3 to 0.9. In this figure, the static pressure P0 measured in the wind tunnel, the generating pressure Pi0 measured in the wind tunnel and the pressure Pi_S1 measured in the stopping region S1 of the probe are given. Other test sequences made it possible to note the good repeatability of the pressure measurement Pi_S1 in the stop region S1.

There shows a comparison between the Mach number M0 measured in the wind tunnel vein and the Mach number Mc calculated from the measured pressure Pi_S1.

The difference between the two Mach numbers M0 and Mc is linked to the difference between the two measurements of the stopping pressure, that measured in the wind tunnel noted Pi0 and that measured by the probe noted Pi_S1. The difference between the measurements of Pi0 and Pi_S1 is however relatively small. This difference is almost linear. The least squares line gives a multiple correlation coefficient R ² of 0.9996. The difference between the Mach numbers M0 and Mc is also almost linear. The least squares line gives a multiple correlation coefficient R ² of 0.9999. These deviations are therefore not important in themselves since, due to their monotonic and almost linear evolution, they can be easily corrected by correction laws. Thus, in certain embodiments, a linear correction law is used for the pressure measurement Pi_S1 or for the dynamic pressure Q0_S1 resulting from the pressure measurement Pi_S1. This leads to the determination of a rectified dynamic pressure, Q0_R.

The steps to apply this fix are as follows:

(Step 1) Calculate the Mach number Mc with the static pressure P0 measured in the wind tunnel, and the stopping pressure Pi_S1 measured by the probe (which is considered as an approximate measurement of the stopping pressure) using the following relationship .

(Step 2) Calculate the dynamic pressure Q0_S1 with Mc using the following relationship.

(Step 3) Apply a correction law to calculate a rectified dynamic pressure Q0_R. Such a correction law is established beforehand, following calibration tests carried out in a wind tunnel. The correction law is, for example, of linear form with parameters a and b, so that:

(Step 4) Calculate the rectified Mach number McR from Q0_R using the following relationship.

By applying these steps, a value of the rectified flow Mach number McR within 0.002 of the actual Mach number M0 was obtained. This is illustrated on the which shows the effectiveness of the proposed correction. Such a result perfectly meets current precision requirements for measuring the Mach number, particularly in the field of aeronautics.

The embodiments described in this presentation are given for illustrative and non-limiting purposes, a person skilled in the art can easily, in view of this presentation, modify these embodiments, or consider others, while remaining within the framework of the invention.

In particular, a person skilled in the art can easily consider variants comprising only part of the characteristics of the embodiments previously described, if these characteristics alone are sufficient to provide one of the advantages of the invention. In addition, the different characteristics of these embodiments can be used alone or combined with each other. When combined, these features may be as described above or differently, the invention not being limited to the specific combinations described herein. In particular, unless otherwise specified, a characteristic described in relation to one embodiment can be applied analogously to another embodiment.

Claims

Pressure sensing probe including:
a wall (12) defining a tube (10) into which fluid can penetrate; And
a pressure tap (40) passing through the wall (12), from which the pressure is measured;
in which the tube (10) is open at its two ends (10A, 10B) so as to channel the flow of the fluid along the tube (10),
in which the probe (1) comprises an obstacle (30) having a front face (32) which faces the channeled flow of the fluid and opposes this flow, the obstacle (30) forming a projection on the wall (12) and being dimensioned so as to create a stopping region (S1) of the fluid upstream and at the foot of the front face (32), while allowing the fluid to flow around the obstacle (30), between the obstacle (30) and the wall (12),
in which the pressure tap (40) is located in alignment and upstream of the obstacle (30), in the stopping region (S1).
Probe according to claim 1, in which the front face (32) of the obstacle is delimited in height by an upper edge (31) and a lower edge (35), and in width by lateral edges (33), in which the lower edge (35) is connected to the wall (12), and in which the upper edge (31) and the side edges (33) are free, so that the fluid can flow over the obstacle (30), between the upper edge (31) and the wall (12), and on the sides of the obstacle (30), between the side edges (33) and the wall (12).
Probe according to claim 1 or 2, in which the tube (10) delimits a minimum passage section and a maximum passage section for the fluid, the minimum passage section being located at the level of the obstacle (30) and being at less equal to 20% of the maximum passage section.
Probe according to any one of claims 1 to 3, in which the front face (32) of the obstacle (30) is substantially perpendicular to the wall (12).
Probe according to any one of claims 1 to 4, in which the obstacle (30) is located inside or at the outlet of the tube (10) and in which the section of the obstacle, at the level of its face front (32), measures between 20% and 80%, in particular between 30% and 70%, of the passage section of the tube located just upstream of the front face (32).
Probe according to any one of claims 1 to 4, in which the downstream end (10B) of the tube is delimited by an outlet plane (PS) of the tube, in which a portion of the wall (12) extends downstream of the exit plane (PS), in which the obstacle (30) is connected to the wall portion, and in which the front face (32) is located downstream of the exit plane (PS).
Probe according to claim 6, in which the front face (32) is located downstream of the exit plane (PS) so that XF < 0.5 dS, where XF is the axial distance between the front face (32) and the outlet plane (PS) and dS the largest dimension of the section of the tube (10) in the outlet plane (PS).
Probe according to any one of claims 1 to 7, in which the pressure tap (40) is located upstream of the obstacle (30) so that 0.2·H ≤ XP ≤ 2·H, where XP is the axial distance between the pressure tap (40) and the front face (32) of the obstacle, and H the height of the front face (32).
Pressure measuring system comprising a probe (1) according to any one of claims 1 to 8, and a pressure sensor (P) pneumatically connected to the pressure tap (40).