Electromagnetic transducer to measure three-dimensional velocity of conductive fluid flow

Abstract

To provide an electromagnetic transducer intended to measure three-dimensional velocity components of a flow of a conductive fluid.SOLUTION: An electromagnetic transducer 10 intended to measure three-dimensional velocity components of a flow of a conductive fluid, comprises: a cylindrical metal tube 11 forming a core with high magnetic permeability and extending along a central axis (Z), with a central part and two end parts, the two end parts being on either side of the central part and each having three projections 13.1 to 13.6 arranged at 120° to each other around the central axis (Z), each defining a flat surface parallel to the central axis (Z); an electric coil 12, called the primary coil, wound around the central part of the tube; and six electric coils 14.1 to 14.6, called receiver coils, each wound around one of the flat surfaces or six Hall effect sensors each arranged on one of the flat surfaces.SELECTED DRAWING: Figure 13

Description

Technical Field

[0001] The present invention relates to the field of instrumentation and measurement, particularly in the field of three-dimensional point velocity measurement in conductive fluids, and more particularly to the field of transducers dedicated to local point velocity measurement of conductive fluids.

[0002] The present invention relates to an electromagnetic transducer for measuring the velocity components of a conductive fluid.

[0003] The present invention is generally applicable to any conductive fluid. Examples of such fluids include conductive ionic solutions such as salt water, and furthermore liquid metals. Typical examples of such metals are sodium, potassium, lead, lithium, aluminum, copper, iron, zinc, titanium, and their alloys.

[0004] More particularly, the present invention is applicable to measurements in fluids of the type of high-density liquids having a density in the range from 100 kg·m -3 to 10,000 kg·m -3 and above.

[0005] The present invention is particularly suitable for measuring the velocity of fluids whose melting temperature range is typically from approximately -50°C to above 1,500°C, which is the melting temperature range of metals processed, shaped, or used in liquid form.

[0006] One contemplated advantageous application is to measure the heat transfer fluid velocity, particularly in fission and fusion reactors.

Background Art

[0007] In many applications, it is necessary to recognize the velocity field of a moving conductive fluid.

[0008] This applies in the metal casting industry, where the quality of the parts to be produced can be predicted and defective parts can be limited by recognizing the velocity field in the mold and the mold supply circuit. In fact, recognizing the flow velocity makes it possible to control and optimize the filling of the mold.

[0009] In the nuclear industry, the velocity field of the metal heat transfer fluid used in the circuits of some nuclear reactors is a major factor in terms of the stress on the contacting metal structures. For this reason, recognition of the velocity field is essential.

[0010] The velocity field is also a major factor from the perspective of heat exchangers and the heat transfer present in the nuclear fuel of these reactors. Recognition and analysis of the velocity field in important areas of the reactor (heat exchangers, reactor core outlet, pumps, etc.) are also indicators of correct operation, and by extension, means of enhancing safety and generally means of enhancing the ability to monitor these machines.

[0011] Scientific experiments involving large volumes of liquid metal and tests carried out for the purpose of recognizing the flow distribution in heat exchanger headers also require recognition of the velocity field of the flow involved.

[0012] In the various flow regions mentioned, the flow conditions are three-dimensional. In most cases, the flow is also characterized by those temperature heights that are often several hundred degrees and the density of the fluid used, which can range from several hundred kg·m -3 to several thousand kg·m -3 and up to several thousand kg·m.

[0013] Various velocity measurements are known and are used to measure the velocity components of the flow of conductive liquids.

[0014] These techniques include electromagnetic techniques, which are particularly relevant and reliable from the perspective of the resistance of the material to the stress applied to the material by the environment in which the measurement is made. These techniques are even more interesting in the case of highly dense and chemically reactive fluids such as liquid metals.

[0015] The operating principle of the electromagnetic transducer is shown by the mathematical formula of Ohm's law in a moving fluid exposed to a magnetic field.

[0016] This mathematical formula shows that the conductivity σ of the fluid results in the development of an electric current (current density J) under the action of the velocity of the movement u combined with the external magnetic field B.

[0017]

Number

[0018] This occurs even in the absence of an electric field E.

[0019] Current density J u is the source of the magnetic field B u . This field B u distorts the external magnetic field B.

[0020] It should be noted that, for the sake of brevity, the vector symbolized by the letter B, which is the magnetic flux density or magnetic induction, is referred to as the magnetic field throughout this application. It should also be noted that the various formulas provided later are written in the context of a semi - permanent approximation that can ignore certain quantities involved in Maxwell's equations, such as displacement current.

[0021] So far, the measurement of a single velocity component of the flow has been performed by an electromagnetic transducer generally known by the acronyms FDFM ("Flux Distortion Flow Meter"), ECFM ("Eddy Current Flow Meter"), or PSFM ("Phase Shift Flow Meter").

[0022] A conventional FDFM generally designated using Symbol 1 is shown in FIGS. 1, 2, and 2A. The FDFM is axisymmetric about the central axis Z and typically consists of a core 2, an electrical transmission coil called a primary coil 3, and one or two electrical receiving coils called secondary coils 4, 5. The core 2 is formed by a solid rod 20 extending along the central axis Z and solid disks 21 evenly spaced along the central axis Z. The solid rod is integrally connected to the solid disks. The primary coil 3 and the secondary coils 4, 5 are wound around the solid rod 20 between two of the solid disks 21.

[0023] A current is applied in the primary coil. This current flow creates an external magnetic field B in the immediate environment of the primary coil according to Maxwell - Ampere's equation.

[0024]

Number

[0025] Here,

[0026]

Number

[0027] is a differential operator, μ is the permeability at μ = μ r μ0, μ0 is the permeability of free space, B passes through the receiving coil.

[0028] The primary current is an alternating current, so B is also alternating. In this way, B induces a voltage in each of the receiving coils according to Maxwell - Faraday's equation.

[0029]

Number

[0030] Where:

[0031]

number

[0032] is the electric field.

[0033] Also, B is the current density J induced not only in the fluid but also in the surrounding conductors exposed to this magnetic field, including the metal of the tube. i 3 and 4 show the evolution of the induced current density under the action of an external magnetic field in the absence of flow velocity for an FDFM with one secondary coil 4 and with two secondary coils 4, 5.

[0034] current density J i is the magnetic field B that distorts the external magnetic field B. i Therefore, field B is not the same depending on whether the FDFM is surrounded by a conductive fluid or not.

[0035] In the absence of fluid movement, one or more receive coils receive the external magnetic field B and field B. i The output voltage is a function of

[0036] In the presence of fluid movement, the new current density J u appears, and the magnetic field B u This new field alters B so that it is, in effect, blown by the conducting fluid flow and distorted towards the fluid flow as shown in Figures 5A, 5B, and 6.

[0037] The magnetic flux passing through the receiving coil or coils depends on the flow velocity.

[0038] Therefore, one or more receiving coils receive magnetic field B, which distorts the external magnetic field B. i and B. u The output voltage reflects the effect of the

[0039] This is shown by digital simulation. FIGS. 7A and 7B are digital simulations of the magnetic field around the FDFM, with and without a flow velocity of the conductive fluid, respectively.

[0040] By analyzing the voltage delivered by the receiving coil, it is possible to determine the flow velocity of the moving fluid in the region of action of the magnetic field B.

[0041] As shown in FIG. 8, for a single receiving coil 4 of the FDFM1, when it is upstream with respect to the direction of fluid flow, the magnetic flux is decreased as the velocity increases (and increased as the velocity decreases). The voltage e1 it supplies decreases by Δe1.

[0042] The voltage e1 supplied by the FDFM is an indication of the flow velocity (by comparing the amplitude of the current signal with the amplitude of the signal without velocity, and by the indication of the relative direction).

[0043] In addition to the above, for an FDFM having two receiving coils, in the case of the downstream receiving coil, as the fluid velocity increases, the magnetic flux passing through that receiving coil is increased. Its voltage e2 increases by Δe2.

[0044] Therefore, |Δe2| = |Δe1|.

[0045] Generally, the two receiving coils 4, 5 of the FDFM are electrically connected in a reverse series configuration, as shown in FIG. 9.

[0046] In this method, the signal V supplied by the two - coil FDFM is V = |e2| - |e1| where |e x | is the absolute value or amplitude of the voltage e x .

[0047] The signal V is proportional to the velocity component of the flow projected onto the axis of rotation of the FDFM.

[0048] In practice, for an FDFM having two receiving coils, the combined use of the voltages sent out by these two coils doubles the sensitivity and eliminates the dependence of the FDFM response on irrelevant quantities such as temperature. V = (|e2| - |e1|) / (|e2| + |e1|)

[0049] The sign of V provides the direction of the velocity without the need to compare the amplitude of the signal without flow velocity.

[0050] Regarding the placement of the FDFM with respect to the fluid flow, the FDFM can be inside the flow, i.e., positioned on the axis of the tube within the characterized flow [1]. Thus, the FDFM is in the fluid flow surrounding the FDFM.

[0051] In practice, as shown in FIG. 10, the internal FDFM1 is generally placed at the center of the annular space defined by two concentric tubes T1, T2 through which the fluid F whose velocity is to be measured flows.

[0052] Other FDFMs can be outside the flow. Thus, the coils and cores of the external FDFM are arranged around the fluid flow whose velocity is to be measured.

[0053] In practice, the external FDFM is arranged around the tube to measure the velocity of the fluid flowing through the tube [2].

[0054] When the FDFM is used to evaluate the velocity of the fluid flowing through the tube, the FDFM can only measure one velocity component, i.e., the component along the axis of the tube, and by extension, the component along the axis of symmetry X, whether it is inside or outside the tube. In fact, the tube guides the fluid flow and provides the fluid in its main direction.

[0055] Generally, for a conventional FDFM disposed in an open medium, i.e., a conventional FDFM disposed in a large volume of a moving conductive fluid, or rather, a conventional FDFM disposed in a moving conductive fluid where the boundary is far enough from the FDFM so as not to place the velocity vector of the flow in the correct direction in the vicinity of the FDFM, it can be seen that the FDFM can only consider a single velocity component of the flow, which is the velocity component projected along the axis of symmetry of the FDFM. This is due to the axisymmetric configuration of the FDFM.

[0056] As a result, the use of a conventional FDFM in an open environment is not decisive enough to characterize some of the velocity components at which the FDFM is positioned. Specifically, measuring the velocity of a high-density conductive fluid in an open environment is a problem in itself.

[0057] Modeling and simulation of prior art FDFMs in an open environment with different velocities of three-dimensional components prove this.

[0058] The inventor modeled a prior art FDFM and its operation was simulated for different velocity stresses surrounding the flow of a moving liquid metal (sodium). The analytical orthonormal coordinate system in which the velocity is represented is x, y, z.

[0059] Figures 11 and 11A show the magnetic flux density, velocity vector, vertical section y, and vertical section z for this prior art FDFM with the velocity component x.

[0060] Figures 12 and 12A show the magnetic flux density, velocity vector, vertical section x, and vertical section z for the same prior art FDFM with the velocity component y.

[0061] Therefore, it can be seen that when the prior art FDFM is made to have a velocity component field along x, it provides the same response signal as when it is made to have a single velocity component field along y.

[0062] As a conclusion, the internal or external FDFM according to the prior art cannot be used to simultaneously measure some components of the multidimensional flow velocity of a fluid at a given point location.

[0063] For example, the simultaneous use of several FDFMs, one for each velocity component, positioned and oriented to form a Cartesian coordinate system or any other arrangement is also not possible due to the magnetic field interaction of the various FDFMs arranged close to each other.

[0064] Furthermore, transducers are also known [3], [4], [5] that can measure some velocity components of the fluid flow at substantially a single point.

[0065] These include wire or hot film probes for aerodynamic measurements. Since these probes are fragile, they are limited to use at speeds of at most a few millimeters per second.

[0066] Potential probes can be used to measure the local velocity for potentially several velocity components. However, their operation relies on the electrical contact between their electrodes and the fluid to be characterized. Potential probes are also very sensitive to oxidation, especially in liquid metals. Electrical insulation is also required between the electrodes and the metal structure of the probe for use with liquid metals. This limits their use to a lower fluid temperature range than non-contact electromagnetic measurement techniques.

[0067] Therefore, there is no measuring transducer that can evaluate multiple components of the flow velocity of a conductive fluid, which can be of high density, over a high velocity range and / or at high temperatures.

[0068] Non-contact induction tomography methods have already been tested for measuring multidimensional fluid flow velocities.

[0069] Publication [6] describes one such method where currently it is only possible to measure two velocity components at a point in the radial plane of the fluid. The ability to measure three velocity components has not been demonstrated.

[0070] Patent EP1285277B1 also describes a non-contact inductive tomography method.

[0071] The main limitation faced by non-contact inductive tomography methods is that the useful magnetic field observed is on the order of 2 to 5 orders of magnitude smaller than the useful magnetic field of the magnetic field that needs to be applied.

[0072] Furthermore, these methods also typically require acting on a fluid with a relatively small volume, on the order of 1 m, so that the external magnetic field can propagate through the volume to be characterized.

[0073] Also, these methods require complex processing algorithms.

[0074] Since the external magnetic field has to pass through the material of the wall containing the moving fluid as the equipment for implementing the measurement method is placed outside, the performance capabilities of the method depend on the nature of the wall material, the thickness of the wall material, and the overall shape of the tomography.

[0075] In summary, the prior art FDFM cannot simultaneously measure multiple velocity components. The prior art FDFM cannot be combined together in close proximity to each other to measure several velocity components at a given location due to the interference where they are transmitted to each other.

[0076] Existing measurement transducers cannot evaluate multiple velocity components of a conductive fluid that can be at high velocity ranges and / or at high temperatures and can be of high density.

[0077] The three-dimensional flow measurement methods using non-contact tomography are comprehensive. These methods use equipment placed outside the fluid volume to be characterized. The performance capabilities of these methods depend on the structure containing the fluid volume. The signals of these methods are difficult to process. The size of the fluid volume that these methods can characterize must be limited. Therefore, these methods cannot be implemented in large volumes, such as inside a sodium-cooled reactor vessel.

[0078] Therefore, even for large volumes, there is a need to propose a solution for the three-dimensional measurement of the flow velocity of a conductive fluid in a high-speed range and / or at high temperatures, where the fluid can be of high density.

Prior Art Documents

Patent Documents

[0079]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0080] An object of the present invention is to at least partially address this requirement.

Means for Solving the Problems

[0081] To that end, according to a first alternative, an object of the present invention is an electromagnetic transducer intended to measure the three-dimensional velocity components of the flow of a conductive fluid, - a cylindrical metal tube forming a core with a high magnetic permeability, extending along a central axis (Z) and having a central portion and two end portions, the two end portions being on both sides of the central portion and each comprising three protrusions arranged at 120° to each other around the central axis (Z), each defining a flat surface parallel to the central axis (Z), - an electric coil called a primary coil, wound around the central portion of the tube, - Six electric coils, each wound around one of the flat surfaces, called receiving coils, or six Hall effect sensors, each disposed on one of the flat surfaces and an electromagnetic transducer.

[0082] According to a second alternative, the subject of the present invention is an electromagnetic transducer intended to measure the three-dimensional velocity components of the flow of a conductive fluid, - A cylindrical metal tube forming a core having a high magnetic permeability, extending along a central axis (Z) and comprising a central portion and two end portions, the two end portions being on both sides of the central portion and each having three protrusions arranged at 120° to each other around the central axis (Z), each defining a flat surface parallel to the central axis (Z), - A permanent magnet disposed around the central portion of the tube, - Six electric coils, each wound around one of the flat surfaces, called receiving coils, or six Hall effect sensors, each disposed on one of the flat surfaces and an electromagnetic transducer.

[0083] Preferably, the core has a low conductivity in order to limit the losses induced by variable magnetic induction, i.e., the Joule losses associated with the circulation of the induced current, and the hysteresis losses.

[0084] Thus, the present invention mainly includes an electromagnetic transducer that can be operated with an alternating current (first variant) or a direct current (second variant) to non-contact measure the three three-dimensional components of a conductive fluid.

[0085] The careful arrangement of the receiving coils or Hall effect sensors at 120° to each other can enable each contribution of the components of the local velocity vector measured by the distortion of the electromagnetic flux without interference from other contributions.

[0086] The flux distortion electromagnetic transducer according to the present invention can measure velocities from a few millimeters per second to a few meters per second.

[0087] Also, the bundle strain electromagnetic transducer according to the present invention typically has a high density in the range of from 100 kg·m -3 to 10,000 kg·m -3 super and is adapted to measure the velocity of a conductive liquid at a high temperature in the melting temperature range for metals that are typically processed, shaped, or used in liquid form.

Advantages of the Invention

[0088] Ultimately, the electromagnetic transducer according to the proposed invention overcomes the limitations identified in prior art devices, - the ability to simultaneously measure the three velocity components of the flow of a conductive fluid in the volume of the fluid in the immediate vicinity of the flow, - unlike in the case of prior art FDFM, there is no need to combine the electromagnetic transducer with other transducers of the same type, which risks invalidating the measurement, - the ability to position the electromagnetic transducer within the flow characterized in the region under investigation, - even for a very large volume of fluid, characterizing the velocity components of the flow, - processing the signals generated by the electrical transducer, which is much less complex than the reconstruction algorithms required for the method of measurement by tomography and includes many advantages.

[0089] A further object of the present invention is the use of the electromagnetic transducer described above for measuring the three-dimensional velocity components of the flow of a conductive fluid such as liquid metal in a nuclear reactor.

[0090] Further advantages and features will become more clearly apparent by reading the following detailed description, which is illustrative and non-limiting, with reference to the accompanying drawings.

Brief Description of the Drawings

[0091]

Figure 1

Figure 2

Figure 2A

Figure 3

Figure 4

Figure 5A

Figure 5B

Figure 6

Figure 7A

Figure 7B

Figure 8

Figure 9

Figure 10

Figure 11

Figure 11A

Figure 12

Figure 12A

Figure 13

Figure 14

Figure 15

Figure 16

Figure 17

Figure 17A

Figure 18

Figure 19

Figure 19A

Figure 19B

Figure 20

Figure 21

Figure 22

Figure 23

Figure 24

Figure 25

Figure 26

Figure 27

Figure 28

Figure 29

Embodiments for Carrying Out the Invention

[0092] Throughout the present application, the terms "upstream" and "downstream" are to be understood as referring to the direction of fluid flow along the Z-axis around the converter.

[0093] Throughout the present application, the electromagnetic converter according to the present invention has three axes that are perpendicular to each other in a pair, namely, - the X-axis defining the transverse direction, - An X-axis, a Y-axis defining a transverse direction that defines the XY plane, - A Z-axis that defines a longitudinal direction, is perpendicular to the XY plane, defines a general direction along which the transducer extends, and defines the axis of rotation of the primary coil is defined at a position with respect to the XYZ orthogonal coordinate system that forms a trihedron including them.

[0094] Conventionally, in the remainder of this description, the Y-axis is an axis perpendicular to the upper surfaces of two protrusions on the same measurement line L1. The measurement line is defined as a virtual straight line that is parallel to the Z-axis and passes through the centers of the upper surfaces of the two protrusions on the same perpendicular line.

[0095] The same subscript i used to geometrically define the transducer protrusions and coils is the one used for electromagnetic coupling and signal processing, as will be described later.

[0096] All the protrusions and coils arranged at the same end portion of the transducer core have either the same odd or even subscript. In the following simulations, the upstream end portion of the core supports coils with odd subscripts.

[0097] The voltages generated by the six receiving coils are represented by e1, e2, e3, e4, e5, and e6, respectively.

[0098] Figures 1 to 12A have already been described in the preamble. Therefore, they will not be described in detail hereafter.

[0099] Figures 13 to 16 show the electromagnetic transducer 10 according to the present invention, which is intended to measure three velocity components of the flow of a conductive fluid.

[0100] The transducer 10 first includes a cylindrical metal tube 11 that forms an electromagnetic core. The cylindrical metal tube 11 extends along the central axis Z and includes a central portion 110 and two end portions 111 and 112 on both sides of the central portion. Preferably, the length of the central portion 110 is equal to the length of each of the end portions 111 and 112.

[0101] The upstream end portion 111 includes three protrusions 13.1, 13.3, and 13.5 that are arranged at 120° to each other around the central axis Z and each define a flat surface parallel to the central axis Z.

[0102] The downstream end portion 112 includes three protrusions 13.2, 13.4, and 13.6 that are arranged at 120° to each other around the central axis Z and each define a flat surface parallel to the central axis Z.

[0103] Preferably, all the protrusions have the same size and shape.

[0104] Advantageously, each protrusion has a T-shape when viewed in a front view orthogonal to the central axis Z, and the head of the T is a flat surface.

[0105] The primary electric coil 12 is wound around the central portion 110 of the tube 11.

[0106] Six electric receiving coils 14.1, 14.2, 14.3, 14.4, 14.5, and 14.6 are respectively wound around one of the flat surfaces of the protrusions 13.1, 13.2, 13.3, 13.4, 13.5, and 13.6.

[0107] Here, the operation of the electromagnetic converter 10 will be described in relation to a simulation performed by the inventor.

[0108] As previously defined, the converter 10 has three measurement lines L1, L2, and L3.

[0109] An alternating current is supplied to the primary coil 12.

[0110] This current creates an external magnetic field B having three symmetric planes P1, P2, P3 that intersect on the Z axis. Each of these planes passes through one of the measurement lines L1, L2, and L3. The measurement plane P1 is associated with the pair of coils 14.1 and 14.2. The measurement plane P2 is associated with the pair of coils 14.3 and 14.4. The measurement plane P3 is associated with the pair of coils 14.5 and 14.6.

[0111] For simplicity, the magnetic coupling existing between the primary coil 12 and each of the pairs of coils 14.1 and 14.2 in the measurement plane P1, the pairs of coils 14.3 and 14.4 in the measurement plane P2, and the pairs of coils 14.5 and 14.6 in the measurement plane P3 is considered.

[0112] As can be seen in FIGS. 17 and 17A, there is a field B that does not change the symmetry of B and also does not change the coupling between the primary coil 12 and the receiving or secondary coil. i exists.

[0113] The three-dimensional flowing fluid surrounding the transducer 10 creates a field B u which changes the magnetic field coupling between the primary coil 12 and the six secondary coils 14.1, 14.2, 14.3, 14.4, 14.5, 14.6. This distortion can be measured thanks to the induced voltage present in the receiving coils.

[0114] The movement of the conductive fluid around the transducer 10 having only a positive velocity component along the Z axis similarly changes the coupling of the pairs of coils in each of the three measurement planes P1, P2, P3. In other words, the receiving coils 14.1, 14.3, 14.5 have an induced voltage that increases by Δe at the terminals of those receiving coils, while at the same time, the coils 14.2, 14.4, 14.6 have an induced voltage that decreases by Δe at the terminals of those receiving coils. This bundle distortion under the action of the velocity flow along the Z axis is shown in FIG. 18.

[0115] The same kind of signal processing as that applied to the coils of the prior art FDFM as described in the premise part is applicable to the pairs of coils 14.1, 14.2, the pairs 14.3, 14.4, and 14.5, 14.6 in order to measure the velocity component z. Therefore, the voltage differences e1 - e2 = e3 - e4 = e5 - e6 between the coils are linear functions of Z.

[0116] In order to increase the sensitivity of the transducer 10 for the measurement of the velocity component along Z, it is possible to determine the sum of these voltage differences (e1 - e2)+(e3 - e4)+(e5 - e6).

[0117] The flow, which is represented by velocity vectors contained in all planes passing through the Z - axis and has no single component along this axis, will distort the coupling between the primary coil 12 and each of the coils in the groups at the end portions, namely, the groups of coils 14.1, 14.2, 14.3 and coils 14.4, 14.5, 14.6.

[0118] Therefore, FIGS. 19, 19A, 19B show the distortion of the bundle under the action of the velocity flow along the X - axis.

[0119] FIG. 20 for a part of it shows the distortion of the bundle under the action of the velocity flow along the Y - axis.

[0120] Therefore, the flow velocity having three - dimensional components can be characterized by the transducer 10 according to the present invention.

[0121] Generally, a matrix relationship can be defined to reflect the voltages generated by the six receiving coils 14.1 - 14.6, e1, e2, e3, e4, e5, e6 as the three - dimensional components (Ux, Uy, Uz) of the local velocity vector U.

[0122] This matrix is represented as follows.

[0123]

Equation

[0124] Therefore, U x = T 11 · e1 + T 12 · e2 + T 13 · e3 + T 14 · e4 + T 15 · e5 + T 16 · e6 U y = T 21 · e1 + T 22 · e2 + T 23 · e3 + T 24 · e4 + T 25 · e5 + T 26 · e6 U z = T 31 · e1 + T 32 · e2 + T 33 · e3 + T 34 · e4 + T 35 · e5 + T 36 · e6

[0125] T ij exists in the measurement plane i and, by extension, in the response of the transducer to the flow velocity present in the expression of the velocity component U x determines the contribution of e j in the transducer.

[0126] T ij depends first on the characteristics of the transducer material, which forms the core 11, the shape of the protrusions 13.1 to 13.6, and the characteristics of the receiving coil, including the number of turns of each winding of the receiving coil.

[0127] T ij also reflects the properties of the conductive fluid and the influence of temperature on the materials present.

[0128] Finally, T ij is also a function of the excitation applied to the transducer, that is, a function of the nature and intensity of the magnetic excitation generated by the primary coil.

[0129] As follows, that is, T ij=k t ·k e ·K ij can be expressed as Here, k t is the influence factor related to temperature on various existing materials. k e is the influence factor related to excitation. K ij reflects the influence of the converter configuration.

[0130] Therefore, the matrix of the three-dimensional components (Ux, Uy, Uz) of the local velocity vector U can be expressed as follows.

[0131]

Number

[0132] Generally, the characteristics of the prior art FDFM as described in the premise part are established through the results of digital simulation or experiments.

[0133] In the embedded tube where the FDFM is positioned around, by giving a known volume flow rate Q of liquid metal, reference can be made to the publication [7] that describes a method for calibrating the external FDFM. Since the flow rate Q is given, the voltages S1 and S2 generated by the secondary coils 4 and 5 are measured and utilized so that the response A of the FDFM is defined as follows. A = A1 / A2 Here, A1 = S1 - S2 A2 = S1 + S2 is.

[0134] The response A is related to the volume flow rate Q by A = T·Q.

[0135] The coefficient T reflects not only the dimensions and material characteristics of the FDFM, but also those of the embedded tube, the liquid metal, and the dependence on the response to temperature and electrical excitation. There is one value of T for the temperature value associated with the electrical excitation, which is determined by the amplitude and frequency of the electrical excitation.

[0136] The velocity field in the embedded tube that generates the flow rate Q measured by the prior art FDFM includes a velocity parallel to the central axis of the FDFM. The calibration is one-dimensional. A series of coefficients T are determined by parameter tests at a given temperature and excitation.

[0137] Regarding the electromagnetic transducer 10 described above, although it is the same method as the calibration in [7], it is possible to proceed by giving a three-dimensional velocity field.

[0138] During the tests at a fixed temperature and excitation, various velocity fields are continuously given by the components Ux, Uy, Uz in one or more directions.

[0139] During each test, the voltages e1, e2, e3, e4, e5, e6 of the coils 14.1 to 14.6 can be recorded. The terms K of the determined matrix K ij The same number of tests as are performed. In this method, a linear system of equations can be established and solved to calculate each of the terms of the matrix of the three-dimensional components (Ux, Uy, Uz) of K ij The tests are also parameterized in terms of temperature and excitation so as to be able to determine the influence of the weighting terms k

[0140] The various connection lines required to supply power to the primary coil 12 and to recover the currents in the receiving coils 14.1 to 14.6 can be routed inside the cylindrical core 11. t and k e The tests are also parameterized in terms of temperature and excitation so as to be able to determine the influence of the weighting terms k

[0141] The various connection lines required to supply power to the primary coil 12 and to recover the currents in the receiving coils 14.1 to 14.6 can be routed inside the cylindrical core 11.

[0142] Examples of incorporating these lines are shown in FIG. 21, where the electrical wire 15 is connected to the primary coil 12, and the electrical wires 16.1, 16.2, 16.3, 16.4 are connected to the receiving coils 14.1, 14.2, 14.3, 14.4, respectively.

[0143] As shown in FIGS. 22 to 27, instead of the coils 14.1, 14.2, 14.3, 14.4, 14.5, 14.6, Hall effect sensors 17.1, 17.2, 17.3, 17.4, 17.5, 17.6 can also be provided together with the same core 11 as described above for fabricating the electromagnetic converter 10 operating with an alternating current. In this embodiment, the Hall effect sensors 17.1 to 17.6 are directly fixed to the flat surface defined by the protrusions 13.1 to 13.6. The connecting wires 15, 16.1 to 16.6 can be arranged as in the previous embodiment.

[0144] As shown in FIGS. 28 and 29, instead of the primary coil 12, a permanent magnet 18 having the same core 11 as described above can also be provided for creating the electromagnetic converter 10 operating with a direct current.

[0145] Other modifications and improvements can be considered without departing from the scope of the present invention.

[0146] (References)

Explanation of Signs

[0147] 10 Electromagnetic converter 11 Cylindrical metal tube, core 110 Central part 111 Upstream end part 112 Downstream end part 12 Primary electric coil 13.1, 13.3, 13.5 Protrusions in the upstream end part 111 13.2, 13.4, 13.6 Protrusions in the downstream end part 112 14.1, 14.2, 14.3, 14.4, 14.5, 14.6 Electric receiving coils 15, 16.1, 16.2, 16.3, 16.4, 16.5, 16.6 Connection wires 17.1, 17.2, 17.3, 17.4, 17.5, 17.6 Hall effect sensors 18 Permanent magnet B External magnetic field B i , B u Field L1, L2, L3 Measurement lines P1, P2, P3 Measurement planes Z Central axis

Claims

1. An electromagnetic transducer intended to measure the three-dimensional velocity components of the flow of a conductive fluid, a cylindrical metal tube that forms a core having a high magnetic permeability, extends along a central axis (Z), and has a central portion and two end portions, the two end portions being on both sides of the central portion and each having three protrusions arranged at 120° to each other around the central axis (Z), each defining a flat surface parallel to the central axis (Z); a cylindrical metal tube, an electric coil called a primary coil, wound around the central portion of the tube, six electric coils each wound around one of the flat surfaces, or six Hall effect sensors each arranged on one of the flat surfaces, called receiving coils An electromagnetic transducer comprising.

2. An electromagnetic transducer intended to measure the three-dimensional velocity components of the flow of a conductive fluid, a cylindrical metal tube that forms a core having a high magnetic permeability, extends along a central axis (Z), and has a central portion and two end portions, the two end portions being on both sides of the central portion and each having three protrusions arranged at 120° to each other around the central axis (Z), each defining a flat surface parallel to the central axis (Z); a cylindrical metal tube, a permanent magnet arranged around the central portion of the tube, six electric coils each wound around one of the flat surfaces, or six Hall effect sensors each arranged on one of the flat surfaces, called receiving coils An electromagnetic transducer comprising.

3. The electromagnetic transducer according to claim 1 or 2, wherein each protrusion has a T-shape in a front view orthogonal to the central axis (Z), and the head of the T is the flat surface.

4. Use of the electromagnetic transducer according to claim 1 or 2 for measuring the three-dimensional velocity components of the flow of a conductive fluid such as liquid metal in a nuclear reactor.

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