BALANCE FOR MEASURING THE THRUST EXERTED ON A TURBOMACHINE
The thrust measurement balance with concentric shells and inductive sensors addresses inaccuracies and complexity in existing systems, offering precise and cost-effective thrust measurement for turbomachines.
Patent Information
- Authority / Receiving Office
- FR · FR
- Patent Type
- Patents
- Current Assignee / Owner
- SAFRAN AIRCRAFT ENGINES SAS
- Filing Date
- 2024-05-23
- Publication Date
- 2026-04-10
AI Technical Summary
Existing thrust balances for turbomachines are inaccurate due to temperature dependence on flexible element expansion, complex and costly implementation, and imprecise strain gauge placement on small elements, leading to unreliable results.
A thrust measurement balance with concentric shells, using inductive displacement sensors and accelerometers to measure displacements and moments along multiple axes, eliminating the need for strain gauges on the tested part and simplifying installation.
Provides precise and reliable thrust measurements independent of environmental conditions, reducing complexity and cost by eliminating the need for strain gauges and complex geometry.
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Abstract
Description
Title of the invention: BALANCE FOR MEASURING THE THRUST EXERTED ON A TURBOMACHINE Scope of the invention
[0001] The present invention relates to the field of aeronautics, and more specifically, to test benches for aircraft turbomachinery.
[0002] More particularly, the invention relates to a balance for measuring the thrust exerted on a turbomachine, so as to simulate and measure the forces and moments exerted by a thrust on all or part of a turbomachine. Prior art
[0003] In aeronautics, it is known to implement thrust balances so as to be able to measure the forces and moments applied on different parts of an aircraft, and for example on different parts of an aircraft turbomachine.
[0004] To do this, techniques are known consisting of deforming flexible elements formed between a fixed part and a part for which the forces and moments exerted are to be measured, these flexible elements being instrumented with strain gauges.
[0005] More specifically, thrust balances consist of creating flexible zones between the part to be measured and the fixed housing. These flexible zones are equipped with strain gauges that make it possible to measure the extension and compression of these flexible zones and thus to deduce the forces and moments exerted on these flexible zones, and by extrapolation to the part to be measured.
[0006] However, such thrust balances have several disadvantages which make their implementation complex and costly.
[0007] Indeed, these thrust balances can prove to be inaccurate because the measurements taken on the extension and compression of flexible areas can depend in particular on the temperature in which they were carried out because temperature has an influence on the expansion of the material of the flexible areas.
[0008] In addition, the placement of strain gauges can prove complex and imprecise when it has to be carried out on small flexible elements, which can also disrupt the reliability of the results obtained.
[0009] Moreover, such thrust balances have a complex geometry which requires the use of electro-erosion processes, making their implementation complex and expensive.
[0010] There is therefore a need to provide a solution that simplifies the implementation of such thrust balances while making them more reliable and less expensive. Description of the invention
[0011] The invention aims to remedy at least in part the disadvantages mentioned above relating to prior art techniques.
[0012] To this end, the invention relates to a thrust measurement balance for a test part of a turbomachine comprising two concentric shells including: - an outer shell formed of a rigid hollow cylindrical wall extending around a first longitudinal axis X, said outer shell being intended to be fixed to a fixed support of said turbomachine, and - an inner ferrule mounted inside said outer ferrule and formed of a hollow cylindrical wall extending around said first axis X and capable of deforming in reaction to a force and / or a moment applied to said inner ferrule, said inner ferrule being intended to be connected to said part to be tested of said turbomachine,
[0013] said outer ferrule carrying measuring means configured to measure: - the displacements of said inner ferrule along said first X axis, a second Y axis orthogonal to said first X axis and a third Z axis orthogonal to said first X axis and second Y axis, and - the moments applied to said internal ferrule around said first axis X, said second axis Y and said third axis Z.
[0014] Thus, the invention proposes a new and inventive approach that makes it possible to resolve at least in part some of the drawbacks of the prior art.
[0015] In particular, a thrust balance according to the invention makes it possible to obtain relatively precise measurements because such measurements of force and / or moment applied on said inner ferrule do not depend on the context in which they are carried out.
[0016] A thrust balance according to the invention is also simple to implement because it does not require the placement of any elements at the level of the part to be tested, but simply the placement of the thrust balance between a support and the part to be tested.
[0017] According to a particular aspect of at least one embodiment of the invention, said outer ferrule carries: - of the first means of measurement oriented axially along said first axis X with respect to said external ferrule so as to measure the displacement of said wall of said internal ferrule along said first axis X, and to measure the moments applied on said wall of said internal ferrule around said second axis Y and said third axis Z; - second measuring means oriented radially with respect to said external ferrule so as to measure the displacement of said wall of said internal ferrule along the said second axis Y and third axis Z, and to measure the moment applied on the said wall of the said internal ferrule around the said first axis X; - third means of measurement arranged tangentially to said external ferrule and configured to measure a tangential displacement of at least one reference element fixed on said wall of said internal ferrule.
[0018] Therefore, this makes it possible to measure the different components of the forces applied to the part to be tested, by measuring the displacement of said wall of said internal ferrule along the three axes and the moment applied to said internal ferrule around the three axes.
[0019] According to a particular aspect of at least one embodiment of the invention, said first measuring means comprise a pair of axial sensors angularly spaced at 90° along a plane orthogonal to said first X axis and said second measuring means comprise a first pair of radial sensors angularly spaced at 90° along a plane orthogonal to said first X axis.
[0020] According to a particular aspect of at least one embodiment of the invention, said second measuring means comprise a second pair of radial sensors spaced axially from said first pair of radial sensors along said first longitudinal X axis.
[0021] This allows the displacement of said wall of said internal ferrule to be segregated along said second axis Y and third axis Z of the moments applied on said wall of said internal ferrule around said second axis Y and said third axis Z.
[0022] According to a particular aspect of at least one embodiment of the invention, said axial sensors are inductive displacement sensors and / or said radial sensors are inductive displacement sensors.
[0023] According to a particular aspect of at least one embodiment of the invention, said inductive displacement sensors are Kaman sensors.
[0024] According to a particular aspect of at least one embodiment of the invention, said axial displacement sensors are glued onto an external surface of said external ferrule and / or said radial displacement sensors are glued onto an external surface of said external ferrule.
[0025] According to a particular aspect of at least one embodiment of the invention, said inner ferrule carries means for vibrating said inner ferrule, and a first accelerometer configured to measure a resonance frequency of said inner ferrule subjected to the vibrations of said vibrating means.
[0026] According to a particular aspect of at least one embodiment of the invention, said inner ferrule carries a second accelerometer angularly spaced from said first accelerometer in a plane orthogonal to said first axis X.
[0027] A second accelerometer makes it possible to ensure measurement in case of failure of the first accelerometer, or even to average the measured acceleration values.
[0028] According to a particular aspect of at least one embodiment of the invention, said vibration means comprise a piezoelectric exciter.
[0029] According to a particular aspect of at least one embodiment of the invention, the measuring balance comprises a plurality of stop screws distributed between said outer ferrule and said inner ferrule so as to limit the relative displacements between said outer ferrule and said inner ferrule.
[0030] This makes it possible to limit the relative displacements between said outer ferrule and said inner ferrule so as to limit the stresses exerted on the thrust balance.
[0031] According to a particular aspect of at least one embodiment of the invention, said stop screws comprise screws provided on said outer ferrule and oriented radially towards said inner ferrule.
[0032] According to a particular aspect of at least one embodiment of the invention, said inner ferrule has: - an upstream flange extending from one end of said inner ferrule and connecting said inner ferrule to said outer ferrule, and - a downstream flange extending radially from an end opposite to said upstream flange and intended to be connected to said part to be tested of said turbomachine.
[0033] The invention also relates to a turbomachine comprising a part to be tested and a measuring balance according to one of the preceding embodiments, said outer shell being intended to be fixed to a fixed support of said turbomachine, said inner shell being intended to be connected to said part to be tested of said turbomachine. Presentation of the figures
[0034] The invention, as well as the various advantages it presents, will be more easily understood in the light of the following description of illustrative and non-limiting embodiments thereof, and of the accompanying drawings among which: [Fig.1] is a schematic cross-sectional view of a turbomachine; [Fig.2] is a partial schematic side-section view of a thrust balance according to an embodiment of the invention, connected on one side to a part to be tested and on the other side to a fixed support; [Fig.3] is a partial schematic front cross-sectional view of a thrust balance according to the embodiment of [Fig.2]; [Fig.4] is a partial schematic lateral cross-sectional view of a thrust balance according to the embodiment of [Fig.2]; [Fig. 5] is another partial schematic lateral cross-sectional view of a thrust balance according to the embodiment of [Fig. 2], and [Fig.6] is a partial schematic perspective view of a thrust balance according to the embodiment of [Fig.2].
[0035] Detailed description of an embodiment of the invention
[0036] It should be noted that the invention applies to all types of turbomachinery, and in particular to aircraft turbomachinery.
[0037] This turbomachine 1, which extends along an axis L, is for example intended to be mounted on an aircraft (not shown), such as an airplane or a helicopter, for example under the wing of the aircraft, on the wing or at the rear of the fuselage of the aircraft.
[0038] The turbomachine 1 illustrated in [Fig. 1] is a twin-spool, twin-flow, direct-drive turbojet. This is not, however, limiting, since the turbomachine 1 may not be intended for mounting on an aircraft, may be another type of turbojet, such as a geared turbojet, a turboprop, or an auxiliary power unit (also called an "APU").
[0039] Throughout the description, an axial direction corresponds to the direction of the longitudinal axis L and a radial direction is a direction perpendicular to the longitudinal axis L and intersecting the longitudinal axis L. Similarly, an axial plane is a plane containing the longitudinal axis L and a radial plane is a plane perpendicular to the longitudinal axis L.
[0040] Similarly, the adjectives "interior" (or "internal") and "exterior" ("or external") are used with reference to a radial direction so that the inner part of an element is, along a radial direction, closer to the longitudinal axis L than the outer part of the same element.
[0041] Furthermore, unless otherwise specified, the terms "upstream" and "downstream" are used with reference to the overall direction of gas flow through the operating turbomachine.
[0042] As can be seen in [Fig. 1], the turbomachine 1 comprises, from upstream to downstream, a blower 10, a compressor section 12, a combustion chamber 14 and a turbine section 16. The longitudinal axis L forms the axis of rotation of at least a part of the compressor section 12 and the turbine section 16, which are capable of being driven in rotation about the longitudinal axis L relative to a casing 18 of the turbomachine 1.
[0043] During operation, the blower 10 draws in a flow of air, a portion of which, circulating within a primary vein 100, is successively compressed within the section The compressor 12 is ignited within the combustion chamber 14 and expanded within the turbine section 16 before being ejected from the turbomachine 1. In this way, the turbomachine 1 generates thrust. This thrust can, for example, be used to power the aircraft on which the turbomachine 1 is mounted.
[0044] In certain situations, it proves important to measure the thrust applied to one or more elements of this turbomachine.
[0045] This element, or part to be tested, can for example be a stator disc equipped with blades, or a rotor disc equipped with blades.
[0046] The invention described below finds its use particularly in this application.
[0047] We now present, in relation to figures 2 to 6, an embodiment of a balance for measuring the thrust for a part to be tested of a turbomachine.
[0048] As illustrated, the thrust measuring balance comprises two concentric ferrules 2, 3 including: - an external ferrule 2, and - an internal ferrule 3.
[0049] The outer ferrule 2 is formed of a rigid hollow cylindrical wall extending around a first longitudinal axis X. This outer ferrule 2 is intended to be fixed to a fixed support 8 of the turbomachine.
[0050] This fixed support can, for example, be a housing of the turbomachine.
[0051] As for the inner ferrule 3, it is mounted inside the outer ferrule 2 and is formed of a hollow cylindrical wall extending around the first axis X. This hollow cylindrical wall is capable of deforming in reaction to a force and / or a moment applied to the inner ferrule 3.
[0052] This inner ferrule 3 is intended to be connected to the part to be tested 9 of the turbomachine. The part to be tested may, for example, be a bladed disc of a turbine or compressor.
[0053] As illustrated, in this embodiment, the inner ferrule 3 has: - a downstream flange 31 extending from one end of the inner ferrule 3 and connecting the inner ferrule 3 to the outer ferrule 2, and - an upstream flange 30 extending radially from an end opposite the downstream flange 31 and intended to be connected to the part to be tested 9 of the turbomachine.
[0054] For its part, in this embodiment, the outer ferrule 2 has a downstream flange 21 extending from one end of the outer ferrule 2 and in contact with the downstream flange 31 of the inner ferrule 3 so as to connect the inner ferrule 3 to the outer ferrule 2.
[0055] The downstream flange 21 of the outer ferrule 2 and the downstream flange 3 of the inner ferrule 3 are connected to the fixed support 8.
[0056] The outer ferrule 2 also includes an upstream flange 20 extending radially from an end opposite the downstream flange 21 and intended to be provided opposite the upstream flange 30 of the inner ferrule 3.
[0057] According to the invention, the outer ferrule 2 carries measuring means configured to measure: - the displacements of the internal ferrule 3 along the first X axis, a second Y axis orthogonal to the first X axis, and a third Z axis orthogonal to the first X axis and the second Y axis, and - the moments applied to the internal ferrule 3 around the first X axis, the second Y axis and the third Z axis.
[0058] More specifically, and as can be seen in particular in [Fig.3], the outer ferrule 2 carries: - the first means of measurement 41 oriented axially along the first axis X with respect to the external ferrule 2 so as to measure the displacement of the wall of the internal ferrule 3 along the first axis X, and to measure the moments applied to the wall of the internal ferrule 3 around the second axis Y and the third axis Z; - second measuring means 42 oriented radially with respect to the outer ferrule 2 so as to measure the displacement of the wall of the inner ferrule 3 along the second axis Y and third axis Z, and to measure the moment applied to the wall of the inner ferrule 3 around the first axis X, and - third measuring means 43 arranged tangentially to the external ferrule 2 and configured to measure a tangential displacement of at least one reference element 430 fixed on said wall of said internal ferrule 3.
[0059] Because this reference element 430 is fixed on the wall of the inner ferrule, a tangential displacement of this reference element will be equal to the tangential displacement of the wall of the inner ferrule 3. As a result, the third measuring means 43 measure a tangential displacement of the wall of the inner ferrule 3.
[0060] This reference element 430, otherwise called a gauge, can for example be a metallic part detectable by measuring means.
[0061] This metal part may, for example, have a cylindrical shape, a rectangular prism shape, or a prismatic shape.
[0062] Only one reference element 430 is illustrated in [Fig.2]. However, embodiments comprising several reference elements could be envisaged.
[0063] In the illustrated embodiment, the first measuring means 41 comprise a pair of axial sensors angularly spaced at 90° along a plane orthogonal to the first X axis.
[0064] Furthermore, in this illustrated embodiment, the second measuring means 42 comprise a first pair of radial sensors 42a angularly spaced at 90° along a plane orthogonal to the first axis X.
[0065] The second measuring means 42 also include in this embodiment a second pair of radial sensors 42b spaced axially from the first pair of radial sensors 42a along the first longitudinal X axis.
[0066] The implementation of a first pair of radial sensors 42a and a second pair of radial sensors 42b makes it possible to segregate the displacement of the wall of the inner ferrule 3 along the second axis Y and the third axis Z of the moments applied on the wall of the inner ferrule 3 around the second axis Y and the third axis Z.
[0067] In this embodiment, the axial sensors are inductive displacement sensors. More specifically, here, the axial sensors are Kaman sensors.
[0068] Furthermore, in this embodiment, the radial sensors are inductive displacement sensors. More specifically, here, the radial sensors are Kaman sensors.
[0069] As illustrated, in this embodiment, the inner ferrule 3 carries vibration means 6 of the inner ferrule 3, as well as a first accelerometer 5 configured to measure a resonance frequency of the inner ferrule 3 subjected to the vibrations of the vibration means 6.
[0070] These vibration means 6 here include a piezoelectric exciter.
[0071] The vibration means 6 cause the inner ferrule 3 to vibrate. The frequency is recorded by the first accelerometer 5 and allows to measure the evolution of the modulus of elasticity of the material of the wall of the inner shell 3 as a function of temperature, because the natural frequency of the inner shell 3 evolves linearly with the modulus of elasticity.
[0072] Furthermore, in this embodiment, the inner ferrule 3 carries a second accelerometer 5' angularly spaced from the first accelerometer 5 along a plane orthogonal to the first axis X.
[0073] This second accelerometer 5' allows for measurement to be taken in the event of failure of the first accelerometer, or even to average the measured acceleration values.
[0074] These accelerometers and vibration means can, for example, be glued onto an upper surface of the wall of the inner ferrule 3. They could also, according to other embodiments, be welded or fixed by fastening means.
[0075] When using the thrust measuring balance on the part to be tested 9 of a turbomachine, it may be useful to limit the relative displacements between the outer and inner shells so as to limit the stresses exerted on the thrust balance.
[0076] Therefore, in this embodiment, the thrust balance comprises a plurality of stop screws 7 distributed between the outer ferrule 2 and the inner ferrule 3 so as to limit the relative displacements between the outer ferrule 2 and the inner ferrule 3.
[0077] More particularly, here, the stop screws 7 comprise screws formed on the outer ferrule 2 and oriented radially towards the inner ferrule 3.
[0078] Therefore, during a relative movement of the inner ferrule 3 with respect to the outer ferrule 2, the movement is radially limited by these stop screws.
[0079] In this embodiment, the stop screws 7 also include screws provided on the downstream flange 31 of the inner ferrule 3 and oriented axially towards the downstream flange of the outer ferrule 2.
[0080] It should be noted that, according to the embodiments, these stop screws can be distributed uniformly on the downstream flange and / or on the internal ferrule.
Claims
1.
2. Demands Thrust measurement balance for a test piece (9) of a turbomachine comprising two concentric shells (2, 3) including: - an outer shell (2) formed of a rigid hollow cylindrical wall extending around a first longitudinal axis (X), said outer shell (2) being intended to be fixed to a fixed support (8) of said turbomachine, and - an inner ferrule (3) mounted inside said outer ferrule (2) and formed of a hollow cylindrical wall extending around said first axis (X) and capable of deforming in reaction to a force and / or a moment applied to said inner ferrule (3), said inner ferrule (3) being intended to be connected to said part to be tested (9) of said turbomachine, said outer ferrule (2) carrying measuring means configured to measure: - the displacements of said internal ferrule (3) along said first axis (X), a second axis (Y) orthogonal to said first axis (X) and a third axis (Z) orthogonal to said first axis (X) and second axis (Y), and - the moments applied to said internal ferrule (3) around said first axis (X), said second axis (Y) and said third axis (Z). Thrust measuring balance according to claim 1, characterized in that said outer ferrule (2) carries: - of the first means of measurement (41) oriented axially along said first axis (X) with respect to said external ferrule (2) so as to measure the displacement of said wall of said internal ferrule (3) along said first axis (X), and to measure the moments applied on said wall of said internal ferrule (3) around said second axis (Y) and said third axis (Z); - second measuring means (42) oriented radially with respect to said outer ferrule (2) so as to measure the displacement of said wall of said inner ferrule (3) along said second axis (Y) and third axis (Z), and to measure the moment applied on said wall of said inner ferrule (3) around said first axis (X); - third measuring means (43) arranged tangentially to said outer ferrule (2) and configured to measure a tangential displacement of at least one reference element (430) fixed on said wall of said inner ferrule (3).
3. Measuring balance according to the preceding claim, characterized in that said first measuring means (41) comprise a pair of axial sensors angularly spaced at 90° along a plane orthogonal to said first axis (X) and said second measuring means (42) comprise a first pair of radial sensors (42a) angularly spaced at 90° along a plane orthogonal to said first axis (X).
4. Measuring balance claim 3, characterized in that said second measuring means (42) comprise a second pair of radial sensors (42b) spaced axially from said first pair of radial sensors (42a) along said first longitudinal axis (X).
5. Measuring balance according to one of claims 3 or 4, characterized in that said axial sensors are inductive displacement sensors and / or said radial sensors are inductive displacement sensors.
6. Measuring balance according to any one of the preceding claims, characterized in that said inner ferrule (3) carries vibration means (6) of said inner ferrule (3), and a first accelerometer (5) configured to measure a resonance frequency of said inner ferrule (3) subjected to the vibrations of said vibration means (6).
7. Measuring balance according to the preceding claim, characterized in that said inner ferrule (3) carries a second accelerometer (5') angularly spaced from said first accelerometer in a plane orthogonal to said first axis (X).
8. Measuring balance according to any one of claims 6 or 7, characterized in that said vibration means (6) comprise a piezoelectric exciter.
9. A measuring balance according to any one of the preceding claims, characterized in that it comprises a plurality of stop screws (7) distributed between said outer ferrule (2) and said inner ferrule (3) so as to limit the relative displacements between said outer ferrule (2) and said inner ferrule (3).
10. Measuring balance according to the preceding claim, characterized in that said stop screws (7) comprise screws formed on said outer ferrule (2) and oriented radially towards said inner ferrule (3).
11. Measuring balance according to any one of the preceding claims, characterized in that said inner ferrule (3) has: - an upstream flange (30) extending from one end of said inner ferrule (3) and connecting said inner ferrule (3) to said outer ferrule (2), and - a downstream flange (31) extending radially from an end opposite to said upstream flange (30) and intended to be connected to said part to be tested (9) of said turbomachine.
12. Turbomachine comprising a test piece (9) and a measuring balance according to any one of the preceding claims, said outer shell (2) being intended to be fixed to a fixed support (8) of said turbomachine, said inner shell (3) being intended to be connected to said test piece (9) of said turbomachine.