ASSEMBLY FOR AIRCRAFT TURBOMACHINE, PARTICULARLY FOR A TEST BENCH, COMPRISING A ROTATING SECTION ON WHICH IS MOUNTED A FLOATING SECTION EQUIPPED WITH A MEASURING HEAD

Abstract

The invention relates to an assembly (100) for an aircraft turbomachine, particularly for a test bench, comprising a rotating part (20) including: - a drive shaft (8); - a plurality of rotating blades (14); - a rotating aerodynamic fairing (12), the assembly further comprising a floating part (120) mounted for rotation relative to the rotating part (20), the floating part (120) comprising a floating support (36) and a floating measuring head (34) of a device (34a) for measuring at least one characteristic of the gas flow (10a), the floating part (120) being configured to have an eccentric center of gravity, so as to return the floating measuring head (34) to a reference angular position. Figure for the abstract: Fig. 2

Description

Title of the invention: ASSEMBLY FOR AN AIRCRAFT TURBOMACHINE, IN PARTICULAR FOR A TEST BENCH, COMPRISING A ROTATING PART ON WHICH IS MOUNTED A FLOATING PART EQUIPPED WITH A MEASURING HEAD Technical field

[0001] The invention relates to the field of aircraft turbomachinery, and more specifically to the field of test benches and the measurement of at least one characteristic of a gas flow conforming to a fairing of the turbomachine.

[0002] The invention finds applications in all types of aircraft turbomachinery, such as turbojets or turboprops, and in particular turbomachinery comprising a rotating aerodynamic fairing, defining an external surface intended to be followed by the gas flow to be characterized. Prior art

[0003] In flight or during testing, it proves useful to measure certain characteristics of one or more gas flows of an aircraft turbomachine, such as the pressure and / or speed and / or temperature of an airflow conforming to an aerodynamic fairing of the turbomachine.

[0004] For example, measurements can be useful for characterizing the boundary layer of an airflow conforming to the aerodynamic fairing of the turbomachine. To perform these dynamic measurements, a measuring head is generally mounted on a stator part of the turbomachine, such as a housing. The measuring head is a component commonly shaped like a bar, equipped with several sensors to measure parameters such as total pressure and temperature. Keeping the head stationary ensures the reliability of the measurements. Otherwise, the speed of the measuring head would, for example, alter the pressure measurements.

[0005] A difficulty arises when the turbomachine does not have a stator section in the immediate vicinity of the flow to be characterized. For example, in the case of a turbomachine receiver with unshod rotating blades, the absence of a housing around the blades prevents the installation of the measuring head. These blades generally protrude radially from a rotating aerodynamic shroud. The latter could then support the measuring head, but the reliability of the measurements would remain too low due to the rotating, and therefore non-static, nature of the measuring head. Description of the invention

[0006] To address at least partially the drawbacks mentioned above relating to prior art inventions, the invention first relates to an assembly for an aircraft turbomachine, in particular for a test bench, the assembly being centered on a longitudinal central axis of this assembly, and comprising a part rotating about this longitudinal central axis, the rotating part comprising:

[0007] - a drive shaft;

[0008] - a plurality of rotating blades;

[0009] - a rotating aerodynamic fairing, from which the rotating blades protrude radially outwards, the fairing defines an outer surface intended to be followed by a flow of gas.

[0010] According to the invention, the assembly further comprises a floating part mounted to rotate relative to the rotating part, about the longitudinal central axis, the floating part comprising:

[0011] - a floating support comprising a circumferential surface intended to be fitted by said gas flow;

[0012] - a floating measuring head of a measuring device of at least one characteristic of said gas flow, the measuring head being carried by the floating support,

[0013] the floating part being configured so as to have a center of gravity eccentric with respect to the longitudinal central axis, so as to return the floating measuring head to a reference angular position around the longitudinal central axis, during the rotation of the rotating part of the assembly.

[0014] The invention advantageously provides a floating, or non-rotating, portion carrying the measuring head, which can thus remain static, or substantially static, while the rotating portion of the assembly performs its rotational movement. Measurements taken with the head remaining static are therefore perfectly reliable.

[0015] The principle implemented in the invention, which can be likened to that of a non-rotating or floating hubcap in the radically different field of motor vehicle wheels, offers a wide choice for the angular reference position of the measuring head.

[0016] The invention preferably provides for at least one of the following optional technical features, implemented individually or in combination.

[0017] Preferably, the assembly includes a bearing interposed between the drive shaft and the floating support.

[0018] Preferably, the rotating aerodynamic fairing has two sections spaced axially apart from each other, the floating part being arranged axially between the two sections of the rotating aerodynamic fairing.

[0019] Preferably, the measuring head is located upstream of the rotating blades.

[0020] Preferably, the rotating blades have variable pitch.

[0021] Preferably, the rotating blades are unfaired.

[0022] Preferably, the assembly further comprises a balance wheel rotatably mounted on the floating support, so as to further limit the oscillatory movement of the floating part with an eccentric center of gravity.

[0023] Preferably, the measurements taken by the measuring head will be transmitted wirelessly to the acquisition device located on the ground, for example by radio transmission.

[0024] The invention also relates to an aircraft turbomachine comprising at least one assembly as described above.

[0025] Preferably, the aircraft turbomachine is a test bench turbomachine, but it could alternatively be a turbomachine intended to be installed on the aircraft, in order to provide its propulsion.

[0026] Finally, the invention also relates to a test installation, comprising such an aircraft turbomachine, as well as a test bench, and apparatus for generating the gas flow so that it conforms to the outer surface of the rotating aerodynamic fairing.

[0027] Other advantages and features of the invention will become apparent in the detailed, non-limiting description below. Brief description of the drawings

[0028] The following detailed description refers to the attached drawings on which:

[0029] [Fig.1] is a perspective view of an aircraft turbomachine;

[0030] [Fig.2] is a schematic longitudinal cross-sectional view of a part of the turbomachine shown in the previous figure, in the form of a preferred embodiment of the invention;

[0031] [Fig.3] is a cross-sectional view taken along line 111-111 of [Fig.2]; and

[0032] [Fig.4] is a schematic side view of a turbomachine test installation represented in the previous figures; Detailed description of implementation methods

[0033] With reference first to [Fig. 1], an aircraft turbomachine 1 is shown. This is a turbojet engine whose receiver 3 includes an unfaired fan 4, preferably located upstream of the turbomachine. Hereafter, the terms "upstream" and "downstream" are given with respect to a principal direction 5 of gas flow through this turbomachine, these terms can respectively be replaced by the terms "front" and "rear", with the same meaning.

[0034] With reference to figures 1 and 2, the turbomachine 1 comprises, from upstream to downstream, the unshod blower 4, and a gas generator 6. The latter is conventionally made using one or more compressors, a combustion chamber, and one or more turbines.

[0035] This gas generator 6 is configured to deliver mechanical power to the receiver 3 via a drive shaft 8 centered on the longitudinal central axis X of the turbomachine. In a direct-coupled configuration, this shaft 8 can be a shaft of the gas generator 6, or in an indirect-coupled configuration, it can be an output shaft of a gearbox (not shown), driven by the gas generator 6.

[0036] In operation, a total airflow 10a flows over the front part of a rotating aerodynamic fairing 12 of the receiver 3, before passing through rotating blades 14 forming the fan 4. This consists of an annular row of rotating fan blades 14, each projecting radially outwards from an outer surface 13 of the rotating fairing 12, this surface 13 being intended to be flowed over by the total airflow 10a. In the preferred embodiment described, the blades 14 have variable pitch, i.e., a rotating part 20 of the turbomachine includes not only the drive shaft 8, the rotating fairing 12, and the fan blades 14, but also devices 22 for controlling the pitch of the blades 14 in angle of incidence.In addition, the rotating part 20 includes arms 24 or other mechanical connecting elements, allowing the shaft 8 to be coupled in rotation with the other elements of the rotating part, in particular the blower blades 14 and the fairing 12.

[0037] After passing through the unfaired blades 14, the total flow 10a continues to propagate downstream, before encountering a flow separation nozzle 26. The total flow then divides into a primary airflow 10b entering a primary channel 28b, and a secondary airflow 10c entering a secondary channel 28c. The latter is not faired radially outwards, but fictitiously delimited by the ends of unfaired outlet guide blades 30, also called OGVs (from the English "Outlet Guide Varies").

[0038] It is noted that the rotating shroud 12 extends downstream, beyond the fan blades 14, to the vicinity of the inlet of the primary flow 28b. Consequently, the space available at the level of the stator portion 32 of the turbomachine, upstream of the primary flow 28b, may be non-existent or too narrow to allow the installation of a measuring head for characterizing the total airflow. Furthermore, typically, the entire forward portion of the receiver upstream of the blades 14, formed by the fairing 12, is also rotating, so such an implantation is not recommended for a measuring head intended to remain static.

[0039] The invention provides a solution enabling the implantation of a floating measuring head 34, capable of measuring characteristics of the total airflow 10a, upstream of the unshod blower blades 14. More specifically, the measuring head 34 makes it possible to measure the pressure and temperature of the total airflow 10a, in particular in the boundary layer.

[0040] To this end, the invention relates to an assembly 100 centered on the X axis, comprising the rotating part 20, as well as a floating part 120 specific to the present invention, and integrating the measuring head 34.

[0041] The floating part 120, also called the non-rotating part, functions as a non-rotating hubcap for a motor vehicle wheel, this type of hubcap also being called floating.

[0042] Indeed, the floating part 120 includes a floating support 36, generally annular in shape centered on the X axis. The inner periphery of this support 36 is carried by a bearing 38, interposed between this support 36 and an upstream end 8a of the shaft 8, which can be made by several shaft sections, mounted one on top of the other.

[0043] Thanks to this bearing 38, the floating part 120 is mounted to rotate relative to the rotating part 20, along the X-axis. This allows for a relative rotational movement between the two parts 20 and 120, which is used so that the floating part 120 remains static or substantially static, while the part 20 rotates around the X-axis during the operation of the turbomachine. This is why the floating part 120 is also called the non-rotating part. It comprises, at its outer periphery, a circumferential surface 40 designed to accommodate the total airflow 10a, and is aerodynamically continuous with the outer surface 13 of the rotating fairing. The measuring head 34 is carried by the floating support 36, projecting radially outwards from the circumferential surface 40.This head 34 is an integral part of a measuring device 34a, other elements of which can be integrated into the support 36, but preferably arranged more inwards so as not to protrude into the flow 10a. In this regard, it is noted that the measuring device 34a can communicate the data measured by the head 34 to a rotating telemetry system 42, for example integrated on or near the arms 24.

[0044] In the preferred embodiment described, the rotating aerodynamic fairing 12 has two sections 12a, 12b spaced axially apart. Section 12a is the most upstream, incorporating the nose of the rotating part 20, while the downstream section 12b is the one from which the fan blades 14 protrude. Other radial arms 124 can connect the shaft 8 to the upstream section 12a, these arms 124 being arranged upstream of the bearing 38, while the arms 24 are arranged downstream of this same bearing, in order to carry the downstream section 12b as well as the shim control devices 22.

[0045] Between them, the two sections 12a, 12b define a free axial space, in which the floating part 120 is arranged, as is best seen in [Fig.2]. On either side of this floating part 120, the junctions are preferentially flush between the circumferential surface 40 of the floating support 36, and the outer surface 13 of the two sections 12a, 12b.

[0046] The floating part 120 is configured to have a center of gravity eccentric with respect to the X-axis, for example by exhibiting mass heterogeneity in the circumferential direction. This heterogeneity can, for example, be achieved by locally varying the thickness of the support in the radial and / or axial directions. The center of gravity of the floating part 120 is determined so that, when the turbomachine is stopped, the support 36, by gravity, brings the measuring head 34 into a reference angular position around the X-axis. Indeed, when stopped, the floating part 120 automatically positions itself by gravity in a so-called vertical position, in which the center of gravity is vertically aligned with the X-axis in the radial direction.Furthermore, as will be described below, this eccentricity of the center of gravity makes it possible to obtain the effect of a floating hubcap during the operation of the turbomachine, so that the measuring head 34 is constantly returned to its reference angular position, despite the rotation of the rotating part 20.

[0047] Figure 3 illustrates that the reference angular position of the head 34 does not necessarily correspond to a 12 o'clock position. This position can be varied and adopted according to the needs and constraints encountered, for example, when seeking to reduce the windage of the head 34. In the example shown in Figure 3, the reference angular position corresponds to a 10 o'clock position, but it could of course be different, such as 3 o'clock, 6 o'clock, etc. In this regard, it is noted that these positions are given considering the turbomachine with a normal orientation, that is, its orientation as observed when it is assembled on the aircraft on the ground.

[0048] To reinforce the non-rotating aspect of the floating part 120 in operation, the assembly 100 further includes a balance wheel 44, or pendulum. It is rotatably mounted on the floating support 36. More precisely, the balance wheel 44 comprises a ring 46 mounted with a small radial clearance 48 around a ring 50 of the floating support 36, this ring 50 preferably being the one carried internally by the bearing 38.

[0049] The ring 46 of the balance wheel 44 carries an eccentric mass 52, which also conditions, due to gravity, a vertical rest position of this balance wheel, shown in [Fig.3].

[0050] At rest, due to the small mounting clearance between the two rings 46, 50, the upper part of the ring 46 rests on the upper part of the ring 50. The X' axis of the ring 46 is thus very slightly offset downwards from the X axis of the ring 50, hence the presence of the small radial clearance 48 in the lower part of the two rings 46, 50. This clearance 48 nevertheless remains sufficient to allow the relative rotation between the two rings 46, 50, guaranteeing the principle of movement compensation described below.

[0051] Also, when the rotating part 20 is not rotating, namely when the turbomachine is stopped, the floating part 120 adopts its reference angular position, dictated by the position of its center of gravity.

[0052] During the operation of the turbomachine, causing the rotating part 20 to rotate around the X axis, the floating part 120 may tend to undergo an oscillatory movement around the reference angular position of the measuring head 34. It is the eccentricity of its center of gravity that constantly returns the head 34 to this reference angular position, allowing this head to maintain a substantially constant angular position, for efficient and reliable measurement on the airflow 10a, upstream of the blower blades 14.

[0053] The presence of the balance wheel 44, rotatably mounted on the floating support 36, further reduces the parasitic movement of the measuring head 34, according to a known principle described in document WO 2000 020231 AL

[0054] Indeed, it is first noted that, due to the different eccentricity distances for the center of gravity Cl of the floating part 120 and the center of gravity C2 of the balance wheel 44, which is closer to the X-axis, these two elements tend to oscillate with distinct oscillation periods, always around their reference angular positions shown in [Fig. 3]. Initially, due to the frictional force exerted between these two elements at the level of their respective contacting rings 46, 50, no relative movement is observed between them, and the measuring head 34 is thus advantageously stabilized in or near its reference angular position.

[0055] Furthermore, when the frictional force is no longer sufficient and the two elements 120, 44 oscillate, they may then exhibit opposite directions of rotation during these oscillatory movements. When this occurs, the frictional force between the two elements 120, 44 causes each of them to oppose the movement of the other. The oscillation amplitudes are thus advantageously reduced. By thereby decreasing the unwanted displacements of the measuring head 34, it remains non-rotating despite the high-speed rotation of the rotating part 20 of the turbomachine. Dynamic measurements carried out in this way on the flow 10a, with the head 34 static or substantially static, are even more reliable and perform better.

[0056] Finally, it is noted that while the principle of the invention can be implemented on a turbomachine intended for installation on an aircraft to provide propulsion, the preferred application of the invention nevertheless lies in a turbomachine for a test bench. In this regard, [Fig. 4] schematically represents a test installation 200, for example intended for testing and / or certification of the turbomachine.

[0057] The installation then includes the turbomachine 1, as well as a test bench 150, and apparatus 152 for generating the total airflow 10a, so that it conforms to the outer surface 13 of the rotating aerodynamic fairing 12. The apparatus 12 can be a conventional wind tunnel.

[0058] Various modifications to the invention described above may be made by a person skilled in the art, solely by way of non-limiting examples, the scope of which is defined by the appended claims. In particular, other types of turbomachinery may be considered, preferably with an unshrouded receiver, driven directly or indirectly by the gas generator, for example, of a twin-body and / or twin-flow design. Furthermore, solutions other than that of the rocker arm 44 may be implemented to contribute to the stabilization of the floating part 120, such as magnetic solutions, or other solutions known in the field of floating hubcaps for motor vehicle wheels.

Claims

Demands

1. Assembly (100) for an aircraft turbomachine, in particular for a test bench, the assembly being centered on a longitudinal central axis (X) of this assembly, and comprising a rotating part (20) about this longitudinal central axis (X), the rotating part comprising: - a drive shaft (8); - a plurality of rotating blades (14); - a rotating aerodynamic fairing (12), from which the rotating blades (14) project radially outwards, the fairing defining an outer surface (13) intended to be followed by a gas flow (10a), characterized in that the assembly further comprises a floating part (120) mounted rotatably relative to the rotating part (20), about the longitudinal central axis (X), the floating part (120) comprising: - a floating support (36) comprising a circumferential surface (40) intended to be followed by said gas flow (10a);- a floating measuring head (34) of a measuring device (34a) for at least one characteristic of said gas flow (10a), the measuring head being carried by the floating support (36), the floating part (120) being configured so as to have a center of gravity eccentric with respect to the longitudinal central axis (X), so as to return the floating measuring head (34) to a reference angular position around the longitudinal central axis (X), during the rotation of the rotating part (20) of the assembly.;

2. Assembly according to claim 1, characterized in that it comprises a bearing support (38) interposed between the drive shaft (8) and the floating support (36).

3. Assembly according to claim 1 or 2, characterized in that the rotating aerodynamic fairing (12) has two sections (12a, 12b) spaced axially apart from each other, the floating part (120) being arranged axially between the two sections (12a, 12b) of the rotating aerodynamic fairing.

4. Assembly according to any one of the preceding claims, characterized in that the measuring head (34) is located upstream of the rotating blades (14).

5. Assembly according to any one of the preceding claims, characterized in that the rotating blades (14) have variable pitch.

6. Assembly according to any one of the preceding claims, characterized in that the rotating blades (14) are unfaired.

7. Assembly according to any one of the preceding claims, characterized in that it further comprises a rocker arm (44) rotatably mounted on the floating support (36).

8. Aircraft turbomachine (1) comprising at least one assembly (100) according to any one of the preceding claims.

9. 9. Test facility (200), comprising an aircraft turbomachine (1) according to the preceding claim, as well as a test bench (150), and apparatus (152) for generating the gas flow (10a) so that it conforms to the outer surface (13) of the rotating aerodynamic fairing (12).

Images