FR3108723A1 - BLOWER TEST MACHINE EQUIPPED WITH A COOLING AIR CIRCUIT OF A BEARING BEARING - Google Patents

Abstract

The invention relates to a wind tunnel testing machine, comprising: a rolling bearing (100) extending along a longitudinal axis (X), and comprising an inner annular ring (104) and an outer annular ring (106), between which circulate rolling elements (108), one of said rings being rotatable about the longitudinal axis relative to the other of said rings, an annular support (102) configured to support said bearing, a casing (110 ) fixed annular ring arranged around said support, characterized in that it also comprises an air circuit (120) arranged in said casing and extending at least in part around said support and being configured to perform heat pumping in said support . Figure for abstract: Figure 8

Description

WIND TUNNEL TESTING MACHINE EQUIPPED WITH A COOLING AIR CIRCUIT WITH A ROLLING BEARING

The invention relates to the field of wind tunnel testing machines, and more specifically to the field of cooling the rolling bearings of such testing machines.

In a known manner, aircraft turbomachines are tested, at least partially, on test machines. For example, a turbine engine fan and compressor can be tested on a wind tunnel test machine. The wind tunnel is the study of the action of the air flow on the fan and the turbomachine compressor (simulation of flight speed or Mach conditions).

In the context of partial tests on a test machine in a wind tunnel, the limitation of the master torque of the turbomachine in the air inlet duct (i.e. of the maximum cross section of the fan of the turbomachine) imposes reduce the number, as well as the diameter of the pipes thereof. In these pipes generally circulate air, oil and/or an air/oil mixture.

The various means of guiding the rotating shaft(s) for the operation of the testing machine are made by rolling bearings (also called bearings), for example ball and roller bearings.

A rolling bearing is mounted between an inner part (fixed or rotating) and an outer part (fixed or rotating), and comprises rolling elements, such as balls or rollers, mounted on a raceway between an integral outer ring of the outer part and an inner ring integral with the inner part. The rolling elements can be kept spaced apart by a cage. The inner and outer rings are coaxial; and one of the rings is intended to be fixed and the other to be rotatable in operation, or both rings may be movable.

Due to the maximum operating conditions, such as rotational speeds, axial and radial loads and the thermal environment, partial test machines generally include lubricated and oil-cooled bearings.

In such a partial testing machine, out of the entire flow of oil injected into the bearing, only about 1% of it is used to lubricate the contact of the rolling elements with the raceways (internal and external), thus as the centering between the cage and the rings. The rest of the oil flow injected, i.e. the remaining 99%, allows the calories generated by the bearing to be evacuated. These calories come from the thermal power dissipated in the bearing, due to the effects of internal friction and oil mixing. This cooling of the bearing makes it possible to ensure satisfactory internal clearances in the bearings in operation, i.e. a limitation of the clearances and an absence of tightening of the rings.

FIG. 1 represents a test machine for an assembly consisting of a fan and a turbomachine compressor, which makes it possible to test the aero-acoustics of the assembly, with the effects of an aircraft simulator plus flight attitude effects (tilt during ascents and descents and rotation to the right or left in a horizontal plane). The machine 10 comprises a mast 12 supporting drive means 14, a support 16 supporting an aircraft simulator 18 and a pylon 20 connected to an external nacelle 22. The external nacelle 22 is connected to the drive means 14, and is coaxial with an air inlet lip 24. The outer nacelle 22 also surrounds at least one compressor with its air inlet 26 arranged to be traversed by the air coming from the air inlet lip 24.

FIG. 2 represents an axisymmetric and schematic view of the bearings in the test machine of FIG. 1, and their position relative to the mast 12. The bearings R1, R2, R3, R4, R5 and R6 support a shaft 30, which rotates the rotor of a fan 32, a compressor 34 and a turbine 36. The bearings R1, R3, R4 and R5 are roller bearings, while the bearings R2 and R6 are ball bearings . Each bearing R1-R6 is surrounded by a lubrication enclosure 38, shown in dotted lines. All R1-R6 bearings are lubricated and oil cooled.

FIG. 3 more precisely represents the bearing R1 in its enclosure 38, and FIG. 4 represents the whole of the entire return line of the air/oil mixture coming from the enclosure of the bearing R1.

Bearing R1 comprises an inner ring 54 and an outer ring 56, between which are arranged rolling elements 52 in the form of rollers. The bearing R1 is lubricated with oil from an oil line 42, which is connected to a nozzle 60 which projects oil between the rings 54, 56 on the rolling elements 52, as shown by the arrow B. The air/oil mixture surrounding the bearing R1 is then sucked in, as shown by the arrows A in FIGS. 3 and 4. More specifically, the pressurization of the enclosure 38 of the bearing R1 is ensured upstream by a pipe 44 d air inlet which is supplied by an air circuit and downstream not the suction of the air/oil mixture in the return line by means of a vacuum pump (not shown). The use of a suction system for the enclosure 38 of the bearing R1 makes it possible to avoid the addition of pressurizing air circuits and thus the number of pipes which cross the mast, the latter being exposed to the air from the blower. Thus, in this test machine, the functions of pressurization and recovery of the air/oil mixture are carried out, in particular downstream, by the same circuit (return line from the enclosure of bearing R1 – mark A in figure 4 ). In addition, the enclosure 38 does not have a degassing system, which also makes it possible to limit the number of pipes which cross the mast 12.

In the mast 12 and the casings 58 of the test machine are integrated the pipes 42 for supplying oil, but also pipes for recovering the air/oil mixture to an oil tank 40 (see FIG. 1) which is configured to separate oil from air. Each bearing enclosure is connected to its own air/oil mixture recovery pipe. The oil tank 40, which represents a large volume, is located under the mast 12. The mast 12 makes it possible to support the test machine relative to the ground, and can also support a turbomachine.

However, the bearing R1, which is arranged at the level of the fan, is furthest from the mast 12, and therefore requires long lengths of air/oil mixture return pipes.

A modeling of the pressure drops of the air/oil mixture of the return line of the bearing R1 makes it possible to highlight the difficulties and the complexity of integrating this bearing, an additional manufacturing cost for its integration, as well as an absence of margin in recovery of the air/oil mixture. The consequences of this are a potential risk of oil overflowing from housing 38 of bearing R1, and therefore a potential risk of leakage. Indeed, when there is no suction of the oil for its recovery, the oil can overflow from the enclosure of the bearing, and thus create a leak. The oil then circulates in cavities where it should not be.

Figures 5 and 6 represent the return line of the air/oil mixture of bearing R1. A pipe 46 for recovering the air/oil mixture from enclosure R1 is formed in a fixed casing. Between the bearing R1 and the pipe 46, two orifices 48 for recovering the radial air/oil mixture are formed. The area surrounded by dotted lines F represents an area of uncertainty regarding oil leaks downstream of bearing R1 enclosure.

The extreme operating conditions of the test machine, such as with cold oil, at maximum rpm, with maximum oil flow and air flow entering (by suction) into the enclosure of the maximum bearing R1 lead to wear of the sealing means upstream and downstream of the enclosure. All this also results in a mass flow of air equal to 2 g/s, i.e. 12% air in the mixture, and a mass flow of oil equal to 10.5 g/s, i.e. approximately 41 l/ h.

The pressure drops of the air/oil mixture in the return line of a bearing are directly proportional to the mass flow rate of the mixture. The mass flow rate of the mixture to be evacuated under these extreme operating conditions is therefore 12.5 g/s, and is essentially composed of oil (by mass).

In operation, the bearing heats up, and dissipates power, which is a function of bearing geometry, rotational speed, loads, oil type and oil inlet temperature. In order to evacuate this thermal power, the bearing is cooled by means of an oil flow.

FIG. 7 represents the bearing R1, on which the heat fluxes are highlighted. The arrows C1 represent the heat flux evacuated by conduction, and the arrows C2 represent the heat flux evacuated by convection. Thus, the power dissipated by the bearing R1 is evacuated by conduction in the inner 54 and outer 56 rings and the support 62 of the bearing, and by convection by the oil.

The order of magnitude of the thermal levels encountered in a bearing are, with an inlet oil temperature of 60° C., from 70° C. to 80° C. for an inner ring 54, and from 100° C. to 160° C. for an outer ring 56. With a rotating inner ring 54 and a fixed outer ring 56, the thermal gradient in the bearing (difference between the temperature of the outer ring 56 and the temperature of the inner ring 54) varies between 20°C and 90°C.

The evolution of bearing internal clearances is a function of the thermal gradients of the rings themselves, which undergo thermal expansion. This thermal expansion is also a function of the dissipated power which depends on the geometry of the rings, loads, speed) and centrifugal effects (mass, radius, speed).

It is therefore necessary to cool the bearing elements in order to control the internal clearances. In particular, the cold diametral play must be limited in order to prevent the rolling elements 52 from slipping on the rolling tracks. Indeed, if the temperature difference increases, there will be a significant expansion, and therefore an increased radial play, and the rolling elements will no longer roll, but slide on the rolling tracks. This leads to bearing wear.

The limitation of the thermal gradient in the bearing is achieved by the flow of cooling oil injected into it.

A device for detecting overheating of a bearing is known, which comprises a cooling fluid intended to spread at the level of the bearing.

Patent application FR 2 976 357 A1 also discloses a device for qualifying strain gauges. Strain gauges are intended to be mounted on rotating parts such as turbomachine parts. The qualification device includes an oven which makes it possible to reproduce the environment of the turbomachine in which the gauge must be installed by raising the temperature to 1100°C. The qualification device further comprises a cooling device for cooling the rotational guide bearings of the disc on which the strain gauge is mounted and for preventing the propagation of heat to the other parts of the device. The cooling device surrounds the wall of the oven and is secured to the disk. The cooling device may include a Ranque-Hilsch tube, which is a thermodynamic device with no moving parts for producing cold air.

Thus, there is a need to cool the bearings to evacuate the heat generated during the rotation of the test machine.

In order to evacuate a maximum of calories, it would be necessary to have pipes with a large diameter, to increase the flow of oil, and also of a considerable length (approximately 2 m), to convey all the oil towards the bearing. However, this is cumbersome and creates high pressure drops in air/oil mixture recovery.

The aim of the invention is to propose a solution making it possible to remedy at least certain drawbacks.

As lubrication only concerns the bearing contacts (rolling elements, inner and outer rings, and possibly cage), and the need for oil flow for this function is very low in quantity (between 1 l/h and a few liters per hour), it is necessary to have a minimum lubricating oil flow. In fact, the rest of the oil flow (approximately 99%) is used by bearing heat.

The aim of the present invention is to reduce the overall oil flow which supplies the bearing furthest from the mast of the test machine, by reducing the part of the oil flow dedicated to cooling it.

To this end, the invention relates to a wind tunnel test machine, comprising:

• at least one rolling bearing extending along a longitudinal axis, and comprising an inner annular ring and an outer annular ring, between which rolling elements are arranged, one of said rings being rotatable around the longitudinal axis by relative to the other of said rings,
• an annular support configured to support said bearing,
• a fixed annular casing arranged around said support,

characterized in that it also comprises an air circuit comprising:

• at least one first pipe, one end of which is connected to an air inlet, said first pipe extending along the longitudinal axis,
• a first annular groove connected to a second end of said first pipe,
• a plurality of pipes connected at a first end to said first annular groove, the plurality of pipes extending along the longitudinal axis,
• a second annular groove connected to a second end of the plurality of pipes and to a radial air outlet,

said air circuit being arranged in said casing, the plurality of pipes extending at least partly around said support and being configured to perform heat pumping in said support.

According to the invention, instead of all or part of the cooling of the bearing with oil, air ducts are added in the casing of the testing machine to cool the rolling bearing. A portion of the calories received by the bearing outer ring is thus extracted via heat pumping carried out in the bearing support, via the circulation of air in the plurality of ducts of the air circuit. The air circuit makes it possible to cool the outer race of the bearing as closely as possible, with an extraction of heat flux (evacuation of calories both by convection and by conduction) in the mass of the casing itself, which is in contact with the bearing support, which itself receives a conduction flow from the bearing.

This advantageously makes it possible to reduce the fluid passage sections of the air/oil mixture recovery line of the bearing and therefore to reduce the diameter of the air/oil mixture return pipe.

This also makes it possible to simplify the integration of the radial air/oil mixture recovery orifices in the casings of the test machine, in particular in view of the mechanical strength of the latter. Indeed, as there is air which cools the bearing instead of part of the oil, the flow of oil to cool the bearing is reduced, and there is therefore less oil to recover. . The radial recovery orifices can therefore be smaller.

In addition, this allows a reduction in the diameter of the pipes in the mast of the testing machine, and therefore a saving of space within it.

According to one embodiment, the diameter of the first pipe is between 7.0 mm and 15.0 mm. This advantageously makes it possible to evacuate between 25% and 100% of the thermal power generated by the bearing in operation. Preferably, the diameter of the first pipe is equal to 10.3 mm. This makes it possible to evacuate 50% of the thermal power generated by the bearing in operation.

According to another embodiment, the air circuit also comprises a second pipe, a first end of which is connected to the air inlet and a second end of which is connected to the first annular groove, said second pipe extending along the longitudinal axis. The diameter of the first and second pipes may have internal sections whose sum is equivalent to the internal section of a pipe with an internal diameter of between 4 and 11 mm. Combined with an air flow of between 25 and 50 g/s, this advantageously allows evacuating between 25% and 100%, or even 50% of the thermal power generated by the bearing in operation.

If it was desired to evacuate 99% of the power dissipated by the bearing (1% of oil flow remaining necessary for the lubrication of the rolling element/ring contacts), the air flow/pipe diameter pair would be 96 g /s; 15mm.

The plurality of pipes may be arranged equidistant from each other over 360° around the support.

The air circuit can be configured so that an air flow of between 10 g/s and 150 g/s flows through the first and second ducts. This advantageously makes it possible to evacuate between 25% and 100% of the thermal power generated by the bearing in operation. Preferably, the air circuit is configured so that an air flow of between 40 and 60 g/s circulates in the first and second pipes. This makes it possible to evacuate 50% of the thermal power generated by the bearing in operation.

The testing machine may include a primary air stream, the air outlet opening into said primary air stream. This advantageously makes it possible not to add an air evacuation circuit dedicated to the cooling air circuit of the bearing and having to convey in return via the mast 12.

The testing machine may comprise an air supply system, the air supply being supplied by said air supply system. In other words, the cooling air can come from the air supply system of the testing machine.

Thus, the cooling air circuit is channeled and open.

The testing machine may comprise a lubrication enclosure arranged around said bearing, and a pipe, a first end of which is connected to an oil inlet and a second end of which opens into said enclosure, said pipe being configured to lubricate said bearing with an oil flow of between 10 and 30 l/h. Preferably, the oil line is configured to lubricate the bearing with an oil flow between 15 and 25 l/h. Such an oil flow corresponds to half the oil flow necessary in the test machines of the prior art to lubricate and cool the bearing.

The fact of lubricating the bearings to a minimum, and partly cooling them with air, instead of oil, makes it possible to reduce the diameter of the oil inlet and oil return pipe or return air-oil mixture and thus simplify the integration of these pipes in the casings of the test machine. This also reduces the oil flow needed to lubricate and cool the bearing and therefore reduces the capacity of test machine equipment such as pumps (supply and recovery).

The test machine may include telemetry means and a cooling circuit configured to cool said telemetry means, the air inlet being produced by a tapping on said cooling circuit. In other words, the supply of the air circuit for the heat pumping can be carried out via a cooling circuit, and in particular of cooling air, already existing in the test machine, for example the cooling circuit of the means of telemetry.

The present invention will be better understood and other details, characteristics and advantages of the present invention will appear more clearly on reading the description of a non-limiting example which follows, with reference to the appended drawings in which:

Figure 1 is a schematic perspective view of a wind tunnel test machine for a fan and a turbomachine compressor,

figure 2 is a very schematic axisymmetric view of the wind tunnel test machine of figure 1,

Figure 3 is a sectional view of part of the wind tunnel test machine of Figure 2, and more specifically of a bearing thereof,

FIG. 4 is a sectional view of part of the wind tunnel test machine of FIG. 2, and more precisely of the assembly of a return line for an air/oil mixture of the latter,

Figure 5 is a sectional view of part of the wind tunnel test machine of Figure 2, and more specifically of a return line of the air / oil mixture of a bearing thereof,

Figure 6 is a sectional view of part of the wind tunnel test machine of Figure 2, and more specifically of a return line of the air / oil mixture of a bearing thereof,

Figure 7 is a sectional view of a part of the wind tunnel test machine of Figure 2, and more specifically of an enclosure of a bearing thereof and showing the heat fluxes exchanged,

FIG. 8 is a cross-sectional view of part of a wind tunnel test machine according to the invention, and more specifically of an enclosure of a bearing thereof showing in particular the integration of a circuit cooling air according to the invention,

Figure 9 is a very schematic sectional view of a cooling air circuit of a wind tunnel test machine according to the invention,

FIG. 10 is a very schematic front view of part of a wind tunnel test machine and showing the angular distribution of part of the cooling air circuit according to the invention,

Figure 11 is a graph representing the airflow to be supplied for cooling and the diameter of the air inlet duct as a function of the percentage of thermal power to be extracted in a bearing of a wind tunnel test machine according to the invention.

The elements having the same functions in the different implementations have the same references in the figures.

As shown in Figure 8, the wind tunnel test machine comprises a rolling bearing 100 extending along a longitudinal axis X and an annular support 102 of said bearing 100. The bearing 100 is here the bearing closest to the fan of the test machine, and therefore the farthest from the mast of the latter.

The bearing 100 comprises an inner annular ring 104 and an outer annular ring 106, between which are arranged rolling elements 108, for example balls or rollers. One of the rings 104, 106 is rotatable around the X axis relative to the other ring. For example, the inner ring 104 can be rotatable around the X axis, while the outer ring 106 is fixed, or vice versa; or the two rings 104, 106 are rotatable around the X axis (co-rotating or counter-rotating) in operation of the bearing 100.

The testing machine also comprises an annular casing 110, which is fixed with respect to the axis X, and which is arranged around the support 102.

The testing machine also comprises a cooling air circuit 120 arranged in the casing 110 and extending at least partly around the support 102. The air circuit 120 is configured to perform heat pumping in the support 102 .

The air circuit 120 comprises a first pipe 122 extending along the axis X, a first end of which is connected to an air inlet 124, and a second end of which is connected to a first annular groove 126. The circuit 120 of air also comprises a plurality of pipes 128 extending along the axis X. Each pipe 128 is connected at a first end, to the first annular groove 126 and at a second end, to a second annular groove 130. The second annular groove 130 is also connected to a radial air outlet 132.

The test machine comprises a lubrication chamber 140 arranged around the bearing 100, and a pipe 142, a first end of which is connected to an oil inlet 144 and a second end of which opens into the chamber 140. The second end of line 142 is provided with a nozzle 146, which is configured to eject oil onto the rolling elements 108 of bearing 100, as shown by arrow H. Line 142 is configured to lubricate bearing 100 with a flow rate of oil between 10 and 30 l/h, preferably between 15 and 25 l/h.

Sealing means are arranged upstream and downstream of the enclosure 140, at the place where the fixed or rotating parts constituting the walls of the enclosure meet. The sealing means comprise for example a carbon seal and/or a labyrinth seal. Air enters the enclosure 140 via the carbon seal 141 here upstream and the labyrinth seal 143 here downstream. This air suction is created by the air/oil mixture recovery pump (vacuum pump).

The enclosure 140 is therefore filled with an air/oil mixture, which is evacuated, via pipes 50 for recovering the air/oil mixture (arrow A – FIG. 5), via vacuum pumps (not shown).

The cooling of the outer ring 106 of the bearing 100 is carried out by extraction of heat flux (i.e. by heat pumping) in the mass of the casing 110, which is in contact with the support 102 of the bearing 100, which itself receives a flux conduction from bearing 100.

As shown in Figure 8, the radial arrows C indicate an extraction of calories from the outer ring 106 to the air circuit 120 to lower the temperature of the bearing 100. The air is heated only where there are arrows C, and from left to right. Orifice 132, which represents the air outlet, is used to evacuate the air which has warmed up in the primary aerodynamic vein of the test machine. The air heated in the casing 110 is evacuated directly into the primary duct, via an outgoing air circuit coming from the telemetry means (not represented) of the test machine, and this towards a labyrinth (not represented) under a nozzle (not shown) of the testing machine.

The routing of the air in the air circuit 120 is shown more precisely in FIG. in the first annular groove 126 (according to the arrow F2), then in the plurality of pipes 128 (according to the arrow F3), then in the second annular groove 130, as represented by the arrow F4. The first groove 126 distributes the air in all the pipes 128.

The ducts 122, 128 are arranged so that the air flowing in the first duct 122 has a direction opposite to the air flowing in the ducts 128 (the arrows F1 and F3 are opposite, in FIG. 9, the air circulates from right to left in the first pipe 122, while the air flows from left to right in the pipes 128).

The air can come from an air supply system of the testing machine, and be evacuated in a primary air stream of the testing machine, as represented by the arrow F5. The air inlet can be achieved by tapping on a cooling circuit, and in particular cooling air, telemetry means.

As shown in Figure 10, the ducts of the plurality of ducts 128 may be arranged equidistant from each other over 360° around the support 102. For example, the air circuit 120 comprises six ducts 128, distributed at 60 ° from each other around the X axis, so as to cool the entire support 102, and therefore the outer ring 106 of the bearing 100 over 360°. Of course, the air circuit 120 may include more or less pipes 128.

As a variant, the pipes of the plurality of pipes 128 can be arranged equidistant from each other over an angular sector, for example over 90°, 180° or 270°, around the support 102; or non-equidistant from each other over an angular sector or over 360° around the support 102.

The casing 110 also includes an oil passage orifice 112, arranged between two pipes 128. The orifice 112 is located in the low position in the casing 110, that is to say at six o'clock considering the dial of a clock.

When the air circuit 120 comprises only a first pipe 122 connected to the air inlet 124, the internal diameter of the first pipe 122 is between 7.0 mm and 15.0 mm.

According to another embodiment, the air circuit 120 also includes a second pipe 122, a first end of which is connected to the air inlet 124 and a second end of which is connected to the first annular groove 126. The second pipe 122 extends along the X axis, for example adjacent to the first pipe 122. When the air circuit 120 comprises the two pipes 122 connected to the air inlet 124, the internal diameter of the first and second pipes 122 can be between 4 and 11mm.

According to the invention, there is a compromise between the mass flow rate of the air/oil mixture that can be evacuated, taking into account a margin in recovery of the air/oil mixture, and the flow of cooling air that the we can bring.

For a bearing of the prior art operating at 15,000 and 20,000 rpm, at a temperature of 30° C., with a flow rate of cooling oil between 30 and 50 l/h, the thermal power dissipated by the bearing , and therefore to be evacuated, is between 500 and 1000 W, a sizing margin of 20%.

The graph of FIG. 11 represents, as a function of the percentage of power (P) of the bearing 100 to be extracted, the associated air flow (D) to be supplied by the air circuit 120, as well as the diameter (Di) of the corresponding air inlet duct.

In order to evacuate 25% of the power P of the bearing 100, the casing 110 of the test machine according to the invention can be cooled with a cooling air flow D of between 10 and 30 g/s. The first pipe 122 then has an internal diameter Di of between 4 and 11 mm. In the case where the air circuit 120 comprises several pipes, for example first and second pipes 122, these pipes have internal sections whose sum is equivalent to the internal section of a pipe with an internal diameter of between 4 and 11 mm. .

To evacuate half of the power P dissipated by the bearing, the casing 110 can be cooled with a cooling air flow D of between 20 and 60 g/s. The pipes, for example the first and second pipes 122, have internal sections whose sum is equivalent to the internal section of a pipe with an internal diameter of between 7 and 15 mm.

In order to evacuate 75% of the power P from the bearing 100, the casing 110 can be cooled with a cooling air flow D of between 30 and 90 g/s. The pipes, for example the first and second pipes 122, have internal sections whose sum is equivalent to the internal section of a pipe with an internal diameter of between 10 and 20 mm.

To evacuate all of the power P dissipated by the bearing, the casing 110 can be cooled with a cooling air flow D of between 40 and 120 g/s. The pipes, for example the first and second pipes 122, have internal sections whose sum is equivalent to the internal section of a pipe with an internal diameter of between 12 and 25 mm.

Thus, the air circuit can be configured so that an air flow of between 10 g/s and 150 g/s, preferably between 40 and 60 g/s, circulates in the first and second pipes 122.

By evacuating 50% of the power P dissipated by bearing 100, the flow of oil to be recovered by the vacuum pump is reduced by half. The recovery margin with respect to the air/oil mixture is then around 50%.

Claims (10)

Wind tunnel testing machine, comprising:

• at least one rolling bearing (100) extending along a longitudinal axis (X), and comprising an inner annular ring (104) and an outer annular ring (106), between which rolling elements (108) are arranged, the one of said rings being rotatable around the longitudinal axis (X) relative to the other of said rings,
• an annular support (102) configured to support said bearing (100),
• a fixed annular casing (110) arranged around said support (102),

characterized in that it also comprises an air circuit (120) comprising:

• at least one first pipe (122) of which a first end is connected to an air inlet (124), said first pipe (122) extending along the longitudinal axis (X),
• a first annular groove (126) connected to a second end of said first pipe (122),
• a plurality of pipes (128) connected at a first end to said first annular groove (126), the plurality of pipes (128) extending along the longitudinal axis (X),
• a second annular groove (130) connected to a second end of the plurality of pipes (128) and to a radial air outlet (132),

said air circuit (120) being arranged in said casing (110), the plurality of ducts (128) extending at least partially around said support (102) and being configured to effect heat pumping in said support (102 ). A testing machine according to claim 1, wherein the diameter of the first pipe (122) is between 7.0mm and 15.0mm. Testing machine according to Claim 1, in which the air circuit (120) comprises a second pipe (122), a first end of which is connected to the air inlet (124) and a second end of which is connected to the first annular groove (126), said second pipe (122) extending along the longitudinal axis (X). Testing machine according to Claim 3, in which the diameter of the first and second pipes (122) have internal sections whose sum is equivalent to the internal section of a pipe with an internal diameter of between 4 and 11 mm. Testing machine according to one of Claims 1 to 4, in which the pipes of the plurality of pipes (128) are arranged equidistant from each other over 360° around the support (102). Testing machine according to one of Claims 3 or 4, in which the air circuit (120) is configured so that an air flow of between 10 g/s and 150 g/s circulates in the said first and second lines (122). Testing machine according to one of Claims 1 to 6, comprising a primary air stream, and in which the air outlet (132) opens into the said primary air stream. A testing machine according to claim 7, comprising an air supply system, and wherein the air supply (124) is supplied by said air supply system. Testing machine according to one of Claims 1 to 8, comprising:

• a lubrication enclosure (140) arranged around said bearing (100),
• a pipe (142) whose first end is connected to an oil inlet (144) and whose second end opens into said enclosure (140), said pipe (142) being configured to lubricate said bearing (100) with a flow rate of oil between 10 l/h and 30 l/h.

Testing machine according to one of Claims 1 to 8, comprising telemetry means and a cooling circuit configured to cool said telemetry means, and in which the air inlet (124) is produced by tapping on said cooling circuit.