FR3037398A1 - AIR RECOVERY AUGET FOR AN AIR INTAKE CHIMNEY OF A TURBOMACHINE TESTING BENCH - Google Patents

Abstract

An air straightening trough (14) for an air intake stack of a turbomachine test stand, comprising a leading edge (141) and a trailing edge (142), characterized in that it comprises a movable upstream portion (14b) defining said leading edge (141) and / or a movable downstream portion (14c) defining said trailing edge (142), so that the trough (14) has an aerodynamic profile and a variable length of rope.

Description

BACKGROUND OF THE INVENTION The field of the present invention is that of the ground test stands for turbomachines. STATE OF THE ART Turbomachines require, for their development, or for the verification of their performance at the end of maintenance, a passage on a test bench on the ground. These tests are conducted in a closed facility to avoid environmental damage, including noise. These installations conventionally comprise an air supply chimney, a test room in which the turbomachine is disposed and means for evacuation of the flue gases. The means of evacuation of the burned gases generally comprise an entity commonly named by the skilled person "detuner" (for detuner in French). The detuner is immediately downstream of the turbomachine. Its function is to recover the burnt gases from the turbomachine and channel them in an exhaust room before being released to the atmosphere. In the following, the detuner will be named gas collector. The air passing through the turbomachine is sucked into the test bench room. The speed of the gases at the outlet of the turbomachine causes a circulation of air in the room, called induced air, which passes around the turbomachine and which is driven, by a horn effect, by the gases leaving the exhaust nozzle of the turbomachine. One of the challenges of the closed test benches is to ensure a good air supply of the test room in order to avoid the formation of vortices as well as a recirculation in the bench, while minimizing the distortion of speed and air pressure upstream of the turbomachine.

3037398 2 This role is provided by an air rectifier bucket grid located in the bend of the air inlet chimney and which makes it possible to straighten the flow of air of substantially vertical direction upstream of the chimney in one direction. substantially horizontal directional flow of air downstream of the chimney.

The goal is to obtain an air velocity profile upstream of the engine as flat as possible. The intake bucket is composed of several buckets arranged uniformly or in an arithmetical progression along the diagonal of the elbow of the chimney. Very often, the skeleton of the bucket 10 is a simple quadrant. Sometimes flats are added: - to the trailing edges of the buckets in order to better straighten or channel the flow of air along a horizontal axis in the downstream part of the elbow, - to the leading edges of the buckets to better capture the vertical air flow and thus limit detachments to the leading edges of the bucket, or - upstream and downstream of the buckets to combine these advantages. The flats are attached to the buckets, usually by welding. These air straightening devices have the disadvantage that they do not confer versatility on the test stand. Indeed, a bucket grid adapted to a certain type of engine, and therefore to a certain level of flow, will not necessarily be with another type of engine, having a different flow level. This problem can also arise for the same engine when it has different speeds.

The present invention aims to remedy these drawbacks, by proposing an air straightening device for a turbojet engine test bench, in particular an air straightening trough, which can be adapted to different types of air flow. .

SUMMARY OF THE INVENTION The object of the invention is thus an air straightening trough for an air intake chimney of a turbomachine test bench, comprising a leading edge and an edge. leak. The trough according to the invention comprises a movable upstream part 5 defining said leading edge and / or a movable downstream part defining said trailing edge, so that the trough has an aerodynamic profile and a variable length of rope. . Thus, advantageously, thanks to the presence of the moving part or parts, each bucket can be individually adjusted. It is thus possible to adjust the aerodynamic profile and the length of the rope, the rope being the line segment connecting the two ends of the bucket, and consequently the direction of the air flow for each bucket outlet. In particular, thanks to the displacement of the movable upstream part, it is possible to adjust the direction of the leading edge of the bucket and by moving the movable downstream part 15, it is possible to adjust the direction of the trailing edge of the trough. It thus becomes easier to optimize the direction and the homogenization of the air flow at the outlet of the intake zone, which makes it possible to adapt the air flow as a function of the turbojet engine to be tested. The aerodynamic profile of the bucket is advantageously curved, preferably in the shape of a circular arc.

Preferably, each bucket of the air straightening device comprises at least one moving part. Each bucket is typically disposed in an air intake zone of the test bench, and in particular in an air intake chimney. The at least one air straightening element may in particular be arranged on a support situated in a diagonal of the bend of the inlet chimney. Each bucket is typically adapted to locally straighten the direction of the airflow between a substantially vertical inlet direction and a substantially horizontal exit direction. The movable portion or portions of the trough, which are advantageously of curved shape, and in particular in the shape of a circular arc, make it possible to adjust this direction of exit substantially horizontally by locally adjusting the deviation of the flow of the trough. air relative to the horizontal. Said upstream and / or downstream portion may be movable by sliding. In a first embodiment, said upstream and / or downstream portion 5 is slidably mounted on or in a fixed central body. Said upstream and / or downstream portion and the fixed central body are advantageously of curved shape, and in particular in the shape of an arc of a circle. In a second embodiment, said upstream portion is slidably mounted on or in said downstream portion.

In general, said upstream and / or downstream portion is advantageously of curved shape, in particular in the shape of an arc of a circle. The invention also relates to an air straightening device for a turbojet engine test bench, in particular an air intake chimney for a turbomachine test bench, comprising a grid of at least one trough described above. Said at least one bucket can be fixed on one or more flanges. The chimney may comprise means for moving said upstream and / or downstream part. The invention also relates to a turbomachine test bench, comprising an air intake chimney described above. The invention finally relates to a method of adjusting the direction of the flow of the intake air in a turbomachine test bench. The method according to the invention comprises a step of moving the upstream and / or downstream part of at least one bucket described above. DESCRIPTION OF THE FIGURES The invention will be better understood and other details, features and advantages of the invention will become apparent on reading the following description given by way of nonlimiting example and with reference to the appended drawings in which: FIG. 1 is a general schematic view of a turbojet engine test bench; FIG. 2 is a detailed view of the test stand of FIG. 1; FIG. 3 is a partial perspective view of an air intake stack of the test stand, FIG. illustrates an air straightening trough of the prior art inlet chimney, according to a first embodiment; FIGS. 5A to 5C illustrate a prior art trough, in accordance with FIG. a second embodiment, - Figure 6 illustrates a set of buckets of the state of the art, in a first configuration, - Figure 7 illustrates a set of buckets of the state of the art, in a second configuration; FIG. 8A is a perspective view of an air straightening trough according to the invention, according to a first embodiment, FIG. 8B is a side view of the trough of the FIG. 8A, FIGS. 9A to 9D are perspective views of the bucket of FIG. 7A, in different configurations. Fig. 10 is an open perspective view of an inlet chimney with buckets according to the invention; Figs. 11A and 11B are partial views of the inlet chimney of Fig. 10; FIGS. 12A and 12B are perspective views of two configurations of an air straightening trough according to the invention, according to a second embodiment, and FIGS. 13A and 13B are side views of the bucket of Figures 12A and 12B.

DETAILED DESCRIPTION Referring to Figures 1 and 2, there is shown a test bench for a turbomachine, in use on the ground. This bench comprises a test room 1 in which is positioned the turbomachine 2 to evaluate. This room 1 is connected upstream (the upstream and downstream terms referring in the following description to the direction of flow of air in the turbomachine, as represented by the arrow F) to a device, not shown, whereby the air enters the test room 1. The test turbine engine 2 is suspended from, or positioned on, a pedestal 3 which generally comprises a device for measuring the thrust it exerts, known as the push scale name. On the inlet shell of the turbomachine is mounted an air inlet 4 extending axially upstream and having the shape of a cylinder of revolution which ends upstream by a flared bell, able to guide the air entering the engine. This flag is in some cases locked in a wire cage to protect the engine 2 against possible ingestion of a foreign body. Behind the engine is a gas manifold 6, consisting of a frustoconical horn 6a, forming an inlet bell, continuing downstream by a cylindrical body 6b and terminating in some cases by a frustoconical nozzle 6c. . This gas manifold 6 is movable in translation along the axis of the engine 2 to optimize the flow of gas 11 from the engine nozzle and the air induced 12 by this gas flow. It can be moved longitudinally while remaining, for its downstream part, inside a fixed device called a mixing tube (not shown), where the flow is treated to reduce its temperature and noise. On the aerodynamic level, the air circulating in the test room 1 is divided mainly into two streams: on the one hand, a primary flow 10 which is sucked by the engine, which passes into the air inlet 4 and which leaves via the nozzle 30 in the form of a jet of hot gas 11, and, on the other hand, an induced flux 12 which is sucked into the room 1 by the driving of the primary flow 10, which circulates 3037398 7 around of the engine 2 to enter the gas manifold 6 surrounding the jet of hot gas 11 leaving the nozzle and which mixes with the primary flow 10 at the outlet of the gas manifold 6. The gas manifold 6 thus recover the flue gases from of the turbomachine 2 and channels 5 in an exhaust room 7 (Figure 1). The test room 1 is supplied with air by an intake zone 5 comprising an air inlet chimney 13 provided with baffles 8 and a grid 9 of rectifying vanes 14 (augets). The grid 9 (FIG. 3) is situated in the diagonal 15 of the bend of the inlet chimney 13. The buckets 14 make it possible to straighten the flow of air from a substantially vertical direction of air flow Z to a direction of substantially horizontal air outlet X. Figure 4 illustrates a bucket 14 of the state of the art. Each bucket 14 rectifies the flow of air arriving along the Z direction at the leading edge 141 of the trough 14 into a flow of X-direction air at the trailing edge 142 of the trough. 14. The leading edge 141 of the trough 14 is the end of the trough 14 on which the flow of air arrives while the trailing edge 142 is the end of the trough 14 by which the air flow leaves the bucket 14.

Each bucket 14 is advantageously of curved shape, in particular of section in the form of an arc of a circle, and in particular of a quarter circle. The axis of symmetry R of the trough 14 is advantageously inclined by 45 ° relative to the vertical direction Z and to the horizontal direction X. The air flow is straightened via the upper face 141 of the trough 14 which 25 defines a concave intrados 141, the lower face 14E of the trough 14 defining a convex extrados. One or more flats can be added to the bucket. In a first variant, illustrated in FIG. 5A, a flat part 16b, called downstream flat part, is added at the trailing edge 142 of the trough 14 in order to better straighten or channel the air flow along the axis. X downstream of the diagonal 15.

In a second variant, illustrated in Figure 5B, a flat portion 16a, said upstream flattened, is added to the leading edge 141 of the bucket 14 to better capture the air flow in the direction of the Z axis and thus to limit the detachments at the leading edge 141 of the bucket 14.

In a third variant, illustrated in FIG. 5C, the trough 14 is provided with both a downstream flat 16b and an upstream flat 16a, which makes it possible to cumulate the advantages associated with each of the flats 16a, 16b. . Upstream / downstream flats are appendices which are generally added when it has been found that the feed of the test vein of the closed test rig is unsatisfactory, for example because it has a profile. of increased velocity between the upper part and the lower part of the test bench, thus causing distortion at the turbojet engine, or that vortices are triggered unexpectedly because of a lack of speed in any part upstream of the engine. where there is an increased risk of vortex being absorbed by the turbojet engine. The downflat lands 16b may be inclined relative to the X axis, with a possible progression of the inclination along the grid 9, so as to increase the efficiency of the recovery and correct the speed deficit recorded in a part of the bench. This case is shown in FIG. 6. As illustrated, the distance di between two consecutive buckets 14 can vary according to an arithmetical progression along the diagonal 15. It is also conceivable that the distance di between two buckets 14 Consecutive is constant along the diagonal 15. As shown in Figure 6, the inclination ea between the Z axis and the leading line of the buckets 14 is zero along the grid 9 of buckets . The inclination Of between the X axis and the vanishing line of the buckets 14 varies in turn decreasing as one moves down the grid 9. In the upper part of the grid 9, the flats 16b are thus inclined upwards with respect to the trailing edge of the buckets 14, 30 whereas in the lower part of the grid 9, the flats 16b are aligned with the trailing edge of the buckets 14 (ie the Of inclination is zero).

3037398 9 This arrangement of the buckets 14 can supply air to the upper part of the bench when it is in deficit of air speed. As illustrated in FIG. 7, it can also be envisaged that the inclination E) a between the axis Z and the line of attack of the buckets 14 is not zero all along the grid 9 of buckets. The inclination E) can thus be variable along the grid 9 of buckets, as well as the inclination Of, but not necessarily with the same law of decay. Since the buckets 14 are fixed on the grid 9, and since the flats 16b are welded to the buckets 14, it is not possible to adapt this prior art air rectification device to different types of engine or at different types of engine speed, so as to optimize for each type of engine or engine speed the direction and homogeneity of the air flow at the exit of the elbow of the intake zone. For example, the inclination of the leading edge of one or more buckets may not be adapted to the direction of airflow to the bucket. Another example can be illustrated by the straightening device of FIG. 6 or 7. This device, which can allow for a given engine to supply air to the upper part of the bank when it is in air velocity deficit. , will not necessarily be adapted to another engine, 20 for which the upper part of the bench may be too much air, which will induce a heterogeneity of the air speed upstream of the bench. According to the invention, this problem is remedied by providing the buckets 14 with moving parts, in particular at the leading edge and / or the trailing edge of the buckets 14.

In a first embodiment, as illustrated in FIGS. 8A and 8B, the buckets 14 comprise a central portion 14a fixed with respect to the intake zone, and which is for example fixed to a bucket holder such that a flange of the intake zone, and one or more movable parts relative to the central portion 14a. Each bucket 14 may thus comprise a movable upstream portion 14b whose upstream end defines the leading edge 141 of the trough 14, and a movable downstream portion 14c, 303 73 98 10 whose downstream end defines the edge. leakage 142 of the bucket 14. The central portion 14a may be a curved portion, for example section shaped circular arc, and in particular a quarter circle. The central portion 14a may thus comprise a curved upper plate 14a1 located on the side 5 of the concave intrados 141 of the trough 14 and a lower plate 14a2 situated on the convex 14E extrados side of the trough 14 and substantially parallel to the trough 14. the upper plate 14a1. The movable upstream portion 14b may be a curved U-shaped wrapping structure that embraces the central portion 14a and slides on it. The movable downstream portion 14c may be constituted by a curved plate which penetrates inside the central portion 14a and slides therein between the upper plate 14a1 and the lower plate 14a2. In this configuration, the mobile downstream portion 14c is thus nested in the central fixed portion 14a, which is itself nested in the movable upstream portion 14b. This order of nesting defines a bucket 14 whose thickness decreases in the direction of the air flow, which makes it possible to limit the pressure drops on the trough 14. The arrows illustrate in FIGS. 8A and 8B the possible direction of movement of the moving parts 14b and 14c. Sliding of the movable upstream portion 14b, defining the leading edge 141, causes a displacement of the leading edge 141. This modifies the angle between the leading edge 141 and the direction of the flow. air arriving at the leading edge 141, which will have a consequence on the direction of the air flow at the exit of the trailing edge 142. In the same way, the sliding of the mobile downstream part 14c, defining the edge leakage 142, causes a displacement of the trailing edge 142, and thus allows to directly adjust the direction of the air flow at the output of the trailing edge 142. In a variant of this first embodiment, the order of interleaving the different parts 14a, 14b, 14c of the trough 14 can be modified. It can thus be envisaged that it is the mobile downstream portion 14c that slides on the central portion 14a, while the movable upstream portion 14b slides 3037398 11 inside the central portion 14a. It can also be envisaged that the trough 14 comprises only one upstream or downstream mobile part. Thus, thanks to the presence of the moving part or parts, each bucket can be set individually. It becomes easier to optimize the direction and homogenization of the air flow at the outlet of the bend of the intake zone as a function of the turbojet engine under test. For each turbomachine tested, the engine flow is different and the air flow induced by the latter, which may cause a more or less easy passage through the elbow of the air intake chimney, especially in the upper corner 10 elbow. Thus, depending on the areas that you want to change or rebalance, it will be easier to move one or more moving parts to obtain a speed profile as flat as possible in the test room of the closed bench. Various configurations of the adjustable trough 14 will now be described. Figure 9A illustrates the bucket 14 in its nominal configuration. In this nominal configuration, the movable upstream portion 14b and the movable downstream portion 14c are in the closed position, that is to say abuts on the central portion 14a, and define an angle of 900 between the direction of the edge 20a. attack and direction of the trailing edge. The movable upstream portion 14b may be partially deployed, the mobile downstream portion 14c remaining in the closed position (FIG. 9B). Alternatively, the mobile downstream portion 14c may be partially deployed, the movable upstream portion 14b remaining in the closed position (FIG. 9C). Finally, the mobile upstream portion 14b and the mobile downstream portion 14c may be partially deployed (Fig. 9D). It can be seen that, thanks to the moving parts 14b, 14c, the aerodynamic profile of the trough 14 and its length of rope L are variable according to the configurations. It is thus possible to adjust the inclination of the leading edge and / or the trailing edge of the trough 14, which makes it possible to adjust the direction of the air flow at the outlet of the trough 14.

3037398 12 The buckets may be arranged in the intake zone in one or more stacks. As illustrated in FIG. 10, the buckets 14 are arranged in two stacks, namely a first stack attached to a lateral flange 17 and a second stack attached to a median flange 18. The moving parts of the buckets 14 can be moved using a rack-and-pinion system or any other system capable of ensuring their mobility, and controlled electrically or pneumatically. Guiding of the moving parts can be provided by means of chutes fixed on the flanges 17, 18 and rollers (not shown) mounted on the mobile buckets 14 and which roll in the chutes. FIGS. 11A and 11B illustrate a possible stack of buckets 14 which can be implemented in the case of an air supply requiring different tuning of each bucket 14. In a second embodiment, the trough 14 does not include 15 of fixed part, but two moving parts 14b, 14c nested one inside the other and which slide one into the other (FIGS. 12A, 12B, 13A, 13B). The trough 14 thus comprises a movable upstream portion 14b and a movable downstream portion 14c. The mobile downstream portion 14c may be in the form of an arcuate plate which slides inside a moving upstream portion 14b 14b enveloping the shape of the movable downstream portion 14c.

Claims (10)

REVENDICATIONS1. Air straightening trough (14) for an air intake stack (13) of a turbomachine test stand (2), comprising a leading edge (141) and a trailing edge (142) ), characterized in that it comprises a movable upstream portion (14b) defining said leading edge (141) and / or a movable downstream portion (14c) defining said trailing edge (142), so that the bucket (14) has a variable aerodynamic profile and rope length (L). 2. trough (14) according to claim 1, characterized in that said upstream portion (14b) and / or downstream (14c) is movable by sliding. 3. trough (14) according to claim 2, characterized in that said upstream portion (14b) and / or downstream (14c) is slidably mounted on or in a fixed central body (14a). 4. trough (14) according to claim 2, characterized in that said upstream portion (14b) is slidably mounted on or in said downstream portion (14c). 5. trough (14) according to one of claims 1 to 4, characterized in that said upstream portion (14b) and / or downstream (14c) is of curved shape, in particular in the form of a circular arc. 6. Air intake chimney (13) for turbomachine test bench (2), characterized in that it comprises a grid (9) of at least one trough (14) according to one of the claims 1 to 5. 7. Chimney (13) according to claim 6, characterized in that said at least one trough (14) is fixed on one or more flanges (17,18). 8. Chimney (13) according to claim 6 or 7, characterized in that it comprises means for moving said upstream portion (14b) and / or downstream (14c). 9. Turbomachine test bench (2), characterized in that it comprises an air intake chimney (13) according to one of claims 6 to 8. 3037398 14 10. A method for adjusting the direction of the flow of the intake air in a turbomachine test stand (2), characterized in that it comprises a step of moving the upstream portion (14b) and or downstream (14c) of at least one bucket (14) according to one of claims 1 to 5. 5