Treatment of non-axisymmetric casing with controlled opening

Abstract

The invention relates to a casing (200) of a turbine engine compressor, comprising openings (201) which are made in the thickness of the casing from an inner face (2001) of the casing and arranged next to one another on a circumference of the casing, characterised in that it also comprises a movable ring (220) which is formed by at least two annular portions, is present on an outer face (2002) of the casing opposite the openings and is able to move along the circumference of the casing so as to open and close the openings of the casing in order to activate or deactivate a casing treatment, the movable ring comprising the same number of slits (202) as there are openings in the casing.

Description

[0001] Description

[0002] Title of the invention: Treatment of non-axisymmetric casing with controlled opening

[0003] Technical Field

[0004] The present invention relates to the general field of turbomachine compressors, and more particularly to the treatment of the casing of turbomachine compressors.

[0005] Prior art

[0006] Turbomachine compressors consist of blades rotating inside a casing which seals the air stream with the outside of the engine.

[0007] It is known that the clearance between the ends of the compressor's moving blades and the casing forming the internal wall of the air flow vein degrades the efficiency of the turbomachine engine.

[0008] Furthermore, this clearance can modify and degrade the operation of the compressor until the appearance of a surge phenomenon which results from the air flow detaching from the surface of the blades. Controlling the air circulation at the tip of the blades is a major challenge to obtain both good aerodynamic efficiency of the compressor and a sufficient margin against the surge phenomenon.

[0009] In order to limit the impact of this parasitic flow between the tip of the blades and the casing, the internal surface of the casing can be treated locally by digging cavities arranged in the thickness of the casing opposite the blades. Documents FR 2 989 742, GB 2 408 546 and US 2016 / 153465 provide examples of casing treatment.

[0010] However, the surge phenomenon only occurs when the compressor is heavily loaded, i.e. when it operates in the upper part of its operating range. Outside this zone, crankcase treatments are therefore no longer useful and may even cause a loss of compressor efficiency.

[0011] It is therefore desirable to have a compressor casing in which the casing treatment slots can be closed or opened to avoid the pumping phenomenon while maintaining good compressor efficiency.

[0012] Statement of the invention

[0013] The invention relates to a turbomachine compressor casing comprising openings hollowed out in the thickness of the casing from an internal face of the casing and arranged next to each other on a circumference of the casing, characterized in that it also comprises a movable ring, formed by at least two annular portions, present on an external face of the casing opposite the openings and capable of moving along the circumference of the casing so as to close and open the openings of the casing to activate or deactivate a casing treatment, the movable ring comprising the same number of slots as openings in the casing.

[0014] In the alignment of the openings in the casing and the slots in the moving ring, i.e. when the openings in the casing are opposite the slots in the moving ring, the openings present on the casing form the slots of a non-axisymmetric casing treatment, because they are present along the circumference of the casing and open to the flow path. In other words, they form axial slots arranged in an azimuthal direction and are therefore non-axisymmetric with respect to the axis of rotation of the compressor, whereas axisymmetric casing treatments consist of circumferential grooves and are symmetric with respect to the axis of rotation of the compressor.

[0015] Thanks to the invention, the slots of the crankcase treatment can be opened or closed thanks to the movable ring. This allows for active crankcase treatment when the operating conditions require it, for example during takeoff, to avoid the surge phenomenon and for inactive crankcase treatment when the compressor is no longer loaded, for example in cruising mode, to favor the efficiency of the compressor. Thus, the invention makes it possible to control the opening of the crankcase treatment.

[0016] According to a particular characteristic of the invention, each opening of the casing has a width greater than or equal to the width of the associated slot of the movable ring, and each opening of the casing has a length greater than or equal to the length of the associated slot of the movable ring.

[0017] According to another particular characteristic of the invention, the casing also comprises at least one spring assembling the movable ring to the casing configured so that the openings of the casing are open when the spring is at rest.

[0018] The spring allows the movable ring to return to an initial position or a safety position, in which its slots are opposite the openings in the casing, so that the slots of the casing treatment are fully open for the casing treatment to be active.

[0019] According to another particular characteristic of the invention, the casing comprises an electric motor comprising a camshaft, the cam being configured to move the movable ring along the circumference of the casing so as to open or close the openings of the casing.

[0020] The camshaft allows the movable ring to be moved along the circumference of the casing, and more particularly the cam allows the movable ring to be moved by an amplitude at least equal to the width of an opening in the casing so as to completely open or close the openings in the casing, and therefore so as to completely open or close the slots in the casing treatment.

[0021] According to another particular characteristic of the invention, the casing comprises an actuator configured to move the movable ring along the circumference of the casing so as to open or close the openings of the casing.

[0022] The actuator can play the same role as the camshaft, and therefore allows the movable ring to be moved along the circumference of the casing in order to be able to close or open the slots of the casing treatment. Thus, it allows the movable ring to be moved by an amplitude at least equal to the width of an opening in the casing. According to another particular characteristic of the invention, the dimensions of the slots of the movable ring and the openings in the casing are equal.

[0023] This means that the slots in the movable ring and the openings in the casing have the same length and width. This makes it easier to open and close the slots in the casing treatment, because by moving the movable ring by the width of one opening in the casing, the corresponding slot in the casing treatment can be completely opened or closed.

[0024] According to another particular characteristic of the invention, the number of openings in the casing is between 40 and 850.

[0025] According to another particular characteristic of the invention, the movable ring and the casing are made of the same material.

[0026] Brief description of the drawings

[0027] Other characteristics and advantages of the present invention will emerge from the description given below, with reference to the appended drawings which illustrate exemplary embodiments thereof which are not limiting in nature.

[0028] [Fig. 1] Figure 1 shows, schematically and partially, a turbomachine compressor casing according to one embodiment of the invention.

[0029] [Fig. 2A] Figure 2A shows, schematically and partially, the closed slots of the compressor casing treatment of Figure 1.

[0030] [Fig. 2B] Figure 2B shows, schematically and partially, the open slots of the compressor casing treatment of Figure 1.

[0031] [Fig. 3] Figure 3 shows, schematically and partially, a turbomachine compressor casing according to another embodiment of the invention.

[0032] Description of the embodiments

[0033] Figure 1 shows, schematically and partially, a turbomachine compressor casing 100 according to a first embodiment of the invention. The casing 100 comprises openings hollowed (or cut) in the thickness of the casing from the internal face 1001 of the casing 100. The openings are arranged next to each other on the circumference of the casing 100.

[0034] The casing 100 also includes a movable ring 120 present on the outer face 1002 of the casing 100. The movable ring 120 includes slots the same number as the openings of the casing 100, and can move along the circumference of the casing 100 so as to open or close the openings of the casing 100 by means of its own slots. By aligning the slots of the movable ring 120 and the openings of the casing 100, that is to say when the slots of the movable ring 120 are opposite the openings of the casing 100, a casing treatment is formed whose slots are open when the openings of the casing 100 are open. In other words, the movable ring 120 rotates around the casing 100 so as to close or open the openings of the casing 100.

[0035] Each opening of the casing 100 has a width greater than or equal to the width of the associated slot of the movable ring 120 (or slot opposite said opening), and each opening of the casing 100 has a length greater than or equal to the length of the associated slot of the movable ring 120 (or slot opposite said opening). This ensures that the openings of the casing 100 are fully open when it is desired to activate the casing treatment.

[0036] In addition, the distance between each opening of the casing 100 is greater than or equal to the width of the associated slot of the movable ring 120. This ensures that the openings of the casing 100 are completely closed when it is desired to deactivate the casing treatment.

[0037] The movable ring 120 is formed of two annular portions 121 and 122. In this first embodiment, the two annular portions 121 and 122 are assembled together by a pointed screw 130, but they can, instead, be assembled by any other assembly means, for example a system composed of a centering pin and a screw and nut assembly for holding in position. Having a movable ring 120 formed of at least two annular portions 121 and 122 makes it easier to mount the movable ring 120 on the casing 100.

[0038] The casing 100 comprises a piston 140 fixed at one of its ends to the movable ring 120 and another end to the casing 100 by means of a column 125. The piston 140 makes it possible to control the movement of the movable ring 120 along the circumference of the casing 100 in order to be able to move it by an amplitude at least equal to the width of the openings of the casing 100 in order to completely close and / or open the openings of the casing 100 and therefore the slots of the casing treatment. The column 125 makes it possible to stiffen the casing 100 and to have a fixed point for fixing the piston 140.

[0039] To move the movable ring 120 on the casing 100, the piston 140 can be replaced by an actuator.

[0040] Figures 2A and 2B show a sectional view of the openings 201 opened (Figure 2B) or closed (Figure 2A) of the casing 200 of Figure 1 by the movement of the movable ring 220 and its slots 202. As indicated with reference to Figure 1, the openings 201 of the casing 200 are hollowed (or cut) in the thickness of the casing 200 from its inner face 2001 and are arranged next to each other on the circumference of the casing 200. The movable ring 220 comprises the same number of slots 202 as openings 201 of the casing 200 and is placed on the outer face 2002 of the casing 200 so as to be able to close or open the openings 201 of the casing 200 by moving along the circumference of the casing 200. In this exemplary embodiment, the slots 202 of the movable ring 220 have the same width and length as the openings 201 of the casing 200.In addition, the distance between the openings 201 of the casing 200 is identical to the distance between the slots 202 of the movable ring 220. Thus, when the slots 202 of the movable ring 220 coincide with the openings 201 of the casing 200, the openings 201 of the casing 200 are completely open (FIG. 2B) and the slots of the casing treatment are open. When the slots 202 of the movable ring 220 cover the openings 201 of the casing 200, the openings 201 of the casing 200 are completely closed and the slots of the casing treatment are closed (FIG. 2A). The treatment of the casing 200 is therefore inactive in the case of FIG. 2A (slots of the casing treatment closed) and it is active in the case of FIG. 2B (slots of the casing treatment open).

[0041] Figure 3 shows, schematically and partially, a casing 300 of a compressor 310 of a turbomachine according to a second embodiment of the invention.

[0042] As shown with reference to FIG. 1, the casing 300 includes openings hollowed or cut into the thickness of the casing 300 from the inner face 3001 of the casing 300. The openings are arranged next to each other along the circumference of the casing 300.

[0043] The casing 300 also includes a movable ring 320 present on the outer face 3002 of the casing 300. The movable ring 320 includes slots the same number as the openings of the casing 300, and can move along the circumference of the casing 300 so as to open or close the openings of the casing 300 by means of its own slots for opening or closing the slots of the casing treatment. As shown with reference to FIG. 1, each opening of the casing 300 has a width greater than or equal to the width of the associated slot of the movable ring 320, and each opening of the casing 300 has a length greater than or equal to the length of the associated slot of the movable ring 320. In addition, the distance between each opening of the casing 300 is greater than or equal to the width of the associated slot of the movable ring 320.

[0044] The movable ring 320 is formed of two annular portions 321 and 322. As indicated previously, the two annular portions 321 and 322 can be assembled together by a pointed screw or by any other assembly means.

[0045] In order to move the movable ring 320 and close or open the slots of the casing treatment and therefore the openings of the casing 300, the casing 300 comprises an electric motor 330 comprising a camshaft 332. By pivoting, the cam 332 makes it possible to move the movable ring 320 along the circumference of the casing 300. The cam 332 can bear on a projecting portion 326 present on one of the annular portions 322 in order to be able to pivot and move the movable ring 320. The electric motor 330 and the camshaft 332 make it possible to move the movable ring 320 by at least an amplitude equal to the width of an opening of the casing 300. A pin 327 may be present in order to block the projecting portion 326 during the movement of the movable ring 320.

[0046] The casing 300 may also comprise a spring 340 fixed to the movable ring 320 and to the casing 300 by means of a column 325. This spring 340 is configured so that at rest, the openings of the casing 300 are open, that is to say so that the slots of the movable ring 320 do not block the openings of the casing 300 (case of FIG. 2B) so that the casing treatment is active. As previously, the column 325 also makes it possible to stiffen the casing 300 in addition to forming a fixed point for fixing the spring 340.

[0047] Regardless of the embodiment, the openings in the housing can all be identical.

[0048] Regardless of the embodiment, the slots of the movable ring may all be identical. Advantageously, the slots of the movable ring and the openings of the casing have the same dimensions, i.e. they have the same length and the same width; and the distance between the openings of the casing is equal to the distance between the associated slots of the movable ring. This makes it possible to obtain slots of the movable ring coinciding with the openings of the casing, and to move the movable ring only by the amplitude of its slots to be able to completely open or close the openings of the casing and therefore the slots of the casing treatment.

[0049] Whatever the embodiment, the casing can be a single piece.

[0050] Whatever the embodiment, the number of openings of the casing (and therefore of the moving ring) is between 40 and 850, for example between 45 and 810, for example between 60 and 210. Indeed, the casing treatment requires between 3 and 8 slots per rotor blade and a rotor comprises between 15 and 90 blades. This range of values ​​therefore makes it possible to cover all the possibilities.

[0051] Regardless of the embodiment, the casing and the moving ring can be made of the same material. This allows both parts to undergo the same thermal and mechanical stresses and therefore ensures that opening or closing the casing treatment will always be possible, even in the event of thermal expansion.

[0052] Alternatively, the casing and the moving ring can be made of different materials, but it is necessary that these two materials have similar or even identical physical properties so that their thermal expansion is similar.

[0053] The expression "between ... and ..." must be understood as including the limits.

Claims

Claims

1. Casing (100, 200, 300) of a turbomachine compressor (310) comprising openings (201) hollowed out in the thickness of the casing from an internal face (1001, 2001, 3001) of the casing and arranged next to each other on a circumference of the casing, characterized in that it also comprises a movable ring (120, 220, 320), formed by at least two annular portions (121, 122, 321, 322), present on an external face (1002, 2002, 3002) of the casing opposite the openings and capable of moving along the circumference of the casing so as to open and close the openings of the casing to activate or deactivate a casing treatment, the movable ring comprising the same number of slots (202) as openings in the crankcase.

2. A compressor housing (100, 200, 300) according to claim 1, wherein each opening (201) of the housing has a width greater than or equal to the width of the associated slot (202) of the movable ring (120, 220, 320), and each opening of the housing has a length greater than or equal to the length of the associated slot of the movable ring

3. Compressor casing (300) according to any one of claims 1 or 2, also comprising at least one spring (340) assembling the movable ring (320) to the casing configured so that the openings of the casing are open when the spring is at rest.

4. A compressor housing (300) according to any one of claims 1 to 3, comprising an electric motor (330) comprising a camshaft (332), the cam (332) being configured to move the movable ring along the circumference of the housing so as to open or close the openings of the housing.

5. A compressor housing according to any one of claims 1 to 3, comprising an actuator configured to move the movable ring along the circumference of the housing so as to open or close the openings of the housing.

6. A compressor housing according to any one of claims 1 to 5, wherein the dimensions of the slots in the movable ring and the openings in the housing are equal.

7. A compressor housing according to any one of claims 1 to 6, wherein the number of openings of the housing is between 40 and 850.

8. A compressor casing according to any one of claims 1 to 7, wherein the movable ring and the casing are made of the same material.

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