Treatment of a non-axisymmetric casing with a corrugated plenum
Patent Information
- Authority / Receiving Office
- EP · EP
- Patent Type
- Applications
- Current Assignee / Owner
- SAFRAN SA
- Filing Date
- 2024-06-10
- Publication Date
- 2026-04-15
AI Technical Summary
Turbomachine compressor efficiency is degraded due to clearance between blades and casing, leading to aerodynamic blocking and a pumping phenomenon, with existing non-axisymmetric casing treatments not optimally controlling fluid sampling and reinjection zones.
The compressor casing features an internal annular wall with slots and an external annular wall forming an annular cavity, where the internal face of the external wall includes alternately arranged concave and convex portions to create undulations, allowing controlled fluid flow and reinjection by adjusting the angle and extent of these features.
This configuration optimizes the non-axisymmetric casing treatment by controlling the flow path, reducing pressure losses and increasing the pumping margin by precise fluid sampling and reinjection, thus enhancing compressor efficiency and delaying the onset of aerodynamic blocking.
Smart Images
Figure FR2024050756_19122024_PF_FP_ABST
Abstract
Description
[0001] Description
[0002] Title of the invention: Non-axisymmetric casing treatment with corrugated plenum
[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 slots arranged in the thickness of the casing opposite the blades. The casing treatments considered in the present invention are of the “axial slot” type corresponding to a series of slots arranged along the circumference of the casing (in the azimuthal direction). These slots are located vertically (“above”) a compressor wheel. These treatments are therefore non-axisymmetric with respect to the axis of rotation of the compressor: they are therefore non-axisymmetric casing treatments or TCNA.
[0010] The presence of these slots will locally modify the flow. The objective is to influence the appearance of the mechanisms responsible for the compressor surge. Effective crankcase treatment will increase the compressor's operability range by delaying the appearance of these mechanisms, in particular by reducing aerodynamic blockage at the wheel head.
[0011] Some TCNA concepts propose the addition of an annular cavity or "plenum" in the casing as described for example in document WO9420759, which amounts to adding a cavity above the slots. This cavity extends over the entire circumference of the casing and connects the slots together. This cavity is not directly open to the vein and is not connected to a secondary air circuit. The fluid must pass through the slots to enter and exit the cavity. The addition of the plenum tends to amplify the TCNA's ability to increase the pumping margin.
[0012] The annular cavity is useful to allow a fraction of fluid to be taken from one slot and reinjected from different slots, which improves the efficiency of the sump treatment (compared to a sump treatment without an annular cavity). However, this mechanism is not optimal because the reinjection is distributed among several slots and some of these slots are not in a good position relative to the rotor at the time of reinjection.
[0013] It is therefore desirable to be able to better control the sampling and reinjection zones at the level of the slots.
[0014] Statement of the invention
[0015] To this end, the invention proposes a turbomachine compressor casing comprising an inner annular wall and an outer annular wall delimiting between them an annular cavity, the annular cavity extending in an axial direction between a front bottom and a rear bottom and in a radial direction between an inner face of the outer annular wall and an outer face of the inner annular wall, the inner annular wall of the casing comprising a plurality of slots opening into the annular cavity, the slots being arranged next to each other in a circumferential direction, the slots extending in length along a longitudinal axis between the front bottom and the rear bottom in the axial direction,characterized in that the internal face of the external annular wall opposite the plurality of slots of the internal annular wall comprises concave portions and convex portions arranged alternately in the circumferential direction so as to define in the internal cavity undulations in said circumferential direction, the concave portions and the convex portions each extending between the front bottom and the rear bottom of the internal cavity in a longitudinal direction, in that said longitudinal direction forms a non-zero angle with the longitudinal axis of the slots, or in that said longitudinal direction is parallel to the longitudinal axis of the slots, each undulation extending in this case in the circumferential direction over two or more adjacent slots.,
[0016] In the case where the concave portions and the convex portions each extend between the front bottom and the rear bottom of the internal cavity in a longitudinal direction forming a non-zero angle with the longitudinal axis of the slots, the concave portions forming circulation channels for the flow in the internal cavity make it possible to offset the sampling zone and the reinjection zone of the fluid at the slots. Depending on the value of the angle, it is possible to determine the slot(s) from which the fluid is sampled in the internal cavity and the slot(s) from which the fluid is reinjected.
[0017] In the case where the concave portions and the convex portions each extend between the front bottom and the rear bottom of the internal cavity in a longitudinal direction parallel with the longitudinal axis of the slots and with each corrugation extending in the circumferential direction over two or more adjacent slots, it is also possible to have an exchange between several adjacent slots in the same circulation channel for the flow in the internal cavity and to shift the sampling zone and the reinjection zone of the fluid at the slots.
[0018] The presence of corrugations makes it possible to better control the flow path in the annular cavity. Flow guidance by the corrugations in the internal cavity optimizes the operation of the non-axisymmetric casing treatment (NCCT). Indeed, it is thus possible to control the slot(s) through which a fraction of the flow is reinjected and, consequently, the timing of reinjection relative to the rotor position, which increases the pumping margin gain. The operation of the NCCT is also optimized by reducing pressure losses during circulation in the internal cavity by limiting the azimuthal migration of the sampled flow.
[0019] The non-zero angle formed between the longitudinal direction of the concave portions and the convex portions and the longitudinal axis of the slots is between -60° and +60°, preferably between -40° and +40°.
[0020] According to another particular characteristic of the invention in the case of a non-zero angle formed between the longitudinal direction of the concave portions and the convex portions and the longitudinal axis of the slots, each concave portion has a width at least equal to a width of a slot in the internal annular wall.
[0021] According to another particular characteristic of the invention in the case of a non-zero angle formed between the longitudinal direction of the concave portions and the convex portions and the longitudinal axis of the slots, the number of undulations present on the internal face of the external wall is between 0.1 and 1 times the number of slots present in the internal annular wall.
[0022] According to another particular characteristic of the invention, the amplitude of the undulations formed by the concave portions and the convex portions arranged alternately in the circumferential direction is between 0.2 and 5 times the height of the slots in the internal annular wall.
[0023] According to another particular characteristic of the invention, the casing comprises a treatment ring comprising the internal annular wall and a master ring comprising the external annular wall, the treatment ring being fixed on the master ring.
[0024] According to another particular characteristic of the invention, the treatment ring and the master ring are made of the same material.
[0025] The invention also relates to a turbomachine compressor comprising a casing according to the invention.
[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 is a schematic perspective view of a turbomachine compressor according to one embodiment of the invention,
[0029] [Fig. 2] Figure 2 is a schematic and partial view showing corrugations present on the internal face of the master ring of the compressor of Figure 1,
[0030] [Fig. 3] Figure 3 is a schematic and partial view of the compressor casing of Figure 1,
[0031] [Fig. 4] Figure 4 is a radial sectional view along section plane IV-IV on the casing of Figure 3,
[0032] [Fig. 5] Figure 5 is a radial sectional view along section plane VV on the casing of Figure 3.
[0033] Description of the embodiments
[0034] Figure 1 represents a turbomachine compressor 300 according to one embodiment of the invention. The compressor 300 comprises around its axis A 300 a rotor 200 equipped with a plurality of moving blades 210 surrounded by a casing 100. The casing 100 comprises a treatment ring 110 and a master ring 120 which is structural. In the example described here, the treatment ring 110 comprises a flange 116 which is fixed on a flange 126 of the master ring 120.
[0035] As schematically and partially illustrated in Figure 3, the master ring 120 comprises an outer annular wall 121 while the treatment ring 110 comprises an inner annular wall 111 opposite the outer annular wall 121. The inner annular wall 111 and the outer annular wall 121 each extend lengthwise in a circumferential direction D c, in width along an axial direction D A corresponding to the axis of the compressor 300 and in thickness following a radial direction D R The inner annular wall 111 and the outer annular wall 121 delimit between them an annular cavity 130 forming a plenum. The inner annular cavity 130 extends in the axial direction D. A between a front bottom 131 and a rear bottom 132 and following the radial direction D R between an inner face 1210 of the outer annular wall 121 and an outer face 1111 of the inner annular wall 111.
[0036] The internal annular wall 111 comprises a plurality of slots 115 hollowed out (or cut out) in the thickness of the wall, each slot 115 opens onto both an internal face 1110 and the external face 1111 of the internal annular wall 111 so as to put a flow vein E into communication with the annular cavity 130, the arrow E indicating the direction of the flow in the compressor and, consequently, the upstream and downstream sides thereof.
[0037] The slots 115 are arranged uniformly next to each other in the inner annular wall 111 along the circumferential direction D c . Each slot 115 extends in length along a longitudinal axis Ans over a determined length Lus and in height along the radial direction D R on a height Hn5. In the example described here the longitudinal axis Ans of the slots 115 is parallel to the axial direction D A. However, it can form an angle with the axial direction D A between -60° and +60°.
[0038] In the example described here, the slots 115 are inclined at 45° relative to the radial direction D R The slots 115 may be inclined at an angle other than 45° or be parallel to the radial direction D R . In a known manner, the slots 115 and the annular cavity 130 into which they open constitute a non-axisymmetric casing treatment or TCNA which makes it possible to locally modify the flow in order to reduce the mechanisms responsible for the compressor starting to surge.
[0039] According to the invention, the internal face 1210 of the external annular wall 121 opposite the plurality of slots 115 of the internal annular wall 111 comprises concave portions 1212 and convex portions 1213 arranged alternately in the circumferential direction D cso as to define in the internal cavity 130 undulations following the circumferential direction De (figures 2, 4 and 5).
[0040] As illustrated in Figure 2, the concave portions 1212 and the convex portions 1213 each extend between the front bottom 131 and the rear bottom 132 of the internal cavity 130 in a longitudinal direction D^o. The concave portions 1212 define circulation channels for channeling the flow into the internal cavity 130.
[0041] In the example described here, the longitudinal direction of the concave 1212 and convex 1213 portions forms an angle p W o with the longitudinal axis Al 15 of the slots 115. The angle p Mo is between -60° and +60°, preferably between -40° and +40°. The concave portions form circulation channels for the flow in the internal cavity, it is thus possible to shift the sampling zone and the reinjection zone of the fluid at the level of the slots. Depending on the value of the angle Pwo, it is possible to determine the slot(s) from which the fluid is sampled in the internal cavity and the slot(s) from which the fluid is reinjected.
[0042] An example of offset between the sampling zone and the reinjection zone in the internal cavity is illustrated in Figures 4 and 5 which correspond to radial sections of the casing of Figure 3. The section plane of Figure 4 is located upstream of the leading edge 211 of the blades 210 of the rotor 200 in the axial direction and intersects the slots 115 in their upstream part. The section plane of Figure 5 is located downstream of the leading edge 211 of the blades 210 of the rotor 200 in the axial direction and intersects the slots 115 in their downstream part. The slots 115i to 1156 shown in Figures 4 and 5 correspond to the same slots in the inner annular wall 111. Similarly, the concave portion 12121 shown in Figures 4 and 5 corresponds to the same concave portion of the outer annular wall 121 which defines a circulation channel 136.The concave portion 1212i has a different azimuthal position between figures 4 and 5 due to the angle (3I4O formed between the longitudinal direction DI. 40 concave and convex portions and the longitudinal axis An5 of the slots which here coincides with the axial direction D A corresponding to the axis of the compressor 300 (figure 3). In the example described here, the angle P140 is approximately 37°.
[0043] Due to the inclination of the concave portion 12121 relative to the longitudinal axis of the slots, a fraction F E of the flow is taken by the slots 1154 and 1155 as shown in Figure 5. The fraction F Eis then channeled into the circulation channel 136 to be reinjected into the flow vein E through the slots 1153 and 1154 as shown in Figure 4. It can be seen here that the inclined concave portions allow the flow to be channeled so that it passes from the slot 115s to the slot 1153 during its passage through the internal cavity, that is to say with an azimuthal offset of two slots in the example considered here.
[0044] Each concave portion 1212 has a width I1212 at least equal to a width ln5 of the slots 115 (figures 2 and 3).
[0045] The amplitude of the undulations corresponding to the height H 1212 of the concave portions 1212 is between 0.2 and 5 times the height Hn5 of the slots 115 (figures 3 and 4).
[0046] The number of undulations is between 0.1 and 1 times the number of slots 115 present on the treatment ring 110.
[0047] The number of slots 115 present on the treatment ring 110 is between 2 and 10, the number of blades 210 of the rotor 200. The number of slots can typically be 5 for a blade.
[0048] The master ring and the treatment ring are preferably made of the same material or of materials having similar thermal expansion coefficients in order to avoid differential expansions between the two rings which could lead to mechanical stresses and / or sealing problems in the casing.
[0049] The expression "between ... and ..." must be understood as including the limits.
Claims
Claims
1. Casing (100) of a turbomachine compressor (300) comprising an inner annular wall (111) and an outer annular wall (121) delimiting between them an annular cavity (130), the annular cavity extending in an axial direction (D) between a front end wall (131) and a rear end wall (132) and in a radial direction (DR) between an inner face (1210) of the outer annular wall and an outer face (1111) of the inner annular wall, the inner annular wall (111) of the casing comprising a plurality of slots (115) opening into the annular cavity (130), the slots being arranged next to each other in a circumferential direction (D c), the slots extending lengthwise along a longitudinal axis (An5) between the front bottom (131) and the rear bottom (132) along the axial direction, characterized in that the internal face (1210) of the external annular wall (121) opposite the plurality of slots (115) of the internal annular wall (111) comprises concave portions (1212) and convex portions (1213) arranged alternately along the circumferential direction so as to define in the internal cavity (130) undulations (140) along said circumferential direction (D c ), the concave portions (1212) and the convex portions (1213) each extending between the front bottom (131) and the rear bottom (132) of the internal cavity (130) in a longitudinal direction (DI 40), in that said longitudinal direction forms a non-zero angle (0i4o) with the longitudinal axis (An5) of the slots (115), or in that said longitudinal direction is parallel to the longitudinal axis of the slots, each undulation extending in the circumferential direction over two or more adjacent slots.
2. A housing according to claim 1, wherein the non-zero angle (J3i4o) formed between the longitudinal direction (D o) of the concave portions (1212) and the convex portions (1213) and the longitudinal axis (An5) of the slots (115) is between -60° and +60°.
3. Casing according to claim 2, in which each concave portion (1212) has a width (11212) at least equal to a width of a slot (115) of the internal annular wall (111).
4. A casing according to claim 2 or 3, wherein the number of undulations present on the inner face (1210) of the outer wall (121) is between 0.1 and 1 times the number of slots (115) present in the inner annular wall (111).
5. A casing according to any one of claims 1 to 4, wherein the amplitude of the undulations formed by the concave portions (1212) and the convex portions (1213) arranged alternately in the circumferential direction (D c ) is between 0.2 and 5 times the height (Hn5) of the slots (115) of the internal annular wall (111).
6. A housing according to any one of claims 1 to 5, comprising a treatment ring (110) having the inner annular wall (111) and a master ring (120) having the outer annular wall (121), the treatment ring being fixed to the master ring.
7. A housing according to claim 6, wherein the treatment ring and the master ring are made of the same material.
8. A turbomachine compressor (300) comprising a casing (100) according to any one of claims 1 to 7.