Particle-trapping device for a turbomachine and turbomachine with such a device

Abstract

The invention relates to a particle-trapping device (2) for a turbomachine, said particles being contained in an air stream flowing inside a turbomachine, in particular the air stream flowing in the bypass region (17) of the combustion chamber (13) of said turbomachine. The device is characterized in that it comprises: at least two particle deflectors (3, 3a, 3b, 3c), a member (5) for collecting and storing the particles deflected by said deflector, and means (6) for attaching said trapping device (2) to a part of the turbomachine.

Claims

1. A turbomachine comprising a combustion chamber and a bypass area provided between a wall of said combustion chamber and an outer casing of said turbomachine, wherein the turbomachine is equipped with a particle-trapping device disposed inside said bypass area, said particle-trapping device comprising: at least two particle deflectors for deflecting grains of sand or dust particles, contained in an air flow circulating inside the bypass area of the combustion chamber of said turbomachine, at least one support frame, an element for collecting and storing particles deflected by the at least two particle deflectors, means for attaching said trapping device on a portion of the turbomachine, said particle deflectors having an annular shape and being attached to the at least one support frame so as to be coaxial, to be radially aligned and to be spaced radially from one another or from each other, said deflectors being inclined in the same direction with respect to their axes of revolution (X-X) so as to be turned toward said element for collecting and storing particles.

2. The turbomachine according to claim 1, wherein said support frame is a ring which extends in a plane perpendicular or substantially perpendicular to the axis of revolution (X-X) of the deflectors, in that the deflectors of a pair of contiguous deflectors are attached respectively along the outer circular edge and the inner circular edge of said annular support frame and in that this support frame is perforated with openings for passage of the air flow.

3. The turbomachine according to claim 1, wherein the inner face of a deflector has an angle of inclination (,) with respect to said axis of revolution (X-X) greater than the angle of inclination (, ) with respect to this same axis of revolution (X-X) of the inner face of a deflector disposed radially further inside the device.

4. The turbomachine according to claim 1, wherein the inner radius (R1) of an outermost deflector of a pair of contiguous deflectors is less than or equal to the outer radius (R2) of a deflector located further inside.

5. The turbomachine according to wherein it comprises three deflectors.

6. The turbomachine according to claim 1, wherein at least one of said deflectors has a rectilinear cross section.

7. The turbomachine according to claim 1, wherein at least one of said deflectors has a curved cross section, the concavity whereof is turned toward the particle collecting and storing element.

8. The turbomachine according to claim 1, wherein the collecting and storing element comprises a solid ring coaxial with the axis of revolution (X-X) of the deflectors and which extends in a plane perpendicular or substantially perpendicular to this axis, this ring being continued in the direction of said deflector by a solid outer annular edge and by a solid inner annular edge, said collecting and storing element being disposed facing the deflector.

9. The turbomachine according to claim 1, wherein said attachment means comprise a planar annular flange coaxial with the axis of revolution (X-X) of the deflectors and perpendicular to it, and which is continued in the direction of the particle collecting and storing element by a cylinder with a longitudinal axis coaxial with said axis of revolution (X-X), in that said cylinder is perforated with several openings for passage of the air flow and in that said annular flange is perforated with several openings for passage of attachment members.

Description

PRESENTATION OF THE FIGURES

(1) Other features and advantages of the invention will appear from the description which will now be made with reference to the appended drawings, which show a possible embodiment of it by way of indication and without limitation.

(2) In these drawings:

(3) FIG. 1 is a schematic view in longitudinal section of an exemplary embodiment of a turbomachine,

(4) FIG. 2 is a view of detail A of FIG. 1, on which has further been shown the trapping device conforming to the invention,

(5) FIGS. 3, 4 and 5 are partial perspective views of an embodiment of the trapping device conforming to the invention, taken from three different angles of observation.

DETAILED DESCRIPTION

(6) The particle-trapping device conforming to the invention bears the general reference 2.

(7) As can be seen in FIG. 2, this device 2 is designed to be positioned in the bypass area 17 of the combustion chamber 13, more precisely outside the wall 131 of the combustion chamber 13 and inside the outer casing 18 of the turbomachine.

(8) However, its exact position will be determined by calculation, depending on the trajectory of the particles contained in the air flow circulating inside this bypass area 17. This calculation also takes into account the respective shapes of the wall 131 and of the portion of the wall 180 of the outer casing 18, located facing the rear end of the combustion chamber 13.

(9) The trapping device will thus be advantageously disposed at the place where it will allow a maximum of particles to be collected, before they reach the holes 130 of the wall of the combustion chamber.

(10) A particular embodiment of this trapping device 2 will now be described with reference to FIGS. 2 to 5.

(11) This trapping device 2 preferably comprises, from the front AV toward the rear AR, at least two deflectors 3, a particle collecting and storing element 5 and means 6 for attaching said storing device on a portion of the turbomachine.

(12) All these elements are constructed of a material which resists heat and preferably also the abrasion of particles, for example metal or a composite material.

(13) These different elements will now be described in more detail.

(14) The device comprises at least two deflectors 3, for example three as shown in the figures. It is also possible to have more than three deflectors.

(15) Each deflector has the shape of a ring, with axis of revolution X, X. The different deflectors 3 are attached to a support frame 4, so as to be coaxial with the axis X-X and spaced radially from one another.

(16) In the example described and shown in FIG. 3, these deflectors are called the outer 3a, median 3b and inner 3c deflectors, the outer deflector being that with the largest diameter and thus located outermost. Each deflector is constituted by an element having the shape of a solid blade with a small width closed on itself in the form of a ring.

(17) All these deflectors 3a, 3b, 3c are further attached to the frame 4 so as to be inclined in the same direction with respect to their common axis of revolution X-X, i.e. inclined from the outside and the front toward the axis of revolution X-X and the rear AR. In other words, they have the shape of a frusto-conical ring. However, their angles of inclination are preferably different. These deflectors are turned toward the element 5.

(18) Finally, the deflectors 3, 3a, 3b, 3c are attached to the frame 4 so as to be aligned radially and not to be offset along the axis X-X, so as not to occupy too much space between the wall 130 of the combustion chamber and the wall 180 of the casing and not to restrain the flow of the air flow which circulates at this location.

(19) By radially aligned is meant that all the deflectors 3a, 3b, 3c cut the same plane referred to as P, perpendicular to their respective axes of revolution X-X, these axes being congruent.

(20) The inner face 30a of the outer deflector 3a (i.e. the face turned toward the axis X-X) forms an angle with the axis of revolution X-X, the inner face 30b of the median deflector 3b forms with the axis X-X an angle and finally the inner face 30c of the inner deflector 3c forms an angle with the axis X-X. As can be observed in FIG. 2, the angle is greater than the angle which is itself greater than the angle .

(21) Preferably, the angle is comprised between 65 and 75, more preferably equal to 70, the angle is comprised between 45 and 55, more preferably equal to 50, the angle is comprised between 25 and 35, more preferably equal to 30.

(22) Preferably, as can be seen in FIG. 2, the deflectors 3a, 3b and 3c have a rectilinear cross section. However, this can be curved, its concavity being oriented toward the particle collecting and storing element 5.

(23) As appears better in FIGS. 2, 4 and 5, the frame 4 plays the role of a cross-member between two contiguous deflectors. It has the shape of a ring which extends in a plane perpendicular or substantially perpendicular to the axis of revolution X-X, for example the plane P. The frame 4 is perforated with openings 40 allowing the passage of the air flow. These openings 40 are advantageously distributed at regular intervals and preferably constitute a large portion of the surface of the frame 4. They also allow the frame to be lightened.

(24) In the case where the trapping device 2 comprises more than two deflectors, for example three as in the figures, it then comprises a frame 4 between each contiguous deflector wall (see FIG. 5). The deflectors of a pair of contiguous deflectors are fixed respectively along the outer circular edge and the inner circular edge of the annular frame 4.

(25) Advantageously, the deflectors 3, 3a, 3b, 3c are attached to the frames 4 by welding.

(26) As appears better in FIGS. 2 and 4, preferably the particle collecting and storing element 5 comprises a solid ring 50 coaxial with the axis of revolution X-X of the deflectors 3a to 3c which extends in a plane perpendicular or substantially perpendicular to this axis.

(27) Preferably there is a single collection element 5 for all the deflectors 3, 3a, 3b, 3c.

(28) This ring 50 is continued forward AV by a solid outer annular edge 51 and by a solid inner annular edge 52.

(29) Preferably, the inner annular edge 52 is located in the continuation of the rear edge of the innermost deflector 3c. More preferably, these two elements form only the same single part.

(30) This element 5 therefore has the general shape of a gutter oriented facing the deflectors 3, 3a, 3b, 3c.

(31) Finally, as is most visible in FIGS. 2 to 4, preferably the attachment means 6 comprise a planar annular flange 60, coaxial with the axis of revolution X-X of the deflectors and perpendicular to this axis X-X, and which is continued forward by a cylinder 61 with longitudinal axis X-X.

(32) The flange 60 is perforated with several openings 62 which allow the passage of attachment members 7, such as for example screws. These screws allow the flange to be attached to a portion of the turbomachine.

(33) The cylinder 61 is perforated with a plurality of openings 63 allowing the passage of the air flow circulating inside the turbomachine. Similarly to what has been described for the frames 4, these openings 63 represent a considerable portion of the surface of the cylinder 61, so as not to slow or restrain the flow of the air. The also contribute to reduce the overall mass of the device.

(34) The cylinder 61 is linked to the particle storing element 5. Preferably, the cylinder 61 is welded to the inner end of the ring 50 of the element 5.

(35) The operation of the device is the following.

(36) The air originating in the compressor 12, charged with particles P, penetrates inside the bypass area 17, from the front AV to the rear AR between the outer wall 131 of the combustion chamber 13 and the casing 18 (arrow F in FIG. 2).

(37) This air flow charged with particles strikes the wall 180, so that the particles ricochet (bounce) against it and then strike the outer faces 31a, 31b, 31c of the deflectors 3a, 3b and 3c oriented toward this wall 180. The run of the particles is slowed, these slide inwardly (toward the axis X-X), along the deflectors until they are assembled and collected in the element 5, from which they cannot depart because the walls of it are solid.

(38) The openings 40, however, allow the impact of the trapping device 2 on the circulation of the air flow to be limited, and therefore limits the head losses. In other words, the particles are retained by the element 5 but the air flow can continue to circulate around the outer walls 131 of the combustion chamber 13, so as to penetrate into the holes 130 and to provide the function of cooling these walls.

(39) Finally, it will be noted that, advantageously, the inner radius R1 of the outer deflector 3a (i.e. its smaller radius) is less than or equal to the outer radius R2 of the contiguous median deflector 3b (i.e. its larger radius). The same can be true for each pair of contiguous deflectors.

(40) Thus, if a particle were to ricochet against the wall 180 of the casing 18 and went back toward the front in a direction parallel to the axis X-X, it would unavoidably be trapped by the outer deflector 3a.

(41) Calculations of trajectories of particles must be carried out for each turbomachine, depending on the shape of the walls delimiting the bypass area 17 of the combustion chamber, so as to best position the particle trap 2, in order for it to retain the virtual totality of particles ingested by the turbomachine and entering into the bypass of the combustion chamber.

(42) In addition, the values of the angles , and are also adjusted depending on the shape of the wall 180 and can be different from those previously mentioned.

(43) During maintenance operations of the turbomachine, the particles trapped in the element 5 can then be removed to avoid their accumulation.