BE1030046B1 - MOBILE IMPELLER WITH SEVERAL ROWS OF BLADE - Google Patents

Abstract

Method of manufacturing a turbine engine impeller (38) comprising: the manufacture of a plurality of first blades (40), called internal blades; the manufacture of a plurality of second blades (44), called external; making a disc (41); fabricating a ring (42) comprising a leading edge, a trailing edge, an inner radial surface and an outer radial surface, said surfaces extending from the leading edge to the trailing edge; attaching the inner vanes (40) to the disc (41); attaching the ring (42) to the inner vanes (40); and attaching the outer vanes (44) to the ring (42). The invention also relates to a mobile wheel (38) obtained by this process and a turbomachine provided with such a wheel (38).

Description

Description

MOBILE IMPELLER WITH SEVERAL ROWS OF BLADE

Domain

The invention relates to the manufacture of a moving wheel for a multi-flow turbomachine.

Prior art

Multi-flow turbomachines have the characteristic of using different annular air flows, coaxial with each other, each of the flows meeting or not meeting various components of the turbomachine (compressor, combustion chamber, turbine, stator blades, etc. ).

Thus, it is known to use a moving compressor wheel which is common to two adjacent flows separated by a wall. As such, the impeller includes an intermediate ring that keeps the two flows sealed from each other.

To assemble this intermediate ring, supports are provided on each of the blades and angular sections of the ring are riveted to each of the supports.

On the one hand, such an assembly is complex. It requires significant assembly time and requires the use of specific tools.

On the other hand, such a moving impeller is only suitable for a design where two flows are already separated from each other upstream of the impeller. The geometry of the intermediate ring is not suitable for a zone of the turbomachine where a single flow upstream of the wheel is split into several flows downstream of the wheel, because the geometry known from the state of the art would generate in such a situation significant aerodynamic losses and therefore lower engine performance.

Such flow separation zones are found in particular at the level of a separation nozzle downstream of a fan or downstream of a compressor of the turbomachine.

Summary of the invention

Technical problem

The invention aims to solve the drawbacks identified in the state of the art. In particular, the invention aims to propose a wheel design and its method of manufacture, which allow easier manufacture and which make the wheel suitable for occupying a zone of the turbomachine where an air flow is split without affecting the efficiency. of the turbomachine.

Technical solution

The invention relates to a method for manufacturing a turbine engine compressor impeller, the method comprising: the manufacture of a plurality of first blades, called internal blades; the manufacture of a plurality of second blades, called external; making a record; manufacturing a ring comprising a leading edge, a trailing edge, an inner radial surface and an outer radial surface, said surfaces extending from the leading edge to the trailing edge; attaching the inner vanes to the disc; attaching the ring to the inner vanes; and attaching the outer vanes to the ring.

The manufacturing and fixing steps can be carried out in different sequences, all of which increase manufacturing efficiency. The attachment of certain blades to the disc or to the ring may begin while the manufacture of certain other blades has not yet been carried out. The geometry of the ring facilitates its assembly and promotes the separation of one flow into two flows without negatively affecting the efficiency of the motor.

According to an advantageous embodiment of the invention, the fixing operations are carried out in the following order: the fixing of the outer vanes to the ring; attaching the ring to the inner vanes; and attaching the inner vanes to the disc.

According to an advantageous embodiment of the invention, the fixing operations are carried out in the following order: the fixing of the internal blades to the disc; attaching the ring to the inner vanes; and attaching the outer vanes to the ring.

According to an advantageous mode of the invention, the internal vanes are fixed to the disk by orbital friction, the ring is fixed to the internal vanes by welding by electron beam or by inertial friction, and the external vanes are fixed to the ring by orbital friction.

According to an advantageous embodiment of the invention, the fixing operations are carried out in the following order: the fixing of the internal blades to the disc; attaching the outer vanes to the ring; and attaching the ring to the inner vanes.

According to an advantageous embodiment of the invention, the attachment between the blades and the disc or the ring is made by notches, grooves, dovetails or screw elements. Grooves or notches can be fitted to each blade to pre-hold the ring during its attachment. They thus make assembly easier and potentially more precise. The shape of the groove or notch can be such that the ring is positioned so as to pre-guide the flow in a direction advantageous for its separation (for example a radially outward inclination from upstream to downstream) .

According to an advantageous mode of the invention, an outer ring can be fixed, preferably by welding, to the outer radial ends of the outer blades. This outer ring makes it possible to reduce aerodynamic losses at the interface between the tip of the rotor blades and the stator.

According to an advantageous mode of the invention, the ring can be complete (360°) or be formed of several ring sections, assembled together before their attachment to the internal or external blades. Alternatively the blades can be assembled to the ring sections before these are assembled together.

According to an advantageous embodiment of the invention, the manufacturing and fixing steps are repeated to form three or more concentric annular rows of blades, separated two by two by a ring.

The invention also relates to a mobile turbine engine wheel preferably obtained by the manufacturing method according to one of the preceding claims, the wheel comprising: a disc, a plurality of internal blades extending radially outwardly from the disc, a ring attached to the inner vanes, and a plurality of outer vanes extending radially outward from the ring, the ring comprising a leading edge, a trailing edge, an inner radial surface and an outer radial surface, said surfaces extending from the leading edge to the trailing edge.

We find the manufacturing process on the wheel because we can in particular observe, if necessary by micrography, the welds or other fastening means.

According to an advantageous embodiment of the invention, each outer vane extends radially in the extension of an inner vane and/or an outer vane extends radially in the extension of each inner vane. In such an example, the number of inner vanes may or may not differ from the number of outer vanes. Each inner vane extends in radial continuity into an outer vane, and/or each outer vane extends in radial continuity into an inner vane. This continuity is characterized by a radial differentiability at the level of the ring, of the geometric surface formed by two blades of the same angular position.

According to an advantageous mode of the invention, the number of internal blades is different from the number of external blades. The respective flows propelled by the two pluralities of blades can therefore be brought to different speeds (value or orientation) or pressures. For example, the outer vanes may include more vanes than the inner vanes. The difference in the number of internal and external blades, and their angular positions can be such that certain external blades are in the continuity of the internal blades.

According to an advantageous embodiment of the invention, the inner vanes and the outer vanes each have respective leading and trailing edges, and the leading edge of each inner vane at its joint with the ring is offset circumferentially with respect to at the leading edge of each outer vane at its junction with the ring, and/or the trailing edge of each inner vane at its junction with the ring is offset circumferentially with respect to the trailing edge of each outer vane at its joining with the ring. Thus, the outer vanes can have a different geometry, camber, entry or exit angle from the inner vanes to impart a different propulsion to the flow that the outer vanes "see" compared to that which the inner vanes "see". .

According to an advantageous embodiment of the invention, the wheel comprises auxiliary vanes extending radially internally and/or externally from the ring, the auxiliary vanes having a radial height less than or equal to that of the internal and/or external vanes, and / or the auxiliary vanes having an axial length less than or equal to that of the inner and/or outer vanes.

These auxiliary vanes make it possible to act independently on one of the two downstream flows, thus optimizing the efficiency of the turbomachine by compressing or accelerating one of the flows more than the other. Auxiliary vanes can be moved into position and attached before or after the ring is/has been attached to the vanes. The auxiliary vanes may have a radial height and/or an axial length of about half that of the outer and/or inner vanes.

In a variant with an outer ring, the auxiliary vanes can extend radially internally from this outer ring.

According to an advantageous embodiment of the invention, the ring is essentially formed of composite material and is provided with metal inserts welded to the internal and/or external vanes. This weight gain for a rotating element further improves efficiency. Alternatively, all the elements of the moving wheel are metallic.

According to an advantageous embodiment of the invention, the ring has irregularities on its radially outer surface and/or on its radially inner surface, the irregularities being in particular of the three-dimensional contouring type. These irregularities are bumps and/or hollows, the height or depth of which are of a very low order of magnitude compared to the dimensions of the ring. These irregularities further improve the guiding of the flow and therefore the efficiency of the turbomachine.

The invention also relates to a turbomachine comprising: a splitter nozzle splitting an inlet air flow into a primary annular flow and a secondary annular flow; and a movable wheel arranged directly upstream of the separation spout; the turbomachine being remarkable in that the moving wheel comprises an annular row of internal blades and an annular row of external blades, and a ring radially separating the internal blades from the external blades.

The separation spout can have a circular edge forming its upstream end, rounded or not. From the circular edge extends an external surface, for internal guiding of the secondary flow, and an internal surface, for external guiding of the flow - primary.

The stream is thus pre-guided by the ring before being split into two streams. This pre-guiding reduces the risks of turbulence or separation of the flow and allows an improvement in the efficiency of the turbomachine.

According to an advantageous embodiment of the invention, in the vicinity of the separation nozzle, the primary flow and the secondary flow flow along two respective main directions of flow, respectively defining a primary angle and a secondary angle, with respect to the axis of rotation of the wheel, and the trailing edge of the ring guides the inflow according to a trailing angle which is between the primary angle and the secondary angle. A compromise is thus found to limit losses when the two flows downstream of the separation spout are very divergent. This orientation of the ring also offers flexibility for the design of the veins downstream of the wheel, allowing in particular a steep gooseneck at the outlet of a compressor, and therefore a high compression ratio and better efficiency.

According to an advantageous embodiment of the invention, the transverse profile of the ring has a camber and/or an inflection point. Alternatively, the profile can be straight, presenting a constant angle from the entry angle at the leading edge to the exit angle at the trailing edge. Depending on the geometry of the primary and secondary flow veins, one or the other design is more or less advantageous. In particular, a camber makes it possible to conduct a greater volume of air towards one or the other of the downstream flows.

According to an advantageous embodiment of the invention, the turbomachine comprises a wheel with two or more rings, to split one or more streams into an even greater number of streams.

Advantages of the invention

The invention is particularly advantageous in that it makes it possible to propose a moving wheel adapted to a zone of the turbomachine where a flow is split into two flows (or more) while limiting the effects on the efficiency of the engine and offering a less complex manufacturing than the known wheels.

An additional advantage of the presence of a ring is the protection of the downstream veins in the event of ingestion of foreign objects into the engine.

The pre-guiding of the flows also allows greater freedom in the trajectory of the downstream veins and in particular a more abrupt gooseneck, because the flow which enters the gooseneck can be pre-guided and present less risk of detachment .

Then, the secondary flow (respectively primary) can be “energized”, i.e. accelerated and/or compressed more than the primary flow (resp. secondary).

Description of the drawings

Figure 1 is a sectional view of a turbomachine;

Figure 2 illustrates the separation of a stream;

Figures 3 and 4 represent an isometric view of a mobile wheel according to two embodiments of the invention;

Figures SA and 5B illustrate a third example;

Figures 6 and 7 schematically show two variants of the manufacturing method according to the invention.

Description of an embodiment

In the following description, the terms “internal” and “external” refer to positioning relative to the axis of rotation of a turbomachine. The axial direction corresponds to the direction along the axis of rotation of the turbomachine. The radial direction is perpendicular to the axis of rotation. Upstream and downstream are to be considered with reference to the flow direction of a flow in the turbomachine.

The figures show the elements schematically and are not drawn to scale. In particular, certain dimensions are enlarged to facilitate reading of the figures.

Figure 1 shows a schematic sectional view of a turbomachine 1. An inner casing 2 guides a primary flow F1 which successively passes through compressors 4 (low and high pressure), a combustion chamber 6 and turbines 8 (high and low pressure), before escaping through a nozzle 10. The combustion energy drives the turbines 8 in rotation. The turbines 8 drive the compressors 4, directly by means of transmission shafts, or indirectly by means of reducers.

The turbines 8 also rotate a rotor 12 with fan blades 14 which set in motion a secondary flow F2. Most of the thrust of the turbomachine is generated by the propulsion of the flow F2 by the rotor 12, which is said to be “propulsive”. The primary flow F1 is used as an oxidizer to ensure the rotation of the turbines and the rotor 12.

A fairing 16 and a nacelle 18 delimit a passage 34 which is traversed by the secondary flow F2.

Structural arms 20 take up the forces between the nacelle 18 and the engine casing 2.

An annular row of stator vanes 22 (“outlet guide vanes”, OGV) can be arranged downstream of the rotor 12 to straighten the flow F2.

A reducer 23 can also greatly reduce the speed of rotation (between the turbines 8 and the blades 14).

The turbomachine 1 has a separation nozzle 36 to separate the air flow F into two annular flows.

Figure 2 schematically shows the separation of a flow into two annular flows.

An input stream F is split into a primary stream F1 and into a secondary stream F2. The primary F1 and secondary F2 flows respectively flow in an annular vein 32, 34. These flows can correspond to the primary and secondary flows of FIG. 1 or to other flows separated from each other in the turbomachine.

The separation of the flows is carried out by a separation nozzle 36 having an edge of circular shape around the axis of the turbomachine X. The edge can be sharp or have a rounding. The separating nose 36 or its circular edge defines a radius R up to the X axis.

The ridge is arranged directly upstream of a surface 34.1 which internally guides the secondary flow F2 and of a surface 32.1 which externally guides the primary flow F1. These two surfaces 32.1, 34.1 can be approximately truncated cones in the vicinity of the separation spout 36. The flows F2 and F3 have a main direction of flow which is oriented according to the angles ay and a′ in the vicinity of the separation spout 36 The angle α can be between -60° and +15°.

The angle a, can be between -15° and +60°, while being naturally greater than 04.

Directly upstream of the separation nozzle 36 is located a rotating assembly in the form of a movable wheel 38 equipped with an annular row of blades 40, called internal, extending radially from a disc 41 (or internal shroud ). The impeller 38 may be (but need not be) the rotor 12 of Figure 1 and the blades 40 may be the blades 14. The blades 40 are fixed to the disc 41, for example by welding. Any type of welding can be envisaged (electron beam welding, orbital friction, linear friction, TIG).

Alternatively, the blades 40 can be fixed to the disc 41 by dovetails. Alternatively, the blades 40 are manufactured simultaneously with the disk 41, by machining the same raw material or by additive manufacturing.

At least one ring 42 extends circumferentially over 360° encircling disc 41. Figure 2 shows that ring 42 includes a leading edge 42.1 and a trailing edge 42.2. The latter is located at a radial height R which can in particular be between 30% and 70% of the radial height of the vein 30. The leading and trailing edges of the ring are circular around the axis X of rotation of the wheel 38.

The ring 42 can be metallic or be made of composite material. The ring 42 can be fixed by pins, by screwed elements, or welded to the internal vanes 40.

The internal vanes 40 can comprise a notch or a groove for fixing the ring 42. If necessary, the welding of a composite ring is made possible by the integration of metal inserts in the composite ring.

The ring 42 has an inner radial surface 42.3 and an outer radial surface 42.4, each extending from the leading edge 42.1 to the trailing edge 42.2.

The radial thickness of the ring can vary from upstream to downstream. The surfaces 42.3, 42.4 can be provided with irregularities helping to guide the flow (“contouring”) and thus have local thickness variations.

The profile of the ring 42 can also have a camber and/or a point of inflection. The ring 42 may have an upstream guide angle at the leading edge which is different from the downstream angle at the trailing edge.

Alternatively, the flow guiding angle can be constant from upstream to downstream.

Figure 2 highlights the vanishing angle a which corresponds to the orientation of the inlet flow F in the vicinity of the trailing edge 42.2 of the ring 42. The ring 42 is designed so that this angle is between to, and 02.

Radially outward from the ring extend outer vanes 44. The flow

F is therefore subjected to two compression zones aimed at presenting the flow F according to two conditions of pressure and speed at the point where it separates into two flows F1 and F2. The internal 40 and external 44 vanes impart a movement to the flow F such that the flow F1 and the flow F2 are different in pressure and/or speed at the right of the separation nozzle 36.

Lafigure 3 shows an isometric view of the impeller 38 with its blades 40 and 44, the disc 41 and the ring 42. This figure highlights the leading edges 40.1, 44.1 and trailing 40.2, 44.2 of the blades 40, 44.

In this example, the external vanes 44 are presented in the continuity of the vanes 40, that is to say that a vane 44 forms with a vane 40 a profile similar to that described by a single vane extending radially over the entire height of the vein 30. The leading edges 40.1, 44.1, the trailing edges 40.2, 44.2, as well as the extrados and intrados of the blades 40 and 44 form geometrically continuous lines and surfaces (and differentiable, without angular points at the level of the ring 42).

Figure 4 shows an alternative to the wheel 38 of Figure 3, in which the outer vanes 44 are twice as numerous as the inner vanes 40. There is thus exactly one outer vane 44 out of two which is in the radial continuity of an internal blade 40. Other configurations are naturally possible with other ratios of number of blades, and/or with more internal blades 40 than external blades 44. When the numbers of internal blades 40 and external 44 are not a multiple of each other, a limited number of internal and external blades are in continuity with each other, or even none.

Figures SA and 5B show a variant in which the internal vanes 40 and the external vanes 44 are of the same number but do not present themselves in continuity with each other. This can result in a discontinuity in the profile between the inner 40 and outer 44 blades at the level of the ring 42. The discontinuity can be materialized for example by a circumferential offset of the leading edge and/or the trailing edge of the blades. 40, 44; and/or by shifting the intrados or extrados of the respective blades at the level of the ring; and/or by different entry and/or exit angles. The peripheral surface (leading and trailing edge, intrados and extrados) of an inner blade 40, and that of an outer blade 44 do not together form a continuous and differentiable surface at the level of the ring.

FIG. 5B shows such an offset, denoted A, between the leading edges 40.1 of the internal blades 40 and those 44.1 of the external blades 44.

It is understood that the number of inner vanes 40 may differ from the number of outer vanes 44 in this embodiment as well.

FIG. 6 shows an embodiment where auxiliary vanes 46 are inserted between two outer vanes 44 circumferentially adjacent. The auxiliary vanes 46 are carried and fixed to the ring 42. They can alternatively extend radially from the ring 42 inwards.

The auxiliary vanes 46 can have a height of at least 15%, and in particular about a quarter of the height of the internal 40 or external 44 vanes.

Alternatively, the auxiliary vanes 46 can cover the entire distance between the ring 42 and the disk 41, or the entire height between the ring 42 and the tip of the vanes 44. As to their axial dimension, the auxiliary vanes 46 can be extend between 50 and 100% of the axial length of the blades 40 or 44.

In the example illustrated, the auxiliary vanes 46 are “one” in number per inter-vane space and extend radially outward from the ring 42. It is understood that the number of auxiliary vanes carried by the ring 42 and their orientations (exterior and/or interior) can be chosen according to the compression or the speed to be printed independently to the primary or secondary streams. For example, one auxiliary vane 46 may point inward, and two auxiliary vanes 46 may point outward, with the inner vane circumferentially located midway between the outer vanes.

The invention relates not only to the wheel 38 and the turbine engine 1 but also to the method of manufacturing the wheel 38. This essentially comprises the manufacture of the various elements that compose it (blades 40, disc 41, ring 42, blades 44) and fixing the elements together.

Figures 7 and 8 illustrate two examples of manufacturing methods.

In FIG. 7, the outer vanes 44 are fixed to the ring 42 first, then the heads of the inner vanes 40 are fixed to the ring 42, and finally the disc 41 is fixed to the inner vanes 40 (at their feet).

In the alternative of Figure 8, the inner vanes 40 are first attached to the disc 41, then the ring 42 is attached to the inner vanes 40, and finally the outer vanes 44 are attached to the ring 42.

Manufacturing can be carried out by appropriate techniques (machining, spark erosion, additive manufacturing, etc.).

The fixing of the elements to each other can be done according to any possible sequence, including the overlapping of the fixing of some of the blades 40/44 to the disc or to the ring 42 simultaneously or in temporal overlap with a step of manufacture or fixing of other elements of the wheel 38.

In one embodiment, the ring 42 is formed of several ring sections which, once assembled together, form the ring 42. The assembly of the ring sections can precede the attachment of the blades 40 or 44, or vanes 40/44 can be attached to ring sections before these are attached together.

The various steps for attaching the ring 42 or its sections can be performed before the vanes 40 are attached to the disk, or after.

Also, the attachment of the ring or its sections to the outer vanes 44 can be made simultaneously (or in time overlap) with the attachment of the vanes 40 to the disc 41.

Similarly, auxiliary vanes 46 may be attached to ring 42 or sections thereof, before ring 42 is attached to vanes 40 and/or 44, or after.

In an embodiment not illustrated, an outer ring can connect the heads of the outer blades 44 and can optionally have irregularities (“contouring”) on the inner surface and/or on its outer surface.

The invention is described in relation to an engine architecture such as that which is illustrated in FIG. 1 but the invention is not limited to this architecture.

A person skilled in the art will understand that the invention can be applied to any rotor which precedes a nozzle for separating a stream, regardless of the nozzle in question.

Each technical characteristic of each illustrated example is applicable to the other examples. In particular, the number of blades, the number of rings or ring sections, their arrangement, their transverse profile, their length, their camber, their shape, etc., can be taken from an embodiment and be applied to another.

Thus, the same wheel can include blades in continuity with each other (of the type in Figure 3) and blades that do not have continuity (of the type in Figure 4 or 5).

Also several distinct fixing elements can be provided between the same ring 42 and some of the blades 40 and/or 44. For example, several welding technologies can be used on the same wheel and/or be combined with different fixing means (notch , groove, dovetail, screws).

Claims (14)

Claims 1. Method for manufacturing a moving wheel (38) of a turbomachine compressor (1), the method comprising: - the manufacture of a plurality of first blades (40), called internal; - the manufacture of a plurality of second blades (44), called external; - the manufacture of a disc (41); - the manufacture of a ring (42) comprising a leading edge (42.1), a trailing edge (42.2), an inner radial surface (42.3) and an outer radial surface (42.4), said surfaces (42.3, 42.4 ) extending from the leading edge (42.1) at the trailing edge (42.2); - fixing the internal vanes (40) to the disc (41); - fixing the ring (42) to the internal vanes (40); and - fixing the outer vanes (44) to the ring (42). 2. Method according to claim 1, characterized in that the fixing operations are carried out in the following order: - the fixing of the outer vanes (44) to the ring (42); - fixing the ring (42) to the internal vanes (40); and - fixing the internal vanes (40) to the disc (41). 3. Method according to claim 1, characterized in that the fixing operations are carried out in the following order: - the fixing of the internal vanes (40) to the disc (41); - fixing the ring (42) to the internal vanes (40); and - fixing the outer vanes (44) to the ring (42). 4. Method according to the preceding claim, characterized in that the internal vanes (40) are fixed to the disc (41) by orbital friction, the ring (42) is fixed to the internal vanes (40) by welding by electron beam or by inertial friction, and the outer vanes (44) are attached to the ring (42) by orbital friction. 5. Method according to claim 1, characterized in that the fixing operations are carried out in the following order: - the fixing of the internal vanes (40) to the disc (41); - fixing the outer vanes (44) to the ring (42); and - fixing the ring (42) to the internal vanes (40). 6. Method according to one of claims 1 to 3 or 5, characterized in that the fixing between the blades (40, 44) and the disc (41) or the ring (42) is carried out by notches, grooves , dovetails or fasteners. 7. Impeller (38) of a turbomachine compressor, the impeller comprising: a disc (41), a plurality of internal vanes (40) extending radially outward from the disc (41), a ring (42) fixed to the inner vanes (40), and a plurality of outer vanes (44) extending radially outward from the ring (42), the ring (42) including a leading edge (42.1), a trailing edge ( 42.2), an inner radial surface (42.3) and an outer radial surface (42.4), said surfaces (42.3, 42.4) extending from the leading edge (42.1) to the trailing edge (42.2). 8. Mobile wheel (38) according to claim 7, characterized in that each outer vane (44) extends radially in the extension of an inner vane (40) and/or an outer vane (44) extends radially in the extension of each internal blade (40). 9. Wheel according to one of claims 7 or 8, characterized in that the number of internal blades (40) is different from the number of external blades (44). 10. Wheel (38) according to claim 7, characterized in that the inner vanes (40) and the outer vanes (44) each have respective leading (40.1, 44.1) and trailing (40.2, 44.2) edges, and the leading edge (40.1) of each inner vane (40) at its joint with the ring (42) is circumferentially offset from the leading edge (44.1) of each outer vane (44) at its joint with the ring (42), and/or the trailing edge (40.1) of each inner vane (40) at its joint with the ring (42) is offset circumferentially with respect to the trailing edge (44.1) of each outer vane (44) at its joint with the ring (42). 11. Wheel (38) according to one of claims 7 to 10, characterized in that it comprises auxiliary vanes (46) extending radially internally and/or externally from the ring (42), the auxiliary vanes (46) having a radial height less than or equal to that of the inner vanes (40) and/or outer vanes (44), and/or the auxiliary vanes (46) having an axial length less than or equal to that of the inner vanes (40) and/or external (44). 12. Wheel (38) according to one of claims 7 to 11, characterized in that the ring (42) is essentially formed of composite material and is provided with metal inserts welded to the internal blades (40) and / or external (44). 13. Wheel (38) according to one of claims 7 to 12, characterized in that the ring (42) has irregularities on its radially outer surface (42.4) and/or on its radially inner surface (42.3), the irregularities being in particular of the three-dimensional contouring type. 14. Turbomachine (1), comprising: - a separation nozzle (36) splitting an inlet air flow (F) into a primary annular flow (F1) and a secondary annular flow (F2); and - a movable wheel (38) arranged directly upstream of the separation spout (36); the turbomachine (1) being characterized in that the moving wheel (38) comprises an annular row of internal blades (40) and an annular row of external blades (44), and a ring (42) radially separating the internal blades outer vanes (44).