BE1030472B1 - FLOW SEPARATOR IN A TRIPLE-FLOW TURBOMACHINE - Google Patents

Abstract

The invention relates to a turbomachine (1) with an unducted propeller, comprising a separation nozzle (36) splitting an air inlet flow (F) into a primary annular flow (F1) and a secondary annular flow (F2); and an annular row of rotor blades (40) arranged directly upstream of the separation nozzle (36), each blade (40) having an intrados and an extrados; the turbomachine (1) being remarkable in that at least one of the blades (40) has a fin (42) extending circumferentially from its intrados or from its extrados, the circumferential width (E) of the fin (42) being at least twice the maximum circumferential thickness (A) of the blade (40).

Description

Description

FLOW SEPARATOR IN A TRIPLE-FLOW TURBOMACHINE

Domain

The invention relates to the design of a turbomachine and more particularly a multi-flow turbomachine.

Prior art

Double-flow turbomachines generally have a fan at the inlet which is followed by a separation nozzle. The separation nozzle splits the main flow into two flows, only one of which passes through the compressors, the combustion chamber and the turbines.

To limit vibrations, document FR 2 440 466 A1 describes fan blades equipped with fins providing vibration damping.

Document FR 2 867 506 shows stator blades with ribs to attenuate vibrations. These blades are arranged upstream of support arms at a significant distance from a flow separation.

These fins do not prevent the separation nozzle from being a source of turbulence, risk of flow separation, and therefore loss of efficiency for the turbojet. The problem of turbulence on the separation nozzle is particularly evident on a separation nozzle placed downstream of several rotating elements, which is particularly the case in a multi-flow turbomachine with a non-ducted propeller and a fan upstream of a separation nozzle.

Summary of the invention

Technical problem

The invention aims to resolve the drawbacks of state-of-the-art turbomachines. In particular, the invention aims to propose a design which allows separation of an air flow without penalizing the efficiency of the turbomachine, whatever the conditions of pressure, temperature and speed of the flow to be separated. .

Technical solution

The invention relates to a turbomachine comprising: a non-ducted propeller propelling a tertiary flow; a rotor downstream of the propeller; a separation nozzle downstream of the rotor to separate the flow propelled by the rotor into a primary flow and a secondary flow; and a compressor compressing the primary flow; the rotor comprising an annular row of rotor blades arranged upstream of the separation nozzle, each blade having an intrados and an extrados; the turbomachine being remarkable in that at least one of the blades has a fin extending circumferentially from its intrados or from its extrados, the circumferential width of the fin being at least twice the maximum circumferential thickness of the blade .

The fin (or “fin” or “blade”) has a function of guiding an air flow and as such can have a leading edge (that is to say a rounded edge and not not a front surface which would present resistance to the aerodynamic flow of air), an upper and lower surface which can be domed or curved in the manner of an intrados or extrados, and a trailing edge .

The row of blades is arranged directly upstream of the separation nozzle, which means that no fixed or mobile element is inserted axially between the blades and the nozzle. Alternatively, an element (fixed or mobile) can be inserted between the blades and the nozzle.

From the separation nozzle extends an external surface, internally guiding the secondary flow, and an internal surface, externally guiding the primary flow.

The inlet flow is thus pre-guided by the fin before being split into two flows.

This pre-guiding reduces the risk of turbulence or separation of the flow and allows an improvement in the efficiency of the turbomachine, independently of the pressure and temperature conditions of the flow.

According to an advantageous embodiment of the invention, each blade defines, with a directly circumferentially adjacent blade, an inter-blade gap, and the circumferential width of the fin is equal to at least 30% of the inter-blade gap, preferably at least 50% and more preferably the circumferential width of the fin is close to 100% of the inter-blade distance.

According to an advantageous embodiment of the invention, in the vicinity of the separation nozzle, the primary flow and the secondary flow flow in two respective main flow directions, respectively defining a primary angle and a secondary angle, relative to the axis of rotation of the blades, and the fin comprises a trailing edge which guides the inlet flow according to a trailing angle which is between the primary angle and the secondary angle. A compromise is thus found to limit aerodynamic losses even when the two flows downstream of the nozzle are very divergent. This orientation of the fin also gives flexibility for the design of the veins downstream of the blades, allowing in particular a steep swan neck at the outlet of a compressor, and therefore a high compression rate and better efficiency.

According to an advantageous embodiment of the invention, the trailing angle of the trailing edge of the fin is closer to the secondary angle than to the primary angle.

According to an advantageous embodiment of the invention, the radial thickness of the fin varies from upstream to downstream and in particular the thickness generally increases from upstream to downstream. This also makes it possible to properly pre-direct the input flow towards the primary and secondary flows.

According to an advantageous embodiment of the invention, the fin comprises a first trailing edge and a second trailing edge, the two trailing edges being radially separated by a cavity. Thus, the leaking edges can be oriented as close as possible to the flow directions of the primary and secondary flows.

According to an advantageous embodiment of the invention, an auxiliary fin is arranged in axial and circumferential overlap of the fin. This design makes it possible to properly pre-guide the inlet flow without increasing the weight of the rotating assembly, further allowing a gain in efficiency.

According to an advantageous embodiment of the invention, an auxiliary blade extends radially externally and/or internally from the fin, preferably over a height greater than 15% of the height of the blades. The fin thus offers the opportunity to compress the flow more, or even to compress it heterogeneously between the primary flow and the secondary flow, thus adapting the optimal compression rate for the primary and secondary flows and thus allowing a gain in efficiency. .

Advantageously, the auxiliary blade is welded to the fin. For example, it can be pre-positioned in a notch provided for this purpose on the fin, then welded.

According to an advantageous embodiment of the invention, the fin extends from

Vintrados of a first blade to the extrados of a second blade, circumferentially directly adjacent to the first blade. Thus, the entire inter-blade space is occupied by the fin, thus forcing the flow particles to move either towards the primary flow or towards the secondary flow.

According to an advantageous embodiment of the invention, the fin extends from the lower surface of a first blade and another fin extends from the upper surface of a second blade, the two fins being preferably at the same radial height and separated by a circumferential gap. The gap can be very small and actually form a mounting gap. The gap can be linear and possibly axial. It can alternatively be curved, in particular parallel to the intrados or extrados to follow the camber of the blades. Alternatively, the two fins coming from adjacent blades can overlap circumferentially.

According to an advantageous embodiment of the invention, the fin 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 small order of magnitude compared to the dimensions of the fin. These irregularities further improve the guidance of the flow and therefore the efficiency of the turbomachine.

According to an advantageous embodiment of the invention, the axial length of the fin is less than that of the blades. Alternatively, the axial length of the fin can be greater or identical to that of the blade carrying it.

According to an advantageous embodiment of the invention, the transverse profile of the fin has a camber and/or an inflection point. Alternatively, the profile can be linear, presenting a constant angle from the entry angle of the leading edge to the exit angle of 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 allows a greater volume of air to be conducted towards one or the other of the flows to favor a greater compression rate.

According to an advantageous embodiment of the invention, the row of blades comprises a plurality of fins of which at least two fins differ in their profile, their radial position, their circumferential width, their thickness, their shape and/or their method. Manufacturing.

According to an advantageous embodiment of the invention, the fin is welded to the blade from which it extends or the fin and the blade are machined together from the same stock.

According to an advantageous embodiment of the invention, all the blades of the row of blades and the fin(s) are in one piece, obtained by machining a single stock or obtained by additive manufacturing.

According to an advantageous embodiment of the invention, the fin has a free end whose axial length is at least 30% of the chord of the blade, preferably at least 70%, more preferably approximately 80% of the chord of the blade. 'dawn.

According to an advantageous embodiment of the invention, the fin has a trailing edge whose radial position corresponds to or is close to the radius of the separation beak.

The separation nozzle has a circular edge which forms its upstream end, rounded or not, and which can define the radius of the nozzle. When the edge is very rounded, the radius of the circular edge is no longer a simple value but a range of values (median value +/- the radius of the rounding), the trailing edge of the fin being located at a radial position included in this value range.

According to an advantageous embodiment of the invention, the annular row of rotor blades is arranged directly upstream of the separation nozzle. Thus, no intermediate element is positioned axially between the rotor blades and the nozzle.

Advantages of the invention _ The invention is particularly advantageous in that it makes it possible to split a flow into several flows (two or more) while limiting the effects on the efficiency of the engine.

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

Pre-guiding the flows also allows greater freedom in the trajectory of the downstream veins and in particular a steeper swan neck, because the flow entering the swan neck can be pre-guided and present less risk of separation .

Then, the secondary flow (respectively primary) can be “energized”, that is to say accelerated and/or compressed more than the primary flow (resp. secondary).

Description of the designs

Figure 1 is a sectional view of a turbomachine;

Figure 2 illustrates the separation of a flow;

Figures 3A to 3D show different transverse profiles of the fin;

Figure 4 is an isometric view of the blade and its fin;

Figures SA and 5B show two examples of fins viewed radially;

Figure 6 is an isometric view of the rotor with blades equipped with fins;

Figure 7 shows a variant with auxiliary blades.

Description of an embodiment

In the description which follows, 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 must be considered with reference to the direction of flow in the turbomachine.

The figures show the elements schematically and are not represented 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 interior casing 2 guides a primary flow F1 which successively travels 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 energy of the combustion drives the turbines 8 in rotation around [axis indirectly by means of reducers.

The turbines 8 also rotate a rotor 12 which sets in motion an input flow (F1+F2) which separates into a primary flow F1 directed towards a compressor 4 and a secondary flow F2. In the example shown in Figure 1, a non-ducted propeller 14 propels a tertiary flow F3 in addition to propelling the inlet flow (F1+F2).

A fairing 16 and a nacelle 18 delimit a passage 19 which is traversed by the secondary flow F2.

Structural arms 20 take up the forces between the nacelle 18 and the casing 4.

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

The rotor 12 and the propeller 14 can rotate in opposite directions to each other via a gear reducer (not shown). This gearbox can also greatly reduce the rotation speed (between the turbines and the rotor/propeller).

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

An input flow F is split into a primary flow F1 and a secondary flow F2. The primary flows F1 and secondary flows F2 flow respectively in an annular vein 32, 34.

The separation of the flows is carried out by a separation nozzle 36 of circular shape around the axis of the turbomachine X. The separation nozzle 36 may have an upstream circular edge which may be a sharp or rounded edge. It is arranged directly upstream of a surface 34.1 which internally guides the secondary flow

F2 and 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 nozzle 36. The flows F1 and F2 have a main direction of flow which is oriented according to the angles a, and à » in the vicinity of the nozzle 36. angle a, can be between -60° and +15°. The angle a» can be between -15° and +60°, while naturally being greater than 04.

The separation nozzle 36 or its circular edge defines a radius R up to the axis X.

Directly upstream of the nozzle 36 is a rotating assembly in the form of a rotor 12 equipped with an annular row of blades 40 extending from an internal disk 41.

At least one fin 42 extends circumferentially from a blade 40 of the rotor 12. Figure 2 highlights the fact that the fin 42 comprises a leading edge 42.1 and a trailing edge 42.2. The latter can be located at a radial height R (+/- 10% of the radial position of the nozzle 36).

Figure 2 also highlights the leakage angle a which corresponds to the orientation of the inlet flow F1 in the vicinity of the trailing edge 42.2 of the fin 42. This angle is between a4 and a.

Figures 3A to 3D show different transverse profiles that the fin 42 can have. The fin 42 extends from its leading edge 42.1 to its trailing edge 42.2. A radially lower surface 42.3 and a radially upper surface 42.4 define the fin 42 radially. The thickness e of the fin 42 is the shortest distance between the interior 42.3 and exterior 42.4 surfaces for a given axial position. These surfaces can be provided with shapes that help guide the flow (“contouring”) and thus present local variations in thickness.

In Figure 3A, the fin 42 has an increasing radial thickness e and it extends axially beyond the blade 40. The length L of the blade 40 is smaller than the length | of the fin 42.

In Figure 3B, the fin 42 is confined axially to the blade 40.

In Figure 3C, the fin 42 comprises a leading edge 42.1 and two trailing edges 42.2. A cavity 42.5 separates the two trailing edges 42.2.

In Figure 3D, the fin 42 is arched with an inflection point and directs the inlet flow F towards the secondary flow. A 42’ auxiliary fin, also arched, helps pre-guide the F flow towards the primary flow. An inversion with the auxiliary fin 42' radially outward is also possible.

The embodiments of Figures 3C and 3D are particularly advantageous when the edge of the nozzle 36 is very rounded, each of the two trailing edges 42.2 having a radial position which corresponds to the radius of the separating nozzle (see dotted lines in Figure 3D) .

It is understood that these examples can be modified and each aspect can be combined with another aspect of each of the examples. The different examples can be combined within the same row of blades, or even in the same inter-blade space.

Figure 4 shows an isometric view of a blade 40. This blade 40 includes a leading edge 40.1, a trailing edge 40.2, an intrados 40.3 and an extrados 40.4.

The maximum circumferential thickness of the blade 40 is denoted A.

The fin 42 can be supported by the upper surface or the lower surface, or extend from both.

The fin 42 can be cantilevered, i.e. supported by a single blade, or extend from a blade 40 to a circumferentially adjacent blade. When it is cantilevered, it includes a free end 42.6 which determines the circumferential width E of the fin. According to the invention, E is worth at least 2 times A. Preferably E is much greater than A, for example at least 5 times greater.

Two neighboring blades define an inter-blade gap between them (noted D in the figure

HER). This can vary radially (the blade heads being further away from each other than the blade roots). The width E of the fin can be worth at least 30% of this inter-blade gap and preferably the width E can be approximately equivalent to the inter-blade gap.

It is understood that when the fin 42 is supported by the two circumferentially neighboring blades, the circumferential width of the fin is equivalent to the inter-blade distance.

Length | of the fin may be at least 30% of the axial length L of the blade or the rope C.

The blade 40 and the fin(s) 42 that it carries can be in one piece.

Optionally, several adjacent blades and their fins can be in one piece, thus describing an angular sector of a few degrees of angles to a few tens of degrees (for example 12 sectors of 30° forming the annular row of blades 40), or even up to 'at 360°.

The fins 42 may have a concentric curvature with the axis of the turbomachine. They can thus, for example, coincide with the position of the nozzle 36 over their entire circumferential width.

Figures 5A and 5B show two examples of the fin 42 seen in a plane perpendicular to a radius. Figure 5A shows a single fin 42 with a leading edge 42.1 having an inflection point, to accompany the flow around the two blades. Figure 5B shows two fins 42 with a curved leading edge and trailing edge.

In a variant not illustrated, the leading and trailing edges are rectilinear.

Figures 5A and 5B also highlight the gap 44. This can have a very small dimension, of the order of the assembly clearance. Alternatively, it can be larger to allow access for a welding tool (for orbital friction in particular).

Figure 5A also shows the inter-blade gap D, which is the circumferential distance between the blades.

Figure 6 shows an isometric view of a rotor 12 (“Blisk” for “Bladed disk”) on which all the inter-blade spaces are occupied by a fin 42.

The blades 40 are fixed to a disc 41 by welding, or the blades are manufactured simultaneously with the disc, by machining the same stock or additive manufacturing. Any type of welding can be considered (electron beam welding, orbital friction, linear friction).

Likewise, the fins 42 are welded to the blades 40 or manufactured by machining or additive manufacturing.

Hybrid manufacturing (some fins welded, others machined; and/or some blades welded, others machined) is also possible.

Figure 7 shows a partial view of another variant in which the fins 42 support auxiliary vanes 46. In the example illustrated, the auxiliary vanes 46 are “one” in number per inter-vane space and extend radially externally. It is understood that the number of auxiliary blades carried by the fins and their orientations (external and/or internal) can be chosen according to the compression or the speed to be applied independently to the primary or secondary flow. For example, one auxiliary blade may be directed inwards, and two auxiliary blades outwards, with the inner blade circumferentially located midway between the outer blades.

The radial length of the auxiliary blades 46 is here approximately a quarter of the radial length of the blades 40. They can also extend radially by a greater or lesser value, up to the value of the height of the blades. 40. As for the axial dimension, the auxiliary blades 46 can extend between 50 and 100% of the axial length of the fins 42.

It should be noted that the invention is not limited to the examples described in the figures. Thus, several fins of different types can be provided in the same row of blades (for example, one without gap, the other with fins at different heights, with different cambers, etc.).

The distribution of the fins on the rotor may be symmetrical or not, and the fins may be evenly spaced angularly or irregularly.

The invention is dedicated to so-called non-ducted turbomachines (CROR “Counter-

Rotating Open Rotor” or USF “Unducted Single Fan”) which may have an intermediate fan.

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

Claims (18)

Claims 1. Turbomachine (1), comprising: - a non-ducted propeller (14) propelling a tertiary flow (F3); - a rotor (12) downstream of the propeller (14); - a separation nozzle (36) downstream of the rotor (12) to separate the flow (F) propelled by the rotor into a primary flow (F1) and a secondary flow (F2); and - a compressor (4) compressing the primary flow (F1); the rotor (12) comprising an annular row of rotor blades (40) arranged upstream of the separation nozzle (36), each blade (40) having an intrados (40.3) and an extrados (40.4); the turbomachine (1) being characterized in that at least one of the blades (40) has a fin (42) extending circumferentially from its intrados (40.3) or from its extrados (40.4), the circumferential width (E) of the fin (42) being at least twice the maximum circumferential thickness (A) of the blade (40). 2. Turbomachine (1) according to claim 1, characterized in that each blade (40) defines, with a directly circumferentially adjacent blade, an inter-blade gap, and the circumferential width (E) of the fin is equal to at least 30% of the inter-blade gap, preferably at least 50% and more preferably the circumferential width (E) of the fin is close to 100% of the inter-blade gap. 3. Turbomachine (1) according to claim 1 or 2, characterized in that in the vicinity of the separation nozzle (36), the primary flow (F1) and the secondary flow (F2) flow in two main directions of respective flow, defining respectively a primary angle (a4) and a secondary angle (aa), relative to the axis (X) of rotation of the blades (40), and the fin (42) comprises a trailing edge (42.2) which guides the flow (F) according to a leakage angle (a) which is between the primary angle (a4) and the secondary angle (02). 4. Turbomachine (1) according to claim 3, characterized in that the trailing angle (a) of the trailing edge (42.2) of the fin (42) is closer to the secondary angle (d”) than to the primary angle (a4). 5. Turbomachine (1) according to one of the preceding claims, characterized in that the fin (42) comprises a first trailing edge (42.2) and a second trailing edge (42.2), the two trailing edges (42.2) being radially separated by a cavity (42.5). 6. Turbomachine (1) according to one of the preceding claims, characterized in that an auxiliary fin (42') is arranged in axial and circumferential overlap of the fin (42). 7. Turbomachine (1) according to one of the preceding claims, characterized in that an auxiliary blade (46) extends radially externally and/or internally from the fin (42), preferably over a height greater than 15% of the height of the blades (40). 8. Turbomachine (1) according to one of claims 1 to 7, characterized in that the fin (42) extends from the lower surface (40.3) of a first blade (40) to the upper surface (40.4 ) of a second blade (40), circumferentially directly adjacent to the first blade (40). 9. Turbomachine (1) according to one of claims 1 to 7, characterized in that the fin (42) extends from the lower surface (40.3) of a first blade (40) and another fin (42) extends from the extrados (40.4) of a second blade (40), the two fins (42) being preferably at the same radial height and separated by a circumferential gap (44). 10. Turbomachine (1) according to one of the preceding claims, characterized in that the fin (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. 11. Turbomachine (1) according to one of the preceding claims, characterized in that the axial length (I) of the fin (42) is less than that (L) of the blades (40). 12. Turbomachine (1) according to one of the preceding claims, characterized in that the transverse profile of the fin (42) has a camber and/or an inflection point. 13. Turbomachine (1) according to one of the preceding claims, characterized in that the row of blades (40) comprises a plurality of fins (42) of which at least two fins (42) differ in their profile, their radial position , their circumferential length, their thickness, their shape and/or their manufacturing method. 14. Turbomachine (1) according to one of the preceding claims, characterized in that the fin (42) is welded to the blade (40) from which it extends or the fin (42) and the blade (40 ) are machined together in the same stock. 15. Turbomachine (1) according to one of the preceding claims, characterized in that all the blades (40) of the row of blades (40) and the fin(s) (42) are in one piece, obtained by machining 'a single raw material or obtained by additive manufacturing. 16. Turbomachine (1) according to one of the preceding claims, characterized in that the fin (42) has a free end (42.6) whose axial length is at least 30% of the chord of the blade (40), preferably at least 70%, more preferably approximately 80% of the chord (C) of the blade (40). 17. Turbomachine (1) according to one of the preceding claims, characterized in that the fin (42) has a trailing edge (42.2) whose radial position corresponds to or is close to the radius (R) of the nozzle. separation (36). 18. Turbomachine (1) according to one of the preceding claims, characterized in that the annular row of rotor blades (40) is arranged directly upstream of the separation nozzle (36).