FR3132544A1 - Thrust reverser including improved deflection edge. - Google Patents

Abstract

Device and method Thrust reverser (20) for propulsion system (10), comprising a fixed part (29), a movable part (39), and an actuating device (38), adapted to move the movable part (39) between the closed state and the deployed state, the fixed part comprising a deflection edge (40) adapted to direct a flow of air from the inside of the thrust reverser to the outside through an opening counter-thrust, characterized in that said deflection edge (40) has a surface (50) configured to generate turbulence in the fluid flow along the deflection edge (40) and minimize fluid separation along said deflection edge (40). Figure for abstract: Fig. 8.

Description

Thrust reverser including improved deflection edge.

This presentation concerns the field of thrust reversers, particularly for the nacelles of a propulsion unit.

Thrust reversers are elements of a turbomachine nacelle making it possible to direct part of the air flow passing through the turbomachine forward, in order to reverse the thrust exerted by the turbomachine and slow down the aircraft on which the turbomachine is mounted in the event of landing or emergency braking, for example when abandoning takeoff.

In particular, among the known thrust reversers are gate thrust reversers and gate thrust reversers.

Grid thrust reversers include grids extending around a circumference of the propulsion system and having forward-facing aerodynamic profiles, as well as actuators driving the grids and a movable cover.

In normal times, that is to say when the propulsion system generates thrust, during the flight phase for example, the movable cover is in a closed state in which it covers the grilles thus preventing air from escaping from the propulsion system by the latter, the air thus escaping through a nozzle placed downstream of the inverter. On the other hand, when the reverser is deployed in order to generate counter-thrust, the movable cover slides along the propulsion system and flaps pivot in order to prevent air from escaping through the nozzle. The inverter is then in a deployed state in which it uncovers the grilles, thus allowing the air flow to pass through them and be redirected forward,

Thrust reversers with doors have doors forming portions of the nacelle, and movable between a closed position in which they conform to the geometry of the nacelle to allow air flow through the nacelle, and an open position in which they are tilted so as to block all or part of the air passage through the nacelle, and to deflect the air flow radially outwards passing through transverse counter-thrust openings opened by the deployment doors, in order to push the air flow forward and thus generate counter-thrust.

The present invention thus aims to respond at least partially to these problems.

To this end, the present invention relates to a thrust reverser for a propulsion system, comprising
a fixed part, adapted to be mounted on a propulsion system so as to encircle the latter,
a movable part attached in a sealed manner against the fixed part by blocking a counter-thrust opening in the closed state, while the counter-thrust opening is released in the deployed state, and an actuating device, adapted to move the mobile part between the closed state and the deployed state,
the fixed part comprising a deflection edge adapted to direct a flow of air from the inside of the thrust reverser towards the outside through the counter-thrust opening,
characterized in that said deflection edge has a surface configured so as to generate turbulence in the flow of the fluid along the deflection edge and minimize separation of the fluid along said deflection edge.

By propulsion system, we mean a turbomachine, such as a turbojet, or an electric or hybrid propulsion device.

According to one example, said deflection edge surface has concave recesses formed in said deflection edge surface.

According to one example, said recesses are concave cells having a surface in the shape of a sphere.

According to one example, said recesses are grooves arranged in the surface of the deflection edge, said grooves extending parallel or perpendicular to a direction of air flow on the deflection edge.

According to one example, said surface of the deflection edge has a portion having locally increased roughness.

According to one example, said surface of the deflection edge has vortex generators.

According to one example, said surface of the deflection edge has convex portions forming protuberances on said surface of the deflection edge.

According to one example, said convex portions have the shape of a sphere portion.

This presentation also relates to a nacelle comprising a thrust reverser according to one of the preceding claims.

The present presentation further relates to a propulsion assembly for an aircraft, comprising a nacelle as defined above and a propulsion system, in particular a turbomachine such as a turbojet, or an electric or hybrid propulsion device, and also an aircraft comprising such propulsion assembly.

The invention and its advantages will be better understood on reading the detailed description given below of different embodiments of the invention given by way of non-limiting examples.

There is a side view of an example aircraft.

There represents a side view of an example of a thrust reverser assembly, in which the nacelle is not shown.

There represents a side view of another example of a thrust reverser assembly, in which the nacelle is not shown.

There represents a side view of another example of a thrust reverser assembly, in which the nacelle is not shown.

There is a sectional view along an axial plane representing a first example of this thrust reverser assembly.

There is a sectional view along an axial plane representing a second example of this thrust reverser assembly.

There presents a sectional view of another embodiment of a thrust reverser.

There schematically illustrates the separation of the air flow.

There thus schematizes an effect of the invention.

There is a perspective representation of an embodiment.

There schematically represents another embodiment.

There schematically represents another embodiment.

There schematically represents another embodiment.

There schematically represents another embodiment.

There schematically represents another embodiment.

There schematically represents another embodiment.

In all of the figures, common elements are identified by identical numerical references.

In this presentation, the terms “axial”, “radial”, “tangential”, “circumferential”, “interior”, “exterior” and their derivatives are defined in relation to the main axis of the turbomachine; “axial plane” means a plane passing through the main axis of the turbomachine and “radial plane” means a plane perpendicular to this main axis; the terms “upstream”, “downstream”, “front” and “rear” are defined in relation to the circulation of air in the turbomachine; the angular positions are considered in a cylindrical reference frame having as its axis the main axis of the turbomachine, the angles being counted positively in the counterclockwise direction seen from the downstream side of the turbomachine; finally, the terms “height” and “width” are defined in the local axial plane in the axial and radial directions, respectively; and unless otherwise stated, two elements will be considered "near" or "nearby" (respectively "distant" or "distant") if their angular positions are close (respectively "distant") in the cylindrical reference frame, preferably less than 30 °, preferably still less than 10°.

There is a schematic side view of an example of aircraft 1, comprising a fuselage 2 from which a wing 4 extends laterally via roots 3. The aircraft 1 has a tailplane at the rear, comprising a fin 5 on which a horizontal plane 6 is fixed. A propulsion system 10, in particular a turbomachine such as a turbojet, or an electric or hybrid propulsion device is mounted on each side of the fuselage 2, at the rear of it , via a reactor mast.

The example of aircraft 1 of the is only illustrative, and any other arrangement of the structural elements is possible according to the general knowledge of those skilled in the art. In particular, the propulsion systems 10 are not limited to two, and can be arranged under the wing 4 rather than at the rear of the fuselage 2.

Figures 2, 3 and 4 show different examples of propulsion system 10 having a main axis A shown in phantom. The flow of air (or air flow) in the propulsion system 10 is shown in the diagrams from left to right. The inlet of the propulsion system 10 has a fan 11 driving the air inside the propulsion system 10. The air flow is then divided into a primary air flow I and a secondary air flow II. The primary air flow I is compressed successively by a low pressure compressor and a high pressure compressor, driven respectively by a low pressure turbine and a high pressure turbine. Between the compressors and the turbines is a combustion chamber receiving the air compressed by the compressors and into which the fuel is injected in order to carry out combustion. The combustion gases leave the combustion chamber by driving the turbines and join at the outlet the secondary air flow II, the latter traveling through the propulsion system 10 on the radial periphery of the primary air flow I. A mixer is typically positioned in outlet of the turbines in order to promote the mixing of the two gas flows I, II and thus optimize the total thrust of the gases leaving through the nozzle 18, at the distal end of the propulsion system 10.

A rear part of the propulsion system 10 has a thrust reverser assembly 20, located on a circumference of the propulsion system 10. Figures 2, 3 and 4 present different thrust reverser structures which are described below.

In the example illustrated on the , we show a side view of a propulsion system 10 with a thrust reverser assembly 20. The thrust reverser 20 comprises a fixed part 29, comprising the fixed parts in the engine reference frame, and a movable part 39, in translation relative to the fixed part 29. The fixed part 29 comprises at least one reverser grid 23, extending over a circumferential contour of the propulsion system 10 and positioned in a counter-thrust opening provided in the fixed part 29. The mobile part 39 is movable between a closed state and an open state. In the closed state, the mobile part closes the counter-thrust opening and therefore also closes the inverter grille 23, so that the air flow passes through the nacelle. In the open state, the mobile part 39 closes all or part of the secondary air flow II in the nacelle, and directs it towards the counter-thrust opening and therefore towards the inverter grilles 23, the latter being shaped so as to direct the air flow upstream and thus generate a thrust reversal. Such a thrust reverser 20 is commonly referred to as a gate reverser. There is a detailed sectional view along an axial plane representing an example of such a thrust reverser 20 with grids, in which the movable part 39 is actuated by a drive device 33 so as to at least partially close the passage of air through the propulsion system, which thus redirects all or part of the air flow towards the grilles 23 to achieve the thrust reversal function.

There represents a side view of another example of a thrust reverser assembly 20 which is commonly referred to as a gated thrust reverser.

The thrust reverser 20 as presented comprises a fixed part 29, comprising the fixed parts in the frame of reference of the engine, and a movable part 39. In such a thrust reverser, the movable part 39 defines one or more pivoting doors relative to to the fixed part 29, typically 2 or 4 doors, typically mobile in rotation in the plane perpendicular to the motor axis. The doors 39 can pivot under the action of the cylinder 33 between a closed configuration in which the doors 39 come as an extension of the fixed part 29, and an open configuration as shown in the , in which the air passage within the nacelle is at least partially closed, so that the air flow symbolized by an arrow is at least partially redirected by the doors 39 towards a radial opening which has been released due to of the pivoting of the doors 39. In the case of a door reverser, this radial opening is typically not provided with a grille. The orientation of the doors 39 and, where applicable, their geometry will make it possible to redirect all or part of the flow upstream, and to generate a thrust reversal.

A shroud 25, at the rear of the thrust reverser 20, is fixed and coaxial with the fixed part 29 upstream of the reverser. There presents a detailed sectional view of such an example of a gated thrust reverser.

There represents a side view of another example of a thrust reverser assembly 20, which is usually referred to as a Target type thrust reverser.

The thrust reverser 20 comprises a fixed part 29, comprising the fixed parts in the engine reference frame, and a mobile part 39. This mobile part 39 comprises one or more mobile elements which rotate in the plane perpendicular to the engine axis, and which at least partially block the air flow passing through the nacelle in order to redirect it as in the case of a thrust reverser with doors as described with reference to the . Unlike the example described in the , the thrust reverser 20 presented on the does not include a shroud downstream of the thrust reverser 20. The counter-thrust opening is here defined between the mobile elements and the fixed part 29.

We understand that one problem is to direct the air flow towards the counter-thrust opening or towards the grilles depending on the type of thrust reverser.

For this purpose, the fixed part 29 of the thrust reverser 20 has a deflection edge 40. This deflection edge forms the portion of the fixed part 29 immediately upstream of the counter-thrust opening or the grilles.

The flow of air along this deflection edge depends on several characteristics.

A phenomenon of separation of the air flow relative to the deflection edge is observed, which results from a known phenomenon of separation of the boundary layer of the air flow as shown schematically on the , which illustrates the separation of the boundary layer from the air flow for a gate thrust reverser 20, it being understood that this phenomenon is also observed for a gate thrust reverser. In this figure, the air flow is represented by an arrow F. We see in this figure that the air flow gradually deviates from the surface of the deflection edge 40 due to a recirculation of the air symbolized by the arrow Rc.

Indeed, taking into account the conditions of use of a propulsion assembly, and in particular the air flow speed, such a separation phenomenon tends to occur as soon as the geometry of the deflection edge is not not suitable. The laminar flow along the deflection edge 40 in fact causes the air to move at too high a speed to follow the profile of the deflection edge 40, which results in the separation of the boundary layer. A low pressure recirculation zone is thus formed between the boundary layer thus detached and the deflection edge 40, this recirculation zone being in fact non-functional.

The separation of the boundary layer will reduce the flow of air passing through the grilles 23 or the counter-thrust opening of the thrust reverser 20 due to low pressure recirculation zones, which thus reduces the flow of air. air passing through the thrust reverser 20, and which therefore reduces the performance of the thrust reverser 20.

A conventional solution consists of modifying the dimensions of the deflection edge 40, to increase its elongation, that is to say its dimension in the axial direction, so that the evolution of the deflection edge 40 is more progressive and less abrupt. However, such an increase in the elongation of the deflection edge 40 increases the mass and bulk of the assembly, which is detrimental for a propulsion assembly.

The present invention thus proposes a solution making it possible to minimize the separation of the air flow while minimizing the bulk and mass of the deflection edge 40 and therefore more generally of the thrust reverser 20.

There thus schematizes an effect of the invention.

This figure shows a deflection edge 40 modified according to the invention, having a surface configured so as to generate turbulence in the flow of fluid along the deflection edge.

Such a structure of the surface of the deflection edge 40 will disrupt the flow of fluid, and thus prevent the separation of the boundary layer from the deflection edge 40. The flow of fluid will thus follow the contour of the deflection edge 40 this which will reduce or cancel the separation of the boundary layer. Thus, the adhesion of the air flow on the deflection edge 40 will increase, which maximizes the air flow passing through the grilles 23 or the counter-thrust opening of the thrust reverser 20, and which maximizes thus the effect of the thrust reverser 20.

The invention as proposed thus aims to modify the surface of the deflection edge 40 by introducing irregularities 50 so as to generate turbulence in the flow, and thus to optimize the air flow passing through the thrust reverser 20 avoiding or reducing airflow separation.

In the schematic example on the , the deflection edge 40 is provided with cavities or concavities arranged in the surface of the deflection edge which thus define such irregularities 50 coming to form vortices which disrupt the flow of fluid on the surface of the deflection edge 40 and which thus prevent the separation of the flow.

There is a perspective representation of such an embodiment, in which the irregularities 50 are cells or concave recesses are formed on the surface of the deflection edge 40. These cells or recesses typically have the shape of a portion of a sphere, and are for example regularly distributed over all or part of the surface of the deflection edge 40.

There schematically represents another embodiment, in which the surface of the deflection edge 40 has irregularities 50 which are convex cells, forming protrusions from the surface of the deflection edge 40. These protuberances typically have the shape of a portion of a sphere, and are for example regularly distributed over all or part of the surface of the deflection edge 40.

There schematically represents another embodiment, in which the surface of the deflection edge 40 has an irregularity 50 formed by a concave groove formed in the deflection edge 40, the groove typically extending in the radial direction relative to an axis of rotation of the turbomachine or nacelle considered, that is to say perpendicular to the flow direction of the flow F. The throat is here represented with a rectangular section. It is understood that one or more grooves can be formed, extending radially or not, with a rectangular or other section.

There schematically represents another embodiment, in which the surface of the deflection edge 40 has irregularities 50 formed by several concave grooves formed in the deflection edge 40. In the example illustrated, the concave grooves have a rectangular section, and are formed so as to extend in the direction of the flow F. It is understood that the number and shape of the grooves thus formed can vary.

There schematically represents another exemplary embodiment, in which the irregularities 50 are formed by a plurality of cracks on the surface of the deflection edge 40. In the example illustrated, a plurality of cracks parallel to each other are formed, which are extend perpendicularly to the flow direction of the flow F from the external surface of the deflection edge 40. For example, several cracks can be made next to each other, each having a width of between 1 mm and 10 mm.

There schematically represents another embodiment in which the surface of the deflection edge 40 is modified so as to define a portion having increased roughness which thus define irregularities 50.

By increased roughness, we mean here that the surface condition of a portion is degraded locally, that is to say that a portion of the surface of the deflection edge 40 has a surface condition which is produced in such a manner. to be degraded compared to the surface condition of the rest of the deflection edge 40, for example greater roughness. For example, the portion considered may have a roughness coefficient Ra of between 10 µm to 200 µm, or between 50 µm and 200 µm.

There schematically represents another embodiment in which the surface of the deflection edge 40 comprises irregularities 50 which are formed by vortex generators.

The vortex generators as presented are formed by thin blades projecting from the surface of the deflection edge 40. They are typically installed in pairs, each of the vortex generators then being inclined relative to the direction of flow of the fluid so as to to define a V-shaped configuration.

These different embodiments thus present different alternatives for disrupting the flow of air in contact with the deflection edge 40, and thus generating turbulence such as vortices to prevent, minimize or reduce the effect of detachment of the layer limit along the deflection edge 40, and thus maximize the air flow passing through the grilles or the counter-thrust opening of the thrust reverser 20, that is to say the air flow contributing to reversal of thrust, without requiring an increase in the volume of the deflection edge 40. More generally, the invention aims to create one or more irregularities so as to generate a depression via a non-smooth or non-regular surface of the deflection edge 40 , this depression thus disrupting the flow of the air flow to avoid or reduce the phenomenon of separation.

Such a modification of the deflection edge 40 finds a particular application in the context of a nacelle, or more precisely of a propulsion assembly which can in particular equip an aircraft.

Although the present invention has been described with reference to specific embodiments, it is evident that modifications and changes can be made to these examples without departing from the general scope of the invention as defined by the claims. In particular, individual features of the different illustrated/mentioned embodiments can be combined in additional embodiments. Therefore, the description and drawings should be considered in an illustrative rather than a restrictive sense.

Claims (10)

Thrust reverser (20) for a propulsion system (10), having a main axis (A), comprising a fixed part (29), adapted to be mounted on a propulsion system (10) so as to encircle the latter, a movable part (39) attached in a sealed manner against the fixed part (29) by blocking a counter-thrust opening in the closed state, while the counter-thrust opening is released in the deployed state, and a device for actuation (38), adapted to move the movable part (39) between the closed state and the deployed state, the fixed part comprising a deflection edge (40) adapted to direct a flow of air from the interior of the 'thrust reverser towards the outside through the counter-thrust opening,
characterized in that said deflection edge (40) has a surface (50) configured so as to generate turbulence in the flow of the fluid along the deflection edge (40) and minimize separation of the fluid along said edge of deviation (40). A thrust reverser (20) according to claim 1, wherein said deflection edge surface (40) has concave recesses formed in said deflection edge surface (40). Thrust reverser (20) according to claim 2, wherein said recesses are concave cells having a portion-of-sphere surface. Thrust reverser (20) according to claim 2, wherein said recesses are grooves provided in the surface of the deflection edge (40), said grooves extending parallel or perpendicular to an air flow direction on the deflection edge (40). Thrust reverser (20) according to claim 1, wherein said surface of the deflection edge (40) has a portion having locally increased roughness. A thrust reverser (20) according to claim 1, wherein said surface of the deflection edge (40) has vortex generators. Thrust reverser (20) according to claim 1, wherein said surface of the deflection edge (40) has convex portions forming protrusions on said surface of the deflection edge (40). Thrust reverser (20) according to claim 7, wherein said convex portions have the shape of a sphere portion. Nacelle comprising a thrust reverser (20) according to one of the preceding claims. Propulsion assembly for an aircraft, comprising a nacelle according to claim 9 and a propulsion system.